Let's play... Name that Electrical Doohickie!

Yeah, I know, I need to brush up on my technical terms. lol

So as some of you may (or may not) know, my wagon is on the fritz. '92 Caprice with an L05. So anyway, it's running really... I don't know how to explain it. Sluggish, odd... not right. Dad says it sounds like a misfire. I need to look more into that but before I go out shelling out monies for plugs and wires and all that other stuff... I have something else I noticed.

First: What is this electrical doohickie and where does it belong?

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Second: I seem to have a vacuum line that was loose (and then accidentally broken by me, oops!) It's right next to the valve cover and just under the airbox, and goes to a T-fitting. I capped it for now (since I broke it) but what would this go to as well? EGR maybe?

Thanks for playing!

That looks like one of the coolant temp sensors. And the Vac line you broke sounds like one to the EGR. I forgot to plug one of the EGR lines in and it caused a stalling issue.

Dad said coolant temp sensor too when he perused a Haynes manual at his job, but I just wanted to make sure.

So more to the point, where would that sensor plug in to?

Also do you think the missing EGR line would cause my hesitation and shakiness during driving? It doesn't stall, and it gets good fuel, so I'm getting frustrated here.

Yes it would. My issue was similar in that too much air was getting into the vac line and causing it to stall out. That green line looks like it plugs into the sensor, looks like this:

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Man if my whole issue is solved by just replacing a vacuum line I think I would jump for joy.

Stingroo wrote:

Man if my whole issue is solved by just replacing a vacuum line I think I would jump for joy.

At least you havent spent 4 hours, a tear down of the kick panel to check the ECU, and a trip to autozone to realize its a vac line you forgot to plug back in after you installed intake manifold gaskets.

Coolant temp sensor is by the thermostat housing.

Nope, cause I shop at Advance auto.

phastlt1 wrote:

Coolant temp sensor is by the thermostat housing.

There are two on the TBI's. besides the wire is long enough to stretch that far if its not plugged in.

Stingroo wrote:

Nope, cause I shop at Advance auto.

They suck here. Everytime I shop there there either out of stock on what their website says they have "in stock" the prices are wrong or the store is a mess. Hate Advance.

My dad works there, so I get 20% off whatever I buy. That's enough for me. Plus I can trust him to find the parts I ask for so it's worth it.

But some of the guys he works with are serious assholes, I will admit.

You have headers on your wagon?

Yes sir. They were installed before I bought it though.

I'm debating getting a pair of glasspack header mufflers for it in the winter. I know, I know, some people hate them. I love the sound though.

Cadet57 wrote:

phastlt1 wrote:

Coolant temp sensor is by the thermostat housing.

There are two on the TBI's. besides the wire is long enough to stretch that far if its not plugged in.

.

That is the only coolant temp sensor...the one on the pass side of the engine is the engine temp sending unit...two entirely different animals.

phastlt1 wrote:

Cadet57 wrote:

phastlt1 wrote:

Coolant temp sensor is by the thermostat housing.

There are two on the TBI's. besides the wire is long enough to stretch that far if its not plugged in.

.

That is the only coolant temp sensor...the one on the pass side of the engine is the engine temp sending unit...two entirely different animals.

Thats what I ment. I just called them both "sensors". That looks like the sending unit plug. I just did both on my car. And my cluster still doesnt work, but thats another thread....

EGR would cause an off idle/low throttle stumble, too. Which would probably appear as a shudder at the road speeds you are experiencing. Fix the vacuum line, plug in the CTS, and I bet your problem goes away.

But how does the vacuum line connect? I'll take my airbox back off and take a pic so I can show you guys.

Here's a video to show you the weird sound. Excuse the crappy sound quality, it's a cell phone, but you might still be able to identify the weirdness:

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Also, (shown in the video) there's the green plug that's unhooked, but there's another plug that's plugged in where I assume this green one goes?

Here's a pic of that too:

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As far as the vacuum line, let me ask you this....does your hvac system work on all settings? It may be the vacuum for it? Have you checked the temp sending unit on the pass side of the block to see if the plug fits there? Have you checked the map sensor to see if it's plugged in?

Okay whoa, slow down there. lol

My car knowledge is surprisingly (and sadly) limited.

