Bad ECM?

Topic: Bad ECM? (Read 20646 times) previous topic - next topic

Reply #60 – March 17, 2015, 11:13:21 PM

Haha, yeah I hope it works. I Think perhaps that black mark is the reflection? I didn't suspect while looking at it closely. As far as the O2s, I know the difference in the loops between the auto and manual. But on my speed density harness, the loop off the manual harness goes nowhere. I'm still confused about it. I left it unplugged for now hoping it won't cause issues with the trace if it's unplugged. But I guess I need it to run the engine right. Haha, I just can't find a pin out for the 88 O2 engine Connector harness.

Bad ECM?

Reply #61 – March 17, 2015, 11:19:13 PM

I found this on a mustang forum. So I guess I just need to make sure that there is no voltage being looped back to the sig rtn.

Bad ECM?

Reply #62 – March 17, 2015, 11:50:08 PM

I checked Advance and same o2 sensor is listed for 5.0 in '88 T-Bird plus '87(SD) & '92(MAF) Stang, no doubt are wired same(plus I long ago verified the wiring when I did my swap)...

Bad ECM?

Reply #63 – March 18, 2015, 12:02:32 AM

There are four different plugs for 1986 cougars. I know because I had to order it for a 1987 to get the correct one. 1986 also didn't always have heated oxygen sensors.

Bad ECM?

Reply #64 – March 18, 2015, 12:34:55 AM

When you spliced the manual and AOD wires together at pin 30 this put 12v on pin 46. This is what blew out the land pattern in the EEC.
Take another look at post #29.

Bad ECM?

Reply #65 – March 18, 2015, 12:52:22 AM

Alright. So I needn't worry with the O2 then? Should there be no voltage on pin 46 at any point?

Bad ECM?

Reply #66 – March 18, 2015, 12:59:59 AM

I wonder now if I could even run my factory speed density O2 harness and not even have a problem. Since there would be no loop to worry about. Thoughts?

Bad ECM?

Reply #67 – March 18, 2015, 01:01:12 AM

I find it weird that on my Sport, there were two O2 connectors on the injector harness, and two more on the engine harness. I used the engine harness connectors, but had issues with the O2 sensors connected, so I shortly unhooked them and zip tied the connector ends up out of the way.

I've also read on Corral and a few other Mustang sites about there being differences in the AOD and T5 wiring for O2, and mismatching them will fry the EEC. I think T Moss even has something about it in one of his writeups.

Bad ECM?

Reply #68 – March 18, 2015, 06:14:29 AM

Quote from: ThunderbirdSport302;446282

I find it weird that on my Sport, there were two O2 connectors on the injector harness, and two more on the engine harness. I used the engine harness connectors, but had issues with the O2 sensors connected, so I shortly unhooked them and zip tied the connector ends up out of the way.

I've also read on Corral and a few other Mustang sites about there being differences in the AOD and T5 wiring for O2, and mismatching them will fry the EEC. I think T Moss even has something about it in one of his writeups.

You are correct sir. The manual and automatic o2 harnesses are pinned differently. Mismatch them and poof goes the ECM.

Bad ECM?

Reply #69 – March 18, 2015, 08:48:05 AM

Quote from: ThunderbirdSport302;446282

I find it weird that on my Sport, there were two O2 connectors on the injector harness, and two more on the engine harness. I used the engine harness connectors, but had issues with the O2 sensors connected, so I shortly unhooked them and zip tied the connector ends up out of the way.

Very interesting. How did your bird run without them? I may try tying them up as well.

Bad ECM?

Reply #70 – March 18, 2015, 10:59:26 AM

Quote from: FOX-XR7;446279

Should there be no voltage on pin 46 at any point?

Pin 46 is a ground. The ground used by the electronics in The EEC as apposed to the chassis ground used by the rest of the car stuff.
Don't know about the O2 stuff. I have to do some research on that. If the o2 heater circuit wires get crossed up with the sensor wires, I can see where that would blowup something in the EEC.

Edit: The 93 Mustang EVTM shows no difference in the O2 wiring between manual and AOD \transmission.
The O2 sensor EEC pins are the same as the 1988 Cougar.

Bad ECM?

Reply #71 – March 18, 2015, 12:05:52 PM

Well, I went over today, threw the computer in, and cranked it over. She fired up and idled for a bit. I noticed a coolant leak from the egr passage so I shut it off. She sounded a little rough, but I think that's because I need to adjust timing, fuel pressure and idle yet. More to come when I get that all setup.

Bad ECM?

Reply #72 – March 18, 2015, 12:47:20 PM

The 93 Mustang O2 harness is different than the 88 cougar.
The 88 uses one 8 pin connector C429
The 93 uses one 8 pin connector C101 and two 4 pin connectors C193 (left O2) and C1005 (right O2)
The wire colors are different between 88 and 93.
Looks like you will be connecting Stock harness C429 to Mustang harness C101. ( If your Mustang harness matches mine)
You will have to check that the wires match up right between the two.

I don't see why you cant use the stock 88 O2 harness.

Bad ECM?

Reply #73 – March 18, 2015, 01:16:37 PM

Alright. I'll throw my original back on. Because I know the mustang harness on my cougar eec engine harness didn't match up right before. But I'll check the wiring first. I can get back with colors of wires between the two when I get back over there.

Bad ECM?

Reply #74 – March 18, 2015, 01:25:34 PM

Maybe its a Mustang only thing, in regards to the O2 and the different harnesses.

In any case, it's something I need to concern myself with as my donor car was an AOD, the recipient car is T5 and will be using the donor car's engine, dash, and injector harness. Too cheap and far away from a tuner, or I'd simply have the O2 function bypassed at the EEC via a chip...

As for not running them, if you have catalytic converters, they'll eventually plug up as the lack of O2 inputs causes a bit of richness in the fuel/air mix. The previous owner cut the cats off of my Mountaineer and ran a custom dual exhaust...when i went to get it licensed the first time, the shop insisted there be a cat before they'd pass inspection on it, so they put one way downstream, almost by the back tire. Stupid-assed, I know, but at the time, I need the thing legal ASAP, so I agreed. Anyway, fast forward about 2 years, and late last summer, the son of a bitch plugged up as there's no O2's on the Mounty. I cut the tail pipe off and "unplugged" the cat, and had the pipe put back on. Now she has her power back and all, but now my manifold gasket(s) have a leak due to the increased pressure of the plugged cat from before.

I'd like to put the cats back on (the proper way), but all the ones in junkyards have had the cats torched off. Makes me want to smack the shiznit out of people.

Anyway, unless you can get a tuner to delete the O2 inputs and tune them out, I'd leave them in and functioning, as it will cut down a wee bit on fuel use...My mounty ought to get 15-18 MPG, I'm lucky to get 12 with a tail wind. 5.0, and a bunch of subs, amps, and some tools and gear in the back, too.

But yeah, enough of my hijack..sorry.