Poor low rpm performance, erratic idle

[rudypoochris]

Hmmm. I think the ECU should log the engine codes...

Does yours happen when cold also or just when hot?

 

[steve53]

It normaly throws the code when the motor is hot. The scanner read no codes while running the engine off test. When I tried to use the scanner for the engine running test, it said it was retrieving codes, but after about 30 min I gave up. The store employee said it shouldn't take nearly that long to retrieve codes. Possibly there scanner was FUBAR. Will try another store. Thanks.


Steve

 

[rudypoochris]

Maybe O2 sensors or IAC. If it does it when its hot.

http://fordfuelinjection.com/

Good website.

 

[steve53]

Thanks for the website, it is very helpful. I ran the KOEO test and I am listing what I got: 52,2,52,2,1,17,7,33,6,54,2,54,3,17,7,33,6,54,2,54,3. I am not sure what the single digit numbers are but the double digits I am pretty sure are correct after running the test about 6 times. Looks like rpm with IAC is low, egr open not detected, and ACT sensor signal is high. Thanks for all the help.


Steve

 

[MrShorty]

If this is on a '93, you should be getting three digit codes. Here's what I get (see BrooklynBay's EEC-IV code list in the EEC-IV forum.)

52,2,52,2=KOEO 522,522=PNP switch fault. If you have an automatic transmission, the transmission is supposed to be in park during the KOEO test, if you have a manual transmission, it's supposed to be in neutral for the test. Repeat KOEO test, making sure the transmission is in the proper position. If the code returns, then inspect the PNP switch circuit. This fault should be pretty easy to track down with a voltmeter and a wiring diagram.

1 = separator pulse between KOEO and CM codes.

17,7,33,6,54,2,54,3,17,7,33,6,54,2,54,3=CM 177,336,542,543

CM177=left O2 sensor reading rich
CM336=PFE sensor high
CM542=fuel pump circuit went open during engine operation.
CM543=fuel pump circuit fault during engine operation

SOP with EEC-IV codes is to resolve KOEO codes first, so work on the KOEO 522.

Once that is resolved, move on to the KOER test (see the stickies in the Under the Hood forum and the EEc-IV forum). Resolve the KOER codes. Then clear CM and test drive to see which CM codes come back.

 

[steve53]

Thanks for the info. I will play around with the truck today and see what I come up with. I appreciate your time and help.


Steve

Update: I crawled under my truck to check out the o2 sensors with the key on. The passenger side is noticeably warm where the drivers side is not. The drivers side appears to be a hack job from PO as there are butt connectors hooking it up to the harness and the colors on the harness side do not match wiring diagram colors, they are all white. I will investigate further and possibly buy a new o2 sensor.

 

[steve53]

I removed the drivers side o2 sensor to uncover how bad of a hack job there actually was. There are 4 sets of 4 butt connectors connecting the o2 to the harness. After referring to my Haynes wiring diagram, it shows that HEGO #1 is a 4-wire sensor and HEGO #2 is a 3-wire sensor, but both of mine are 4-wire, the harness for both are also 4-wire. Looking at the wiring diagram for the 1995 explorer, it shows both o2 are 4-wire. Perhaps my 93 diagram is incorrect.

I also ran the KOEO test with the stick shift in neutral and am still getting the 522 code. What does this affect? Thanks

Steve

 

[rudypoochris]

The EFI system changed considerably over the years. My 92 only has 1 O2 sensor. As for your other questions, im no expert in that regards.

 

[MrShorty]

The PCM uses the neutral position switch to know when to expect a load on the engine. A bad switch can effect idle. I'm not certain it would explain all of your symptoms, but that's where I would start.

Will the code go away if you sit in the truck and hold the clutch in during the KOEO test? It's a pretty simple circuit, so it should be easy enough to track down.

As for the O2 sensors, I thought they were both the same (4 wire). The O2 sensor code is for the driver's side, so the code is for the sensor with the homemade wiring job. It would probably be worth the effort to make sure all those connections are good.

 

[steve53]

Last night I rewired the o2 sensor and removed all of the butt connectors. After removing all of the electrical tape, some of the wires fell out of their butt connector. The sensor now heats up. I took my truck for a long drive and did not get any codes and it seemed to run stronger. I was incorrect about the wire colors on the o2 sensor, I thought they were all white but there are in fact there are two white wires which are for the heating element, one black for the ground, and a grey wire for the signal to the pcm.

I investigated the Manual Lever Position Switch also and all I could find on the drivers side of the tranny was a 2-wire connector that is hooked to nothing. It has a LT BLU/YEL wire and a GRY/RED wire. It comes off of the harness for the back-up light connector but I could not find a sensor for it to connect to anywhere. I have not tried pushing in the clutch pedal to see if it would clear the 522 code yet, may try that today. Thanks for all your assistance, it helped me alot.


Steve

 

[91exploreron37]

There should be another connector on the passenger side of the tranny which is probably hard to see because of the exhaust.

 

[steve53]

When I was under the truck I did not bother looking on the passenger side of the tranny because the plug would not reach that far anyway. It only extends about 8 inches away from the reverse light switch. When I get a chance I will look at the passenger side and see if there is a plug. Thanks.


Steve

 

[91exploreron37]

That sensor on the pass side of the tranny has a wire running from it around to the driverside of the tranny where it then connects. I'm assuming because of the exhaust is in the way.