flat spot

duke04 · 10-29-2004, 10:48 PM

Is it just me or does anyone else notice a flat spot or bog when you hit the gas after shifting from 1st to 2nd and 2nd to 3rd? This is just during normal driving, not rodding. It is a new 4.0 with 5 speed, 1600 miles in a 2004. I have even had a pop in the air filter once or twice.
Duke04

FlexyTJ · 10-29-2004, 11:33 PM

a "pop" in the airfilter, like a "hot rod" backfire??

definetly not normal... sounds like a tuneup issue, or maybe vacuum leak.

penguinland · 10-30-2004, 05:36 AM

Unless you are shifting way too early it shouldn't happen. Any error codes in the OBD ?

DarkRubiTJ · 10-30-2004, 05:47 AM

Both ours do it. 03 Rubicon and 04 Rubicon. I notice it if you short shift and then try to jump on it right away. If you feed the throttle in slowly the problem never happens. I think it has to do with the throttle map in the computer. Have you noticed the surge when the engine is still cold? Throttle acts like an on and off switch, no way to regulate the pedal until the vehicle is warmed up.

duke04 · 10-30-2004, 09:30 PM

Yes the pop is about like an old "hot rod" pop. I usually don't short shift. I haven't checked the OBD for codes yet. I'd bet the program is too lean just above idle. if it had a Holley I'd richen up the idle screws and I bet it would be gone.

Spiderman · 10-30-2004, 10:11 PM

Get some 4.56's, I have no problems with power with mine

duke04 · 10-31-2004, 12:21 PM

I don't know if this will help, I found it in another forum.

In this order, next time you start the car, do the following:

1. Insert key. DO NOT TURN.

2. Flat-foot gas pedal.

3. Turn key to crank position. Crank for 5 seconds and stop. Car will not fire with gas at WOT. If car fires, the TPS is either faulty or misadjusted (don't hate me if there's no adjustment, I've never worked on a Jeep TPS, Fords are adjustable).

4. Take foot off gas pedal.

5. Turn key to run position. Listen for fuel pump to prime, then crank it untill it starts.

6. Drive untill car reaches normal operational temperature. With car in neutral, stomp the throttle three times. I guess you could do it with the car cold, but I have a real problem driving a car hard on cold oil.

The first five steps reset the TPS peramaters in the computer. The sixth step resets the MAP sensor. This is particularly useful if you've recently been driving in high altitudes and have returned to lower altitudes.

duke04 · 10-31-2004, 05:43 PM

That didn't help or my TPS is bad. It started with throttle wide open.

Oman Jeep · 10-31-2004, 06:53 PM

Quote:

Originally Posted by duke04

That didn't help or my TPS is bad. It started with throttle wide open.

Bet that was a surprise

10-29-2004, 11:33 PM	#2
FlexyTJ Registered User Join Date: Sep 2004 Location: Crawlorado Springs Posts: 1,209 Profile Gallery Classifieds My Jeeps	a "pop" in the airfilter, like a "hot rod" backfire?? definetly not normal... sounds like a tuneup issue, or maybe vacuum leak. __________________ [SIZE=2][COLOR=Navy]MK Motorsport & Fabrication [/COLOR][/SIZE]

10-30-2004, 05:36 AM	#3
penguinland Registered User Join Date: Jun 2004 Location: York, PA Posts: 699 Profile Gallery Classifieds My Jeeps	Unless you are shifting way too early it shouldn't happen. Any error codes in the OBD ? __________________ 2004 WJ Bone Stock

10-30-2004, 05:47 AM	#4
DarkRubiTJ Registered User Join Date: Oct 2003 Location: Virginia Beach Posts: 240 Profile Gallery Classifieds My Jeeps	Both ours do it. 03 Rubicon and 04 Rubicon. I notice it if you short shift and then try to jump on it right away. If you feed the throttle in slowly the problem never happens. I think it has to do with the throttle map in the computer. Have you noticed the surge when the engine is still cold? Throttle acts like an on and off switch, no way to regulate the pedal until the vehicle is warmed up. __________________ ME- 2004 Rubicon Flash Red Backseat removed including hardware Her-2005 Grand WK

10-30-2004, 10:11 PM	#6
Spiderman Registered User Join Date: Mar 2004 Location: U.P. of Michigan Posts: 1,130 Profile Gallery Classifieds My Jeeps	Get some 4.56's, I have no problems with power with mine __________________ [URL=http://tednugent.com][COLOR=Red]www.tednugent.com[/COLOR][/URL] [SIZE=1] [COLOR=navy]2001 Sport 4.0L, 5 Speed, Patriot Blue 33 X 12.50 BFG A/T's with A/R Atlas 15 X 8 wheels 4.56's, RE 3.5" lift, Currie 1" BL, M.O.R.E. 1" MML Aussie D30 Locker, & other crap[/COLOR][/SIZE]