Straight Pipe Problems?

Loosehead · **Joined:** Fri Feb 02, 2007 7:46 pm **Posts:** 9

Hello everybody,

I recently had a straight pipe installed in place of the muffler on my 2005. Since then, the Jeep has been very erratic in its function. The most noticeable problem is that it tends to stall when accelerating from a stop (more often when engine is cold). The engine shudders and dies. Also, at around 10 -15 mph when coming to a stop, RPMs drop, the engine shudders and recovers (most of the time). The problems only seem to be magnified after a long drive at highway speeds. Yesterday, the Jeep started bucking and making awful noises (seemingly from under the front seats or a little farther forward)...loss of power...all the good stuff. I've experienced the "air in fuel syndrome - no CEL limp mode," but this seems a little different. It happens every time I drive the vehicle now and doesn't seems to be correctable by priming and releasing air from the fuel pump. I've only done the airbox mod and the straight pipe...everything else is stock.

Is this the torque converter failing? Has the straight pipe caused these problems? Has the air in fuel problem finally reached its peak? Is the torque converter covered under the powertrain warranty?

I've searched a number of different threads, but none seemed specific enough to my situation (straight pipe and engine shudder/noise) to answer my questions.

Any insight y'all could offer would be greatly appreciated.

Larry R. · **Joined:** Sun Jan 21, 2007 1:35 am **Posts:** 92

I'd start with the lift pump mod., Its fairly cheap to do and makes it run better in my opinion.

warp2diesel · **Posted:** Fri Sep 05, 2008 9:13 pm

Larry R. wrote:

I'd start with the lift pump mod., Its fairly cheap to do and makes it run better in my opinion.

Dittos

Many of use have discovered that Bean Counters try to but can not defy the laws of Physics.
Pump up your hand primer and hold it down as you open the bleeder, gobs of air should puke out with a little fuel. Then close the bleeder and repeat the operation until you get no more bubbles.
You may have bumped or looked at a fuel line cross eyed which allowed one of the snap fittings to leak in some air when you installed the straight pipe. All it takes for a snap fitting line to suck in some air is hang the work lite on it or bump it when you are installing the exhaust pipe. If you go with the in tank pump that GMCTD developed the idea, the snap fittings will be pressurized and no longer be a problem. I went with a Carter pump and have to be very careful not to disturb the snap fitting between my tank and the pump, the rest are not a problem. Others have gone with the Kennedy pump and also have to be careful of the snap fitting at the top of the tank or have eliminated it. Check the threads on lift pumps and upgrade.

Good luck,

Steve

gmctd · **Posted:** Fri Sep 05, 2008 10:28 pm

Short piece of rubber hose and two hose clamps would fix that right up fer ya, Steve - would also help those who chose to stick with the Ma and Pa Kettle fuel manager head.................

Herk · **Posted:** Sat Sep 06, 2008 1:19 am

I have had a straight pipe now for a couple of weeks and Im very impressed with better acceleration, 2-mpg increase and it coast much faster when the gas pedal is let off. I think its bad timing with another issue.

warp2diesel · **Posted:** Sat Sep 06, 2008 12:01 pm

gmctd wrote:

Short piece of rubber hose and two hose clamps would fix that right up fer ya, Steve - would also help those who chose to stick with the Ma and Pa Kettle fuel manager head.................

Demanding work and honey do puts the hose and clamp project on the back burner.
I am still healing up from the scolding I got from my dear little Klingon for installing the fuel cooler that works great. :lol:

I may need to wait until I get a minor air leak and make it look like the end of the world with an impending $3500 repair bill so I can slip in the hose between the pump and tank :idea:

dieselenthusiast · **Posted:** Sat Sep 06, 2008 11:38 pm

Herk wrote:

I have had a straight pipe now for a couple of weeks and Im very impressed with better acceleration, 2-mpg increase and it coast much faster when the gas pedal is let off. I think its bad timing with another issue.

A 2 mpg increase is a pretty significant upgrade. I received about a 1.5 mpg increase on my Cummins when I installed the Areo muffler. Also, is the KJ running much louder now that you are straight piped? Do you still have the catalytic converter?

Herk · **Posted:** Sun Sep 07, 2008 2:45 am

Yes, it is louder but the little roar is pretty cool. The CAT is still in place and not gutted.

dgeist · **Posted:** Sun Sep 07, 2008 9:34 am

Herk wrote:

Yes, it is louder but the little roar is pretty cool. The CAT is still in place and not gutted.

I did the same (well the muffler shop did) about 6 months ago. Mine's not really louder, just has a lower rumblier tone. The service writer asked what I did to the exhasust the last time it was in the shop. I said, "I replaced the crappy exhaust carryover from the gasser with what the diesel needed, 2.5" diameter pipe." He laughed and nodded, saying he would have never known that it didn't have a muffler unless the tech had mentioned it wasn't stock.

dieselenthusiast · **Posted:** Sun Sep 07, 2008 10:47 am

dgeist wrote:

Herk wrote:

Yes, it is louder but the little roar is pretty cool. The CAT is still in place and not gutted.

I did the same (well the muffler shop did) about 6 months ago. Mine's not really louder, just has a lower rumblier tone. The service writer asked what I did to the exhasust the last time it was in the shop. I said, "I replaced the crappy exhaust carryover from the gasser with what the diesel needed, 2.5" diameter pipe." He laughed and nodded, saying he would have never known that it didn't have a muffler unless the tech had mentioned it wasn't stock.

dgeist, did you notice a significant fuel mpg increase such as Herk when swapping to a straight pipe?

curtis · **Posted:** Mon Sep 08, 2008 6:05 pm

[quote="dgeist, did you notice a significant fuel mpg increase such as Herk when swapping to a straight pipe?[/quote]

I picked up 2-3 mph when I removed my muffler. The Cat will be next to go.

dieselenthusiast · **Posted:** Mon Sep 08, 2008 6:31 pm

curtis wrote:

[quote="dgeist, did you notice a significant fuel mpg increase such as Herk when swapping to a straight pipe?

I picked up 2-3 mph when I removed my muffler. The Cat will be next to go.[/quote]

:shock:

That's awesome, it's amazing what can happen when you let a motor breathe.

dgeist · **Posted:** Mon Sep 08, 2008 10:20 pm

dieselenthusiast wrote:

dgeist, did you notice a significant fuel mpg increase such as Herk when swapping to a straight pipe?

Perhaps a bit, but it was just getting into summer heat, so I had a wash on the mileage. I did notice a definite reduction in turbo spool-up time I'm guessing I'll run better this winter than last. I always loose mileage in the summer months.

Dan

Straight Pipe Problems?

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