Hi I bought an 02 tb LS 4.2L about 4 months ago about a month ago the engine started hesitating upon take off and lacked power thoughtout the entire powerband. At first it was intermittent for a short time. It is now full time and yes I changed the clutch fan as It had a small wobble to it and i thought that was the problem. The motor sounds like a diesel when it starts until it's warmed up and it didn't sound like that when I first puchased the truck. I don't have any codes from my scanner. I found the fuse blown to the cigarette lighter and at first the scanner wouldn't work that had me confused for a bit. So it doesn't idle rough, gets really poor milage now and it has a hard time even pulling my little boat, I have to ride the throttle hard to keep speed but before it had no problems towing it... it's like I lost 100hp gone zilcho no pep just baaaaaa.. Anyone run into this ? please help :banghead: thanks for your time Keith

Welcome to AF, if this is not an obvious misfire then a full diagnostic scan should be done, no quick answer for this, you many need to get professional help here.

PCM re-flash? The dealer or shop that replaced the F/C should have done it. That's all I can think of.

Hi... I replaced the fan clutch assembly myself as it is not to difficult of a job, I have read in the forums that many people have changed this without the "re-flash" and have not had a problem. I'm going to make an appointment today for next week and have a full scan on the truck as you mentioned Max as I am at ends now :banghead: . If they recommend the reflash I will do it at that time. I will keep you posted with the results as soon as I find out some information on the problem !! thanks again Keith :frown:

Hi got my TB back from dealer.. full diagnostic scan performed nothing found.. tech found fuel line kinked near fuel rail said it was installed improperly ? test drove truck and said to be fine :screwy: I picked up truck at closing.. no techs to talk to just service manager asked him about it and he stated he new nothing about truck.. okay ? I start truck up and bingo same problem... I guess I'll have to live with it:banghead: I wish I could dyno this thing cheap to see the bhp and tq curves and compare to see if it's even close cause I know it's way way off.. if my truck has to drop a gear to climb a slight grade hill something is wrong !!! nuff for now :disappoin

could it be a clogged fuel filter? or what about the very known issue of the dirty throttle body?

HI, I cleaned the throttle body 2 weeks prior with no change in performance, it was a little gummy on back side but not to bad. I did however find an article where a person was exp. the identical symptoms I am and he stated finally after many months a code set and it was his o2 sensor in front of his cat converter. He stated he replaced it with an after market unit Bosch I believe, also he said he had to disconnect his battery to reset the pcm cause he believed it was in a loop or stuck in a certain state ?. anywho I guess it worked out great. I'm prolly going to change the fuel filter and that 02 sensor (filter first) but I will use the genuine replacement not aftermarket for the sensor. I willl keep you posted thanks Keith :popcorn:

Hi just an update I replaced the fuel filter this weekend with no change, I will be replacing the o2 sensor in front of the cat within a couple days to see if that helps. I have been trying to figure this out and now I'm wondering if I'm looking in the wrong direction.. could it be the darn transmision torque converter locked up or messed ? would the diagnostic scan the gm garage performed have seen that ? okay enough for now :popcorn: any ideas please respond thanks Keith

Look around the boards and see what you can find on "sun gear" and "sun shell" failures of the transmission. Compare to your symptoms. That's the best guess I can give you. I wouldn't pin it on fuel or emissions if the dealer's scan came up empty.

This is all guess work, someone knowledgeable needs to drive this, feel the symptoms and go from there.,