Oliver Tali

Hello to all!
Also english isnt my native language, so you might encounter some errors.

New to this engine type, have also searched all the forum, very similar symptoms others are having, but not like mine.
So i start the car up, first it ran very well when cold, now it starts up cold, rev counter at 700rpms, then slowly rises to cold idle 1300-1400 rpms, runs very smooth, then when the revs start to come down, the car starts to hesitate, and when the engine in warmed to normaal working temperatuure, it starts running really rough, rpms bounce between 800-300 and wnats to die out, also some hard knocking comes from down under, but not all the time, when i put it in gear, it starts to jump and will die out beacuse the lack of rpms.
Also today a really loud bang came out of the exaust, after i shut it down i can smell gas from the hood vent aswell.
So what id going on, or where to start looking the fault that is causing all this?

cmiller2014

Could be a variety of things. Mine did the same thing years ago and a new o2 sensor did the trick. Either way it sounds like you're running super duper rich!

KyleF

I would start looking at the MAF and O2 sensor. Are you using anything to pull information from the ECM? Any codes?

Oliver Tali

Havent yet, but going to paperclip it tomorrow and see what it throws out.

GeneralDisorder

iTrader: (1)

Sounds like its rich, and may have some exhaust leaks. What year TPI is it that we are working on? MAF or Speed Density?

GD

Oliver Tali

Its a 1989 car, so i quess the Tpi is the same year?
Then its a MAF?

GeneralDisorder

iTrader: (1)

The best thing to do would be to get an ALDL cable and the proper software or a scan tool that can read live data. You should be looking at O2 sensor data, MAF grams/sec, and the Coolant Temp sensor. Without knowing what the ECM is seeing you will have an uphill battle trying to diagnose it.

GD

Oliver Tali

Just papreclipped it, and it throws code 21, so my quess is that the TPS is dead, and thats why the car idles that rough, or is there something else?
Code goes like this: 12,12,12,21,12,21,12,21

GeneralDisorder

iTrader: (1)

Probably not the only issue, but may be contributing. You have a MAF car and the fuel calculation at idle is based on MAF data, not TPS. So even if the TPS was unplugged it should still idle. Don't guess - a high voltage on the TPS may not be from a bad sensor. You need to test the 5v reference from the ECU, and check that the TPS voltage is about 0.54v at idle. But you really need to SEE what the computer is seeing. Get a scan tool.

GD

Oliver Tali

What kind of a scan tool i should get, im having hard time finding some to fit the obd 1 interface from ebay

GeneralDisorder

iTrader: (1)

Either one of the old Snap-On "red brick" style scan tools (MT2500), or the Moates setup to use with a laptop:

https://www.moates.net/aldu1-and-cabl1-p-127.html

GD

Oliver Tali

Its been a long time, but managed to get it running.
Posting this so someone having the exact same issue, can find the fault faster.
The real culprit was the that the rotor had burnt the cap and its contacts, also wires were bad, specialy the one for the cyl 1.
But for the sake of it, i replaced all, all the sensor, plugs, cap and rotor.
Only things i didnt change were the injectors.
Hope it helps someone in the future.
Thank for all that helped me to get to the problem!