Help! LT1/4L60e stalling issue

Hey guys, need some help on this one....also, I'm not sure if this is engine or transmission, but I'm thinking transmission, so I posted it here.

Yesterday in traffic going to the mall for lunch with my girlfriend the car started to shake and then stalled out. I had been idling for a while.

The previous owner told me that it happened occasionally, but I've driven the car about 1000 miles and I had never had anything close to it happen.

Had to bail on the GF But fortunately she was very understanding.

Drove it home, it stalled a couple more times as I was slowing down while getting it home. One headlight was out and it was getting dark really fast due to oncoming rain so I couldn't let it sit for a few minutes and then restart (which is what the previous owner said fixed it), but I got it home and let it sit overnight.

Took it out for a test drive today, things were going smooth....ran great on the highway. Getting off the highway on a 40mph turn it stalled on me (I hadn't hit the gas for a while), which was scary as sh*t, but I pulled it over to the side of the road and got it restarted. Drove a bit, then died again. I nursed it to the restaraunt I wanted to go to and got it parked. About 30 minutes later I came back out and started it up. Let it idle for a while in neutral and it died again.

On advice from my father (who knows a bit about cars but lives out of state) I started dropping it in neutral and giving it a bit of gas like I would a manual and i was able to get it to a local AutoZone to get a headlight bulb. In that parking lot it died before i could move it, but I got it restarted and back home without incident.

After I parked it, I put the parking brake in and put it in neutral. After about 30 seconds it started idling rough but didn't die after a minute, so I put it in drive, died after 35 seconds.

Looked up the diagnostics mode for the HVAC controller this evening and took it to subway with the tacho on. After I parked, while in drive the RPM's started fluctuating up and down and the car started shaking a bit....same in neutral. The lowest I saw it get was 200 then it shot to 1200, then to 700 then 900, etc etc...so I've taken to driving it like a manual..put it in neutral when slowing down and give it a bit of gas keeping RPM's at around 8-900 then dropping it in drive when I gotta move. Seems to work.

Sorry for the long post.

Any ideas on this one? Various people have suggested the torque converter, vacuum system, lockup solenoid on the torque converter, and ignition module. The previous owner thought it was the lockup solenoid on the torque converter.

Sound engine related to me. When in gear there is a load on the engine even if its not moving. Start by checking your fuel pressure. Do you have a check engine light on?

My Caprice did something similar to me, but mine never actually stalled. The problem was the connector for the temp sensor on the water pump wasn't making a good connection. It caused the computer to think the temp was fluctuating wildly between the actual temp and something below zero. When that would happen it would change the fuel mixture to compensate which would almost cause a stall. Its a long shot, but wiggle that wire while its idling and see if anything happens.

How many miles on the car? It sounds fuel related to me. Possibly the fuel pump warning you it needs to be changed....

Dave had a good thought with the coolant temp sensor, too.

86k miles. I believe it's had the fuel pump replaced within the last 5k miles...will have to check service records to verify.

I really can't wrench on stuff yet so I dunno how to check the fuel pressure.

This evening the check engine light was on for the 6 minutes it took me to get to Subway tonight, turned off for the ride home.

Check engine light is a GOOD thing, it tells us where to start.

Go to any of the parts stores and they should be able to pull the codes for you.

was the weather wet or dry?

fuel pump in two thats a record,.

Nick

On advice from a friend who used to have a caprice with an LT1, I unplugged the mass air flow sensor. been idling in park for almost 8 minutes now, and it's cold out....no real dips, just dropped from 800 to 700rpm. Once steak and shake starts their 2-4am happy hour I might take it around the block and test it out.

Weather was humid, 40ish degrees.

okay....took 8 minutes to die this time with the MAF unplugged. Longer than before. Tried to start it-no dice. Plugged the MAF back in...

Still refusing to start. Turns over, but....no catch. I'll give it an hour and see what it does.

