Making Sense of EEC IV Codes and tests

95mustanggt · 08-08-2001, 02:14 PM

My detonation problem is still present and I am getting tires of the timing still being set at 0 degrees.

I connected a jumper cable on the diagnostic port and ran a KOEO test. I did get one code but I'm a little lost on it here how the test went:

start test. 3 single flashes 2 seconds apart.

4 second delay

3 single flashes 2 seconds apart

6 second delay...single flash...5 second delay

single flash, double fash, triple flash. Atleast this is what I saw. I have not run a KOER test yet.

I replaced the IAT sensor and cleared the codes and the car is running better, but is still detonating when the PCM advances the timing every so often. The detonation is fairly light. I am running Exxon 89 octane fuel.

Before I try to test all the circuits (TPS ad EGR are suspect to me) anyone have some ideas. It's well over 100 degrees down here and to a Canadian, it's just too dam hot to spend too much time under the hood.

Help.

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1995 Mustang GT

95mustanggt · 08-08-2001, 07:49 PM

Anyone??

jimberg · 08-08-2001, 08:50 PM

A code 123 means that the TPS voltage is out of range. Hook up a digital voltmeter to the green (+) and black (-) wire of your TPS (The black thing on the top of your throttle body). Turn the key into the on position and the voltage should be .9 to less than 1 V. Move the throttle slowly toward WOT and see if it goes up smoothly to about 4.6 V. If it doesn't, replace it.

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351W 89 Mustang GT Convertible

95mustanggt · 08-08-2001, 09:33 PM

Thanks jimberg.

I tested the entire IAT circuit and it was good, everything in spec.

The TPS was at 1.04 at idle and the KOER test gave a 123 code too.

Guess it is time to change it. I could not check it at WOT as I was by myself

It's on $35 though.

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1995 Mustang GT

PKRWUD · 08-09-2001, 01:44 AM

The ECM determines whether or not you are at idle right at the 1 volt point, in the TPS circuit. If at idle your reading is 1.04, the ECM thinks you are driving, not idling. This could have something to do with your timing. loosen the screws on the TPS and try to rotate it far enough to get a voltage reading of .95, or close to it. Some might suggest getting it as close to 1 volt as possible for more performance, but they are idiots. There is no noticable difference in performance, but the closer you get to 1 volt, the more likely you are to confuse the ECM. The other test you should do with your TPs, that most people don't, is to unplug the connector, and hook up a DMM with a bar graph across the reference wire and the ground wire and set it to ohms. Then watch the bar graph while slowly turning the throttle. It shouldn't back step once. If it's nice and smooth, you're good, but if it jumps back and forth, the potentiometer has worn spots in it's travel (usually right after idle), and must be replaced. This can be done with a voltmeter with the connector plugged in, and by back probing the wires, and turning the ignition on, but it's much more acurate unplugged and by resistance. Anyway, once you have the TPS set, disconnect the battery, turn on your headlights for 2 seconds, reattach the neg. bat cable, pull the spout connector and start it up. Check your timing. Set it at 10 degrees BTDC. reinstall the spout and go for a drive. Post your results.

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

95mustanggt · 08-09-2001, 08:45 AM

Thanks PKRWUD. When I get home from work I'll give that a try. I was going to do it last night after the chat, but it was dark and all I could find was a little pocket flash light. Besides the weather in Dallas is suppose to be cool tonight, working on the car after work will be better.

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1995 Mustang GT

08-08-2001, 02:14 PM	#1
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Making Sense of EEC IV Codes and tests My detonation problem is still present and I am getting tires of the timing still being set at 0 degrees. I connected a jumper cable on the diagnostic port and ran a KOEO test. I did get one code but I'm a little lost on it here how the test went: start test. 3 single flashes 2 seconds apart. 4 second delay 3 single flashes 2 seconds apart 6 second delay...single flash...5 second delay single flash, double fash, triple flash. Atleast this is what I saw. I have not run a KOER test yet. I replaced the IAT sensor and cleared the codes and the car is running better, but is still detonating when the PCM advances the timing every so often. The detonation is fairly light. I am running Exxon 89 octane fuel. Before I try to test all the circuits (TPS ad EGR are suspect to me) anyone have some ideas. It's well over 100 degrees down here and to a Canadian, it's just too dam hot to spend too much time under the hood. Help. ------------------ 1995 Mustang GT

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08-08-2001, 07:49 PM	#2
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Anyone??

08-08-2001, 08:50 PM	#3
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	A code 123 means that the TPS voltage is out of range. Hook up a digital voltmeter to the green (+) and black (-) wire of your TPS (The black thing on the top of your throttle body). Turn the key into the on position and the voltage should be .9 to less than 1 V. Move the throttle slowly toward WOT and see if it goes up smoothly to about 4.6 V. If it doesn't, replace it. ------------------ 351W 89 Mustang GT Convertible

08-08-2001, 09:33 PM	#4
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Thanks jimberg. I tested the entire IAT circuit and it was good, everything in spec. The TPS was at 1.04 at idle and the KOER test gave a 123 code too. Guess it is time to change it. I could not check it at WOT as I was by myself It's on $35 though. ------------------ 1995 Mustang GT

08-09-2001, 01:44 AM	#5
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	The ECM determines whether or not you are at idle right at the 1 volt point, in the TPS circuit. If at idle your reading is 1.04, the ECM thinks you are driving, not idling. This could have something to do with your timing. loosen the screws on the TPS and try to rotate it far enough to get a voltage reading of .95, or close to it. Some might suggest getting it as close to 1 volt as possible for more performance, but they are idiots. There is no noticable difference in performance, but the closer you get to 1 volt, the more likely you are to confuse the ECM. The other test you should do with your TPs, that most people don't, is to unplug the connector, and hook up a DMM with a bar graph across the reference wire and the ground wire and set it to ohms. Then watch the bar graph while slowly turning the throttle. It shouldn't back step once. If it's nice and smooth, you're good, but if it jumps back and forth, the potentiometer has worn spots in it's travel (usually right after idle), and must be replaced. This can be done with a voltmeter with the connector plugged in, and by back probing the wires, and turning the ignition on, but it's much more acurate unplugged and by resistance. Anyway, once you have the TPS set, disconnect the battery, turn on your headlights for 2 seconds, reattach the neg. bat cable, pull the spout connector and start it up. Check your timing. Set it at 10 degrees BTDC. reinstall the spout and go for a drive. Post your results. Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

08-09-2001, 08:45 AM	#6
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Thanks PKRWUD. When I get home from work I'll give that a try. I was going to do it last night after the chat, but it was dark and all I could find was a little pocket flash light. Besides the weather in Dallas is suppose to be cool tonight, working on the car after work will be better. ------------------ 1995 Mustang GT