2001 Tahoe Surging

[Ramsair]

Hi - I have a 2001 Tahoe - 143k on the clock. Recently it has started to surge... more noticeable when the ac is on. It does it through the whole range of speeds... can feel it at idle and all the way up to 70... had the fuel pump replaced by GM about 4 months ago - fuel filter too. Plugs were done at 88k.

The strange thing is that when I feel it lagging I punch it and the check engine light starts to flash - once I am off the gas the light goes off. No codes thrown... any chance this could be a coil pack going bad? How can I tell without hooking up a scanner while I am driving (which I don't have)
Thanks

Chris

[Ramsair]

So here is the update.

Got the AutoZone guy to do a ride in the car with the scanner - P0300 - multiple cylinder misfires... yeah, that can be about 10 things. Figured it was time for some new plug wires, so I threw on some Bosch... interesting how they are about an inch longer than the stockers. Anyway, it is still studdering... and actually feels worse. I have 50k ish on the plugs so I will change those out. If it does not work I will check the fuel reg / pressure - and then one at a time unplug the coils ... could be EGR, or a vac leak... just hard to pin point. Last resort it will go in to the shop for a pro to look at it.

Thx

[777stickman]

With the "CEL" coming on and then going off the VCM should store a "history" code. Check that and post back.

Also, if your going to throw stuff at it, it's best if you throw OEM Delco at it.

One last thing is we need the engine size!

[Ramsair]

P0300 - it did it while we were driving and it was stored.

Thanks

[MT-2500]

Originally Posted by Ramsair

P0300 - it did it while we were driving and it was stored.

Thanks

A good start on it.
Pitch them Bosh wires and plugs in trash can and get AC -Delco parts
Confirm good fuel pressure on the road.
A good engine capable scanner will tell you what cylinders are missing and a lot more .
What is camshaft retard setting?
What is fuel pressure readings?

[j cAT]

Originally Posted by Ramsair

P0300 - it did it while we were driving and it was stored.

Thanks

since you have the 5.3L engine with this code replace the plugs with the ac delco irridium type. do not try to check the gap as this will damage the fragile plat wire. if the gap LOOKS wrong get a replacement !

THIS ENGINE IS PICKY ON PLUG TYPES.

also 50-60,ooo mi is all I use plugs with this engine...

measure the plug wire resistance at this time 400-600 ohms range.

this code could be the crankshaft /cam shaft sensor pick up. this would create this code. this engine will throw this code if towing up a grade that has a poor road surface. the tires slipping on the unstable rough surface will cause the cam/ crank to not properly report to the PCM creating a false missfire code.

the cam/crank sensors or connections/wire to them could be the issue.

I have used bosch +2 plugs with no problems. however many have have had issues with this plug. comparing these plugs the new plug replacement by ac delco slightly increased my MPG. so that is why ac replacement is what should be used in this engine only.

could be like you say many things ..

replacing the PCV and checking those crankcase venting hoses is also important. check engine vacuum. could be intake/throttlebody gasket leak...etc..

[Ramsair]

All great suggestions - thanks.

I changed out the plugs this morning, they did look worn and were a little out of gap... they were ac delco's - I am using new Bosch wires though (AutoZone does not carry ACD). Man is that rear passenger plug and wire a winner...

Have the ac delco irridium in now and it is running very smooth ... feels almost like a new car even with 143k on it.

At least it was not the coils at this point.

Thanks to all...

Chris