Super Low Gas Mileage

[slowestmonte]

So long story short I decided to replace my E4ME and completely remove the CCC and emission systems months ago, dumb idea, I have since put the original system together with a brand new rebuilt E4ME from mountain man carbs.I have EGR blocked off, the AIR system is only about half there, and I don't have the charcoal canister hooked up. The car runs perfect and the timing is perfect, it isn't acting rich or lean, and the only problem I'm having is it shuts off after a few minutes of sitting at idle, but I think that has something to do with the fact that I have the electric solenoid on the throttle lever (meant for upping the Idle when AC is on), wired up to be full time idle, to prevent dieseling. The major problem is I'm getting about 12.5 MPG mixed with a 200-4r and semi gentle driving. And that's mainly in 3rd and 4th gear (though I do have the TCC lockup disconnected). I know the lockup being disconnected can cost me a few mpg, but I think I should be getting more than 12 with a 305 and 2.41 rear gears. Any suggestions?

 

[pontiacgp]

Either install the whole ccc system or use a complete system that is not computer controlled

 

[Z48LT1]

Sorry, friend, but the PM speaks the truth. You can't beat GM's engineers. It's an ugly game, alas. You get props for a noble effort.

Best - Gary

 

[slowestmonte]

Like I said, it has the full ccc system now, but I'm still getting bad mileage.

 

[pontiacgp]

Like I said, it has the full ccc system now, but I'm still getting bad mileage.

you posted you "have the EGR blocked and the AIR system is only about half there, and I don't have the charcoal canister hooked up" so how can you say you have the full cc system?

 

[TURNA]

Brand new the Monte only got about 15MPG city so your are not that far off.

Like said before either 100% on or off with the computer/emissions crap.

 

[oldsmobile joe]

I have EGR blocked off, the AIR system is only about half there, and I don't have the charcoal canister hooked up.

I have the electric solenoid on the throttle lever (meant for upping the Idle when AC is on), wired up to be full time idle, to prevent dieseling

I do have the TCC lockup disconnected

um, well, no you don't.
the egr system allows more ign advance without pinging, promoting better fuel economy.
the air system lights off the o2 sensor sooner for better emissions and fuel economy.
the idle up solenoid may be causing excessive throttle blade opening, causing a drop in fuel economy.
the tcc lowers your eng rpm, promoting better fuel economy.
joe

 

[Clone TIE Pilot]

Have you checked the M/C solenoid dwell with a analog dwell meter? That will tell you for sure if you have any rich or lean problems even if slight. The CCC can run fine without AIR or evap. Missing EGR will cause issues.

The stock CCC O2 sensors are not heated, and prolonged idling will cool them off and cause the CCC to reenter open loop. However, it should not be stalling, and idle stalling issues are usually fuel mixture problems, mainly vacuum leaks causing lean mixtures. The CCC is very sensitive to any vacuum leak. I found Fel Pro gaskets for the intake manifold and carb mounting gaskets tend to leak vacuum more often than AC Delco GM gaskets.The Fel Pros are too hard.

Also not sure about the quality of rebuild from Mountain Man. The carb rebuilding industry is a dying one. Many rebuilders are cutting corners using sub par, non factory spec parts as well as kit bashing mis matching core together, and other forms of butchery. Sadly a brand new rebuilt carb can not mean much these days. Generally it is best to have the original carb that was bolted to the engine rebuilt rather than exchange it as a core towards an already rebuilt carb.

 

[Ribbedroof]

FWIW, I put a Mountain Man reman QJ on my previous Bonneville, it performed very well As I recall, he was a GM tech for many years before he moved into his own business operation.

In my case, it cured the issues I was having, which could, I'm sure, have been cured by rebuilding the original, but it is my understanding that the CCC carbs require some specialized tools to properly set up and said tools are not widely available in today's market.

Personally, I would not hesitate to use him again, although it is nice to know that you have a wealth of knowledge about these systems.

Unfortunately, my current wagon (267, TH350, 2.41 axle) has had a good deal of butchery applied....when i bought it, it was still running the ECM and distributor, but had an earlier non-computer Dualjet on it. I did buy an old stock reman Dualjet for it, didn't really fell like replacing carb dist and intake at the time to go to non-electronic. EGR, EFE, AIR have all been axed by previous owner or their "mechanic" Consequentially, best mpg day-to-day is about 14. Of course, my daily commute is 80 miles, and 42 of that is turnpike at 75 mph.

 

[DRIVEN]

Another aspect is that you're overgeared. 2.41 with an overdrive isn't really ideal for that poor little 305. It's working too hard. I bet if you step up to 3.42 - 3.73 your mileage would increase along with the fun factor.