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 1991 OCC L03 Engine Pinging

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smparr

smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeMon Oct 21, 2019 11:38 am

I have a '91 OCC with the original L03 V8 with 116,000 miles. She has always pinged some but now it seems to be getting louder. I can hear it inside with the radio off. She usually pinged during acceleration and releasing the accelerator when accelerating from a stop or under heavy load/climbing. Lately she is pinging anytime you accelerate regardless of speed and briefly pinging when releasing the accelerator. A loud rattle like marbles in a can.
I bought Bertha last December and in January and February I installed new plugs and wires, coolant temp sensor, PCV, IAC, CAT, resonator, and exhaust piping. The previous owner had the distributor and cap/rotor replaced back in 2012. I recently changed the oil/filter and replaced the belt, air filter, and alternator but that's probably inconsequential.
I depressed the EGR at idle and the car stumbles as expected. I have cleaned the TBI with TB cleaner and cleaned out the air cleaner of oily residue. I have also run Techron Complete Fuel System Cleaner through her and she has been expelling sooty exhaust water on the ground behind it. No blue smoke. She does have a few oil leaks but nothing severe. I've checked many times for leaky vacuum hoses but have not found any. It doesn't hesitate not stall but it idles at 950 RPM in park and 700 RPM in drive. I can't find anything that says what those numbers should be in the FSM.
Since January I had been using 89 octane to lessen the pinging. About 4 months ago I started using 92 octane to combat the pinging but she still does it. It seemed less at first but now no difference between 89 and 92. I haven't tried going back to 87, kind of afraid.
No SES light and no codes in the system.
Probably not related but she has always had a rattle underneath the car that I thought was the tranny. After a fluid/filter change and adding the shudder fix she has shifted without fail for the last seven 10 months but the rattle is always there when she is in gear. Almost sounds like an old speedo cable when it has lost all lubrication.

I remember my Dad's '83 OCC with the 307 was always pingy but I've had a '93 Caprice with the L03 before and don't remember it being this pingy.

I have reviewed the FSM but before I start replacing expensive parts in the shop manual I was just hoping to see if anyone else had experienced these same issues. There was only one other post I could search up about pingy L03s.

Any thoughts? Thank you in advance.
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Fred Kiehl

Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeMon Oct 21, 2019 12:28 pm

Check your timing.

Check the PCV passage in the TBI. The "new" ignition module in the distributor may have failed. If the unit was made in China, I would suspect it. There is a spark control module on the bracket with the fuel pump relay, and the MAP sensor on the firewall. Check the ground at the thermostat housing, it is the ground for the computer and O2 sensor.

There is not much else you can change/replace than you have already done.

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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeMon Oct 21, 2019 12:42 pm

The ignition module is on the back of the distributor right? Not the coil. Is there another name for the spark control module? I can't find it listed on a parts list. The rest I'm good with, know where they are. Thanks Fred.
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occ6.6



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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeMon Oct 21, 2019 12:49 pm

you said the egr valve causes the engine to stumble when you manually move it.but is the egr solonoid working/have vacuum going to it? a non functioing egr will cause pinging,tee in a vac gauge in the line between vlv & sol use a hose long enough to hook gauge to your wiper blade & go for a drive if gauge is moving you have vac going to valve.the egr valve could be faulty you can check it by using a vac pump on it to see if engine stumbles at idle. its common for the plastic lines to break & not allow vacuum to go where it should
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeMon Oct 21, 2019 12:50 pm

The spark control module is a flat module on the passenger's side behind the AC accumulator on the relay bracket. I do not know if they are available.

The ignition module is under the distributor cap. Use white heat sink paste when installing it, not dielectric grease. Check the wiring for missing insulation while you are in that area.

