I'm getting misfires in cylinders 2 and 3 after tranny (clutch shavings at bottom of pan) and PCM were replaced.

The car had O2 sensor errors prior to the tranny being replaced. If the wire harness (out of the car) is turned just right, it no longer misfires. I'm being told to replace the entire harness since it will be hard to pinpoint which wire is causing the issue.

Suggestions:
1) Replace wire harness?
2) How to find the cause of the misfire - a DMM?

I've been quoted the fix will be about $2400 for the new harness and labor. It will be fixed, regardless of the cost, but I'd like to get more feedback from those that may have had the same issue and possibly another route I can take that will fix the issue, but cost less.

Thank you for your input - SD

 

WOW! Im really glad some one is happy receiving your $2400. Hell give me $2400. Ill fly there and fix it for you!

Replacing the ENTIRE HARNESS would be STUPID!

The very first thing that you need to do is read and post the DTCs

Next,,,Misfire on only TWO cylinders and their on different banks.

If your ABSOLUTY sure that it only on cyls 2 & 3, I would concentrate on the section of the harness that runs down the drivers side of the intake manifold. On some C5s the harness is situated so that it rubs a metal bracket at the back of the engine near the fuel rails. If that harness rubs through, it can cause various wires in that harness to ground out. That would be my first recommended check.

How much of that $2400 do I get if Im right!

BC

 

...

 

Mr. Curlee, how are you?

I wish you could come to Colorado and fix it for me! I would rather give the $ to a Corvette owner than a dealership!

Cylinders 2 & 3 are what I'm being told - I went back to the shop to make sure - it appeared to be the issue when they started it up.

I even sent the dealership BD's write up on O2 sensor issues 'cause they were saying they couldn't pinpoint where the problem was - that was fun to do... suggesting to a dealership what might be wrong! BD has helped me before on the O2 sensors (thanks BD!).

The dealership will not provide any codes other than the PO137/PO157. The P1416 (air sensor bank 2) is now gone. The service rep is insistent that the problem lies somewhere else and won't let me talk to the mechanic. If I decide to drive it home as is, would it hurt anything - knowing that it is misfiring? I should just loose HP, correct? If so, I will have it towed back to my house. I want it out of the dealership now! after they told me no other codes have come up (not even for the misfire) and suggested I go ask my insurance company to cover it as damage from a rodant to get it replaced!

I need Corvette contacts in Colorado so I can take the car to them!!!!

When I find another place to take it to, Bill, I will let them know what you suggested as I can't raise the car up at home!

Please let me know if you think it would be okay to drive home. Thanks!


SD

 

I could not disagree more. Since you can induce the problem at will by twisting the harness, then you need only have a multimeter and a wiring diagram to isolate the bad wiring. Time consuming yes..hard?....no.

 

If it is infact misfiring on TWO cylinders or more, NO, I wouldnt drive it any appreciable distance because the RAW FUEL being dumped into the exhaust system will cause the CATs to over heat and burn up.

If I were stranded some where and had to drive the car, you can disconnect the connector off the offending cylinders fuel injector and that would make it able to be driven without doing CAT damage. Will it even run with two dead cylinders?

You can EASILY check that harness from under the hood. Its a snap. If the harness is chaffed, I would just put a piece of rubber around the harness in the bad area, and see if that fixes the issue, Then drive it home!
The wires can easily be repaired if their damaged so a new harness is not really necessary. Take a look at that haness and see if its chaffed.


If you look at this photo, you can see the harness and also see the metal bracket that it bends around.



BC

Find your self a new garage! That steelership are a bunch of loosers!!!

 

Sorry for the delayed response - lost my home internet access over the weekend.

It did run with the two dead cylenders - not too bad either.
...I asked them several times if it was okay to drive home because I no longer wanted them to have the car. They told me I could drive it without damaging anything, it just won't have alot of HP, so I didn't have it towed home. Sounds like I need to keep it parked though!

Couple more new mech issues driving home... the heater will only blow air through the defroster and little out of the front vents and nothing to the floorboard. Bill, in the area you are showing in the picture, is where alot of air is blowing from as well. I don't believe this is normal because you can hear it blowing out; whereas, I've not heard it before. Related?

