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Limp mode with Throttle light flashing and trac light on http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=88&t=89470	Page 1 of 1

Author:	goser [ Thu Nov 22, 2018 3:05 pm ]
Post subject:	Limp mode with Throttle light flashing and trac light on
Hi Folks, have been searching for a solution for this problem, and although it seems to affect a lot of Liberty's, Calibers, Nitros, etc., nobody seems to have a solution that I can find, or the ones that do fix it don't provide enough info on what the repair was. Several times over the last month, the ETC (electronic throttle/lightning bolt) light will start flashing and ESP (traction control/skidding car) light will come on, and the truck will run at around 1500 rpm regardless of throttle or braking. First time it happened I limped home and it was fine when I restarted it... now I just kick it into neutral and restart the engine to make it go away... but I'd like to actually solve the problem! Here's some background: Have had K&N CAI installed for years Last spring, 2 or 3 times, truck ran really rough after starting and narrowed it down to throttle body by the noises it was making. Cleaning TB didn't help. In August I decided to replace TB, and put in a reman 4.7L throttle body (Seemed like a good time to try out the mod since it was cheaper than the 3.7L part anyway) A month ago the problem started while driving home after having the truck oil-sprayed. Occasionally I will get a check engine light... usually goes away before I have a chance to scan it, but when I have been able to it's a P0306 cyl. 6 misfire. Could be coincidence, but it seems to always go into limp mode a few minutes after I've given it decent throttle to get onto expressway or the like. So here's my theories: I know sometimes connectors or relays will corrode and cause similar problems, so wondering if oil from the spraying maybe got in to a bare wire somewhere and is shorting something out? Would be great if someone knew what or where the likely locations of these connectors are. Could be the 4.7L TB is incompatible with the truck, but I know a bunch of people here have done it and don't recall hearing any issues like this. Could be the reman 4.7L TB is defective. Planning to give my old throttle body a really good cleaning and reinstall it tonight to see if the problem happens again with it installed, but would appreciate any suggestions!

Author:	lfhoward [ Thu Nov 22, 2018 5:14 pm ]
Post subject:	Re: Limp mode with Throttle light flashing and trac light on
Sounds like you’re doing some good science, changing one thing at a time like the 3.7 TB and looking to see if it changes the outcome. I’ve never heard of oil shorting something out. Water yes, and frayed wires yes, but oil no. That sounds like a coincidence. Silly question (not meant as an insult or joke): have you disconnected the battery and let it sit like that overnight? When reconnected in the morning the computer will have to relearn the throttle body/driving habits. Maybe that procedure might fix your issue if the computer still thinks you have a 3.7 TB on but it’s actually a 4.7. Or maybe if it’s just a computer glitch resetting it this way might help.

Author:	ajohns1288 [ Tue Nov 27, 2018 8:58 pm ]
Post subject:	Re: Limp mode with Throttle light flashing and trac light on
The ETC lamp will start flashing anytime there is a fault that causes the throttle to be depowered and go into limp-home mode. A solid lamp means there is a fault that will reduce performance, but not nearly as much. This is done for safety, for example if the throttle sticks open, it will depower the throttle and start pulling spark and fuel to slow the engine down. Losing both throttle position sensors or throttle motor control, large manifold leaks, and ECM hardware failure are the faults that will cause the ETC lamp to flash and all should set a DTC, which should be stored for several key cycles after. The fact you said it happens with the 4.7L TB after you accelerate makes me think the computer doesn't like the extra airflow it sees, since it thinks there should be much less than there actually is. If this is the case, you'll be setting either P2172 or P2173. lfhoward's suggestion of pulling the battery should resolve it if that is the cause, since the ECM will re-adapt to the new TB. It may also be the case that the max/min positions are outside the ones that were learned at the plant, which would cause the ECM to think it over-drove the throttle. I don't remember which code it would set, but it should be in the P21xx range. If you can get the codes pulled while the fault is active or the key cycle just after and post them, I can tell you where to look next if it was none of the above causing the issue. Just a heads up that the check engine lamp takes 3 good trips to clear, however the code should remained stored for longer than that. You can also look up the "code read key trick" to have the codes display on the dash.

Author:	Scar0 [ Wed Nov 28, 2018 8:02 am ]
Post subject:	Re: Limp mode with Throttle light flashing and trac light on
I have a 4.7 TB in my rig and never had an issue with it after the computers learned it was there. Only during the first couple of drives did it over rev. I do not baby my rig. W.O.T. is a common thing for me. If the rig did not like the 4.7 TB you would have known in the first couple of days. Not saying that it didn't go bad tho. You could pull that #6 plug and look at it. Also the rocker arm my be popping off and then bouncing back on.

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