XChris1632X Posted May 4, 2011 Report Share Posted May 4, 2011 I was hoping some people more experienced with these engines could chime in with some tech info. I know AJ has prob had plenty of time with these. Anyways, my wifes tahoe has a new fuel pump, plugs and wires. All of this was done a week before I bought it. Since I drove it home from buying it I noticed the miss at stoplights and upon accel when leaving stoplights. It will shutter and cut out like a coil not firing until about 1500-2000rpms or so. Some times it will go away and be fine for awhile but there are times it is worse than others and feels like its going to shake apart at the light. It only does it in drive. The only codes I have found were p0446, which seems to be common after replacing fuel pumps and is usually the vent valve rather than the canister. The code goes away after about 200 miles and will come back after another 200 or so. Since I am on orders and away from work, I am very limited with diag tools. My initial thoughts were maybe a vacuum leak at the intake, throttle body, or fuel pressure reg. Any ideas or common issues that you guys know of before I start trying to test everything down to the bumpers? Quote Link to comment Share on other sites More sharing options...
BigOxley Posted May 4, 2011 Report Share Posted May 4, 2011 wife?!?!?! wtf chris edit: (no homo) Quote Link to comment Share on other sites More sharing options...
STEVE-O Posted May 4, 2011 Report Share Posted May 4, 2011 Check the coils. If there was a aftermarket one put on delphi and there is another type for those they will work for about a month if that then start missing like hell. You ahve to put a oe coil on those or they get pissed Quote Link to comment Share on other sites More sharing options...
spankis Posted May 4, 2011 Report Share Posted May 4, 2011 I chased a similar problem on my parents 03 Suburban w/ the 5.3. Theirs indeed up being a much larger problem lol, but I would bet on either coil or intake gasket w/ what your describing. Swap the coils around and see if the miss follows/changes. The intake gasket rolling over and starting to leak is pretty damn common and there is a revised gasket for them. Quote Link to comment Share on other sites More sharing options...
AJ Posted May 4, 2011 Report Share Posted May 4, 2011 spray the lower intake with carb cleaner and see if the mis goes away. Quote Link to comment Share on other sites More sharing options...
XChris1632X Posted May 4, 2011 Author Report Share Posted May 4, 2011 wife?!?!?! wtf chris edit: (no homo) Yeah you act like you are in another country Wouldn't a coil most certainly throw a code when missing that much for that long? Especially with all the extra fuel coming through. Quote Link to comment Share on other sites More sharing options...
AJ Posted May 4, 2011 Report Share Posted May 4, 2011 unless it was a fuel misfire. clogged injector or so. a scan tool to watch fuel trims and what cylinders are misfiring would be ideal. Quote Link to comment Share on other sites More sharing options...
Cordell Posted May 4, 2011 Report Share Posted May 4, 2011 unless it was a fuel misfire. clogged injector or so. a scan tool to watch fuel trims and what cylinders are misfiring would be ideal. This, they are good for intake gaskets, but it doesn't really sound like that the gaskets are usually a lot worse when cold. really would be nice to have a few diag tools. Quote Link to comment Share on other sites More sharing options...
BigOxley Posted May 5, 2011 Report Share Posted May 5, 2011 Yeah you act like you are in another country i thought we were friends, geez. Quote Link to comment Share on other sites More sharing options...
XChris1632X Posted May 12, 2011 Author Report Share Posted May 12, 2011 spray the lower intake with carb cleaner and see if the mis goes away. This is one of the things I had on my list to do. It seems as though the times i try to do this, the truck wont miss. It has been doing it a little less lately and i don't drive it much. unless it was a fuel misfire. clogged injector or so. a scan tool to watch fuel trims and what cylinders are misfiring would be ideal. I am limited on diag equipment while I am away from my full time job and I don't have a scan tool anymore. I am going to start with the basics and easy stuff to narrow it down I guess. No experience with fuel pressure regulator causing similar symptoms? Quote Link to comment Share on other sites More sharing options...
AJ Posted May 12, 2011 Report Share Posted May 12, 2011 no, if the regulator went bad you would run very rich. Quote Link to comment Share on other sites More sharing options...
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