I just picked up a 95 Firehawk about 2 months ago. It has been doing fine until 2 weeks ago. It ran like crap once warmed up. It would lose power, missfire, and had like a backfire, poping type noise in the exhaust. But not the normal pop these cars have. I figured optispark so I got a new one. Ran fine for a week then its started all over. Iv then replaced alot more stuff and still the same. I dont get a SES light either. Anybody have any ideas? Thanks

Heres what iv done: Optispark, cap and rotor, water pump, both the coolant and tempeture sensors, spark plugs, wires, Ignition coil, Ignition control module, T.P.S., and M.A.P. sensor. I also checked fuel pressure and its 42 with key on engine off and with the engine on its 38.5

 

Could it be timing? Maybe a worn timing chain who knows?

 

What temp is it running?

 

I can almost guarantee its the ignition control module. Very sensitive to heat. When You replace it MAKE SURE to use dialectric grease on the mounting surface. Did You use dialectric grease when You replaced it? Did You use one from the dealer?

 

02 sensors......causing problems after the PCM hits open loop and the 02s start taking readings......during closed loop cycle (warm-up), they are on a table with set values, so it will run normal. my .02!

 

It starts poping as soon as i turn it on. It doesnt start missfiring until another 5 mins. Its prob around the mark after 160 between 160 and 210 whatever that would be if that makes sense?

I put a new Ignition control module when I did the opti for a second time this weekend. Its a Wells and yes I used dielectric grease.

Im starting to think it might be 02 sensors because when on the highway my SES light would turn on for a few min and the go off and someone suggested o2 sensor. But if they were bad now would it trigger the SES light?

Id hate to tear it down all over again to find out its not timing. I just wish I knew what it is so I can fix it! Thanks for the help fellas.

 

O2'S. but there is no telling y it does that when its at a cold crank.

 

That sounds like what my car is doing

 

So if its possibly o2 sensors is there any way of figuring out which one it maybe? The computers not throwing any codes the one time the SES light came on by the time I got to work to scan it the light went off and there were no codes. So yeah I dunno which bank isnt running right if its o2 sensors.

If all else fails I might as well get all 3 o2 sensors im sure they are all factory just like everything else iv taken off of this car so far.

 

I was told if you unplug your 02's it will keep it in close loop and thats one way you could trouble shoot instead of throwing any more money at it yet see if that works

 

That's correct, however some of you guys have it backwards. Open loop is the mode used on startup with only pcm tables used to calculate fuel. Closed loop is the mode that uses the O2 sensors once it's warmed up.

If you unplug one (or both) of the O2 sensors it will not enter closed loop. If the problem goes away you know the sensors are bad.

 

sorry typing faster than i was thinking

 

Im just updating. I changed 1 of the 02 sensos and what a difference itmade. I drove it aroor 3 min and no missfires! I bought bothofthem so I might as ell change out the other one too. Thanks for the help!

 

no prob thats what were here for

 

had basically the same problem and it was my 02s...youve replaced a lot, its probably the 02s =(


Wow i didnt even read that last post you posted....lmao i knew i had the same problem! I'm just editing my post since im retarded