I'm running a 92 SD setup, stock aujp 8d. All new sensors in last week, except knock and map are couple years old. It has zz4 cam, lt1 injectors all 12.4 ohms, no emissions (smog cat egr) car starts right up cold idles 1500,runs great has power no missing. Problem is when it goes into closed loop it wont idle down unless computer is reset. It starts running like crap! Bad miss huge power loss and gotta keep it above 3k for it to move or it just falls out with throttle. Basically if you hold the throttle at bout 2k with load it will basically shut down untill throttle is released then it will stumble and catch its self. Runs decent down highway with rpms up but as soon as it gets in low rpms it will hesitate and jerk and has to be peddled until higher rpms are reached. It will then drive with a surge, and noticeable power loss. Any input on this would be appreciated, I'm not the best at explanation so please ask me questions as this might help me explain problems better. If I don't get too much snow here in kc ill make a video tomorrow and post. Thanks Kyle.

 

Can you datalog?

Not your immediate problem I think but every ZZ4 cam combo I have run has needed the idle raised
from stock 450 rpm to 7-800 rpm in order to get a smooth idle
Any lower and the revs are constantly surging up and down in CL as the ECM tries to pull revs down
to the programmed level that the cam won't let engine run at

 

No I do not have the stuff to data log, if I can find someone in Kansas city area to help with this I would be willing to pay them. I am at the point of taking it to a shop. Funds are tight rite mow or it would have the right high impedance injectors and a tune. Its ran fine the way it is for couple years. But now that car got wrecked and every thing is swapped into an 88 dash and all. After swap this is were its at. What does it take to data log?

 

I would start looking for a vacuum leak first.
Do you have your EGR port completely blocked, and the EGR flag turned off in the chip?

Yeah, unfortunately to be able to monitor what is really going on when you go closed-loop you will need to datalog. It takes a laptop computer, the proper ALDL cable, and datalogging software.

 

Stock tune, egr blocked and no laptop. I got a 750 demon that's probably going on tell I get the money to make the tpi run right.

 

Well been trying to figure this out still, ain't got anywhere yet! Today I pulled all injector clips off and proceed to do some ohm testing. So far I have continuity between grounds and power at injectors. Pull ecm no change, pull fuses for bank 1 and 2 and no continuity between power wires. Does any body know if this correct? Or the correct way to check for both banks firing at the same time? Friend told me a Guy on here was having same problems and his were firing at the same time. I can't seem to find the thread about this. Please any help, I don't want to put a Carb on it. I just don't like them

 

you can use noid lights to test the firing of each bank, the fuse 1 and fuse 2 are the power side of each bank the ecm grounds to pulse the injectors.

 

Okay im not sure where you are going with this? Whats the problem?> Car runs and then dies upon closed loop? Why look at the injectors? they've got to be working if it runs open loop fine? Help me help you i live in kc so if we can't figure this out here ill try my best lol

 

Super rich on start up, getting maybe ten MPG. As I stated above, Guy with similar problem had both banks firing at same time. Its a fuel or spark problem and I can't seem to narrow it down. I already had to run a new wire from ignition switch to the neutral safety switch to get it to start (starter signal wire). Starter relay does nothing no powered on any wire, guess in some way this might cause a running issue. Its a nice day out and stuck at home looking at a few thousand dollar car I can't drive, little fruiestrated

 

Check all the fusible links by the battery, sounds like you may have some wiring problems.

I also recommend a data logging option. If you can use a soldering iron have a near-by Radio Shack, then you can be datalogging in 2 hours. Do a search for WinALDL. If you make the cable long enough you can datalogg from the home pc...

It would be best to see what all the sensors are doing during closed loop operation, and then we can look for patterns that would indicate a problem.

I had similar surging idle/pig rich/low mpg condition that was being caused by leaky injectors and torn FPR diaphragm. What is the fuel pressure and does it hold for 20 seconds after you turn the car off? If you pull the intake tube off the TB and open the TB blades, does it smell like gas in the plenum? Pull the vacuum line to the FPR, does it smell like gas?

Hope this helps.

 

problem solved, there was 2 issues! first issue was found when i was putting on a fuel pressure gauge. pulled the vacume for fpr and of course gas was pouring out. pulled plenum dumped bout half quart of gas out. so the diaphram was torn. skibum, you was a day late thank you tho! now after that was fixed same problem but way worse! FU STUPID KID AT ORIELLYS!!! this dumb a$$ sold me a throttle body fuel pump! 25 psi max! tpi wont run correctly on 25 psi! so that is now fixed. thanks for all the advice. now a new problem, ses that i cant get a scan on it. it wont comunicate with oriellys scanner and when you plug the scanner in it turns my fans on. weird! then i noticed if i pull the prom out the comp. with the key on it turns the fans on! first tpi ive had that does this

 

Glad you got it fixed.

With a torn diaphragm you were probably having cylinder wash too. Change the oil today, asap. There will be tons of gasoline in your oil which will harm the inside of your engine.

My fans come on when you cross the A & B in the ALDL to retrieve the codes. Careful about pulling the chip out when the car is on, I don't think it was designed to do that. Maybe something is crossed in the scanner connector or ALDL port; instead, try to just use a paperclip or piece of wire to cross the terminals and see what happens.

Hope this helps.