91 lumina hunting idle and dieing

[kippersnack1981]

91 lumina with a 3.1, suto with air and 110k miles. new computer, new coolant sensor, new crank sensor. Starts and hunts for an idle. serging up and down around 1500 rpm sometimes up to 2000 and sometime dieing. at first there was "no communication" with the snap on scanner thats the reason for the new computer, ecm. the radiator fans would come on way too early or sometimes not at all. thats the reason for the coolant sensor. and the output of the crank sensor is supposed to be .1 volts or greater. thats the reason for the new crank sensor. but after the crank sensor it still doesnt put our much more than .05 volts. after the new ecm it has fast communtcation to the snap on scanner, but the fans will not kick on and the engine still serges bad and misses. it will die sometime and restart easy. we had a 96 cutlass supreme there with a 3.1 that had many of the same parts. we swapped the map sensor, nothing, swapped the iac, nothing, cleaned the iac and the thottle body throat. still does the same. we unhooked the coolant sensor in order for the fans to kick on so we can try to figure it out, but the engine light is on. it goes off when it is plugged in and still doesnt run any different. still serging or hunting for a continous rpm from aroung 500 up to 2000 and all in between. we have about 40psi fuel pressure. the car has been sitting for about 9 months. the gas doesnt smell too old. we just put head gaskets on the car because they were blown, i got the car off my grandfather. Id say that the fans didnt kick on and he got it too hot and poped the back head gasket. it is driving me crazy, i need to get this car running. we checked the iac like it says in the book. 40 to 80 ohms across a and b and c and d. they are the same. we checked the ohms on the crank sensor and its good. maybe the wires from the crank sensor to the coil pack? help help help. please. thanks

[maxwedge]

Vacuum leaks, egr stuck partly open?

[kippersnack1981]

i checked for vaccum leaks, none, how do you check the egr? it had a dead miss in it last night. we checked the tps, the coils, and the icm. all good. going to the cat converter and the plugs next. it had one felpro head gasket on it when we did the heads. you think someone could have got the pushrods mixed up before. the ex. or intake are longer than the other, i cant remember whick right now. and i dunno if this got worse after my grandfather bought it or it has always done this.

[maxwedge]

You would have bent a valve if the rods were switched, then low vacuum and a misfire, do a compression test if you suspect that, remove the egr clean it and reinstall, leave disconnected for test purposes.

[kippersnack1981]

come to find out that our three long plug wires are the 1 3 5(they are labled). they go to the back of the motor. BUT!!! the intake says 2 4 6 on the back. where the heck is the #1 cylinder. i dont think the motor has been changed by the looks of things. If #1 is up front then it is wired wrong and that would explain the bad exhaust smell, the very quick heat up of the engine, and it running like poop! help max.

[maxwedge]

Check this link.http://www.autozone.com/shopping/rep...00c152800679c5

[Mofraqi]

Did you happen to disconnect the battery lately for anything? I have a 94 that had a haunting idle problem easy fix no cost! I replaced the alternator so i disconnected the battery to do the job, well when you disconnect the battery on a Lumina it resets the idle.

[no2guncntrl]

I found this helpful as well..

[kippersnack1981]

max, the intake says 2 4 6 on the back, thats right because the intake runners cross. so the 1 3 5 cylinders are on the back. i suck. and Mo, i have unhooked the battery a number of times messing with this car. thank you tho.

now it has a miss instead of a hunting idle, we check all of the injectors and all the coils and modual. would the coils check good if they were breaking down? the car has been sitting for about 9 months so we drained all the gas and put new gas in it to the top. we had a fuel pressure gauge on it off the fuel rail. when we hit the release button moslty air and a little fuel came out for about 5 minutes after most of the fuel came out that was pressurized. AIR? where would that come from?

[maxwedge]

Cracked fuel hoses, for one, what was the pressure?

[kippersnack1981]

37 to 40 psi.

[maxwedge]

Press. is ok.

[kippersnack1981]

found a pin hole in the pressure fuel hose, as a temp fix we duck taped it. still has a miss. run good for a second then miss, and on and on. checked resistance on all the pulg wires and changed the coil packs one at a time with some used ones, even though all of them checked good. some times it will idle fast and sometimes slow .

[kippersnack1981]

How hot should the cat converter read on the snanner after running about a minute and a half???? not 700 degrees right? especially when a lazer temp reader read 110 degrees off the cat. i think the O2 sensor is bad. anyone know?? no O2 sensor code though.

[no2guncntrl]

On a cat you want at least 100 degrees hotter coming
out of the cat than going in. If not the cat isn't doing
it's job of reducing emissions.