1G 1990 No spark Bad ECU?

[C-note89ky]

I’m in the same boat. My ecu needs repaired. My car sat for a long time. I have no check engine light and no movement of the boost gauge.

 

[Vincent Pandolph]

I tried yesterday to get codes with a lite bulb , and nothing was happening. I'm going to check the data wire from OBD port to ECU and make sure the ground pin 12 is good. Because, and feel free to correct me, these cars DTC codes are quite specific?

So if I get a code 14 then basically that part needs to be replaced and it's fixed? So I'm thinking if the lite bulb doesn't lite then how will ECMLink help if it doesn't connect?

 

[steve]

Nothing happening can also suggest that the ECU isn't turned on or it's dead. It can also suggest user error or that the ECU diagnostic circuit can't light that bulb. which is why we use a meter, 12v LED or 12v Piezo Buzzer.

The fault codes only point to general problems, you still have to figure out what and how.

So a 14 fault means something is wrong with the TPS circuit. It could be a wiring problem, a bad TPS, a bad IPS, or just that they are out of adjustment.

 

[Vincent Pandolph]

Ok good info there. I don't know what codes are stored, was using 14 as example. It's raining out so not sure I will get to it today. Aside from tach signal, the instructions Steve posted will work for any 1g? For testing connection continuity from PTU to ECU?

 

[steve]

That is how you test continuity for everything. There are other ways to test that there is a good connection between two points but it's generally done with a meter measuring resistance.

I was just using your example to explain that the fault codes don't usually point at a specific part.

You might want to google youtube for how to use a multimeter for other examples on what you can do with the tool.

 

[pauleyman]

I tried yesterday to get codes with a lite bulb , and nothing was happening. I'm going to check the data wire from obd port to ECU and make sure the ground pin 12 is good. Because, and feel free to correct me, these cars DTC codes are quite specific? So if I get a code 14 then basically that part needs to be replaced and it's fixed? So I'm thinking if the lite bulb doesn't lite then how will ECM link help if it doesn't connect?

You do know this has to be key on? Just checking.

 

[Vincent Pandolph]

Yeah . I had KOEO, bulb I was using was too strong. Just tested with red LED bulb and was able to retrieve 1 code #44. I ordered the PTU 2 days ago so gotta wait for that.

What else could it be.

 

[pauleyman]

Code 44 long ago was known to be a good indicator of possible bad ECU.

 

[Vincent Pandolph]

Chart says PTU, but I do have the original ECU being rebuilt RN

 

[pauleyman]

Yes the chart points to that but we've seen this a lot over the years. I would wait for the new ECU.

 

[Vincent Pandolph]

I'm going to test pin #55 for output signal.

I'm going to unplug coil PTU and fuse for fuel pump so I don't flood the cylinders, then if that's good I'm going check signal from the injector pins, I think they were 60-63.

I'm fairly sure ECU is good and in the end it's going to be a wire. I'm checking injector pulse because I've read that not enough fuel can cause same symptoms, fouling plugs and misfires.

It really nice out today so I'm going to get at it.

 

[Vincent Pandolph]

Wiring test good for harness #54 and #55, continuity is there, so it's either the ECU or PTU. I couldn't make a connection with the ECU plugged in to test for signal output. But at least I Know the wiring is good. New PTU ought to arrive by Wednesday-Friday. ECU refreshed by the following week.

 

[Vincent Pandolph]

So the guy from the ECU place told me the ECU needed to be recycled, ribbons bad and throughout, processor no good, caps leaking etc.

I did get the PTU just a few hours ago and installed it and it fires up as normal, I let it warm up and adjusted fuel pressure. Running at AFR of 11.4 at WOT 3rd gear. I think I may have a small boost leak still. But nothing like before.

So PTU was the problem for this particular no spark issue.