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need some help on my jeep running too lean


 
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dirtydeez
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Joined: 06 Nov 2004
Location: Portland, OR

PostPosted: Mon Feb 26, 2007 5:38 am    Post subject: need some help on my jeep running too lean Reply with quote

installed a throttle body spacer recently on my 97 xj, seemed to do fine until I put a flowmaster muffler on. Took it up for a day of wheelin and in the higher altitudes it starting running rough and was wanting to die. I ran the code which said it was running too lean, so I pulled the tbs out, reset the code and its been fine ever since. It did fine for a month or so before installing the flowmaster, but I dont see how the combination of the 2 would be an issue. Any comments or ideas on what the problem may have been, or does the fuel injection just not like a tbs?
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dancerman
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Joined: 08 Jun 2006
Location: Atlanta

PostPosted: Wed Feb 28, 2007 3:02 am    Post subject: Reply with quote

This is interesting problem. It sounds like the combo of the spacer and the higher flow exhaust has told the computer it can't make enough adjustments to run within specs. The spacer may affect the air flow sensor in a way that it was not designed to operate. I am guessing that it is telling the computer the wrong air flow. It was able to adjust until you added the muffler and it could not adjust fuel, timing, etc. to run within specs.
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Brad The Best
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Joined: 14 Jan 2007
Location: Kamloops B.C Canada

PostPosted: Sat Mar 03, 2007 8:38 pm    Post subject: Reply with quote

you will probably need some sort of tuner and higher flow injector's , unfortunately there aren't any adjustable fuel pressure regulators for '96 and newer engines (i believe)

for that new of an engine you should be able to get a tuner and injectors easily .

To calculate optimum injector size, use the following formula:

Injector flow rate (lb/hr) = [Expected HP x 0.5 (BSFC)] / [no. of cylinders x 0.8 (injector duty cycle)]

The actual injector flow rate from each injector depends on the fuel pressure (FP) in the injector rail. Most injectors have rated flows at 43.5psi fuel pressure. The actual flow rate from each injector is:

Actual injector flow rate = Rated injector flow rate at 43.5psi x square root of (FP/43.5)

hope that helps some . i would start with a tuner , im not sure what your regulator is like or really anything about your fancy new engine sorry i can't be more help
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dirtydeez
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Joined: 06 Nov 2004
Location: Portland, OR

PostPosted: Sun Mar 04, 2007 1:53 am    Post subject: Reply with quote

Thanks guys for the input. Definitely helpful. I have had quite a few probs with the ecm not liking the few things i've dont to it, maybe ill just quit messin with it for now.
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Brad The Best
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Joined: 14 Jan 2007
Location: Kamloops B.C Canada

PostPosted: Sun Mar 04, 2007 7:25 pm    Post subject: Reply with quote

i would look into some sort of after market tuner for the computer i bet it could fix some of your problems

what fun things have you done to your jeep?
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