Really acted up Saturday and Sunday, dry, not even muuch humidity. When it starts cutting out it will run fine if you floor it, or feather it, just nowhere in-between. This time I actually heard it backfireing when it missed (didn't know EFI 'could' backfire ... live'n'learn). This time it finally threw a CEL while it was acting up.

 

OBDII code P0420 the old 'somewhere in the catalytic universe' code.

 

Other than checking connections, where do I start replacing parts on the shortest possible road to a cure (which is all the stealership will do ... 'cept they'll take the longest road).

You could try cleaning the throttle position sensor. Also replace the fuel filter if it hasn't been changed. You may also want to check the fuel pressure.

Really acted up Saturday and Sunday, dry, not even muuch humidity. When it starts cutting out it will run fine if you floor it, or feather it, just nowhere in-between. This time I actually heard it backfireing when it missed (didn't know EFI 'could' backfire ... live'n'learn). This time it finally threw a CEL while it was acting up.

 

OBDII code P0420 the old 'somewhere in the catalytic universe' code.

 

Other than checking connections, where do I start replacing parts on the shortest possible road to a cure (which is all the stealership will do ... 'cept they'll take the longest road).

I don't know if this helps but I have hesitation and other problems, I don't even need a code on my case I can see the sparks all over the engine, so take a close look at your ignition wires

Thanks,

 

1. Where, oh where is the throttle position sensor, and what does it look like?

 

2. New fuel filter, and pressure is good.

 

3. Will do spray bottle test on wires after it gets dark.

The TPS should be behind the coil area and in front of the air cleaner.

Ok diagnosticians, add this to the mix.

 

Driving to Spokane all was well from Whitefish to Sandpoint, from Sandpoint (1/2 tank) all the way to Spokane the bucking and missing was the worst it has ever been. At Spokane I spotted a Standard station (we don't have them in NW MT) and filled up with Chevron Supreme (ouch!) AND added a can of Techron. This had cured the miss the very first time it happened last spring in Billings, when I assumed we had water or somesuch in the tank.

 

INSTANT CURE! Missed as same for about thirty seconds, then smoothed out and ran perfectly. The car was parked outside at GEG for ten days. Came back from Mexico scooped a foot of snow off her, and drove back to Whitefish with nary a hiccup (good thing too, it was heavy snow all the way).

 

I'm back down to a quarter tank, and will refill with local gas and see what happens now. I bought another can of Techron to keep in the car, but at about $8.00 a can, that isn't a viable on-going fix.

 

Whadya think is going on here?

 

Thanx, Smitty

 

BTW, Mexico central Pacific coast was beautiful, my daughter's wedding was stunning, the surfing was excellent, the food, beer and tequila great, and we came home to 18" of fresh powder ... what could be better?

what is techron??? and my gas tank had two drain plugs on it. one on each side. If you think you have something in the tank.

Techron is a fuel additive that Chevron makes to help clean fuel systems.