My 92 firebird 3.1 liter v6 runs rough after startup. it sometimes stalls out at low speed and idels very bad. if i cruise at 80 to 90mph it runs allright but as the rpms go down so does preformance. when i first start it up it will run good for a minute or two, even if its not cold and only been sitting for about ten minutes. i suspect it might be running rich due to a bad o2 sensor or mabey i have a coil or something going out in the ignition system. I recently moved to england for my job so i can't just get parts from the local auto store anymore. if anybody has sugestions or some good troubleshooting tips for this problem i would apperciate it. it takes awhile to get parts shipped over here so i would like to narrow my possibilities befor i go ordering a bunch of stuff.

I replaced the spark plugs about a week ago but they didn't help.

 

Sounds like a decent assumption to me. If you have an ignition spark tester, test your spark....see how strong that coil is. Any rich operating condition or weak spark will make it run bad down low but as the rpms get higher, the problems will start to disappear. Also, make sure you don't have any vacuum leaks.

A clogged fuel filter could cause some problems like that too.

 

i would think a clogged fuel fillter would get worse at higher rpms. of course my experiance is with motorcycles so i dont know alot about how the fuel pump might change that symptom. where is the fuel filter located on the 92 firebird? we have a auto hobby shop on base where i can work on my car. they should have a spark tester. what type of results should i expect from a good or bad coil?

 

Can't tell ya where the filter is...can't remember. But when I had my Camaro, mine was clogged and felt decent up top but it wanted to stall a LOT at low speeds.

If the spark tester is gapped properly, best you can hope for is white. Blue is acceptable too. Orange is not too good, and red is crap.

 

Inst there some funky thing with the 3.1 that you gotta reset min air or something if the car loses power or the batt is unhooked???

Matt

 

Not that I've ever heard of....

 

There was a thread about it over in the V6 section. might wanna move the thread there. I remember it clearly and made a mental note, incase I come across a car cheap with a 3.1 that runs bad.

The 3.1 is one strange creature.

Matt

 

No more strange than the 2.8 was at certain years! Like when they had a serpentine AND v-belt setup.. Or when they had the cold start injector... Or when they had the adjustable TPS.... Straaaaaange stuff, man...

 

well i found a spark plug wire that was intermittantly shorting. the shop had a used one in a drawer i put in for a temp fix. the wires are old so i'm going to order a whole new set + cap. i can't get replacement over here because gm coils will melt down typical euro plug wires due to a higher current. or at least thats what the guy at the parts store said. it's still not purring like a kitten but it's a big improvement. i'll look into the fuel filter and and order the o2 sensor while i'm at it just to cover my bases. hopefully once all that is done it won't want anymore parts for awhile.

 

Well I found what I was thinking about and its a 3.1 only thingy.

"Originally posted by TomP
The 3.1l auto equip'd engines require an idle learn procedure to be done whenever battery power is lost or the IAC has been changed/played with. The symptoms of not having done the idle learn are: surging idle, stalling, hesitation and bucking, in general a lousy running engine at low speeds.
"
https://www.thirdgen.org/techbb2/sho...le#post1477944

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Step by step how to

https://www.thirdgen.org/techbb2/sho...hreadid=158052

The 3.1 is one odd ball as its the only one that needs this. Thirdgen or what ever, all them GM 3.1 motors.

Be on the lookout for nice cars with a funky running 3.1


Matt

 

i have a 3.1 and have disconnected the battery many times without doing the "idle relearn procedure". starts right up after its been disconnected. only time the IAC causes it to surge and bog in my experince is if you take the IAC module out and push the pintle in by hand. the first time you start the car up it will surge a LOT and rpms go down real low but as soon as you shut the car off and restart it, its perfect again. but just pulling the power, ive never had to reset anything. i think that procedure is a bunch of BS

 

Lol I second that one. Never had any problems. It'd always stall once after disconnecting the battery but after that it idled perfect.