need advice please

[jutt26]

specs:
95 camaro 3.4L M5 - completely stock except K&N FIPK 120k miles

Here's the issue:
The car has developed a skip (maybe even a miss). I noticed this the other day when driving home from the airport. Under load, the car would shutter horribly, however would never backfire. Since then, I have pretty much determined that it is caused by heat/closed loop operation. If I keep my A/c on (which kicks on the cooling fan) and the car stays around the thermostat range of 160-180, the car runs fine. If I turn off the A/C and heat the car up to say 210, the car idles like crap and under load has a ship/miss that is absolutely horrible. The first time it did this, I thought the Tranny was starting to fail. No codes are being thrown, however the SES light is possibly burned out (since it does not come on at start up, however fan does not come on when skipping/missing so I am assuming no DTC code?). Happens in all gears reguardless of speed.

parts replaced in the past months:
Fuel filter
Clutch

parts replaced this past weekend in search of this issue:
plugs
both O2 sensors
plug wires

Any ideas would be helpful.

Thoughts on moving forward.

I just ordered a OBDII cable for my laptop (through AKMcables) and downloaded FreeScan software. The software has been verified to work on a 95 LT1, and I assume that GM used the same software (OBDI) on the 3.4, just a different tune. Does this sound logical?

Also, I am leaning towards the coolant temp sensor going bad. Anyone with thoughts?

[jutt26]

Re: need advice please

update...

Through a bunch of looking around, I have found that there was no software out there to pull codes off the car.

Took it to the dealer today and they said plug wires are needed, however they kept playing with the car until the car got too hot for them to change them out.

The ECM is also losing communication with their scantool. They want to look at it for an entire day or two now. Taking it back to them on Monday so they can have it for 2 days.

Geez.

[bradmb]

Re: need advice please

ive had the same problem before. try the ignition coils. in mine, it felt like the car wasnt running on all the cylinders under a load. i have had to replace them twice in 80k miles.

oh and sometimes mine kicked in like it had vtec or something. lol. but hope this helps.

[Camaro Dom]

Re: need advice please

well if the ECM keeps losing communication with the scantool i'd say that very well could be the problem the ECM controls so much, i wouldn't doubt it could make the car behave very oddly..

[jutt26]

Re: need advice please

just got the car back.

Diagnosis:
Ignition Module
Crankshaft sensor
Plug wires

$1033 later...car runs pretty well.

I am providing this that someone in the future may do a search on these symptoms.

Apparently the crankshaft sensor does not throw codes.

Anyway...car seems ok for now, however the scantool keeps losing communication with the computer but does not effect the car during these times.

[Stock98camaro]

Re: need advice please

Wow... Isn't it like totaled? :P Glad you got it fixed.

[bradmb]

Re: need advice please

i knew it had something to do with the ignition. glad you found out what was wrong. and my highest trip to the mechanic was about 1500 dollars.