99 obs suburban 2500 issues

C.Berry

C.Berry

Bad News
Joined
Aug 10, 2008
Location
Blacksburg, Va
So I've had a sluggish ass burb with 5.7 since I've bought it! It had a bad fuel pump swapped that with Delphi/delco filter that helped a little! Have replaced tps, delco plugs/wires, had it timed bc it was 11deg off, it's been on two separate snap On scanners and no one can find any issue... could it's possibly be the 4l80e? Or any of the solenoid* in it? Was gonna drop pan and do filter and new fluid but read that some selanoids can cause a vibration? Mine has a vibration and a power surge not harsh but noticeable at idle also started hard shifting into every gear when getting on highway! Anyone ever seen this type of behavior? 5.7/4l80e got a date with stealership next week but damnit I hate giving them money!!!
 
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Both shops said it's a GM "problem child"... lol thing is I don't believe they know how to properly operate the computers given I had to show the one fella how to pull up the cam retard in the scanner!
 
Most GMs I've ever driven with a 4 speed auto had a shudder in OD at about 55 and I think it's some kind of torque converter issue. Not sure what the actual issue is though.

Also, is the distributor gear good? The late 90s trucks were bad about wearing them out for some reason.

Oh...one last thing: solenoid. Sole-eh-noid.
 
lol I thought I had that right shoulda proof read it! Yeah above 55mph it runs great it's gettin to 55 that kills me! Was going up a 8ish% grade yesterday at 4K rpm 53 mph all it had...
 
Found a bad plug wire so that's a start I reckon! Timing gear is good pulled dizzy when we timed it on scanner, dizzy is actually a billet one looked new! The fella I bought this from was trying to figure same issue out I'm assuming bc it also had the spider injection upgraded to mpfi... it's got me stumped I have a ground wire that's corroded almost in half and when I bought the truck one ground strap on pass side was disconnected all together!?
 
Different engine but my 01 6 liter had what I perceived as a transmission slip or shudder and it turned out to be multiple misfires caused by a bad crank sensor. Have you done a compression check?
 
Not yet! was looking to buy a gauge here soon just to have in hand. It's back to driving normalish after I replaced the broke plug wire def the cause of my 4000rpm hill climb two days ago! I was gonna do crank sensor during tune up but was told there's no need it'll either work or it won't... im gonna grab one just to be safe I have a front main seal bad I believe so my cps is soaked in oil...
 
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