I finally got to talk with the tech... he said bring it back in and he will look at the "concentrate on the section of the harness that runs down the drivers side of the intake manifold. On some C5s the harness is situated so that it rubs a metal bracket at the back of the engine near the fuel rails".

Since the car is now back home, I will take a look at that haness and see if its chaffed. Thanks - I'll get back to you.

SD

 

Hey, you should ask for shop suggestions in the regional forum http://forums.corvetteforum.com/forumdisplay.php?f=46 Unfortunately , there are not a lot of good service places in town. A lot of stealerships and scammers, at least thats the way I feel. Some have reported that Purifoy is a good dealership. Me, I don't want to go that far north...

I can tell you that for a 2000 an engine wiring harness is $2,400 by itself from an on-line GM parts dealer. Usually in the Denver area dealers get about a %25+ premium on parts above that price. Throw in the amount of work that is necessary, I hate to think what they would realy charge you. Ask them what exactly they are suggesting replacing. Have them list exactly what all is covered by the harness.

I'd start with some easy things like pugs and wires, then take a look at the grounds and clean them up. Beyond that I can't help much, what part of town are you in?


By the way, you can get the codes your self on the DIC. Press the options button until you get to "language english", then press and hold, while holding it press the top button (fuel) 4 times. You will get a list of the codes, you'll only really be interested in the PCM codes that start with a P. While its listing the codes you can push the options button and it will let you scroll through the codes rather than watching them go by. Use the E/M button to get out of the codes.

 

I'm from the Loveland/Greeley area. Purifoy is not a good dealership! They mounted some 3-piece HRE's for me and ended up breaching seals on the wheels and tires. I'm not sure of their ability to mechanically service Vettes, but they lied to me and put nails in three of my tires because they trashed the insides of them so bad. I can't believe they let me drive on them! Lost any further service from me!

While I'm on a role... Champion Chevrolet and Ghent are both scammer dealerships too!

 

The set of harness wires that bend around the metal bracket look good. I don't see anywhere it has broke through the tape. You can see it is rubbing though.

sd

 

If that area of the harness looks good, examine the connectors and plugs for the coil packs. That the only area left.

BC

 

Cear the codes and restart it if not drive it and see what codes come back. Those will be the ones to tell you whats up (if you get codes). p0137 and p0157 are both O2 sensor codes, the p0137 can make it run rough, but not really misfire. No offense, but are you sure its mis-firing or is it just running rough? Also, are you sure that two cylinders are dead? If its really p0137 an p0157, I'd be thinking it a grounding issue (if the wires are otherwise intact).

But, BC is the go to guy for electrical issues! So, I'm sure he will be able to help you more than I can.

 

Thanks to both of you! Your feedback is very helpful...

BC: I will dig into my manual to find where my coil packs are. Guessing... is that one showing in your picture above - purple plug/orange wires? I checked all those lastnight (only on the passenger's side though). All look okay - but I will take a look at the other side too.

MB: Dealership shows Code PO758 appeared... "The engine misfires on cylinders 2 & 3 under load... that is what the dealership is saying. I'll try to come back with more info!

 

I used to wire aftermarket electronics professionally in autos for many years, many years back. I came up with a rule that says spend a certain amount of time looking for a problem and then just rewire it. I don't mean get a new harness, but you can add wires to the harness bypassing the old ones, tap into the harness at the pcm and the coils and injectors at #2 & #3 cylinders. It's only a few wires. If you do this, I recommend solder and heatshrink. You could monitor voltage and possibly pulses if needed with your DMM while twisting on the harness to help you isolate the troubled wires.

 

That's not a bad approach, provided you are sure you only have one or two wires affected. In this case, with bundled wires, there may be an area of concern i.e chaffing, burns, shorting, etc. Other wires may be affected in the same area if a problem exists, so simply bypassing a part of the harness does not fix root cause. Perhaps it's just my avionics background, but I always have to find the problem.

 

It will take me some time, but I would like to pull all the electrical tape off and inspect the wires where I can and then re-tape them back. My only concern is possibly creating more problems. Thoughts on a "rookie" doing this?

 

Guys - thanks for your help!

I'm going to have the stealership finish the work - I'm not technical savvy! I can't afford to drive it anymore and I didn't want to sell it like it is!