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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeMon Oct 21, 2019 1:30 pm

Got it, thanks!
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeSun Mar 29, 2020 10:52 pm

Sorry, it has taken so long to get back but now that I have all the time in the world to poke at it. I took it for a drive and the vacuum did change every time I placed a load on the engine. I followed the OEM Service manual and tested it with a vacuum pump at idle and it did nothing as expected since it is a positive backpressure valve. When I jumpered it directly from the TBI it was slow to react to high RPMs. If my daughter brought it to 2000 RPM slow I could not feel it move but if she gunned it up I could. the manual doesn't specify RPM raise speed. The passages were clear and I couldn't find any cracked vacuum lines. It always pings under load nut more so when it is warmer. I did find an original ESC module and it is on its way. I'm still bidding on an original EGR valve. Thanks for the help.
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeSun Mar 29, 2020 11:23 pm

Did you check your knock sensor? It is on the right side of the block. It goes through to the water jacket, and could be rusty, and not grounding properly.

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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeMon Mar 30, 2020 2:28 am

No actually hadn't. I forgot about it. I hope it's not that, I really don't want to drain the cooling system.
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeMon Mar 30, 2020 9:10 am

If you are slick, you can swap them and only loose an ounce or so. If you keep the system sealed otherwise, the vacuum produced will keep the loss of coolant to a minimum.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeFri Apr 03, 2020 3:05 pm

Didn't know that. If it ends up being that that would be way easier than draining it. Hopefully it would come out easy enough.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeSat Apr 04, 2020 5:18 pm

You probably need a negative backpressure valve. I have been dealing with this issue for six years now myself(getting around the issue with premium fuel)

I have just today, with some sleuthin, discovered that the EGR that every single auto parts store will try and sell you is a positive valve. I have bought many EGR hoping for a better outcome each time but none of them work any better than the last.
I have found, walking through the parts list, the EGV385 valve. It is a negative BP valve and has compatibility with a 92 caprice. I am taking a chance ordering it but maybe, just maybe this time it will work properly.
So use me as a guinea pig. The part is due to arrive April 14th, and I will tell you if it works after I install it.

Do not waste your money or time doing anything else. I have already replaced literally every sensor and doodad on my motor. Giving any of my past and current valves vacuum at idle produced no movement, just like you.
But since the L03 OCC lives life below 2500 rpm, that may not be enough to allow a Pos BP EGR to open.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed Apr 08, 2020 12:21 am

That is interesting. I just replaced the EGR with an original positive BP valve. I also replaced the MAP sensor, ESC module, and all of the vacuum lines except for the HVAC system (I don't want to mess with that spaghetti since it is working.) with standard vacuum hose. She does run smoother but is still pinging under load, especially around 1500 RPM. On the plus side I found the source of my small coolant leak. It is not the heater core tube like I thought, it is the heater bypass valve leaking around the top cap! Not even a loose hose. I'll end up replacing that soon, but it is such a slow leak I'm not that worried about it. I haven't bought a knock sensor yet, so I'll wait and see how you fair. For now it's not running terrible.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed Apr 08, 2020 5:07 am

That sounds identical to my issue. 1500 rpm is where the ping begins.
I just had to redo my heater core/hoses a couple weeks ago. Somehow my restrictor was in good condition and functional as well
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed Apr 08, 2020 9:22 am

Have either of you tried putting some anti-studder in the transmission. I had what I thought was pinging at light throttle, and it turned out to be the trans chattering.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 1:19 am

I have the shudder fix in my tranny along with fresh fluid and have not had any shuddering since last January. I will say this is smoothest she has run in the two years I've had her except for the light pinging. Just like a quiet rattle when accelerating around 1500 RPMs. The AC in mine doesn't work, only the heat and defrost. Last owner said it leaked Freon since like 2003 and never fixed it because R12 was expensive. I planned on converting it but I don't know if the compressor works because the safety switch for low Freon has it cut out, but even still when the climate control is on it does seem to increase the ping some.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 1:20 am

Sorry, forgot, before I put the shudder-fix and fresh tranny fluid in when I first bought it the tranny shuddered horribly when shifting out of overdrive. Basically slammed into the next gear.
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 8:21 am

The shudder occurs at light throttle when maintaining about 50 mph in OD. Mine did that, and soon after I added the shudder fix the trans gave up.

