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CATEGORY LISTINGS > GM DIESEL > 94 6.5 diesel, 72 mph for 10 sec =limp mode [ REFRESH ]
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94 6.5 diesel, 72 mph for 10 sec =limp mode

Created On Thursday December 01, 2005 18:37 Diesel Talk
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Note Thursday December 01, 2005 18:37 View thread in raw text format
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i have a 94 chevy 6.5 truck, that if you drive 72 miles an hour for more than 10 sec, kicks a 78 code then loses power(limp mode), i can keep driving it this way, it just doesn't have any power. if i shut it off and restart it the code light goes off and the power comes back.
78 code is wastegate solenoid fault, i already had to replace it once and it fixed the boost problem, but didn't fix the losing power at 72 mph. i can run 71 all day and no problem. it will also kick this code if you put it to the floor from the start. it does that at about the top of second gear. the turbo is new from bullydog, it's a 96 upgrade(16lbs boost). the vacuum pump is new and the wastegate solenoid is new, i rebuilt the transmission(4L80e), and replaced speed sensor on the transmission, which was faulty. i checked the map sensor for correct voltage and it seems fine. i can drive over 72mph as long as i keep letting of the gas every 9 seconds!! CAN ANYONE HELP???????????? confused

Edited: Thursday December 01, 2005 at 18:58 by mudpuppy
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Note Saturday January 28, 2006 22:42 View thread in raw text format
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same thing with me, all i did was switch the hoses around, on the solenoid wastegate thats is on top of your engine on left side above valve cover, try switch the 2 plastic hoses around.. it fixed my problem when i was replacing the old plastic hose, they cracked so i used brake linings and installed them wrong and i got the same problem you had.. but my truck is 1994 chevy silverado 3500 with manual 5spd 4x4 but the problem you described is very similar to mine ! so try switch the plastic hoses around.. it should fix it..let me know if it solves the problem for you..
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