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surging at part throttle
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=73027		 Page 1 of 1
Author:  rictek [ Thu Dec 27, 2012 2:07 pm ]
Post subject:  surging at part throttle
I have been driving about a year now with the MAF unplugged. Last night I plugged it back in and cleared the engine codes and went for a 10 mile drive. I noticed a lot of black smoke when leaving a stop light and surging. Without moving the pedal, the rpms oscillate between 1500 and 2000 rpm. Boost goes from 4 to 15 lbs. Codes P0299 Turbo underboost, and P0401 EGR flow insufficient.
Runs great with MAF unplugged. Whats going on?
Author:  papaindigo [ Thu Dec 27, 2012 3:29 pm ]
Post subject:  Re: surging at part throttle
IIRC unplugging the MAF totally disables the EGR so plugging it back in would bring the EGR back into the circuit which may have triggered your P0401 code although I don't know why. P0299 and black smoke suggests a bad boost pressure solenoid or leaky vacuum hose in the same area. See viewtopic.php?f=5&t=70602&p=757348&hilit=boost+solenoid#p757348 for how to test for a bad solenoid. Again I don't know why this would only appear after plugging the MAF back in though.
Author:  rictek [ Thu Dec 27, 2012 5:54 pm ]
Post subject:  Re: surging at part throttle
Thanks, I am familiar with the bypass trick. That is how I diagnosed a bad solenoid last year.
So, I did the bypass and test drive anyway. The surging, black smoke and 0299 code are still there.

So, I also put on new cooler hoses I had bought a while back. The old ones were not cracked but they were coated inside with oil. Still smoking, surging.
Author:  rictek [ Sun Dec 30, 2012 8:16 am ]
Post subject:  Re: surging at part throttle
The dealer says the EGR valve has to be replaced and quoted me $1600.
Author:  papaindigo [ Sun Dec 30, 2012 8:53 am ]
Post subject:  Re: surging at part throttle
EGR valve can be cleaned instead of being replaced. See viewtopic.php?f=5&t=62495 and viewtopic.php?f=5&t=59352&p=659410#p659410
Author:  kjjet [ Thu Jan 03, 2013 10:30 am ]
Post subject:  Re: surging at part throttle
rictek wrote:
The dealer says the EGR valve has to be replaced and quoted me $1600.


Get a GDE tune and forget about the EGR for 1/2 the cost.
Author:  papaindigo [ Thu Jan 03, 2013 12:22 pm ]
Post subject:  Re: surging at part throttle
At $1,600 that dealer should be locked up for theft. The part goes for like $200 online (list is like $270) and install shouldn't take more than 4-5 hrs if that.
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