my yukon is driving me nuts.....

[SunlitComet]

hi, im new to this site and new to my tahoe lol, so sorry if this question is dumb. After i change my distributer gear and i find top dead centre the pcm over time will reset my timing or do i need a dealer scan tool?

No such thing as reset timing and it does not have to be a dealer. A gm tech2 that dealers have can do it as wel as most snap-on and otc scanners that can read gm enhanced perimeters. I use a laptop based scanning system. The specific perimeter is called"CAM_RETARD".

---------- Post added at 04:29 AM ---------- Previous post was at 04:26 AM ----------

Yeah, you don't set the "timing" on these 96-2000 engines, you set what they call "CMP offset retard" (Camshaft Retard Offset). If you dropped in a new distributor you will need to set the CMP offset retard. The only way I know to do this is with a scanner while reading the engine's data stream. Your new distributor should come with some sorta instructions on how to set it, but basically you need to be at -1/0/+1. To do the engine needs to be warmed up, engine set at 1000 RPMs & if you have to adjust the distributor you need to turn the engine off when doing this. If your distributor comes with a clamp on it that don't allow you to turn the distributor take if off & use the original distributor clamp, mine was at something like -15 with the fixed clamp & set the P1345 code right away. The only time I know that the fixed clamp is correct is on the 4.3 liter engines.

I might have forgot a few things, but basically this is how it is done. For most people it would be best to take their truck over to a shop that can set the CMP offset retard for you after dropping in a new distributor.

actually it give you more leeway. +-2° from 0° and the engine speed is year dependent.

 

[frontyard mechanic]

thanks guys

 

[bubbz]

Just an update... .... I have so many new parts on this thing and it still has the miss... got new cats and muffler... spider injectors, and all the normal... plugs wires, distrib.fuel pump ... I was wondering if there is a vacuum leak some where or something... it runs like new in park but, drop it in gear and roll a few feet and the miss /stumble starts... I drove it home today and it barely would go unless I let on and off the gas making it down shift and such... then all of a sudden it started running like new... for 8 or 10 miles all the way home it done great... pulled up shut it off and told my brother to hop in... started it up rolled a few feet and same stumble/ miss was back.... Any body

 

[Phone Man]

Strange things happen when the grounds have bad contact. There is one on the back of the block on the passanger side as well as one on the thermostat or in that general area. Give that a shot.

 

[retorq]

Have you actually hooked this pig up to a real time scanner to see exactly what it is and isn't doing??

 

[bubbz]

They hooked it up but couldn`t tell until I replaced the cats that were cut out... now I just dont have the cash for a scan at this time.... got a bank 1 sensor 1 code.. replaced it then got p0300 missfire detected.... running out of options.... I`m going now to look for grounds.... Thanks for at least a direction to look... I`m totally lost at this point....

 

[bubbz]

still waiting on a scan but get this.... if i start it up... give it gas and try to hold it steady at any rmp it slowly kind of bogs and misses more and more... almost like it is loading up with fuel.... ????????

 

[SunlitComet]

Or running out or an egr acting up or a maf sensor acting up.

 

[bubbz]

i replaced the maf but not the egr... maybe look into it... trying to find someone who will hook me up on a scan tool for cheap... and see just whats going on... today i got a misfire on #4 instead of random.... ?? going to try a leak down test on injectors asap as well...

 

[SunlitComet]

Just try cleaning them first before replacing them. As in any part you deal with.