Truck Studdering

[rcman989]

Hi all,

Lately my truck has been studdering around 55-60mph. It gets up to speed no problem, but then feels like it skipped a gear tooth and studders. Its a really odd feeling and I was wondering if anyone can help diagnose this.

Along side of doing that, it also has a random misfire sometimes, then you shut the truck off and an hour later it runs just fine. It will throw a code for a misfire, but only happens maybe twice a week of normal driving. For the entire time you drive it during this time it feels like it is misfiring and runs completely terrible as if it keeps misfiring. But like I said after you shut it off and let it sit for a while it will run just fine.

I will be home from school for 3 weeks so I want to get this problem fixed. I have heard everything from a bad EGR valve, to the timing is off, to a broken valve spring, or bad distributor cap. Any input would be great. And thanks in advance.

 

[rcman989]

Also, did plugs, wire, and cap last 2 winters ago. Fuel filter and fuel pump this past spring.

 

[Gatorboy]

The timing is probably off. Had the same problem a while back

 

[LoudnLifted88]

edit read it wrong... no idea

 

[SAATR]

Distributor cap or drive gear would be my bet. I bought a quality cap and it only lasted about a year and a half to two years. Pull the cap and check it out, if it looks good, it could still be crossfiring (issue with crab style caps). Mark the location of the distributor and pull it out. Look for worn, knife edged teeth. If that's your problem you can get just the gear or a new distributor, your choice. If the gear is good, replace the cap and rotor and see what happens.

 

[RHamill]

Could be intermittent coil issues. Timing shouldnt be off unless you moved the distributor which you shouldn't have for replacing a cap.

 

[Gatorboy]

The timing on my truck was off from the PO. If you own a timing light check it first before throwing out money all over the place, if not, do a tune up.

 

[SAATR]

The timing on my truck was off from the PO. If you own a timing light check it first before throwing out money all over the place, if not, do a tune up.

You can't check the timing on a Vortec with a timing light, as there is no pointer on the timing cover nor timing mark on the harmonic balancer. The only way to set (or check) the timing is with a good scanner that can read the "Camshaft Retard Offset". You have to set it to 0 degrees (plus or minus 2) or it will (usually) throw a code. Once this is done, no other timing adjustment can or should be made, unless you have your own tuning software and want to change the timing maps.

 

[Gatorboy]

You can't check the timing on a Vortec with a timing light, as there is no pointer on the timing cover nor timing mark on the harmonic balancer. The only way to set (or check) the timing is with a good scanner that can read the "Camshaft Retard Offset". You have to set it to 0 degrees (plus or minus 2) or it will (usually) throw a code. Once this is done, no other timing adjustment can or should be made, unless you have your own tuning software and want to change the timing maps.

Ah I'm on Tapatalk I can't see his sig to see what he has. Yeah if you have a vortec check for a worn distributor gear, pretty common problem. The timing thing like I said is for TBI only.

 

[firefighter_2319]

The timing on my truck was off from the PO. If you own a timing light check it first before throwing out money all over the place, if not, do a tune up.

cant use timing lights.....i already did that in the past and got it all screwed up. timing is all done by the PCM. only thing you can adjust is the cam retard, but you gotta have a scanner to do this. if the dizzy is installed correctly is should read 0* +/-2 . if you dont have that then it needs to be adjusted. (+) meaning advance (-) meaning retarded.