89 Firebird Formula 350 Tuned Port Injected
I am inquiring information to help me rectify a problem I have a Tuned port fuel injected 350 I have removed both catalytic converters and replaced them with test pipes the rest of the exhaust system is stock.Here is my problem the engine now oscillates between a low and high RPM idle I really have to stand on the brakes at a trafic light or even when I put the car in reverse also seems to be running very rich.
Can someone Please inform me of the correct procedure to rectify this problem and how to go about it.
I have listed this under 2 different areas because I am not sure if I was under the right topic.It is also listed under DFI & ECM

 

Have you changed anything else or did it just start doing this for no reason? Removing the cats alone won't cause this to happen.

 

It started doing it for no reason.When we first put the test pipes it in ran fine the car sat for a few weeks because it is not drivin daily went to take for a spin and this is my outcome.Do you think I should take it to a perfomance shop or a dealer to have it analyzed.And what may be the problem any suggestions would be greatly appreciated It has me stumped.Thanks

 

PrdnJoy

What may be happening is that your NBO is cooling down during idle. Since the cats are gone now, and NBO is mounted upstream of cats - the back pressure crated by the cats is gone and at idle it is not uncommon for single wire NBO to get cold enough to drop ECM into an OL. OL is richer - hence idle surge.

You need to verify few things - get a scanner or ALDL cable and a lappy running WinALDL to see what ECM is doing during idle surging.
If you confirm that ECM drops in & out CL then a simple solution to install three wire NBO - Delco AFS-74 - use search function for three wire conversion.

//RF

 

No way. The NB is so close to the heads on stock manifolds that's there is no way that it's getting too cold. Case in point, my 88 has stock manifolds with no cat. Has been this way for 5 years now and I have no issues with it jumping in and out of open loop due to a cooling O2 sensor.

The usual place to start diagnosing an idle surge is to clean and re-set the IAC and passages. The procedure can either be found by a search or by going to the homepage and looking under tech articles.

 

If I were to look under tech articles or a search what would I look under idle surge? I did do a search in this site under that and found nothing am I stating topic wrong?

 

https://www.thirdgen.org/tpimod2

Do a search on cleaning the IAC

 

Viprklr:
I want to Thank You a women needs to comprehend this also so I am doing my best and your help and everyone elses is greatly appreciated.I had done a complete restore on body the interior was imaculate.But this part has really got me guessing and taking it to a dealer is the last thing I want to do I have heard to many horror stories.
So Thanks again.

 

This site will become your life.

 

And I Thank People like you.Here is my next question again please bear with me If I were to be looking dead on the engine would it be to the right or left I think I know but am not sure.Thanx again

 

If you're looking dead on the engine it'll be on the bottom/side/left of the throttle body. It should have a 4 wire connector plugged into it.