Hey guys I have a 2000 Chevy Silverado 1200 w/4.3 and Manual Trans. It is hard to start and when it does it idles up to 1200 and as low as 300 but after about 45 seconds of that it levels out at about 1150 and stays there. The throttle response is very sluggish and causes almost a backfire sound through the exhaust. The intermitten code it pops is MAF signal low and ckp sensor cam position senor no coralation or something like that. My scanner says the my timing is 10% advanced on distributor timing and cam timing is -12. I really don't even know where to start. I don't have any vacume leaks and new intake gaskets and head gaskets, new crank position sensor and all new tune up gear and pvc valve. Please anything would be great. Thanks

 

Makes me wonder if it has jumped time, I would say make sure to get #1 cylilnder on TDC and check under the dist cap and see if the rotor buitton is pointing at the #1 sprak plug wire location just so you can check and see if its still timed right. This will not be exact method to see if its jumped but its about the only way to check without pulling the timing cover off. Also how many miles are on the truck, I know you said you tuned it up make sure you have it wired right. I wouldnt say it was a vacum leak it should throw a bank1 &2 lean code with that. Just check this stuff and let us know what the outcome is, hopefully I was some sort of help.

 

I have already checked to make sure it is TDC and it was and I verified I put the timing gears on corectly as well by pulling the timing cover and to no eval. Now the weard thing is TDC it won't start and I did as much research as I could and i found it needed to be 180% advanced from TDC blew my mind on that one. But I have checked all that stuff very throughly. Now as far as runing lean, on the real time scanner it bounces from rich to lean and the timing is off it is 10% advanced but adjusting the distributor takes me back to -10 there is no medium, and I don't know how to fix the cam timing cause it is -12% so IDK sorry I didn't put all this in the first post and keep it coming cause I am hoping it is somthing I missed or didn't know about. Thank you The truck has 106000 on it and all the wiring is good checked that with a spark tester and I got good fuel pressure.

 

please guys anything

 

Ok guys I really need help with this one, it is my daily driver and I don't have the money to take it to the dealer. So even if your not sure just give me some ideas or maybe places to look. Again thanks for any information.

 

im having similiar problems and im thinking it could be a burnt valve, try a compression test

 

this could be a long shot but try cleaning ur MAF, maybe its not reading the right amount of air flow and that could cause similar issues that would mimic timing ..?

 

Definitely start with cleaning the MAF with the special MAF cleaners sold at automotive stores. Anything else could ruin the sensor. Also, the catalytic converter could be clogged. One final thing to check would be fuel pressure, find out what pressure your engine should be running and test it.

 

does it have a egr valve? could be bad