So the dealership seams to be sure that I have a bad engine wire harness and that that could also be part of why I'm having catalytic converter problems. They also think some of it is a cracked intake manifold gasket.

I know cracked intake manifold gaskets are kind of a common problem with these but is the engine wire harness getting brittle and going bad common? The dealer says it's common...

How hard is it to replace the engine wire harness?

it's a major pain in the <img src="/forums/images/graemlins/butwiggle.gif" alt="" />.
Consider this in order to removeit you need to pull the dash, heater core & a/c evaporator. And that's only on the inside. Under the hood you need to remove the radiator & a lot more other stuff. You are looking at least 4-5 full days of work if you are doing it alone & for the first time.

The above is in regards to the harness that goes from left to right in the engine bay.

If they are talking about the one that is on the engine, than you would have to pull the engine to replace it.

Not as bad as PAYING someone to do it! Zu's have a sensible harness, connectors only fit connectors in the appropriate area.
Since your prob seems to be in engine control. you're only concern is in the engine bay and ECM.
Never seen a bad wire harness on an Isuzu, or any ***** horse for that matter, unless some ham-fisted radio, alarm system or fog light installer got there first. Odds are your problem lies elsewhere. Zu's are mostly relay controlled with fuseable backup. Wire insulation is more than adequite too.
Perhaps if you could give more specific HISTORY to what led up to this diagnosis, more of us can help you...Cal

It sounded like they were talking about the one on the engine. They want some were around $1k to do it and I asked how much it would be if I skipped the intake manifold gasket and they said they have to take the manifold off when they replace the harness any way.

I was hoping I could do it myself cuz I'm in collage and have no money so my dad would have to pay for it and since he already says I need to look for a new car cuz this thing gets only 12mpg, so he would probably not pay for it and say get a new car.

I wish I had the car here so i could look at it and get an idea of how much work it is but I guess I'll have to check AllData next time I'm at school and see if it lists how to replacing the harness.

I had the pleasure of removing a harness from a 94 Rodeo <img src="/forums/images/graemlins/shiner.gif" alt="" />. I had the benefit of not caring whatsoever about the vehicle I was removing it from, and it was still a royal PITA <img src="/forums/images/graemlins/angry.gif" alt="" /> I hope that's not what you're up against <img src="/forums/images/graemlins/confused.gif" alt="" />

<img src="/forums/images/graemlins/cheers.gif" alt="" />Andre

Ok little long history. Sorry it's really long.

About 4 months ago it bogged down on the freeway well I was passing someone and would barely accelerate and throw a flashing check engine light with these codes:

P0157 - O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2)
P1171 - Unknown Powertrain DTC (Manufacturer Controlled; Fuel and Air Metering)
P0300 - Random/Multiple Cylinder Misfire Detected

Here is the thread I started then.

Then the dealership looked over it for a long time and ended up taking every thing off to get to the timing belt and told me the belt had slipped and that was the problem and wanted $500 for having to do so much work diagnosing it and $400 to replace the belt. So I wasn't happy about that and told them I would call them back. A day or so later they called me back saying they had the tech's run a few more test and found out that the passenger side catalytic converter was partially plugged up, had flow but not enough, and replaced it under warranty and that fixed the derivability problem and it drove fine again. So they didn't charge me the $500 cuz they were wrong about the timing belt being the problem. I still don't know how they can look at the timing belt and tell me it slipped then tell me its fine. So that seamed to fix things for then.


Then about a month ago I was merging onto a freeway that goes over the local mountains and had to have it floored for close to a minute to get up to speed with traffic when the check engine light came on again. I got home and it was a P0137 - o2 Sensor Circuit Low Voltage (Bank 1, Sensor 2) code. So I cleared the code and it didn't come on again until the next time I had it floored merging onto the freeway up the mountain when the same code tripped. So I cleared it again and decided to swap the two rear most o2 sensors to see if the problem moved too (bad o2 sensor) but it turned out that the dealer never used anti-seize when they replaced my catalytic converters the 4 times before so the sensors were seized in the exhaust so I couldn't swap them. A thread about that all here. So I just left it cuz I couldn't do any thing at the time.

Then a week or two ago I was on the freeway accelerating but not very hard when I had a flashing check engine light again. After that it acted the same as last time I had the flashing light, hard to accelerate on the freeway and stay up to speed go up hill. And the codes it showed this time were:

P0137 - O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)
P1171 - Unknown Powertrain DTC (Manufacturer Controlled; Fuel and Air Metering)
P0300 - Random/Multiple Cylinder Misfire Detected

But this time it was easy to trip the flashing check engine light again, stay over 3K rpm longer then say 30 seconds and it started flashing again, were as the first time I only tripped the flashing check engine light once. Also the first time it was really hard to keep up to speed on the freeway, pretty much had to keep it kicked down in 3rd to keep up, were as this time I could keep it in 4th but could barely accelerate.

