1992 Stalls out

[iwonder]

Greetings ---
Thank you for reading this - I hope you can help.
The diagnosis is always the hardest part ...
I have fixed or replaced several things over the last three years, but, for the most part, for having 175,000 miles, the car is doing great. It has served me well, considering I deliver pizza part time.
My 1992 Skylark, with a 3.3 engine is stalling out and not wanting to restart right away.
What I have done recently -
Replaced a bad alternator - last week
New Plugs and Wires - last week
Normal operating: Start up, go, stop at light, get to work, all run fine.
After warmed up, however, idling in front of someone’s house, or shifting from Park to Drive results in a stall.
Sometimes, it will start right up and go again. Other times it will just crank over like it's not getting gas. I wait 5 - 15 Mins and it starts and runs fine . . . Until the next time.
I did find, (after several episodes of this), that if I released the pressure from the (?) valve on the Fuel Rail, < it is like a valve stem on a tire - right where the fuel line comes to the Fuel Rail, by a half-dollar size 'chamber' - (I think you check Fuel pressure here) - If I push in on it, fuel squirts out onto the manifold> Then it starts up and goes fine, until, it stalls out again.
Checked for Codes for 2 days until I finally got a 22; a Voltage Low on the TPS circuit.
Replaced the TPS unit.
Checked the Vacuum hoses. No apparent leaks.
Ran it again - Seemed fine ... Until it was warmed up and then it did the same thing.
Get out and going down the road was great. Pull in the driveway and shift from Drive to Reverse and it stalls.
Start it up and let it drop into idle and it chugs and stalls.
Start it up and let it sit in Park for 3 Mins and it stalls.
Air filter is new.
Plugs and wires are new.
Throttle Body is clean.
Checked All Fuel System Wires for Voltage. All checked out.
No blown Fuses.
Pulled the Battery cable - Still popping a 22-error code.
Any help would be gratefully appreciated.

[Blue Bowtie]

Welcome Aboard!

IIRC, the TPS on your engine is non-adjustable, so it's not a question of adjustment. Make sure the TPS has a 5.0VDC reference signal across the A and C terminals.

You mentioned that the TB is clean, but did you also clean the IAC stepper motor?

[iwonder]

Thanks for the reply.
I will check the voltage next, however, if it is incorrect, any ideas as to the cause.
I'm still getting a 22 code, even after clearing the memory again.
Also, I will try cleaning the IAC.
The thing that kills me is tht there was no problem before I changed the alternator. The next day, this started.
I keep reading that similar symptoms are a result of the fuel pump, but I can't see how, cause it runs fine ... when it's not stalled out.
Thanks for your time.

[iwonder]

Also, what would be next if the voltage was off on the TPS?

[Blue Bowtie]

If the TPS voltage reference is not 5.0 ± 0.15V, there is eother a connection problem or voltage regulator problem in the ECM. Since a regulator problem in the ECM would likey manifest itself in several other ways (more error codes) it's more likely the connections between the ECM and TPS would be the issue.

The other, more remote possibility is that the alternator has a failing diode, and is imparting some level of AC voltage on the system. The older ECMs are supposed to tolerate up to 2.0VAC according to the factory information, but ai don't see how anything over 0.5VDC would not cause a problem. You can connect your voltmeter to the alternator output stud and battery ground, set if on an AC voltage scale, and get the reading while the engine is running. If you get anything over 0.25VDC, it would be interesting to know.

[iwonder]

Thanks for the info - - -
Unfortunatly, I had no choice but to take it to a guy.
He has done honest and affordable work for me in the past.
I need to get to work and I also use this car for another job, (delivering pizza), so ...
I'll post what I find out from him.
I appreciate your time, Thanks again.

[iwonder]

Where are all the Skylark fans?
Well, anyway - I have found that the problem was with my ECM.
2 of the QUAD 4 modules (?) were burned out and stuck in low/high - I'm not sure which he said it was. The last one was not enough to keep things running smoothly.
He said an arch or power surge prbly burned them out.
I did have the Negative battery cable disconected while replacing the alternator, so who knows . . .
An $82 part, (a new ECM), and a couple hours labor and hopefully I'm back in business.
I will report back when all is done.

[maxwedge]

Keep in mind they usually fail from the circuit they control overloading.