4.3ltr Seriously Bogging

Bogs · October 3, 2011

2003 GMC Jimmy 4x4 vehicle eng vin code X, 2 door

Wow..where to begin guys, this things been a nightmare, I'm actually a mechanic for a golf course ( after years in small auto garages ) myself and I can't figure this one out...

Well boys, it all started when the 4L60E tranny went... working as a mechanic you know you really dont feel like comming home and starting to work on your own car after a days work so I bought a used tranny from a scrap yard with real low miles and sent it off to a tranny shop to have it done...mistake number one as he didnt change the torque convertor, nor did he replace the front & rear seal or change the filter, all which I had supplied to him with the tranny, in addition he snapped an exhaust stud and actually broke the y pipe which he denied and I had to weld at my work. In addition it drove with the torque locked up all the time...Loooooooong story short I bought ANOTHER tranny and put it in myself ( also found he didnt tighten three bell housing bolts, broke the neutral switch because he didnt have a heat gun to unglue the connector, and ruined the seal on the output shaft causing it to leak and lock up the convertor...anyways, I rant, I'm just a little ticked at the place ).... so now the new tranny is in but the engine is bogging, seems to start & idle fine, but ANYTHING passed idle and I have a bog,it wont drive because if you give it gas it will bog and ultimately die, sudden acceleration will result in a stall...now codes with my Innova OBD II scan tool are for the mass airflow sensor and a rear left bank oxygen sensor... I replaced the mass airflow sensor and have 3 new oxygen sensor AND a new front Y pipe with convertor on the way... This truck wont get the best of me , might make me broke, but it WILL freaking run when I finish !! anyway error codes, which dont always trigger are P0101 & P0102, I only got the P0102 with the old mass airflow sensor and with the new one I am getting both P0101 & P0102, but not always, I can start it fine and if I give it gas you can here it start to bog and it doesnt trigger a code, as the new mass airflow sensor is giving me a code like the old one did, I've cancelled that out as a source for the bogging, along with the rear oxygen sensor as that being faulty shouldnt cause a bog, I've checked the continuity of the three wires from the mass airflow sensor to the control module and they checkout. I've also changed my distibutor cap and rotor.

I suspect either a vacuum leak at the intake itself ( checked all hoses already , there is one on drivers side that is not connected to anything and has vacuum when engine running, I plugged it, plugged or unplugged makes no difference whatsoever, engine bogs the same) or perhaps a fuel pressure problem...I'm just wondering if any of those would cause the intermitent P0102 error and the oxygen sensor error I see once in awhile... oh yes the front y pipe when i had it off I can hear the convertor rattling around and I know a clogged convertor can cause a bog, but it made noise before the tranny and ran perfect like that....

I guess I'm looking for the common problems that go on this truck to have an idea where to look, I suspect that driving it home from that tranny shop with it locked in OD put alot of strain on either the fuel system to supply it under that load or the intake and blew the gasket but I dont see any kind of leak nor hear a hissing and when I yank the PCV with the engine idling its sucking really good and If I give it some gas it moves, so the pcv isnt jammed.

I suppose my next task is to test the fuel pressure and check for bad pump or regulator ??

Then if that checks out yank the intake and look for a leaking /blown gasket ??

One other problem I've had with the truck since I bought it is when i fill up the pump clicks off 300 times, something to do with the vent valve but that never made it bog or given me engine problems before ...I'm wondering if whatever the problem is there could have worsened and is now causing the bog ??

I guess I know where to go, just looking for some confirmation and conjecture based from people with experince working on these trucks

I just find it funny that I didnt have any problems like this before it went to that tranny shop but the tranny seems to be working fine, cant test drive it to see but on idle in drive and reverse it creeps and goes into all gears, and the 4X4 woks too.

thanks for your time and replies