00' Rodeo engine knock under load

[bishop242]

00 Rodeo 3.2 115,000
Runs like a champ. No sign of the typical ticking but under slight load such as going up an incline (usually at 35-55 mph) I hear a subtle knocking sound from the engine. If I let off the gas slightly or step on it, it quits. Octane numbers or additives have little effect. This knock is subtle but it has gotten more noticeable in the last 5000 miles.
Does this 3.2 require valve adjustment at certain intervals?
Thanks!

[amigo-2k]

how many miles do you have on it?

[rodeo02]

If it was a valve clearance issue, it would tick all the time. Since it does it only under light load, I'd look into a loose exhaust heat shield. Other than that, the timing belt tensioner maybe? Those usually just give a knock at idle.

Joel

[Ramblin Fever]

Try cleaning your EGR, seriously, it may help.

[bishop242]

Originally Posted by amigo-2k

how many miles do you have on it?

Hey Ryan, 115,000. Thanks.

I bought a can of O2 sensor safe carb cleaner today, gonna tackle my first EGR cleaning tomorrow.

[joewildlife2001]

My 2001 does the same thing. I never thought of cleaning the EGR and THANKS for the suggestion. It will get done this weekend. Higher octane gas does help my situation. The only other thing it could be is the engine knock sensor but it is located under the intake manifold, requiring a big tear down to replace a sensor that may or may not be the real problem.

BUT if the computer senses a knock, it 1) activates the EGR to send exhaust gas into the combustion cylinder to reduce cylinder pressures upon air/fuel ignition, and maybe 2) richens the fuel mixture.

My gas mileage sucks so I wonder if the EGR isn't working good enough, the computer richens the fuel mixture, hurting mileage.???

Let us know how it turns out!
Joe

[amigo-2k]

http://isuzufaq.ibctech.ca/#faq8
MPG info.

[joewildlife2001]

Originally Posted by amigo-2k

http://isuzufaq.ibctech.ca/#faq8
MPG info.

Thanks Amigo! That is a long list of info there, some I didn't even know existed. I always wanted to know how to get them fogs on all the time!
I did it on a Honda CR-V I had by figuring out the wiring diagram, but couldn't figure out the Isuzu wiring diagram.

Interesting sidenote, I just spoke with a St. Louis Isuzu dealer about the knock problem and he thought it was something that could be fixed with, can you beleive, Seafoam? Too much carbon in the cylinder or carbon in the EGR. Never heard of the stuff but your link caught me up to speed. And yes my 2001 uses oil so maybe it can help on that too.

My Rodeo had 59,800 miles and got towed, courtesy of Isuzu Roadside, to the dealer in St. Louis for them to fix the fuel level sending unit, under warranty for 200 more miles ONLY because it is attached to the fuel pump and not available separately on the 2001 model. MAYBE this will also help the unsteady accelleration that other members reported, which was fixed by the fuel pump replacement.

what a day!

You guys and gals saved me BIG bucks on a repair that I found out today, just barely, was still under warranty. (I'm second owner) I'll get this SUV fixed up in no time. The flashing lights on the dash were bothering me!

Joe

[rodeo02]

Originally Posted by joewildlife2001

My 2001 does the same thing....The only other thing it could be is the engine knock sensor but it is located under the intake manifold...

There is no knock sensor on the 2000+ 3.2.

Joel

[joewildlife2001]

Originally Posted by rodeo02

There is no knock sensor on the 2000+ 3.2.

Joel

Joel, Really?

the Haynes manual says the 3.2 has one. I'll have to look on my CD to see what it might say. thanks for the head's up though. The Haynes manual is from 98 on I think, and doesn't differentiate between the years in this case.

In looking at the dealership tech CD, you are right, there is no knock sensor in the '01. interesting.

Off to buy some Seafoam...er when I get my SUV back!

Joe

[bishop242]

Originally Posted by Ramblin Fever

Try cleaning your EGR, seriously, it may help.

Cleaned the EGR and I believe it may have solved the problem. Is it my imagination or could my Rodeo be running this much smoother and more peppy after such a simple process??? The EGR was loaded full of carbon and junk and the pintle had TONS of buildup on it.

[rodeo02]

Originally Posted by bishop242

..Is it my imagination or could my Rodeo be running this much smoother and more peppy after such a simple process??? The EGR was loaded full of carbon and junk and the pintle had TONS of buildup on it.

The 3.2/3.5's have to be the only engines known to man that need to injest recycled exhaust gas to run right! By principle, the only thing the EGR system does is reduce combustion temperature a bit to reduce NOx output. An added 'bonus' is the cooler combustion temp should reduce knock/ping.

G/luck
Joel