sick 96 Regency
I have a 1996 Oldsmobile 98 Regency with the 3.8 (3800) V-6.
A few weeks ago it started losing coolant and the idle speed was high. I pulled the upper and lower intakes and replaced both sets of gaskets. Both had failed allowing coolant to leak and causing a vacuum leak.
Got that ll put together and now the car stalls once it warms up. Stalls in park or driving down the road. If you get slow enough for it to idle, it stalls.
Put it on my Snap-On MT2500 scanner and no codes stored. Looking at data stream I get no reading from the map sensor. The reading actually shows -0.55 volts for the voltage on the map sensor. From what I'm finding in the help section of the scanner is I should be showing right at 5 volts on the map sensor with the key on, but engine off. Then when the engine starts I should have about 1 volt. I can backprobe the connector on the ECM (pin 12) for the map sensor input and I have those readings on my volt meter, but no reading on the scanner. I'm thinking ECM is bad so I replace it, and still have the same readings.
Also, on the MAF sensor, I am reading Hz, but not reading g. I have one reading on the MAF, but not the other, and this issue is the same with the old ECM or the rebuilt ECM
It has new MAF, new MAP, new TPS and new IAC.
The IAC counts drop to 25 at idle once it warms up to go into closed loop.
I have 55 pounds of fuel pressure and 16 inches of vacuum at idle (cold start).
Do i have another bad ECM? The wiring all ohms out to be good between the sensors and their pin on the ECM. I've cleaned grounds on the engine and body thinking I might have a bad ground.
I'm lost as what to do next.
From a cold start it runs well, until it gets warm enough to go into closed loop, then the stalling starts.