I had to drive with it like that for about a week cuz the local dealer refused me service now because I always spotted all there mistakes and the bad work they did and said a lot of bad stuff about them online, and since I had to go out of town to another dealership I had to wait for my dad to get back from business so he could drive me home for the dealership.

So I get it to the new dealership last night. So since last time it had a bank 2 code and they replaced the passenger side cat. and this time i had a back 1 code I figured bank 1 was the driver side and told the dealer I suspected the driver side cat.

So I got a call from the dealership a little while ago explaining how they thought it was the engine wire harness and the intake manifold gasket. They had moved around the wire harness when it was all cold and the engine idle would fluctuate a little now and then or something like that. Also they sprayed starter fluid (I think they said starter fluid) around the intake manifold and the idle would change just a little bit. So they said that the cracked intake manifold gasket could cause the P1171 code I had, they said the code was something about being lean (forget exactly what he said) then they said that the bad/shorting engine wire harness could trigger 02 sensor codes and misfires.

Now the part that confused/interested me was that they said the bank 1 o2 sensor code is the passenger side, but last time when I had a bank 2 code they replaced the passenger side converter. So if they are right about passenger side = bank 1 and driver side = bank 2 then last time I had a driver side code and the passenger converter was replaced and this time I have a passenger side code.


Again sorry that was so long, but that's the full history of this problem. Please help this could be the factor that decides wether I HAVE to get a new car or can keep my this one and I love this one.

Thanks
Noah

The people you are dealing with sound like complete morons, either that or cunning businessmen. I vote for a little of both. The way you spot someone who doesn't know what they're talking about is when they try to assign humanlike qualities to something they don't understand. Wiring harnesses don't "go bad"--they are not replaceable items. they do not "get possesed". It is never "hey it would be a good time now on that car to replace the wiring harness". They aren't even considered an item. It may be an item to the dealership in that it has a part number and can be ordered and installed in exactly 11.25 man hours which equates to X dollars of service revenue, but they aren't an item in the troubleshooting sense. What are they going to do next, replace the computer? "Hey Noah must be a bad computer, we should probably replace it." Or, "a bad frame, and engine, have to replace that too."

Rubo thought you were talking the entire wiring harness, maybe you are, if not, the engine harness can be replaced while the engine is in the vehicle.

If you had a problem with your engine would you throw away the entire engine? No, you might want to consider finding the problem first right?

My advice would be to find another dealership. Are you even under warranty?? You're not right? Why are you even going to a dealership? Here's lesson number one about dealerships. They sell cars so they sell service with the same mindset. They do not earn their reputation in the community based on the repair business, it is based on the selling cars business. They earn customers by selling cars then they try to tack on as much extra work as possible to sell more labor hours for repairs. I have two friends that work in sales in the service department. they make commissions on selling stuff you don't need. Everybody has to make money, and I can't fault them for that, but you really should consider having repair work done at a place where their work is the basis of their business.

I would have the dealership replace the intake manifold gaskets then find another shop to examine the other symptoms if they even continue. My guess is they won't.

The construct of an OBD II computer is such that it has no way to explain to a human being what is happening during an unexpected event. Air entering the system that is not accounted for by the MAF, TPS, and IAT sensor is going to throw off the combustion and timing events such that you'll get misfires. I bet it is the intake manifold gasket and your wiring harness is not posessed by the devil.

I also wanted to say the Isuzu wiring harnesses I pulled out of my 92 pickup only used plastic looms in one small section and the rest was electrical tape manually wrapped around it. Sometimes 2-3 layers thick. I was really impressed. The wire inside looked brand new and it was on a section that was submerged regularly, definetly waterproof.

To be more exact I think they said it was shorting out. It would be nice if they would actually test it instead of wiggling it and seeing if something changes.

I am still under warranty till mid next year and 85k miles, extended warranty. That's the only reason I bring it to the dealer, otherwise I do all my own work. But since I had the same codes and symptoms as 4 months ago just with a bank 1 instead of bank 2 and the cat being replaced fix that, I figured I would bring it in and they would replace the other cat under warranty and fix it again. But this guy seams to think that the bad cat is only the affect and that something on the engine is causing it to fail, shoring engine wire harness and intake manifold gasket.

This already is another dealer, my local one refuses to provide me service after I gave them such a hard time about there bad work last time, so this time I had to go out of town.

So the bad intake manifold gasket it likely correct but that's something not to hard that I would do myself. So any one have a better guess as to what else is wrong?

bad engine, replace it