Ref this thread:

https://www.thirdgen.org/techbb2/sho...threadid=196934

I can now hard fault the problem when driving around city streets. Once the engine warms up the rough running and backfiring is happening between 2000-3000RPM all the time. I tested the coil and pick-up coil. No faults found. There still is no code. The car has great power and pull during the first 10 minutes of running. After that is all sluggish,sounds like crap, runs rough and of course the backfiring. I also did a fuel preassure diagnostic. No faults found. As I've mentioned theres no codes in the system and no SES light when the trouble is occuring.

Please someone have an idea on this.

Thanks again

 

That thread seems to be gone. Are you sure you have the right link?

Since the thread is no longer available, is there any other information that might give us some background?

 

Here is a copy of the old thread:


This is bizzare...and its causing damage.

The last month while driving on the highway i've notice a surge and rpm jump at a sustained 2200RPM. Then, on Saturday it happened again. This time I had back fires and tonnes of black and brown smoke out the tale pipe. I couldint get past 2000 rpm. If I stopped or kept below 2000 it was ok. This only seems to happen on the highway. I have no codes at all. I tried to duplicate the problem by warming up the engine from bombing around the local streets. Different RPM in the gears. (350, 700 R4) but nothing.

So last night I went for about a 30km drive to a friends at around 120 kph no problem. We left his place. I follwed is 4th gen back onto the highway. As we got on we both hammered them all the way up to 170 kph. Then all hell broke loose. My backfire and bogging along with huge smoke reappeared. Couldint get passed 2200 rpm. I pulled over and idled with no problem. This time it backfired so hard the exhaust gaskets blew. So i limped it home at 80 kph no problem. Tried getting it to a 100 kph at around 2000RPM. and it started to backfire again. Put it in idle. Reved it to about 3500 and let off. It backfired hard again. Got it home left it till now started it, and nows theres no problems. It revs perfect. But I know if it hits the highway for any length of time ill be exploding again.

What the hell is going on here?

 

O.K. I searched the archives and found about thirty threads in various fora about your problems.

Have you checked the CTS resistance yet?



Did you test teh pickup ciol when it was hot? What resistance readings did you get?

Is the reluctor in good condition? If it is badly rusted, cracked, or bent, you'll get poor signal generation.

Is the HEI switching module well connected and grounded? Did you test teh tach filter? Did you try to bypass the EST to see if the problem persists?

 

Hello vader.

I tested the coil and pickup coil as per the Pontiac service manual both hot and cold. Both were in spec. However, I did take the ignition module out and put it in my freezer for 30 minutes and re-installed it in an engine that at the time was reading about 70 celsius. The car seemed to respond a little better. There was still a jump in the RPM but I had some power back. But 5 mins later it went back to backfireing.

How do I by-pass the EST?

How long does it take genereally to get into closed loop?

When I did the module in the freezer thing and installed it, the plenum was still hot enough to burn so Im assuming that it would get into closed loop very quickly.

Thanks

 

Just an update. Problem fixed. It was the ignition module *****!

 

i was having the same problems as edge was and i tested the pick up coil and it was good so i changed the ignition module and thats what it was too,runs great now again, thanx for posting edge, helped me out alot