Test Results on ECT and EEC-IV: HELP!!

95mustanggt · 09-29-2001, 06:46 PM

Hey guys I've done a little more testing and here's what I've got:

Error codes on KOEO and continuous Mem test:

181: Adaptive Fuel rich limit reached at part throttle, right side.

189: Adaptive fuel rich limit reached, left side

543: Fuel Pump Circut Open: PCM to motor

I also tested the resistance of the ECT sensor (PCM). The resistance was 32,200 ohms when the temp gauge was at the "N" in normal (I wish I had a thermometer)

So what could all this mean? My first impression is this. There is a short between the pump and the PCM and this is causing a lean condition and detonation.

The rich condition could be caused by the coolant temp sensor causing the PCM to think that the car is cooler than it really is and cause detonation.

The only thing that is really confusing me is that I have had this detonation problem for several months and this is the first time that the fuel pump open circuit error code has come up.

I would make sense since, the detonation gets worse when the A/C is on.

Anyone have some ideas. PKRWOOD? jimberg? anyone?

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1995 Mustang GT

95mustanggt · 09-29-2001, 06:55 PM

Just as a point, the manual that I have says that the resistance of the coolant sensor is between 58,000 and 40,000 ohms when the temp is between 50 and 65 degrees and between 1800 and 3600 ohms when the temp is between 180 and 220. The T-stat was open full and the resistance was at 32,000 ohms.

Does this make sense with what you all think?

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1995 Mustang GT

jimberg · 09-30-2001, 12:30 AM

It does sound like your ECT is reporting lower temps to the ECM than it should. If it never reports a temp that is warm enough, your car will stay in open loop mode and not adjust fuel delivery according to O2 sensor readings. Like PKRWUD has been saying, though, the computer should catch that when you do a KOER (Engine running) test.

It sounds like your problem may be a little more systemic, though. Have you checked your engine block ground strap to make sure it is making good contact? You may have a simple grounding issue somewhere.

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351W 89 Mustang GT Convertible

95mustanggt · 09-30-2001, 06:40 AM

Quote:

Originally posted by jimberg:
It does sound like your ECT is reporting lower temps to the ECM than it should. If it never reports a temp that is warm enough, your car will stay in open loop mode and not adjust fuel delivery according to O2 sensor readings. Like PKRWUD has been saying, though, the computer should catch that when you do a KOER (Engine running) test.

It sounds like your problem may be a little more systemic, though. Have you checked your engine block ground strap to make sure it is making good contact? You may have a simple grounding issue somewhere.

Ya, I've checked the block for ground and it seems good. I'm going to change out the ECT sensor and see what happens. If it fixes it great, if not, back to the drawing board...

95mustanggt · 09-30-2001, 02:32 PM

So far so good. I ran the car until it was warm then took it for a quick spin. It was sit running a little hot (at the "N" in normal) but there was no detonation. I'll have to take it out later to really run it hard and see what happens.

The old sensor that I took out had some blackening on it. It wasn't black, but the copper was darker coloured in some spots and was no longer as bright as the hex flats. It would not wipe off either. Don't know what that means though.

I hope this is it and I can turn my energy to tuning what I have, and my money to some more mods. I'm crossing my fingers...

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1995 Mustang GT

09-29-2001, 06:46 PM	#1
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Test Results on ECT and EEC-IV: HELP!! Hey guys I've done a little more testing and here's what I've got: Error codes on KOEO and continuous Mem test: 181: Adaptive Fuel rich limit reached at part throttle, right side. 189: Adaptive fuel rich limit reached, left side 543: Fuel Pump Circut Open: PCM to motor I also tested the resistance of the ECT sensor (PCM). The resistance was 32,200 ohms when the temp gauge was at the "N" in normal (I wish I had a thermometer) So what could all this mean? My first impression is this. There is a short between the pump and the PCM and this is causing a lean condition and detonation. The rich condition could be caused by the coolant temp sensor causing the PCM to think that the car is cooler than it really is and cause detonation. The only thing that is really confusing me is that I have had this detonation problem for several months and this is the first time that the fuel pump open circuit error code has come up. I would make sense since, the detonation gets worse when the A/C is on. Anyone have some ideas. PKRWOOD? jimberg? anyone? ------------------ 1995 Mustang GT

09-29-2001, 06:55 PM	#2
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Just as a point, the manual that I have says that the resistance of the coolant sensor is between 58,000 and 40,000 ohms when the temp is between 50 and 65 degrees and between 1800 and 3600 ohms when the temp is between 180 and 220. The T-stat was open full and the resistance was at 32,000 ohms. Does this make sense with what you all think? ------------------ 1995 Mustang GT

09-30-2001, 12:30 AM	#3
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	It does sound like your ECT is reporting lower temps to the ECM than it should. If it never reports a temp that is warm enough, your car will stay in open loop mode and not adjust fuel delivery according to O2 sensor readings. Like PKRWUD has been saying, though, the computer should catch that when you do a KOER (Engine running) test. It sounds like your problem may be a little more systemic, though. Have you checked your engine block ground strap to make sure it is making good contact? You may have a simple grounding issue somewhere. ------------------ 351W 89 Mustang GT Convertible

09-30-2001, 02:32 PM	#5
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	So far so good. I ran the car until it was warm then took it for a quick spin. It was sit running a little hot (at the "N" in normal) but there was no detonation. I'll have to take it out later to really run it hard and see what happens. The old sensor that I took out had some blackening on it. It wasn't black, but the copper was darker coloured in some spots and was no longer as bright as the hex flats. It would not wipe off either. Don't know what that means though. I hope this is it and I can turn my energy to tuning what I have, and my money to some more mods. I'm crossing my fingers... ------------------ 1995 Mustang GT