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1991 Lumina Z34 (3.4L) Stalls After Sitting In Traffic


thepooper
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If this has been addressed I apologize, I searched and didn't find anything that matches this problem.

 

I have a '91 Z34, which has the 3.4L engine (I think all Z34s have the same engine.) Anyway, after driving the car in city traffic it'll randomly stall. Example: I was driving around a few days ago, with a lot of sitting at red lights, etc. After about 30-45 minutes my car stalled out when I stopped at a light. She started right up, but it's a bit concerning.

 

 

The SES light pops on a lot, typically after being warmed up and/or idling in traffic for 5-10 minutes total, and shows the following two codes:

 

No tach signal to ecm - system normal

 

 

Open or grounded M/C solenoid (feedback carburetors)

 

 

I'm not sure if either of these codes will cause the problem. I just purchased the car 2 weeks ago, and maintenance records were included. It looks like a tune-up hasn't been done for at least a year, otherwise everything looks to be on the up and up. The car accelerates well, shifts well and runs great most of the time. No engine noises or leaks of any kind. The stalling issue concerns me because it may be the beginning of a major problem.

 

Any help/suggestions are greatly appreciated!

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If you have a z34 with a 3.1 engine you have the most rare one yet, therefore they apparently don't all have the same engine based on yours :lol:

 

Are you sure it's a 3.1 and not a 3.4?

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Well, if it hasn't been swapped it's a 3.4, or it's a base that someone. Put the cladding on.

 

At any rate, regardless of engine, do a tune up and check the vacuum lines. Do you have any rev jumping while sitting?

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The revs do jump all around once the car sits in traffic for a while. It's a precursor to the stalling issue. Could it be a problem with the EGR? Now that I think about it one of my Camaros had a similar issue and that was the culprit.

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I'm a little confused about the M/C solenoid code, as your vehicle is fuel injected, and doesn't use a carb...

 

I'm guessing since you have checked for codes, you have a scantool handy? I'd be curious about the actual trouble code number.

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I was confused by that too. I can run the codes again, a friend checked it for me and maybe they were wrong? I questioned them and they said the codes they gave me were correct.

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This is more or less an educated guess, but assuming you're actually getting a code that shows no tach signal to the ECM, I'd check the wiring from the crank sensor, and associated wiring to the ignition control module.

 

Again, this would be a guess, but a bad ICM would cause a stall...but usually that won't set a code, as the ECM simply thinks the engine isn't running, and shuts off the ignition.

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Looking up trouble codes, I'm guessing you're seeing a Code 23, which for fuel-injected vehicles means

 

"  23- intake air temperature (iat) sensor circuit (fuel-injected models)"

 

In earlier cars, it would indeed be for a mixture control solenoid.

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Yes, it's code 23!!!!  Thanks for clearing that up!

 

I'm glad I was able to verify the engine via the VIN; whenever I checked the engine bay the only thing is says is "Twin Dual Cam V6" on the intake manifold.  That's alright, at least I know it IS the 3.4L!

 

My plan for the weekend is to clean the IAC and EGR, then drive her around and see if I still have the rev jumping/stalling issue.  I'll get the tune up in a little over a week, a friend has a lift and is going to assist with the work; plugs 1-3 aren't fun to change.  :-)

 

Thanks everyone!

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I don't remember the Lumina having a strut brace, but if it does, remove it for plug service. Additionally, peel off the rubber hood seal on the lip at the back of the firewall lip. You might find, as I did, that someone prior to my buying the car cut three small notches in the lip that is hidden under that rubber, which makes it easy to get a long extension down to the plugs.

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Awesome, thanks for the tips!  I'm not looking forward to the service, but at least it isn't something I'll have to do often!

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Be prepared for the possibility that the plug wires fall apart at the plug when they're removed. My first plug replacement I ended up discovering 3 bad wires. Rockauto has the OEM AC/Delco wires for $47.00...P/N 716S---which beats the $150.00 I paid for mine 6 years ago when I first bought my LQ1 Cutlass convertible.

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I'm glad I'm planning on replacing plugs and wires; I ordered both.  :-)  Thanks for all of the advice, I really appreciate it!

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plugs 1-3 aren't fun to change.
 
Easy, with the right tools.  I used to disconnect the dogbone, then roll the engine forward for clearance.  Discovered later that rolling the engine was unnecessary.  Remove the rubber strip as said previously.  Then you just need the right combination of extensions and U-joint to go with the spark plug socket and ratchet.  This combo slides right into place and requires nothing other than pulling the rubber seal at the firewall.
 
Lumina_Spark_Plug_Tool.jpg
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plugs 1-3 aren't fun to change.
 
Easy, with the right tools.  I used to disconnect the dogbone, then roll the engine forward for clearance.  Discovered later that rolling the engine was unnecessary.  Remove the rubber strip as said previously.  Then you just need the right combination of extensions and U-joint to go with the spark plug socket and ratchet.  This combo slides right into place and requires nothing other than pulling the rubber seal at the firewall.
 
Lumina_Spark_Plug_Tool.jpg

 

 

I did a writeup a few years ago of something really similar, mostly for my reference :lol: But I can do all three of the rear plugs in about 5 minutes

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It makes me feel so much better to know it isn't nearly as bad as I thought it would be. I'm hoping to do the tune up along with cleaning the EGR and IAC this weekend, and it's supposed to be in the 90s all weekend. I hope it goes as fast as possible!

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You mentioned replacing the plug wires...it will go much easier if you unbolt the power steering pump (3 bolts between the pump and pulley), and move it out of the way, since the front bank wires are routed underneath the power steering pump. Pulling the pump is a little counterintuitive. Once the 3 bolts are removed, you have to "roll" the pump body clockwise to clear the pump reservoir from the mount, and "roll" the pump counterclockwise to reinstall.

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Actually come to think of it I may have re routed the new wires under it as factory since I want it looking decent, not I know I didn't on my previous lq1s

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  • 2 weeks later...

Sorry for not updating more quickly!  Last weekend I wasn't able to work on my car, and the weekend before it rained all weekend.  I'm cleaning it this weekend for sure, it stalled again 2 days ago (fired right back up, like always.)

 

Thanks for all of the help guys!

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