Isuzu SUV Forum banner
1 - 20 of 48 Posts

·
Registered
Joined
·
101 Posts
Discussion Starter · #1 ·
I started a thread on Oct 10, 2011 called Bucking and Hesitation - 2002 Rodeo. The problem was tracked down to an apparent short in a portion of the wiring harness. I removed the flexible tubing and tape and then separated the wires that were stuck together. The car immediately started running fine and there have been no further issues - until 2 days ago.

We took a road trip to Atlanta and drove about 600 miles over two days. The car was running great until I exited the interstate in Atlanta. Then, the engine started the same type of hesitation, although the issues are a little different. The hesitation was most severe only between 2-3K rpm. Above 3K rpm, the engine only had slight hesitation once in awhile. If I accelerated hard, shifting in the 4-5K rpm range, the engine ran without any hesitation. The 600-mile trip home was mostly at 3.0-3.5K rpm and there were only occasional misfires. The temperature gauge stayed in the normal position and the check engine light never came on. My OBD reader shows no stored codes and the all of the monitoring systems are OK.

In the original thread, there was a suggestion that there may be a crack in the air intake. I'll be checking for that possibility as soon as I post this thread. In October, I also checked the fuel pressure, changed the fuel filter, cleaned the throttle body around the butterfly (did not remove from engine) and cleaned the MAF sensor.

Any other suggestions are appreciated.

David
 

·
Registered
Joined
·
1,842 Posts
spark plugs ?
 

·
Registered
Joined
·
11,877 Posts
If you have no codes you may have have contaminated fuel. There are few actual component failures that can occur on a 02 Rodeo without causing a DTC to be set and the CEL illuminated.
 

·
Registered
Joined
·
101 Posts
Discussion Starter · #5 ·
I thought about bad fuel and possibly partially clogged injector(s). It may have been something in the fuel that caused a problem between the fuel pump and injectors. Yet, it runs better the higher the rpm, so that did not seem like an injector issue - but I don't know. Is the injector spray pattern more sensitive at lower engine speed? It is not due to simply a single bad tank of gas since the problem has remained unchanged for more than two full tanks of fuel purchased in different parts of GA and FL. Any suggestions on a component failure that would have these symptoms?

David
 

·
Registered
Joined
·
11,877 Posts
OBDII does not monitor fuel pressure on your 02, so if the pump is momentarily losing power or stopping due to a malfunction no code will be set.
 

·
Registered
Joined
·
13,615 Posts
Is it possible that every once in a while the flyby wire throttle is just being glitchy. My 2000 will act like a potato is stuffed in the exhaust or your pulling a heavy load. Boggy and slow to take off. At 35-4000 rpms and it comes alive as usual. Most of the time it's fine after a few higher rpm pulls. I go back and forth between work gas( PAC pride) and putting plus in at chevron. To me it's more electronic related. It seems to do it on colder start ups.
 

·
Registered
Joined
·
101 Posts
Discussion Starter · #8 ·
It looks like the problem is the same wiring issue that I found back in October that I described in my original post. I had covered the exposed wiring with a piece of flexible sheath and lightly taped the wires where they make a sharp bend from the edge to the top of the valve cover. I removed the tape and protective sheath and separated any wires that were stuck together. That is all I did before taking the car on a long test drive and it ran fine. The strong hesitation in the 2-3K rpm range just disappeared. There are some wires in that part of the harness that just want to be free. For now, I'm leaving that section of the harness unwrapped and see what happens.

Happy New Year
David
 

·
Registered
Joined
·
62 Posts
Interesting. I just rebuilt my 3.2 because it had 190K miles and i ASSUMED it was tired. Machine shop said I had some burned exhaust valves. Now, close to $3000 later, and just started the NEW engine today and it ran like crap!!! since everything is NEW, we tested everything including plugs, wires, coil packs and injectors. My failure is in cylinder 3 and possible another unidentified cylinder.

What cylinders are you having problems with? is the wiring you mentioned, the wiring that goes to the injector? because I am thinking i have a short as well. has this happened to many Isuzu's? Mine is a 92 Troop. can you post a pic, or tell me specifically which wires and where they are located that you found your problem?
 

·
Registered
Joined
·
62 Posts
it was running and firing order is correct. plug wires are fine. its the injector for sure, but injectors are good. After reading this post and searching the zoo forum, i am going to check the engine wiring to the injectors. that is the only logical solution.
 

