94 tbi issues!

C.Berry

C.Berry

Bad News
Joined
Aug 10, 2008
Location
Blacksburg, Va
94 gmc suburban 5.7 tbi I believe a have a cracked flex plate to start it all off! But recently (last week) the burb started to hiccup I guess you could say going up hills or on cold start I thought it was a tcc but I feel like it's actually a engine issue instead I've replaced water pump, tips, egr valve and sensor, plugs, wires and vac lines, fuel filter, belt, alternator... Still an issue my mechanic can't get me in till next week to put on scanner so I'm trying to pinpoint the problem before then! Any suggestions? Idle in park is 850rpmish 600rpm in drive. Also have what I believe is valve seal bad bc I have oil smelling smoke every startup! That's just the drivetrain issues tho whole new thread on suspension to come! Haha help before I park this truck in the field!!
 
Don't have any pressure gauges to Che k fuel pump but will be purchasing that soon as I'm not fixing my DD vehicles
 
So I'm still under hood while making tbis thread I found the new egr valve is not holding vac with the old thumb test and idling when I press egr diaphragm idle doesn't drop!? Would egr cause the truck to jerk like its bogging out then clear up like this? Has me and apparently 400,000 other gmc owners baffled.. Almost feels like tc shudder then it'll slip/bog could be two completely diff issues lol i thought map sensor also but haven't heard of them going bad and having these affects!
 
Sounds like a crank position sensor to me.
 
Cps in dizzy? Could it be possible knock sensor going bad? It jerks hard enough it pops my bad cv shaft up on pass side of truck shit sucks replaced the bad egr and pvc thinking my ticking noise in old pvc was setting knock sensor off but still nothing changed! No codes is it possible the new tps I have is bad? I'm at a loss on this thing till the scanner tells me what's wrong
 
Just Checked tps voltage and grey wire shows .03c white wire shows 5v and blue wires .03v so does that make it a pcm issue? I'm not good with electrical stuff so he'll I could be using meter wrong!? Lol had it on 20v dc I believe
 
Unplugged map sensor to see if it fixed problem and truck dies right away same if I just unplug vac to map sensor!? Thought it should idle with map unplugged guess not?
 
Well just out of curiosity I wanted to see if it would jerk while in park I revved engine up and got an awful grind/crunch noise from engine! I have major smoke on startup was guessing bad valve spring or maybe the crank wants out of this 5.7? I'm drinking now to hell with it
 
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