2000 gmc safari bucking at part throttle

[mikesfastss]

Also easy to diagnose the distributor with a good dry out with a hair dry are and then hit the inside with some wd-40 and see what it does from there.

[lone racer]

I have it in the heated garage with dog house out, and heat light for myself plus I spray wd as a routine, cap& dizzy had a squirt with new cap about a month ago

[lone racer]

no visual signs of water or a thick kinda dust on cap,still shiny

[lone racer]

not having luck printing data, I have watched videos and have a very small idea what to look for, the cat is empty and oil foulers are used but has been that way for a year or so.
o2b1s3 (v) bounces every frame.
THIS IS WHILE DRIVING! 130,.125,.115.100.130,.095,.105,.295,.105,.130,.12 0,.195,.510,.675,.490,.220,.240,.195. etc..
SHRTFTB1S3% 99.2

[CMYZ28]

4.3's hate dirty throttle bodies which might make sense with the no issues under full throttle etc.. Didn't see where you'd cleaned it unless i missed it. I'd start there https://youtu.be/lHLZfg5GYoA

[WhiteHawk]

Does the truck have EGR? Try unplugging the connector to the valve if it does. I had a car do similar stuff once, and it was EGR.

-Geoff

[lone racer]

Pulled it and cleaned it but it wasn’t bad at all, no real build up.
Scanner is saying no Egr off idle and failing throttle down test?
The more I play the more I find. Didn’t even realize I could watch live graphing, data yes but graphing no! Gives a little better visual seeing a graph over a number,lol.
I will check the book for test procedures, the springy thing moves easily and seats fully, no carbon build up or binding.

[lone racer]

4.3's hate dirty throttle bodies which might make sense with the no issues under full throttle etc.. Didn't see where you'd cleaned it unless i missed it. I'd start there https://youtu.be/lHLZfg5GYoA

That vid makes it look easy, BUT in a van not so much. I did a sea foam treatment thru the intake tube just before the TB last year, I might go ahead and pull it but really doubt that is the cause, had that issue before with a 5.3 and it was a way different kinda miss off idle to maybe 2000 rpm the van is more like 2000 and up before it starts acting up. But I have wanted to chop off that dohickey on the the blade tho.

I do try to maintain and do preventative maintenance on her vehicle, put fuel cleaner, actually flush systems and ensure I have done my best to keep her safe. My car is another story, but it seems to like no maintenance and full throttle racing to the next light. 214,000 Focus wagon, swear I try but I cannot seem to kill it. Maybe time to quit doing oil changes?

[dave89iroc]

ac delco cap only, never had any other brand worth a damn

[WhiteHawk]

Pulled it and cleaned it but it wasn’t bad at all, no real build up.
Scanner is saying no Egr off idle and failing throttle down test?
The more I play the more I find. Didn’t even realize I could watch live graphing, data yes but graphing no! Gives a little better visual seeing a graph over a number,lol.
I will check the book for test procedures, the springy thing moves easily and seats fully, no carbon build up or binding.

Just try it unplugged because if it is unplugged, the engine will know it, and run different timing and fuel. You can watch on your scantool too. If the trucks starts bucking when EGR comes on, then unplugging it will fix it.

-Geoff