Cutting out shortly after cold start

[Raykahn]

Since I have owned my Z there has been an odd behavior that shows up often.

From a cold start the engine sometimes starts stumbling and cutting out, and eventually it stalls. Load or idle doesn't seem to matter, other than load inducing the stall more quickly. After this stall, if you restart the engine it functions 100% normally. You can turn it off and turn it back on any amount of times, and so long as its not a cold start there will be no problem.

It isn't a fuel PSI issue, the PSI doesn't change at all while this happens. It feels electrical when the engine starts stumbling.

In the documentation that came with the car there was an old thread from these forums that had been printed in its entirety. Found here.

The symptoms are very similar, but not exactly the same. It finally ended up being the Coil Packs for him. Does that sound correct for my symptoms?

[Paul Workman]

One of the best tools I ever bought for my Z was a scanner that reads out OBD-1 (for both my 90 and Ami's 91 ZR-1 cars coupled with the FSM to provide normal reading parameters and locations for sensors. Without a method of scanning these older cars, there are just too many variables and troubleshooting becomes a crap shoot.
Find a shop with OBD-1 capability - or better yet, buy your own scanner and put it in the glove compartment. Otherwise, you'll be chasing around and "replacing parts until the problem goes away".

My wife's 91 Z would often start then stutter and stall on cold startup. The IAC voltage was a tad off and once it was set and an idle adjustment made (cammed motor), the issue with her 91 was resolved. But, the scanner told of the IAC voltage issue AND identified a lazy O2 sensor as the issue(s) in her case. A scanner is THEE approach to troubleshooting and will pay for itself in short order in frustration and wasted $ for parts thrown at the problem(s). (And, things REALLY get interesting when there multiple issues, and/or if a new replacement part is "DOA"!

Good luck. Get it scanned!

[dredgeguy]

Paul, looks like the Tech 1A's are hard to find. Any alternatives that do the same job?

[1991 Corvette ZR-1]

FastazU mentioned he uses what I believe he stated is an OTC Genisys 5.0. A quick search says it reads OBD 2 but I believe it is also backwards compatible. Upside is they are easy to find for sale. Downside is it?s just as much as you?d expect to pay for a Tech 1. There may be a cheaper alternative out there besides this one.

[JG95ZR1]

Yes a clone Tech 2


Sent from my iPhone using ZR-1 Net Registry

[XfireZ51]

U can use an app like ALDLdroid on an Android tablet to scan and datalog for a lot less money than a Tech 1.

Paul,

Are u thinking u reset the TPSv not the IAC? Or are u thinking Min Air adjustment? There?s no voltage adjust for the IAC.

[Paul Workman]

Originally Posted by XfireZ51

U can use an app like ALDLdroid on an Android tablet to scan and datalog for a lot less money than a Tech 1.

Paul,

Are u thinking u reset the TPSv not the IAC? Or are u thinking Min Air adjustment? There?s no voltage adjust for the IAC.

DOH! Yes, Dom. Thanks for catching that. AND, thanks for the tip on an alternate to a Tech 1. (I use an AutoXray - no longer avail.)

[Raykahn]

Thanks for the responses. The scanner is definitely the longterm play here.

Does this look to be the correct thing?

- Zach

[Young1]

I use a SNAP ON MT 2500 with good results. You can find them on e bay. Make sure you get the cartridges for up to 1999

[Young1]

Paul is right. A few hundred dollars of investment of FSM and scanner and digital multimeter is necessary. The learning is part of the fun.