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I own an 86' irocz z28 (LB9) and I've been having issues with it the last while. If it sits for a while it'll run amazing for about 10-15 mins then stalls out and won't start up after. It'll start to run really rich after. I'm a little lost on whats happening. I've replaced the 02 sensor, MAF, IAC, pick-up coil, fuel pressure regulator and put in new spark plugs. I might be missing somethings. Can anyone give me some advice on the issue?
Without live data/scan tool this will be tough to diagnose without knowing what the computer is seeing... Any check engine light or codes? Have you checked the injectors by ohm readings them warm and cold? Have you tested the Ignition Control Module? Just throwing a few ideas out there.
Without live data/scan tool this will be tough to diagnose without knowing what the computer is seeing... Any check engine light or codes? Have you checked the injectors by ohm readings them warm and cold? Have you tested the Ignition Control Module? Just throwing a few ideas out there.
When I scanned it, it was only coming up with code 34. I've checked the injectors and they were reading correct (I can't remember of the top of my head but they matched the book) I also put in a new ICM when I did the pick-up coil.
Do you have a scanner that can get live data? Check your wiring for the MAF and its relays, these cars are also sensitive to aftermarket MAFs and sometimes a cleaning with MAF cleaner helps. Also have you checked the Throttle Position Sensor to be sure it is set at proper voltage (.54v) and voltage readings are smooth and not erratic when opening and closing the throttle? Any fuel pressure readings? I wonder if you have some leaky injectors?
Do you have a scanner that can get live data? Check your wiring for the MAF and its relays, these cars are also sensitive to aftermarket MAFs and sometimes a cleaning with MAF cleaner helps. Also have you checked the Throttle Position Sensor to be sure it is set at proper voltage (.54v) and voltage readings are smooth and not erratic when opening and closing the throttle? Any fuel pressure readings? I wonder if you have some leaky injectors?
I had a friend with the Obd1 scan tool hook up and TSP seemed to be in good order (we used the scanner months ago and everything was to the book) I am reading fuel pressure, I haven't put a gauge on but It does have pressure. If my injector is leaking would there be any signs? I'm a younger guy and I'm learning everything as I go. As per MAF, I see no wire issues and I did get a new MAF to see if it would resolve the issue. Correct me if I'm wrong but I believe code 34 does pop up if it doesn't start. I do have the EGR deleted. Maybe my vacuum is the issue?
I had a friend with the Obd1 scan tool hook up and TSP seemed to be in good order (we used the scanner months ago and everything was to the book) I am reading fuel pressure, I haven't put a gauge on but It does have pressure. If my injector is leaking would there be any signs? I'm a younger guy and I'm learning everything as I go. As per MAF, I see no wire issues and I did get a new MAF to see if it would resolve the issue. Correct me if I'm wrong but I believe code 34 does pop up if it doesn't start. I do have the EGR deleted. Maybe my vacuum is the issue?
If your injectors are leaky fuel pressure would drop down pretty fast, but you will need a gauge to tell, after shutting the engine down, also say you go for a ride and shut it off for a brief time and try to restart and it will not want to start unless you floor the accelerator and once it starts it will have a smoky/gas smell from fuel leaking from the injector/s. I would buy or get a fuel pressure gauge and see what's happening there, that tool is needed with these cars.
If you have a vac leak you will hear a hissing sound and idle will be high or erratic. You can make a simple smoke tester with a $5 harbor freight fluid exchanger and a cheap cigar, there is a good video on YT that shows you how.
I would hook up the scan tool and see what the data reports when the issue happens, that way you can see what may be causing the issue.
I did yes. I also closed the vacuum system when doing so, well to my knowledge I did. I've been using this very helpful forum along my journey but with this current issue, I've yet to come across a solid lead.
As per your last message. I will test for a vacuum leak and run a gauge to see what's going on. Using the scanner is hardly an option for me at the moment. Been trying to find one to buy. Will keep the thread up to date for other members.
Keep us posted, a snap on MT2500 aka The Brick is a solid choice and can be found used on ebay etc but be sure to get the right cartridges for your car. I use a BT scan tool from 1320 electronics that has worked great for me and is inexpensive but last I knew he had supply issues but may be worth a look. Actron9690 is also supposed to be a good one too
Keep us posted, a snap on MT2500 aka The Brick is a solid choice and can be found used on ebay etc but be sure to get the right cartridges for your car. I use a BT scan tool from 1320 electronics that has worked great for me and is inexpensive but last I knew he had supply issues but may be worth a look. Actron9690 is also supposed to be a good one too
Thank you so much! I will look into getting a scan tool and going from there. That 1320 looks very interesting and will do so research. Thanks again for everything, hopefully I'll have an update soon!
also one other easy thing to check is since it seems to be once it warms up you are having trouble and you think it is running rich, make sure the temp sender to the ECM is working... if it fails open circuit the ECM will think it is -40 outside and be adding a lot of fuel
Been busy with life and got time now to look back into my issue. I started checking wiring and seeing if there was damages in the harness and and came across I assume a ground?(brown and black with white stripe) Not sure trying to look at the wiring diagram but it's difficult for myself to determine what it's for. Anyone able to inform me?
Btw does this run any better ? If it has the AUM memcal in the computer I’ve seen that cause all kinds of running issues. Might check it and search some of vaders old posts on that calibration issues.
Btw does this run any better ? If it has the AUM memcal in the computer I’ve seen that cause all kinds of running issues. Might check it and search some of vaders old posts on that calibration issues.
Unfortunately it's still acting up. It'll run perfect then slowly kill itself still. I have videos of it happening not sure if they can be posted still new here. That's why I started going through the wiring thought maybe when it gets warm a wire is loosening up. But I will look into that. I'll have to learn all about that. Still new to this and it slows me down lol
Having the o2 ground might really help it actually going into closed loop. Here’s some information about the AUM calibration. Just a thought you might want to see what’s in the ecm.
Okay thank you, it does have an aftermarket e-prom in it. I still have the factory one. That was my next look if I can't find something more noticeable.
I think the blue one says any not a bad tune i don’t think. Might be better than a jets.
Okay thank you for your knowledge! I remember when I first got the car running it had the stock one in. It ran pretty good, when I put the jets one in, it was like a different car it sounded healthier smoother idle and sounded like it it wanted to lay down 11's 😂
So after putting everthing together the issue was still there. I swapped out the proms and the car ran perfectly fine, even made to operating temperatures. Guess the jet prom had issues
07-08-2023, 07:04 PM