You can get the codes out of the climate control the same way you pulled up the tach. select 00 and hit the middle button and it will display the code number, press the middle button again to advance to the next code (if there is one). You'll probably have a code for the MAF now that is was unplugged. Still sounds fuel related. Go to autozone or advance and rent a fuel pressure gauge and hook it onto the schrader valve on the back of the fuel rail, towards the passenger side back of the intake. If you have a harbor freight near you you can buy one from there too.

Okay....now I guess it gets fun.

Tried to start it up this morning, it caught eventually, but was tryin to die no matter what gear I had it in, running really rough, I had to give it lots of gas, and it was really shaking and horrible sounding. Guess I should have recorded the noise, but oh well.

Got into the diagnostics, got error codes of 48 and 15, 15 is low coolant temp, 48 is misfire diagnosis...

Killed it, got out...smelled gas really bad. Looked under the tailpipes and saw two small puddles of liquid, which I smelled to be uncombusted gas.

FWIW it's 28 out with a 24 degree windchill (Farenheit).

Check and see what it thinks the coolant temp is at, sounds like the same thing I went through. Number 24 in the diagnostics will get you the reading off the temp sensor on the water pump in celcius. I think -40 C means the sensor isn't making a connection or is really bad. The misfire could be caused by it dumping too much gas because it thinks its extremely cold out. Next time it does start, mess with that wire on the sensor and see if anything changes.

best internet guess you have an ignition problem,.the water/gas mixture out of the tailpies is nothing to worry about,. if it really was raw fuel the exhaust would have blown off by now,.
check your coil wire both ends and see what it looks like,.it is located dr side head,. unplug it (the big spark plug wire) and then unplug it where it goes down between the waterpump and block to the distributor,.make sure your gas cap is just a tad loose,.and check your airfilter to make sure it isn't plugged,.
we'll see after that,.
when i,ve had bad fuel pumps, the car will start and idle on all 8 but flame out with any throttle movement,.then eventually won't start,. you may be heading there,.but lt1's are tricky sometimes,.
Nick

phantom 309 wrote:

but lt1's are tricky sometimes,.

That's why 4 out of 5 dentists recommend TBI in the event of a malfunctioning LT1.

Seriously though, could it be an Opti issue?

Olds Weighty Eight wrote:

phantom 309 wrote:

but lt1's are tricky sometimes,.

That's why 4 out of 5 dentists recommend TBI in the event of a malfunctioning LT1.

Seriously though, could it be an Opti issue?

It COULD be an opti, but the main code is the 15 (low coolant temp). That would cause the misfire as the 'puter thinks it's -40 outside and DUMPS fuel trying to compensate for the uber dense air..... that doesn't exist.

That explains the fuel out the pipes and the rough running and eventual stall as fuel does not burn well without air.


Also, David, the temp on the dash and the temp in the Climate Control come from 2 different places. The gauge on the dash comes from the passenger side head and the computer takes it's readings from the water pump. The pump has a sensor screwed into it. Wiggle that wire and check the connections. Bad wire/sensor would read REALLY cold.

Olds Weighty Eight wrote:

phantom 309 wrote:

but lt1's are tricky sometimes,.

That's why 4 out of 5 dentists recommend TBI in the event of a malfunctioning LT1.

TBI in the event of a malfunctioning LT1,. is like pulling all your good teeth out to go with dentures because of 1 cavity,.sure dentures might look good,. and are easily cleaned,but they are still fake ,and they won't have the bite of real teeth,.

seriously, it could be a lot of things,. it is always a crap shoot trying to do internet diagnosing,. I just do the basics,. i check for strong spark,.good wires etc,. he mentioned something about spinning out in the rain,.and if the opti harness or the plug wires coil wire etc,. are bad,. it'll run like crap,. sometimes folks think the motor is loading up on fuel and in reality it,s leaning itself out,.etc,. etc,. we have a driver with little automotive experience,.and oft times in such a case the description of the problem is different to what a more experienced driver might report,.and as we found out painfully with stingaroo and the distributor debacle,. things are not always as they seem, After an accident mebbe something is unplugged,. and it,s not noticed,. could be a bunch of things,.as i said when you are not standing there in person it's a crap shoot,.
sometimes you guess right and look like a hero,. next time you have a different idea, but someone elses guess is better etc,. etc,..
Je me souviens,. 18436........

