steveczi

Hi I have a 1999 Tahoe,With 5.7. At highway speed (65-75) it starts to shudder randomly. and not allways but do get a code PO305. I have had fuel pump and filter changed, #5 fuel injector, wires plugs and pick up sensor " under cap", cap and rotor changed. Have had it to two shops nor I or them can figure out problem. Used bore scope to check valves. Took off valve cover to check spring and rocker Shop did leak down test and compression test. I love this car but its about to be put out to pasture.

GDELGADO

if you replaced distributor then your next step is to check your timing chain.. this could be your solution asuming you checked your cam/crank sensors...

steveczi

Hey thanks for the advice. I gave the tahoe to my brother in law and I'll pass on the info

sgf123

hello, has anyone found the problem with a misfire/shutter after replacing the fuel spider with upgraded Mpi one? I have new heads,distributer,plugs,wires, and replaced the top intake to reduce vacuum leak. Still now and then does a hard mis when letting up on gas at cruising speed. Other then that it runs great. Thanks

cdwillia

I've heard about one guy solving the issue. He found a BAd wire going to the cam sensor. I don't see how he possibly found a grounded wire for the cam sensor because it's buried behind the motor. My 1998 Chevrolet k1500 does the same damn thing. I'm going to try and find a bad wire tomorrow after work. If anyone else has found another solution please let me know

JCam550

Hi guys. New here. I began poking around the forum because my 99 Burb is going the same thing. I'm running out of ideas. I'm hoping someone solves this widespread issue. Thanks!

jrhope

Unfortunately no. It just broke the 210,000 mile mark and still bucking. Actually I have conceded and no longer try to troubleshoot it. The last attempt was a custom tune to the ECM to see if it could be tuned out. That didnt work either, however I have much better throttle response, power and fuel economy. She was extremely rich on the low end and lean on the top. So it wasn't a complete waste of money.

Curious, have you had any recent repairs? What has changed prior to this happening?

jrhope

Any Luck? It would seem that if it was wiring the cam sensor circuit it would trigger a CEL. Just an opinion...

GDELGADO

Hey sorry to hear about your problem I have a 1996 silverado was doing the same thing it took me a little while but I got to the problem turned out my distributor gear was worn and the timing chain was worn as well so this was replaced and now it runs great.. I hope this info helps... Also replaced distributor cap and rotor not just the gear...

JCam550

I've only owned the truck for 11 months. It came on shortly after buying it, so I think it's been there prior to me owning it. I did a full tune up after I bought it to see if that would help, but nothing. Last summer I dumped in a bottle of Marvel Mystery oil because I read it may be a sticky lifter. That seemed to help for a while, but it has since returned. The truck runs great other than that. I bought it with 93K on it. It now has 109K. I've had no other repairs except for a new radiator. I've had the truck hooked up to the computer a couple times. All it shows is the same misfire code.

One thing I have noticed with it is that when it happens, and the code is thrown, a few seconds later, I will feel something change (feels like the computer is adjusting something) and the shudder will go away. The tach seems to be reading a couple hundred rpm's higher after this happens.

Reading on here and other sites, it seems that this is a widespread issue. I'm surprised no one had found the cause yet. It's very frustrating.

Curious, what custom tune did you use? I'd love to squeeze out a few extra mpg.