I'm hoping to get some good advice from this forum. I have a 198x TPI 305 that's showing some strange behavior, and I'm running out of ideas here in Sweden.
Here’s what’s happening:
The car is very hard to start and always needs start gas. Once it finally starts, it runs fine—until I hit higher RPMs. At that point, it sounds like it's choking, and the air/fuel mixture doesn’t seem right. When I start driving, it goes about 300 meters, then something kicks in and it seems to go into a sort of "safe mode." After that, I can only drive at low RPMs—if I give it more gas, it either stalls or backfires. So far, I've checked everything I can think of: wiring, relays, vacuum hoses, ignition system, fuel pump, etc. I even took it to a workshop, and they noticed something odd with the temperature sensors sending signals to the ECU. We replaced one sensor, but the issue remains. Also, some voltage readings are jumping between 12V and 24V, which seems very unusual. The workshop told me to change the ECU and hope that the problem. At this point, I'm stuck. Any suggestions or ideas would be greatly appreciated!
Thanks in advance.

 

Got pictures of the data. TPS,CTs, map, iat are all ran off 5v reference that you can only see the 5v feedback from the tps. Are you saying they replaced the CTs in the front of the intake ?

 

Thanks for the reply maybe I am not follow you now. (Might be language) what is CT? I changed the sensor that give the temperature signal to the ECU no difference with engine. At the workshop they couldn’t get any identification that’s some sensors / components are damaged. After some start gas the engine start with high revs. Then I can get full throttle and I works fine. So the car works fine with this mode. But then some happens and the engine change mode to somekind of safe mode. It goes only on low revs.

Appreciate all kind of hint and tips!

 

This is a cts coolant temperature sensor. Not sure what all you’re saying. If data is skewed on A scanner any check engine light ? So it’s running good clod just not when warmed up ?

 

 

Thanks, yes I changed this sensor but the same behaviour remains.

 

It’s running good once it starting but with high rpm. Once I ve drive around for 5min the engine change mode and only goes on low revs.

 

Whats the fuel psi?
are the injs original silver/gray? If so, ohm chem them cold and hot.
has the distributor ever been serviced or tested?

 

I think the communication is the limiting factor here. Is this a iac issue with minimum idle speed setting or something else.

 

 

I will check more tomorrow based on your comments, the distributor har never been checked since years back. Cables and sparkplug yes. I reply once I digged a little bit more.

 

oh wow, that’s not a 92 tuned port

 

Btw what is this engine even in ? Looks closer to 85-86

 

 

The engine is in this pick up.

 

Some updates, I continued on the fuel tip and I have another fuel pump. I changed it and needed to replace some poor wiring. And the engine changed behaviour to the better. Although I would not say it solved yet I need to run it more.

that was a surprise regards to the engine if it’s not 1992 it’s more like 198X? Really a surprise since I trusted the previous owner and so far I haven’t digged anything in this.

 

Valve cover are 85-86, the ecm if it’s a 1226870 it’s a 85 1227165 more than likely a 86. Tpi Maf was 85-89 speed density 90-92.

 

ECM no is 1227165 so most likely-86 than, thanks for clarification.

 

Here comes an update, I didn’t have time to work on the car but I think the case is closed now. I also believe it’s was two fault. No one, something with the fuel pressure, I check it and the valve for checking the fuel pressure didn’t seems ok. I removed checked and cleaned it. Then the car work better, still problem with high revs and hard to start. Then I checked the TPS and yes I was not ok! I order an new one and today it came and the car works as fine as it can. Well as always it was pretty obvious that the TPS was the main problem here but it’s always easy to say once the problem is fixed.
thanks for your support and ideas!