Vehicle - 89 Formula 350 5.7 TPI, Auto. Carroll-Paxton supercharged. Otherwise stock.

Idle has been pretty good for the longest time. Not perfect (a little jumpy) but very good. Went to take it to and through NJ emissions testing on Thursday and after a long, slow, hot drive of construction and detours, I made it to inspection. In the long inspection line, I shut the car down several times because I could tell it was hot, not overheating at all but hot.

During the emissions test, the idle was hunting up and down between 550 and 850 or more. Never saw this before. Anyway, she failed emissions since something isn't right. The HCs and COs were very high. I am told from the builder of the car that the car should fly through emissions as everything is stock except for the supercharger. Just had the cat conv looked at last week and it was fine.

I've read about 50 threads all over the net, including here, trying to find similar symptoms and answers.

As far as the list I've tried to clear this up:

- Injector Cleaner
- Checked all fluid levels
- There are no coolant or fluid leaks
- Checking like crazy for vacuum leaks
- I cleaned the MAF with MAF cleaner
- I changed the IAC valve
- I changed the TPS

It's "a little" better than it was but the warm/hot idle hunting is still happening.

I am also hearing a little intermittant click coming from what seems like the passenger side of the engine compartment. I have never heard this before in 9 months of working on this car.

Before I continue with throwing parts at it, does anyone have an idea as to what this can be?

I'm wondering if the factory fuel injectors are gone? 22 years old but only 30,000 miles. Several people have told me to check or change these. I guess I could OHM them tomorrow to find out........?

Other thoughts of mine...

Air Pump?
MAF itself?
M.A.T?
IAT?
CTS?

Thank you in advance for any suggestions.

 

If the injectors are the stock multechs, very possible. Ohm them out warm and cold just to rule them out. Do you know what to look for in results of the ohm test?

AIR pump: I dont think so personally. I believe the air pump only works when the engine is warming up, to lean out the exhaust becuase its running rich. Shouldnt be doing anything when hot.

MAF/MAT/IAT/CTS: possibly. Heres when you have to start testing and go from there.

I would reccomend checking fuel pressure, especially when its warm/hot and the problem is happening. Also, hook up a vac. gauge so you know what your pulling. Checking isnt nearly as accurate as actually hooking up a vac gauge.

Side note.. I see you have a stock 5.7 tpi other than supercharger. Have you dyno'd it? Or taken it to the strip?

 

Car has a tuner package on it that was sold through a few dealers. Spec sheet says it makes 400hp/475tq at the motor. Original owner said the dealer took the car to Atco in NJ when it was new, threw sticky tires on it and it ran 12.8s and 12.9s. The only changes since then are a B&M shift improver kit and a B&M stall - original owner does not remember how big the stall is (he thinks 2800) but given its street manners and driveability, it must not be that big as I never notice it and she shifts like butter.


Thank you on the other suggestions by the way. The rain is prohibiting me from doing much on the car today.

 

Yes, I read the thread on that. I think anything under 12 ohm is bad and they should all be within .5 ohm of each other.

 

Before I dive into it this weekend, anyone have any other ideas on this topic?

 

I'm wonderin if the EGR is being flakey? maybe sticking open a lil bit??
Did you look in the book yet under surges and or chuggle ?? there is somthing else but I cant remember it right now.

 

I kinda agree with Black88Z.
Ohm out the injectors as he said.....cold and hot.
The stock injectors are extremely prone to coil failure, especially when
they are hot.
Keep us posted

 

Well, I think it's the injectors. I am told anything under 12 OHMs is bad.

Here are the cold OHM readings. Cold readings are fine.

1: 16.4
3: 16.5
5: 16.4
7: 16.4
2: 16.5
4: 16.5
6: 16.5
8: 16.4

Here are the hot readings and here is where the problem is. Probably gets worse the hotter the engine temp gets, like when I waited in all that traffic, construction and then the inspection line. These were tested at about 155/160 degrees which, believe it or not, is normal operating temperature for this car. The day I had the real jumpy idle after traffic and the long lines, the car was running about 200/220 degrees.

1: 17.0
3: 17.1
5: 11.7
7: 17.1
2: 8.9
4: 17.6
6: 17.4
8: 17.4

Clearly, injectors # 5 and # 7 are bad.

So, for a stock 350 TPI + supercharger running about 5# of boost and alc/water injection, should I stick with stock 22# injectors or move up a notch to 24# or 27#???

If I move up a notch, will I have to fix or adjust any other settings anywhere? I don't want my fuel injector fix to force me to "fix" 5 other things.

Thx!