5.3 not running so great!!

[acechevy]

We just put a 05 5.3 in my brothers 2000 ext cab z71. the mottor runs great but its starting to idle funny sometimes it idles around 700 other times around 1000 rpm. Also when you ridiing down the road and you level out at say 55 it revs up and down a little you can hear it in the exshaust. And when you floor it sometimes it boggs out a little and you can feel it slowly picking up then other times you floor it it'll ride out. Ne one know or have any ideas

[chvy=power]

is it thowing any DTC's??

[Botlfed]

could be O2's maybe, check your plugs, maybe get some injector cleaner, id start with the small things first.

[skeet]

We just put a 05 5.3 in my brothers 2000 ext cab z71. the mottor runs great but its starting to idle funny sometimes it idles around 700 other times around 1000 rpm. Also when you ridiing down the road and you level out at say 55 it revs up and down a little you can hear it in the exshaust. And when you floor it sometimes it boggs out a little and you can feel it slowly picking up then other times you floor it it'll ride out. Ne one know or have any ideas

some info would be great

is it just a stock 5.3?

is there any other mods to it?

who's tuning it?

[acechevy]

everything is stock besides the converters are missing and the the single in dual out flowmaster. And it has the check engine light on but the converters are out also. He just bought the truck a few weeks back the 5.3 that was in it had a cracked head so we stuck his 05 5.3 that he had bought for his regular cab in it didnt have but like 45k miles on it. Some time when it goes from first to 2nd gear it has a very hard snatch then other times it dont so im thinking what ever messing with the ideing has something to do with that also. My friend is looking for his codes checker but soon as we get that on there ill post the codes that are being thrown. Thanks

[GT killer]

did you do the crank sensor relearn after you put the 05' motor in? the snatching hard in 2nd makes me think its something else though

[96/chevy/pu]

Is it possible that maybe the 05 ran different size of injectors than the 2000. Maybe a vacuum leak, did you get to read the codes yet?

BB

[skeet]

who's tuning it? sounds like or could be a tuning issue

[acechevy]

no i didnt do the relearn. we still looking for the scanner. and it has the stock pcm no tune!!

[Smoky02]

They are the stock injectors. And my dad's 4.8 does that on occasion as well, he just turns the truck off and back on and it shifts normally. I know that's not a fix. Also his truck is completely stock. I always just figured his tranny was going out. Although I did recommend taking it to chevy for a reflash...just incase the ECU was messing up or something.