engine flat spot

[OPPYLOCK]

I'm currently running a TBS and this didn't seem to effect it at all. It idles fine and I can't find any air leaks on the intake side of things.
One thing I have heard of before is people running K&N filters over oiling them, the oil builds up on the IAT sensor and stuffs it up. I'm going to check mine out.
I think the real problem is in the factory ECU tune. I can't believe no one has broken the factory code and can tune them. I know Commodores when standard have a torque management system programed into the factory tune to protect driveline components. Maybe Jeep have done he same.
Its just plain annoying when you know your engine isn't working efficiently.

[GUY]

well i don't know about the 05 models but the 06 models have mini cat converters in the header pipes wich are restricting the exhaust flow wen u chomp the throttle, and there is no way around this because there is an 02 sensore before and after the cats... unless anyonehas manufactured a maffless tune but last time i checked they hadn't

[zudoo]

Mines the same, 2006 with only 5000km's on it. I've also got a 12/2004 wrangler atm that does'nt do it. It also has the two cats in the header pipe so I can't see it being that. So what did jeep change from 2004 to 2006???

[MuppoTJ]

I bought my TJ with 175000klms on it and it had all of the problems listed above. Thinking it was age and a noisy engine it didn't think much of it untill I did the build up which included a engine rebuild. Once it was back on the road it was still driving like a dog under load. Gas analyser, scan tool all showed a engine running beautiful, but still run like a dog under load. A lean miss fire was the culprit but where? TPS changed, O2 sensor changed, Injectors cleaned and retro fitted inline fuel filter changed. Much better to drive but still a problem under load, it was time to stop guessing and a 4 wheel Dyno was next and the problem was found straight away. TJ's have a low pressure fuel delivery system that runs at 4bAR pressure. Mine was running at 2.5 bAR and when unload 1.5 bAR and the computer was over fueling by 20%, it was the fuel pump. I changed it over with a Bosch one for a third of the price of a genuine Jeep one and what a difference, it flys now with smooth acceleration, more responsive to throttle input and heaps more power. Finally solved, hopefully this my help others.
A inline fuel filter is good insurance as the filter on the fuel pump is very ordinary.

[bonza]

that was a very interesting and informative update.

also didnt realise Bosch made an equivalent fuel pump for TJ's

did you fit an online filter?

[OIIIO]

Originally Posted by bonza

that was a very interesting and informative update.

also didnt realise Bosch made an equivalent fuel pump for TJ's

X2..........

Any part number, or better still what's involved in swapping out the stocko pump?

[OPPYLOCK]

Thanks for the update. What year model is your TJ? Just wondering if Jeep used the same fuel pump throughout the different year models.