You can bypass the low pressure switch to check for compressor operation, just like when you want to fill the system.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 1:45 pm

My ping can be manipulated by changing fuel types and changing the timing. If I retard it enough, the ping goes away but then its slower than a turtle in a wheelchair.
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 7:17 pm

It could be that there is a hefty buildup in the cylinder heads, increasing compression ratio.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 8:01 pm

That technically should be long gone. I set the timing to factory a couple years back. Been using the premium ever since
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 8:12 pm

Premium will not make any noticeable difference in cleaning, or performance, unless you have a problem with timing, or mixture.

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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 8:34 pm

The latter is what I know I have a problem with. I know my carbon buildup is better than it was since my timing is now correct. I ran it retarded for quite a while with 87. That will increase carbon buildup.

But my engine pinged on the first drive when it was brand new.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 09, 2020 10:15 pm

How do you bypass the low pressure switch for the AC Compressor?  The transmission works flawlessly now and I do not have loss of performance like you guys are talking about. She accelerates and runs as quick as I would expect.  She idles at 1000RPM in park and 800RPM in drive.  Nothing in the service manual says what is normal, just says the computer will set it.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeFri Apr 10, 2020 7:13 am

Don't get me wrong, the performance is great, its just that damn ping and an inability to use regular gas that has me nonplussed.
Related....
The low pressure switch can be jumped out with a single wire across the plug. However I wouldn't expect any bit of your A/C system to be capable of holding pressure after 30 years. Mine lost its ability to do that years ago. I ended up replacing all the rubber hose and the compressor itself since they leak around the edges. Also another dryer and orifice tube. So while you can test the compressor, unless its newer and the rest of the system is too, it'll probably never pass a pulldown test.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeFri Apr 10, 2020 8:02 am

Whoohoo. I got the valve in my grubby little hands. Even though it says "standard motor parts" on it, the valve has "GM Rochester" stamped into it. So somehow I got a genuine GM valve. Vacuum holds on this one, it actually OPENS THE DIAPHRAGM! That has never happened to me.
Its not on the car yet. That will happen this afternoon for I am at work.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeFri Apr 10, 2020 2:58 pm

I kinda figured that about the AC system but I thought it was worth a shot. I have all new seals, orifice, cycle switch, and desiccant tower. All that needed to be changed for R-134 conversion anyway. I didn't buy a compressor in hopes it might work. They aren't cheap. Did you replace the evaporator core or the condenser? I'm trying to avoid those headaches also. It's only hot here in Washington for about a month and even then it isn't bad so the AC isn't that big of a deal. The heat/defogger works and that is more important. I'm originally from the southeast so this is nothing here.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeFri Apr 10, 2020 4:03 pm

The dessicant. A new compressor was 163 bux on rock auto, a genuine Delco, so I got it all.

I have the new EGR installed. Its funny. It does better at some rpm's but way worse in others. So I guess the old EGR was doing "something" right.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeSat Apr 11, 2020 12:35 am

I read somewhere that the negative backpressure valves are for earlier models and require a different ECM to work properly.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeSat Apr 11, 2020 8:09 am

I hadn't heard that one. I read that they need a looser exhaust to work properly. Once activated they are all supposedly self regulating. Pos wont open until there is enough backpressure, negs don't close until there is enough negative backpressure.
If my car is any example, then I don't have a restrictive enough exhaust, or in the case of the neg valve, its too restrictive.