1. Yes, my AC and heat both work on all settings (and it's ridiculously COLD which I love).
2. What's a MAP sensor and where is it?
3. Uhhh... no, I didn't check that. I shall do this now.

I believe the map sensor is on the pass side upper firewall....I'm about 250 miles away from my car right now, so I dont have a refference to verify that.

Ok, since I was challenged elsewhere, I'm back to help here. Sting, you know I have a busy day tomorrow When I have a moment, I will pop the hood on my 92 RMW and see what I can see for you.

Awesome.

The connector in the first pic is for the air injection pump. You obviously do not have one because of the headers. I tie-wrapped mine to the wire that goes to the temp sensor so that it does not flop arround.

Thank you! Now I feel good about that part.

So any idea about the vac line? Other possibilities?

It is dark here right now, so I can't check it for you tonight. I think it does go to the EGR solenoid. There is a manifold of vacuum lines on that side of the engine. It includes the T and goes to what used to be the air injection valve, and EGR soleniod. The plastic lines get really brittle (I guess you knew that part). Hook it up the best you can, You probably do not need the T any more. You may be able to just run a new line to the EGR solenoid. The OEM is formed hard plastic line. I have broken mine and used a piece of straight connecter tubing to patch it up. A replacement part from the JY would have the air injection portion on it, and you would have to cap it.

I'll wait until tomorrow, it's dark here as well.

I capped the part of the T the loose (and then subsequently broken) line came off of.

My thought is, if by chance these two lines have been loose since I bought the car (very possible) maybe the EGR is just dirty and needs to be taken off and cleaned. Does this sound probable?

Having the line to the EGR blocked/open to the atmosphere would only cause the EGR to be inop. All you have to do is reconnect it, and it should function normally. It does not do much except at over 50 MPH. If you have a line between the port on the TBI, and the EGR solenoid it should work properly. If you pull the EGR, you will probably need a new gasket, they usually self destruct when you pull the EGR valve.

Okay, so if the EGR doesn't really do much until you're at highway speeds... I have another thing to ponder for you:

What about my muffler? The vibration exists at all speeds and RPM, and the car actually does sound different. I don't know how old it is, because I haven't done anything to the car since I've owned it.

Thoughts?

The vac line may be for the MAF. Like I said, mine was unplugged and would stall at idle/ any speed above 20-30. What side of the car is the vac line on?

It's on the passenger side.

The car doesn't stall at all though. It's good to drive it just vibrates.

Stingroo wrote:

It's on the passenger side.

The car doesn't stall at all though. It's good to drive it just vibrates.

Hmm. Then maybe that vac line actually has nothing to do with the problem. Did you check tires for loose/ lost lugs or bubbles? U joint? Out of balance tire. Something tells me its not engine related.

I haven't checked the U-joints, no.

But I don't think it's tire or lug nut related, because it happens even when stopped at a light.

The vac line for the MAF comes off of the back of the TBI.

Does it vibrate at idle? If not, it is probably not the exhaust.

Does the vibration increase in frequency with speed, or just engine RPM? If just with speed, it could be a lost wheel weight or universal. If just with engine speed, then it could be a hole in the exhaust, maybe muffler, maybe not.

A bracket may have broken that holds the exhaust to the undercarriage. You are going to have to look under the car to confirm any of the exhaust possibilities.

It does vibrate at idle. It seems to increase (like, the car hesitates more) at speed.

Did you try cleaning the ground at the thermostat. Wait until the car cools, and remove the post and clean it as well as the lugs. It does not sound like that is your problem, but is a culprit in many strange symptoms.

You should make sure the vacuum line that is broken, is capped on the TBI side, so that you do not have a vacuum leak.

Hesitating at speed and vibrating are totally different animals. You might want to check your plug wires and plugs. A cheap fix might also be a distributor cap and rotor. Be careful, the distributors tend to get rusty, and then the rotors do not like to go back on and seat properly.

Since you have headers, you could have a broken/loose header bolt. Not likely, but something to check.

Another often overlooked troublemaker is the PCV valve. Another really cheap fix that should be replaced occaisionally anyway.

Still confused on this. Car's going up on the lift Sunday or Monday in my neighbor's garage to check some stuff (u-joint, muffler hole, etc. etc.)

I want my car fixed. lol