OK, 2001 GC Sport modifed for wheelchair lift 20X,XXX miles.

This thing has had lots of codes but it has been running relatively well as far as I can tell.

Today I finally got around to changing out the rotten after market muffler. Since this was modified for wheelchairs, the exhaust system was changed. It has pipe all the way to behind the rear axle, then a round muffler pointed straight back, then a pipe coming back, then across with the factory... uh Resonator? mounted across.

So the boss says to just stuff in this oval muffler and get rid of the resonator. OK. I got it all welded together and take it for a test drive.

I could tell right away that there was a problem. In neutral, it revs to 3950ish andthen it starts... well puffing... and if you try to rev it past that it puffs more, faster. It also tops out at 4000 RPM, though now that I think of it, on the road, it would rev above that when the transmission downshifted.

Can you gess what the code was? P0202 for those that forgot the title of this thread.

Searching here, that tells me that I have a misfire on cylinder #2. This code has never come up and I don't believe this symptom has happened before.

So my question is could removing that resonator thingie cause a change in the backpressure causing a problem like this?

While searching for this, I found that I need to dig into the wiring harness to look for melted wires, but I'm not sure where exactly to look for that. Is it on the back of the engine, as in above the bell housing, or will I need to reach over the engine to along the rear bank of the engine to find this harness?

Thanks for any help.

 

Did I mention it's a 3.3 V-6er?

 

I have checked the harness that powers the injectors running both ways from the 10 pin connector and only found some insulation melted together, but no wires shorted together. Hopefully this is the right area to be looking.

Anyway, bumping with some new info.

 

So what else is needed to know to help me with this? I'm really stuck on if this is an exhaust problem or an engine problem.

 

I am still wondering if changing the exhaust system could somehow cause this problem.

Is there anyone that has any kind of an opinion on this or any suggestions on what to check, or what to search for here? I am very stumped.

Thank you.

 

So a few things today. One, I did plugs, and wires. B, I talked with the regular driver and was told the sound has been there, but driving it caused no problems. The first time I drove it after replacing the muffler, it definitely had driving troubles. Tonight when I drove it after plugs and wires, it drove fine. So I don't know what the trouble has been. I just can't imagine that it will only rev to 4000 RPM in neutral.

If anyone wants' to throw in their two cents, I would love to hear from anyone. Heck, I'd just like to know that people have read this.

 

Yes, I've been reading this but just haven't had much expereince with your type of problem. I do think it's exhaust back pressure related. Just not sure how you would go about proving it. I do know that when a plugged cat converter is suspected you can drill small holes fore and aft of the cat, insert a pressure gauge and compare pressure readings. Maybe that's something to look into. Hope someone with some know how can help.

 

my 06 won't rev past 2700 in park or neutral due to the Rev Limiter

and sorry I have no experience with exhaust

 

I am a diesel mechanic and I have no experience with having a rev limiter that would keep an engine from revving to redline, so this is certainly something for me to look into and study on. Thanks for the suggestion.

Cougar, I did smell a bit of a rotten egg smell in the exhaust. (The secretary must have thought it odd when I kneeled down to smell the exhaust! LOL) Isn't that a sign of a failing cat? Also, thank you for your suggestion on testing the cat. At least now, I have an idea I can pursue.

For now it's running fine and I don't have any codes whereas before I have had up to 12 codes for lots of stuff. I will ask the driver to pay attention to when the CEL comes on and try to let me know the conditions that bring it on. The things that I think may be important are; Coolant temp, accel/decel, cruise control on/off, load, turning, bumps, how long driving, stop and go or flat cruise,,, That's all off of the top of my head.

Thanks guys for the suggestions. I was wondering if I had ticked people off with my first post.

Now If I can just get my name changed...

 

Found this.

Other than my TDIs, the diesels I am used to all rev to something less than 3000 RPM so I am certainly in new waters here.

So, since what I am hearing is actually the rev limiter, for some reason it was hitting it on my test drive after replacing the muffler. It isn't now, so I'm not real worried about it, but now I can rest easy knowing that isn't another problem for me to deal with.