What is confusing that the service manual says the cars may use either. I think GM was just doing some lazy copypasta as I have not come across the situation of an OCC having a Neg. EGR.
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MildBill



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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeSat Apr 11, 2020 7:16 pm

Remove you'r cat converter !
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeSat Apr 11, 2020 8:12 pm

She's long gone, Mr.Bill. not by choice, mind you.
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Swaggerwagon

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeSun Apr 12, 2020 5:12 pm

Did the OP get a chance to verify ign timing yet? Fred suggested it back in October.
Might be worth doing, if only to rule it out
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeTue Apr 14, 2020 1:28 am

I'll try this weekend. Gotta find my timing light. I'm replacing the O2 Sensor tomorrow. I'm still getting the fireworks smell with the new cat after a year.
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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed Apr 22, 2020 3:43 am

Did not get the O2 Sensor out. Welded into the exhaust manifold. Wouldn't budge after a week of heat and penetrating oil. I stopped before it broke since it isn't throwing any codes. I'd rather wait and let a shop with extra tools get it out before I break it off. I cleaned a bunch of oil and gunk off of the Knock Sensor but didn't notice a difference in the pinging. I started working again and I've been doing some Comfortron troubleshooting on my '70 98 so I have not gotten to checking the timing but I did get the window sliders fixed on the CC's passenger rear window. Now it doesn't fall in the door anymore. Waiting on a new motor to show up for the other side. It'll be here Friday. With my kids home from school I haven't needed to drive the wagon, so it's just sitting waiting for me to have time work on it.
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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed Apr 29, 2020 3:23 am

Is 0 TDC the line next to the 0 or is it the actual divot pointing at the 0 on the timing mark?  I can't tell if I'm at 0 or 2 degrees advanced.  Would a 2 degree advance cause pinging under load? On a different note, I received the new window motor but the screws it came with don't fit under the regulator gear. Now I'm waiting for rivets to show up Friday to put the driver's side rear door back together.
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OurCircuitMessSlobmodel

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu Apr 30, 2020 8:14 pm

0 degrees is right on top in the center of the biggest divot. If its off 2 degrees in the wrong direction, it won't help the ping situation but I wouldnt think its the entire reason its happening.

I bit the bullet and ordered a new ESC module, so far its running about the same as it was. Only things left I havent changed are the MAP sensor and the fuel injectors. I hate running out of ideas, and options.
One question I may have asked before, is it actually possible to run 87 in an L03?
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeFri May 01, 2020 3:29 pm

Yes, I had a 1993 Caprice wagon with an L03 10 years ago that ran on 87 all the time. My '96 Roadie also ran well on 87. I don't remember either pinging. My Dad's '83 Olds CC with the 4bbl 307 Oldsmobile V8 pinged all the time. I just assumed they always did since he had been an Olds mechanic since 1948 and even his car did it. But I just don't remember my '93 doing it.
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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeTue May 05, 2020 11:06 am

OurCircuitMessSlobmodel, I've replaced my ESC module, MAP sensor, EGR valve, plugs and wires, PCV, IAC, Cat, muffler and piping, reinstalled the resonator, cleaned the TBI, used 89 and 92 octane, and run several complete fuel system cleaners through it and it still pings around 1500 RPM and under load. I tried to replace the O2 sensor but couldn't budge it (need to bring it to the shop I use when I can't get stuff). I bought an original TPS, Knock sensor, and Intake Air Charge sensor but they haven't showed up yet. It has never thrown any codes but sometime smells like fireworks (I think that may have something to do with the O2 sensor). I now know my timing is advanced 2 degrees which I plan on fixing today. I don't know what else to do. I have no performance loss, so I may just give up.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeTue May 05, 2020 11:26 am

Fixed my driver rear window motor. Had to shave a screw as none of the rivets I got fit right. Probably some special GM rivet to pass under the regulator arm. I can drive it again so I can start checking stuff again. Still running okay this morning but pinging as usual.
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smparr

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeTue May 12, 2020 4:22 pm

So somebody monkey-fisted the distributor hold down bolt so I have to use some penetrating oil before I can retard the timing back to zero. Nothing can ever be easy.
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed May 13, 2020 8:13 am

