Vortec Mystery Miss

[TerryD]

I have no way of seeing that particular parameter, but I had the chevy place do a crank relearn and it didn't change anything. They didn't say anything about it being out of spec our having to correct it.

 

[98_k1500]

Does my description of the symptoms sound like what yours is doing?

 

[TerryD]

Pretty close, yup.

 

[Johnc1500]

Try unplugging the EGR, my Vortec had a mystery miss, I changed plugs/wires/distributor/new exhaust everything I could do haha, then a older mechanic said "unplug that egr and it will fix her" and surprisingly it did.

 

[Johnc1500]

Which mine missed just cruising, but I could lock it in gear when I wanted to race or screw around and it would hiccup I couldn't feel it in gas pedal but could sure hear it. Might be ur problem aswell.

 

[TerryD]

Well, anything that causes a check engine light makes it go away. I do want to take the egr off and check it though. Might do that tomorrow, don't think I'm going to get to go home today. All morning spent on a carry over job from last night when I've usually got 10hrs of stuff to do on a Thursday anyways.

 

[TerryD]

It set a P753 this morning and again this evening after clearing leaving work. Transmission shift solenoid A (1-2 per gm manual).

 

[TerryD]

Well, rechecked the grounds. Found the one behind the EGR valve loose, and snugged up the one beside the CPS and the one at the back of the block near the coil. No more solenoid codes, but I'm not holding out much hope til the engine cools down again and I do a cold start. Still missing though.

Got it to happen in the driveway. Loaded up the engine in reverse, when easing the throttle down there was a definite hard miss and 1&4 would count it. Only when throttling down though, not full throttle.

 

[TerryD]

Still fighting this thing....

List so far:
Swap MAF from K2500
Swap EGR from K2500
TPS
MAP x2
Plug wires x3
Plugs x2
CPS
Valve Lash Check
Distributor gear
Check grounds


Still getting the exact same miss. Shift solenoid turned out to be just that and it wasted the trans in November. Had it rebuilt in January then had to put a fuel pump in it three days after getting it back. Been driving it thought the miss figuring it'll either get bad enough to give us some indication what's going on or will miss till the day I decide to burn it to the ground. This is racking my brain guys. Still no means of checking offset. I drug my feet and let a Snap-on scanner get away from me for a stupid good price. Any suggestions or reasonable offers to buy? LOL

 

[99'Subourbon]

My issue wasn't while letting off the throttle, but I had the 'buck' you were talking about when cresting a hill etc, in my Ford. In turned out to be a partially clogged fuel filter. Cheap enough to replace...