IROCZU2

Hello there! I read several threads about simular issues but none exactly like my issue that I am having with my car. About 5 or so weeks or so ago I noticed that the car was weak when I stepped on the gas. It would run rough when you gave it gas but would do it only from time to time. Then it just stopped and did not give me any problems. I only drive the car for leisure on the weekends ect..Last week I purchased some STP Fuel System Cleaner in a full tank of fuel. The car sat for a whole week in storage, I pulled it out today to drive it and it ran find with a bit of hesitation when I gave it some gas. I drove the car around for abour 20-30 minutes and then it started running rough, then worse to where it wouldn't even idle at a stop light. It went dead 5 or 6 times. When I was starting the car it seemed to start rough. I finally got it back home and parked it. I let it sit for a few hours; returned to the car about an hour or so later and the car started up fine. I did not drive it anymore. I let it run for about 30 minutes idling with no problem. What is the problem with this car? The car only has 38,500 original miles on it and its in "mint condition"..Is it something with the fuel system? What could be the problem. Please help!!!

Thanks,

1970Firebird

its hard to diagnose without scanning for codes. Is there a SES light coming on when the car starts to deteriorate perf wise? A few things to consider...

1.) MAF and/or bad maf burnoff relay
2.) O2
3.) bad ignition wire/fouled plug
4.) bad ignition module
5.) Did you move the TPS sensor?
6.) vacuum leak---check around carbon canister (driver's side).... if the hose comes off the canister..this can lead to crappy idle and stall. Did you do something to move it?

When the car is idling smoothly... I would tap to top of the Maf sensor with a screwdriver...if the car's idle deteriorates...then the MAF wire is broken and the MAF sensor is defective.

A fouled plug and/or faulty ignitition wire can cause car to accellerate rough..and die during deceleration.. BUT the MISS would be consistent and not clear itself up--you said it was idling find at times

A bad igntion module---you would lose spark..either at startup (car wont start)...or it might give out completely in drive...(car dies at idle or when cruising)...ususally when it get's hot...

1970Firebird

its hard to diagnose without scanning for codes. Is there a SES light coming on when the car starts to deteriorate perf wise?

1.) MAF and/or bad maf burnoff relay
2.) O2
3.) bad ignition wire/fouled plug
4.) bad ignition module
5.) Did you move the TPS sensor?

When the car is idling smoothly... I would tap to top of the Maf sensor with a screwdriver...if the car's idle deteriorates...then the MAF wire is broken and the MAF sensor is defective.

A fouled plug and/or faulty ignitition wire can cause car to accellerate rough..and die during deceleration.. BUT the MISS would be consistent and not clear itself up--you said it was idling find at times

A bad igntion module---you would lose spark..either at startup (car wont start)...or it might give out completely in drive...(car dies at idle or when cruising)...ususally when it get's hot...

IROCZU2

Thanks for the response. There is no SES light coming on at anytime. I do know that the car needs its 36,000 tune-up but I have not seen any light. I have not tapped on the MAF sensor yet, I will have to locate it and give it a try. I will check for vacuum hoses that may be disconnected...... It seems that this car will start up fine but will run rough after you get it out on the road and drive it a bit. I ask someone at a dealership what it could be and they said it could be a clogged inline fuel filter or the fuel pump. They did not bring up the things you have made me aware of.

I went out this morning and started the car up with no problems. and idled at about 1500 RPM's. After about 5-7 minutes the car fell off to about 1000 RPS's. I pressed the accelerator and raced the engine several times up to 4500 or 5000 RPMs' without any misses. It has sat there and run without even a miss. Now that may be a different story after it has run for a while...not sure about that.

Yesterday, after I drove the car around for about 30 minutes and came back home, it would not even idle. When I tried to start it up it was very rough starting and for a few minutes would not start at all. After it sat there for several hours it started up with no problems. If it was a bad ignition wire/fouled plug, bad ignition module, or vaccum leak wouldn't it run this way all the time?

So I am not sure about it.

Fuel Pump, Filter, O2 Sensor, ?

Thanks

D's89IROCZ

Just wondering if it may be fuel also . Change the filter . Ohm out the injectors . WHats the fuel preasure when it's acting up ?


After you get this stuff it may lead you to other questions

IROCZU2

After many different tests and thinking I had a problem with the fuel system, it turned out to be nothing with the fuel at all. I changed the fuel filter and was still getting about 58-61 pounds of fuel pressure on the fuel rail. I took it to the shop and run the system scan on it. It showed no errors at all when it was running fine or when it was running rough.

It turns out that the problem was with the pick-up coil, distributor and ignition module. They were corroded I suppose from moisture build up over time and it had started to rust. The car would run fine sometimes but once you got it out on the road it sometimes would loose power and eventually die. The pick-up coil was corroded. This was replaced and 650.00 later it is running fine.

The shop mechnic told me that it was because the car had been sitting up. It only has about 38.000 original miles on it and over time it had just built up some corrosion.

The car is running like new!!

Thanks,

Eric