TOPIC: 2001 Silverado 4.8L Cap-Gap-n-Groove

Hello Fellow Gadgetmen!

I wanted to let you know about my 2001 Silverado w 4.8- The best mileage I got on it before any changes was 15.1 mpg.

My first step was to Cap the PCV and Breather ports, then I put $3 Bosch platinum plugs in and gaped them at 20% over spec (from .060 to .072). Then I left for my 1000 mile trip to MT to get certified with Ron. My first mpg check was after going over Mt Lassen and doing 80 on the hwy I got 18.7 mpg. Then I recorded 20.1 and 20.3 rolling into Hamilton. AWESOME!!!

I was looking forward to see how the groove would perform on my return home. After grooving the TB and clearing the ECU- my mileage went DOWN to 18 mpg coming back across the country, stopping at exactly the same spots for gas.

I'm so glad I did the Cap-n-Gap separate so I can tell what the groove's effect was on it's own. I have not not done an in-town mileage check since my return yet but will post it tomorrow.

Ron suggested it has to be the MAF sensor and that installing the MapSter should bring us back some gains and the O2 sensors could need replacing. I installed new upstream O2's a couple days ago and I plan on installing the MapSter tomorrow as well.

I will post again soon!

GM Tim - Gadgetman Redding

One correction, Tim.

I said it had to be the MAP, the pressure sensor...

Keep us posted!

Ron

Hey Tim. I agree w/ your findings on "Cap 'n Gap" I capped and re-routed PCV on my '74 Dart 225 slant six, that made it finally run like a normal Slant Six!

I'ts not Grooved yet, not much material in the Carter carb's TB. Though when I do Groove it I'll post all 'bout it, it will be another Carburetor Adventure.

As for Ignition, it's basically stock electronic ignition, w/ Pulstar plugs. I don't think those plugs would like a bigger gap, haven't tried it yet.

It is wild 'bout your Chevy there's a ghost in both of yours for sure. Be interesting if Mapster does the trick, if it does then that will be another Validation of Mapster! Hey if ya find the Ghost does that make ya a ghostGroover...(groan)

Would be cool if there was a vacuum guage sensitive/fast enuf to see the Groove effect, but it probably would cost more than I did! Gee I guess there is it's called a MAP Sensor...I don't know what kind of scan tool could track and graph the vac. fluctuations--the ECM sure does though?

Ok somebody smack me...

Tracy G

Keep swingin' at it Tim!