I have a really bad misfire problem. It all started about two weeks ago when I started noticing an occasional misfire at idle. It steadily got worse to the point that it would misfire every 10 seconds or so and stall about once every half hour. It then started to misfire while under load as well and got to the point on Friday where I had to get it towed home. It starts, but misfires really bad and all of my plugs foul in the span of about 10 mins. I have replaced my rotor and cap. I am using an MSD 6AL and blaster coil, both about 6 months old. I have also been using an external ignitor (http://web.archive.org/web/200...ement). Everything was running really well until about two weeks ago. I have not changed my tune and the AFR when it does not misfire is fine. These are some of the symptoms:

-at idle - it idles fine for about 10 secs after start up then starts to misfire. It is very random and the car will eventually stall after about a minute or so.
-Revving at idle - it almost feels like it hits a rev limiter at times, while at other times it revs freely.
-Under load - I get a heavy bog and the car gets VERY jerky when it misfires. Sometimes it will completely not fire the plugs so the revs will suddenly drop and then all of a sudden pick back up after a second or so, my foot on the throttle the whole time.

I did just changed the rotor and cap today and I was using some carb cleaner and sea foam as I am sure the combustion chamber was full of carbon. I very well may have fixed the problem, I just need to work out the sea foam and put new plugs in. I checked the battery and alternator, they are fine. The IAT and coolant sensors are fine. I have not changed my timing (cam or ignition).

Any Ideas?



Modified by LST2 at 2:11 PM 6/29/2008

 

Could be a head gasket, r u losing coolent?

 

Try changing your distributor.

 

Head gasket is a possiblity. I have lost some coolant lately. I am going to do a compression test tommorow. Would a head gasket cause a problem in all cylenders. I am fouling all my plugs evenly.

As for a new distributor, I was hoping to try the basics before a new dizzy. I did replace the cap and rotor though. Not much else to replace since I have an external coil and ignitor.


Modified by LST2 at 8:41 PM 6/29/2008

 

Theres ways to check the dizzy with a ohm meter, just revert to the manual. If you started losing coolent all of the sudden I would assume the hg. Have you checked your oil (not that its a determining factor).

 

toss that msd coil and ignitor and go back to the stock stuff and it will be fixed

 

It was a bad TPS.

 

Hi,
I'm having a similar problem. My tps is reading values when throttle is pressed/depressed.
How did you find out the TPS was faulty?