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Old 01-05-2013, 09:43 AM   #1
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great idle but bogs when accelerated

98 tj 4.0 IL6 manual

I recently replaced the exhaust mani. Which I had to do twice due to not properly installing the bolts. Now she cranks and idles beautifully, when I give her gas its like there is no fuel/ air. Checked the fuel rail which had nice pressure and fuel. Checked air filter and housing those where in nice shape as well. Yet I still can't get her RPM's up! I disconnected the TPS and MAP sensors inspected, cleaned and re-connected. Not sure what to look for to tell if they are shot. There is no check engine light. I also did the turn the key 3 times trick to see if I can get her to tell me something, with no results. I also just replaced the plugs.

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Old 03-07-2013, 06:26 AM   #2
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I know I'm late but mine does the same thing

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Old 03-07-2013, 09:42 AM   #3
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disconnect the negative battery terminal and reconnect? Do a system check?
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Old 03-07-2013, 12:32 PM   #4
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Have you replaced the cat on your truck cause your cat internals could be broken and clogging exhaust creating the lag in your truck and could ultimately be the cause of ur exhaust manifold failure cause this is what trashed my oem exhaust manifold
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Old 03-07-2013, 12:58 PM   #5
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X2, my first suspicion would be the catalytic converter has busted up inside clogging your exhaust too. Or perhaps a bad upstream 02 sensor.
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Old 03-07-2013, 08:45 PM   #6
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No bad codes. No cat on my jeep either idles perfect but just under torque it Boggs. And only sometimes like I am drive it a while before it starts but when it starts it is bad
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Old 03-07-2013, 08:50 PM   #7
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Couple people said that it would be the fuel filter? Any thoughts
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Old 03-07-2013, 10:14 PM   #8
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No, it's not caused by the TJ's fuel filter which has a positively enormous surface area. The factory considers it a lifetime part, you have to drop the gas tank to replace it.
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Old 03-08-2013, 11:49 AM   #9
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No cat, so you removed it cause it was no good, could still have remnants of cat internals in ur muffler if its not a glass pack that could be causing the bog down. X2 with Jerry no way it's a fuel filter issues and on fuel rail ur getting good pressure that cancels out fuel pump unless u have a fuel line leak that's pullin in air when you go to accerate that's very far fetched
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Old 03-08-2013, 07:11 PM   #10
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No the cat has been cut off and it's just a muffler. Now when I put it in 4lo it Boggs down under torque. Can't even go forward
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Old 03-08-2013, 07:12 PM   #11
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And I replaced fuel filer. Didn't help. Replaced spark plugs didn't help ran seafoam thinking the injectors might be gettin clogged and still nothing. Should I post a video of what it's doing??
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Old 03-09-2013, 06:31 PM   #12
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Update on progress. Took te old spark plug wires off and forgot the firing order but got them on in order finally. Took it for a spin still no help? I am stumped. Open to any suggestions. My dad thought compression but then it would do it all the time right? Would it be caused by a bad coil pack? Is it not getting enough spark? Should I run seafoam more to rule out faulty injector. Would it be a fuel pump or pressure regulator going bad? This is my dd so I need it fixed!!
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Old 03-09-2013, 07:45 PM   #13
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I'd borrow a fuel pressure tester from your local auto parts store & check your fuel pressure at the fuel rail when you rev the engine. It should be pretty close to 49 psi even when the engine is being revved.

The finger is pointing at the Schraeder valve where you connect the fuel gauge.
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Old 03-10-2013, 11:16 AM   #14
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Ok will do that when I get off work. Will they let me just borrow one?
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Old 03-10-2013, 11:24 AM   #15
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You will have to put a deposit down on loaner tools from parts house and will get it back when you return it,if it's not damaged.
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Old 03-10-2013, 11:25 AM   #16
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Ok will do that when I get off work. Will they let me just borrow one?
I dunno about your auto parts store but my local Autozone loans out tools like that at no charge. I'd call around to find which in your area even have fuel pressure gauges, some do and some don't. The way my local stores do it is they'll put a deposit on your credit card but credit it all back when you return the tool in good condition.
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Old 03-10-2013, 04:36 PM   #17
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Could it be the Throttle Position Sensor? i had one go bad on a 2000 Xj but it did not present with a CEL. Same symptoms and replacing the TPS Fixed all my woes.
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Old 03-10-2013, 05:28 PM   #18
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Where is the throttle body sensor? Don't flip out because its the THROTTLE BODYsensor. But where at?
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Old 03-10-2013, 06:24 PM   #19
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Quote:
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Where is the throttle body sensor? Don't flip out because its the THROTTLE BODYsensor. But where at?
??

There is no throttle body sensor. There are two sensors on the throttle body, Throttle Position Sensor (TPS) and Manifold Absolute Pressure (MAP).
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Old 03-10-2013, 07:44 PM   #20
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The Tps is attached through the throttle body to the butterfly valve should be the TB and the fire wall
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Old 03-10-2013, 07:47 PM   #21
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* between the tb and firewall
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Old 03-11-2013, 02:40 PM   #22
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Ok will change it out and let you know if it fixes it
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Old 03-11-2013, 05:14 PM   #23
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Replaced the throttle position sensor still no help. So picking up a distributor cap to see if that fixes it. Maybe the one I have got cracked or just went bad?
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Old 03-11-2013, 07:45 PM   #24
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UPDATE. Got a new distributor cap. Still nothin. I still can't go forward but I can go in reverse just fine. Looking for any ideas now. Even my local mechanic is stumped.
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Old 03-12-2013, 01:35 AM   #25
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Hey man I'm not at all mechanically inclined, but I found your thread doing a search for the TPS since that is the code I'm getting out of my rig. I saw that you replaced yours with no help, but at least one of the other threads I've stumbled on talk about resetting your truck's computer after replacing that sensor so it can "relearn" how to process the now-correct signals. May be worth checking out if you are still spinning your wheels:

http://www.wranglerforum.com/f5/repl...tps-41963.html
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Old 03-12-2013, 08:44 PM   #26
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Thanks for the help. Still no solution. Trying replacing the coil next.
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Old 03-13-2013, 06:04 PM   #27
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Well still nothing. I keep posting in here incase someone else has this problem they won't have to keep trying things like I did. Replaced the coil today nothing. So put it on a trailer. That was hard since it was under a lot of torque luckily I used my winch to help me get it up. Dropping it off at the jeep dealer tonight. Will post results
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Old 03-19-2013, 03:12 PM   #28
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My jeep is having a similar problem... pretty mild right now, but occasionally while driving it will just seem to stop getting fuel... i have been reading around to try and find a solution, and am still lost. Hope you are able to figure it out and pass it along, because i have run into a few people seeing this type issue. Let us know what you come up with.
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Old 03-19-2013, 05:01 PM   #29
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Well jeep dealership said they couldn't get it to do the problem. Mine started out very mild and then one day got extremely worse. Getting it aligned tomorrow then driving it around will post results
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Old 03-20-2013, 05:40 PM   #30
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Ok I'm thinking crankshaft sensor (forgot the whole name). Still does it but very mildly.

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