Nick

y'all are onto something with the temp sensor...Popped the hood, found the sensor connector, looked plugged in but I couldn't reach it to mess with it (there were things in the way, obviously)

Just tried to start it up and it sounded like crap but I gave it some gas and as it started to smooth out I pulled up 24 in the diagnostics and the output was 00. I went back to the tach as it was smoothing out...seemed to run okay, so I closed the hood and it didn't die at that point without my foot on the gas, so I drove it around a couple blocks and watched the output of the temp sensor...at first it was up at 51, then it went back to 00, then it hovered around 21-22 for a while...then it dropped to 0, the car started to shake, and I gave it some gas and it started to even out when the sensor went back to 22. It didn't shoot up again but cut to 0 a couple times for a couple seconds.

I guess the next step is to get to the sensor connector and ohm out the connectors on both sides, yes?

vinyldavid wrote:

y'all are onto something with the temp sensor...Popped the hood, found the sensor connector, looked plugged in but I couldn't reach it to mess with it (there were things in the way, obviously)

Just tried to start it up and it sounded like crap but I gave it some gas and as it started to smooth out I pulled up 24 in the diagnostics and the output was 00. I went back to the tach as it was smoothing out...seemed to run okay, so I closed the hood and it didn't die at that point without my foot on the gas, so I drove it around a couple blocks and watched the output of the temp sensor...at first it was up at 51, then it went back to 00, then it hovered around 21-22 for a while...then it dropped to 0, the car started to shake, and I gave it some gas and it started to even out when the sensor went back to 22. It didn't shoot up again but cut to 0 a couple times for a couple seconds.

I guess the next step is to get to the sensor connector and ohm out the connectors on both sides, yes?

Hmmm,. for a guy that knows nothing you seem to be pretty smart,.
unplug it and cleen the pins,.make sure both wires are good,. make sure you have water in the rad,.

Nick

I'm an audio guy...I can do lots of basic tlc and some circuit level repairs on audio gear and some video gear, and I am comfortable with multimeters, soldering irons, most of ossiloscopes. I just know nothing about how cars go together and what systems make them tick.

David ,you are miles ahead if you can do that much technical diagnosing.As many here including
me can attest to the horror of wiring diagrams and multimeter magic.
Jim

hey guys...what's the part number of the coolant temp sensor, or where can I get one and how much does it cost? was busy all day and couldn't tear into it, but I'm hoping to tomorrow...just need to get finances inline.

Don't have the part number off hand, but its a stocked part at my local autozone and costs around $20. Make sure they get you the temp sensor not the temp sending unit, they are 2 different sensors.

i think this is right,.
GM PART # 25037332

AC-Delco # 213-77

nick

That looks like it, guys! Thanks! I was thinking it was a really expensive part. I'll head down to AutoZone tomorrow and pick one up.

Y'all are awesome.

World class LT-1 advice from others here and you cant beat the price either.I am just
here for moral support.
Jim

Y'all are freakin geniuses. Bought a $25 Kobalt toolkit and a $17 sensor, just put it in (the old one was horrible), and the wonderful LT1 now runs better than I've ever heard it running.

Now onto fixing the crash damage.

Krzdimond wrote:

but the main code is the 15 (low coolant temp). That would cause the misfire as the 'puter thinks it's -40 outside and DUMPS fuel trying to compensate for the uber dense air..... that doesn't exist.
. The pump has a sensor screwed into it. Wiggle that wire and check the connections. Bad wire/sensor would read REALLY cold.

Robert was right on,^^^^^^.

glad it,s working better, now you have incentive again,...

Nick

Feels great dont it David?Now get busy and fix that damage.
Jim