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post #1 of 2 (permalink) Old 01-25-2009, 02:21 PM Thread Starter
Cobalt Specialist
Join Date: Nov 2007
Location: Sunshine State
Posts: 1,250
LSJ DP/Cat on 2.4L Auto

Ok for youse guys and gals that like to get every ounce of power out of your engine without CELs the LSJ DP will free up your exhaust a bit and keep the ECM from sending you the dreaded CELs.

It appears that the LSJ DP will fit the manual tranny equipped 2.2/2.4 Cobalts but do not simply fit-in the Auto tranny equipped Cobalts.

I have installed an LSJ DP on my 07 auto 2.4L but it took Mad Hatter to cut it apart and reweld piping in to get it to fit. First it is about 1 1/4" too short for the auto cars and causes the cat-back exhaust to be pulled forward and hit the bottom of the car, second the LSJ DP sits lower in the car (possibly the engine in an auto car sits lower in the engine bay) and causes the Cat to rest on the sway bar. Mad Hatter ended up cutting the DP apart and rewelding 2 3/4" pipe to make it fit on my car -- no other way around it.

I ran a diagnostic on my car and scanned/watched the HO2S-2 sensor: the readings are well within the factory requirements so the ECM shouldn't give any CELs. I've been driving it and haven't seen a CEL...nor does my scanner pick up any pending CELs.

BTW: the LSJ DP has 2 3/4" OD pipe in addition to the large Cat (about 60% bigger then the 2.4L Cat) but the pipe is crimped down to 2 1/8" ID at both ends. The 2.4L auto Pipe is 2" OD and is actually enlarged to 2 1/8" ID at the ends.

Here you can see the differences in the pipe and Cat sizes. It is of interest that the bend in the upper pipe is right out of the manifold connector on the LSJ while the bend is near the Cat on the LE5 DP -- It makes a difference!:

This shows how much shorter the LSJ DP is than the LE5 Auto DP (different part numbers between auto and manual Cobalts):

Here you can see the LSJ cat is resting on my Cobalt's sway bar -- took rewelding in new pipe to get it to clear the sway bar:

Vendors should take note that there is a difference between auto and manual Cobalt's DPs!!!

Ex-Cobalt Owner

Last edited by Red07SSNA; 02-08-2009 at 08:06 AM. Reason: Spell Check!
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post #2 of 2 (permalink) Old 02-08-2009, 08:13 AM Thread Starter
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Join Date: Nov 2007
Location: Sunshine State
Posts: 1,250

The 2.2 auto has the same problem...the LSJ DP will not fit without rework...but it's worth it. With aftermarket DPs you will find the same problem on auto equipped Cobalts.

If you have an auto equipped car and want to install the LSJ DP be prepared to buy some 2 3/4" exhaust pipe (chances are that your exhaust shop doesn't carry this size) and expect that a muffler shop will have to cut it apart and weld in the new pipe to get the converter to fit in the floor hump. No way around it. The auto equipped engines are positioned more forward and down then manual equipped engines.

Ex-Cobalt Owner
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