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Murf
10-12-2003, 16:08
2003GMC - 7,000 miles - towing a 9,500 lb trailer - T/H mode. Things are working fine - no problems - when going uphill in TH mode around 2700-2900rpm its like suddenly the engine valve train gets several db louder - best way to explain it, its kinda of like taking off the ear muffs - performance is fine - its not the tranny - to me, sounds like the valve train or something? Is it normal or am I hearing things? Anybody know what it is?

Thanks, Murf
deerhunter7
10-12-2003, 16:16
That's about the RPM the pre -injection kicks out. That would be my guess..
DmaxMaverick
10-12-2003, 16:27
Sounds normal.

2600-2700 RPM is when the pilot injection is disabled (goes to one shot of fuel per event) and timing becomes more aggresive. The result is more Diesel clatter.
dmaxalliTech
10-12-2003, 16:34
Ditto on the pilot injection
Murf
10-12-2003, 17:29
Who Knew!! - thanks guys - appreciate the replies -
Murf