·
Registered
Joined
·
101 Posts
Discussion Starter · #12 ·
contdevelop said:
Interesting. I just rebuilt my 3.2 because it had 190K miles and i ASSUMED it was tired. Machine shop said I had some burned exhaust valves. Now, close to $3000 later, and just started the NEW engine today and it ran like crap!!! since everything is NEW, we tested everything including plugs, wires, coil packs and injectors. My failure is in cylinder 3 and possible another unidentified cylinder.

What cylinders are you having problems with? is the wiring you mentioned, the wiring that goes to the injector? because I am thinking i have a short as well. has this happened to many Isuzu's? Mine is a 92 Troop. can you post a pic, or tell me specifically which wires and where they are located that you found your problem?
The first time I had the hesitation problem, the check engine light eventually came on. The codes were P1295, P1125 and P1515, which all point to the throttle position sensor (TPS) or the motor that moves the butterfly in the throttle body. I bought a new TPS, but the resistance measurements were nearly the same as my original. Then I found a thread that described the same problem. That person found that the wire that sends the 5V signal to the TPS had broken in the harness. If I remember correctly, the wire is red with a white stripe on my 2002.

In my cases, it seems that there may have been some sort of minute shorts where the wires are wrapped together due to the heat of the engine and the right angle bend in the wires. I never figured out which wire(s) was the problem. I simply separated the wires that were stuck to each other and the problem stopped immediately. This most recent issue seems to be the same type of problem, but there were no codes in about 600 miles of driving. If you have the same problem, you will probably find that the engine will stumble if you loosen the wiring harness and shake it from the point where it makes a bend around the valve cover on the driver's side and then goes to the PCM.

I hope this helps.

David
 

·
Registered
Joined
·
13,615 Posts
contdevelop said:
it was running and firing order is correct. plug wires are fine. its the injector for sure, but injectors are good. After reading this post and searching the zoo forum, i am going to check the engine wiring to the injectors. that is the only logical solution.
You might test your coils to. Your working on a 92 it's more full proof to the wiring issues. You might take a look at your temp sender sense it's all new. They make the engines do all kinds of funny stuff.
 

·
Registered
Joined
·
50 Posts
Sounds similar to what me '00 was doing, except I would get a cruise and check trans light flash at same time it would stall. Opening wiring harness at the bend over drivers side valve cover helped some but did not fix it. Ended up replacing complete harness with an OEM harness this past weekend. Not very difficult, took me about 8 hours to do. Had to remove intake, so I replaced gaskets and cleaned intake and EGR while I was there. Bucking is gone now. Your harness should have a part number close to the end by the computer behind the air box.

Hope this helps, David V.
 

·
Registered
Joined
·
13,615 Posts
Wow what a headache Vilos ..... I hope it doesn't come to that for me to. I haven't had any stalling issues as of yet.
 

·
Registered
Joined
·
33 Posts
Yeah that seems like a pain Vilos. I am having the same issues on a 00 rodeo. If i pull on the wiring harness at the bend closet to the MAF sensor, the car stalls to the point of shut off. Hopefully its prominent,
 

·
Registered
Joined
·
13,615 Posts
I opened up my wiring harnes to fix the kinks and stuff. I actualy spun the loom 360 deg. Going to the brain...!
This was my write up.... I'm still getting a boggy acceleration at times. It's like a slow sensor reaction time.

viewtopic.php?f=1&t=58193
 

·
Registered
Joined
·
33 Posts
I guess im going back out there today on this issue. I removed the intake Manifold yesterday to replace the Coolant hoses that run to the TB. Apperantly after i got everything back together the short was gone? but after about an hour od driving it returned. Is there a Diagram that I can follow? I want to make new traces from the ECU to the TPS harness, that follow a better route with a less harsh bend at the corner, and then snip the current wires.
 

·
Registered
Joined
·
13,615 Posts

·
Registered
Joined
·
33 Posts
I cut and re ran new wires to the TB. Yes it was a pain in the neck..
I also re-ran a ground wires to the base of the power steering fluid resevoir.

This seems to have fixed the issues. I can now grab the wires and it stays steady. I have been driving it for the last 3 hours and not a hickup at all. I wrapped the new wires in E-tape and inserted them into loom and taped over it as well. I made sure that it had enough slack and that they are not stressed.

But this seems to have had worked for me. Just something for you to check into.
 
1 - 20 of 48 Posts
Top