A 2 degree advance should not make it knock. Did you try putting some anti-shudder in the transmission? Mine sounded like it was knocking, and it was the trans. If that fixes it, you may be looking at a trans rebuild in the not too distant future.
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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed May 20, 2020 1:38 am

I did a long time ago when the transmission was violently shuddering. I haven't tried that again.
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Fred Kiehl

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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed May 20, 2020 7:04 am

There is also a spark control module on the relay mount at the right rear of the engine compartment that no one ever thinks about.
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smparr

smparr

Posts : 112
Join date : 2018-12-18
Location : Bremerton, Washington

1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu May 21, 2020 2:29 am

I replaced that one too.  Funny thing I found, in our 1990 CC's owner's manual for the 307 Olds it actually says pinging under load is normal and to disregard it unless it becomes a loud knocking.  Thought that was interesting to find in the owner's manual.  I didn't see it anywhere in the '91 manual about the SBC 305.


Last edited by smparr on Thu May 21, 2020 2:35 am; edited 1 time in total
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smparr

smparr

Posts : 112
Join date : 2018-12-18
Location : Bremerton, Washington

1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu May 21, 2020 2:34 am

I do have a new TPS, Air Intake Charge Sensor, Knock Sensor, and O2 Sensor to install. I just haven't had time. The car isn't running terrible, it's just an annoying ping so I haven't been as focused on it. Right now I have a tune-up to do on my '70 Olds and we just bought my son a 1990 CC that needs some minor stuff, and I'm also doing yard upgrades so I've been distracted.
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smparr

smparr

Posts : 112
Join date : 2018-12-18
Location : Bremerton, Washington

1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeThu May 21, 2020 3:46 pm

I looked today, turns out the same statement about pinging is in the 1991 CC's owner's manual. Pinging under load and acceleration is normal and only to seek assistance if it is a loud knocking. It's on the fuel page under service and maintenance. I've been chasing my tail, but at least now I have all new, all GM sensors.
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OurCircuitMessSlobmodel

OurCircuitMessSlobmodel

Posts : 58
Join date : 2017-12-25

1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeTue Jun 02, 2020 12:43 pm

I am about to pull my computer out to look at the chip in it. The previous owner's son was a gearhead and the computer says its remanufactured. Maybe he stuck a different ROM in there.
After I do that I will probably replace the MAP. I also have a small exhaust leak on the drivers side.

Funny thing is with mine it doesn't ping under load or during acceleration, it really only pings when at cruising speed between 50-70mph. I usually don't drive it faster than that so cant say if it pings above that.

It'll do 35-45mph turning 1100-1200 rpm without pinging at all. Just the rpm band betwixt 1300-2000 it shows up under light throttle.

I was hoping you could find the problem but don't worry I haven't given up yet.
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smparr

smparr

Posts : 112
Join date : 2018-12-18
Location : Bremerton, Washington

1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed Jun 10, 2020 4:07 pm

The firework smell seems to be getting worse especially at idle. Everything I've read points to a rich fuel mixture and the O2 Sensor, but the ECM isn't throwing any codes ever. The light pinging is still there but seems to be a louder almost diesel sounding rattle sometimes. I'm taking it in next week to have the Knock Sensor and O2 Sensor replaced. I gave up trying to get the O2 sensor out and I don't want to mess with a coolant mess in my garage. Flushing the 70's cooling system was enough fun a few weeks ago. Hopefully these fix something. All I have left that I can replace is the Intake Air Sensor, TPS, and EGR Solenoid after that.
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smparr

smparr

Posts : 112
Join date : 2018-12-18
Location : Bremerton, Washington

1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitimeWed Jun 10, 2020 4:21 pm

On a funny side note, the 307 in our '90 CC doesn't ping at all and runs great!
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1991 OCC L03 Engine Pinging Empty
PostSubject: Re: 1991 OCC L03 Engine Pinging   1991 OCC L03 Engine Pinging Icon_minitime

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