TBI MPG and other observations.

[randomguy]

This thread is not what you think.

I’ve put 4000 miles on my k2500 light duty in the last year, pretty solid 11 to 12 MPG but living where we do with mountains and canyons all around MPG sucks even in the best of cars. Best MPG has been 13. It’s all 55 or 65 MPH driving. I’m a little OCD about my vehicles and have tracked my fuel mileage and maintenance expenditures.

I’ve been slowly repairing and doing maintenance on the truck since I got it. Latest repair was all new front end components including a steering gear. My alignment was way out before I did the front end work as well. It also has all new AC Delco ignition components, excluding the distributor that has 214k on it. Truck has 3.73 years and 31x10.5r15 Michelin LTX tires on it and the front axle is permanently engaged with a Standard Motor Products TCA19. The engine is a Goodwrench L05 that was put in in 1998 and has 114k on it. Engine is filled with Valvoline Maxlife 5w30 and the 700R4 is filled with Maxlife ATF.

Took it out on its first real interstate run, 150 miles with 45 of those local highway and the rest interstate. Averaged 15.1 and shocked the hell out of me. I did 70-75 on the interstate and it just hummed right along. I’ll be doing the same trip next week and it’ll be interesting if the trend holds.

Intake gasket is weeping coolant on the front of the motor and my distributor cap is only held on by one screw because the other is stripped. I’ll be replacing the intake gasket, rebuilding the throttle body, and putting a new distributor in this summer.

Any thoughts on the World Power Systems distributor from Rock Auto?

If my highway MPG holds I may just keep running 31x10.5 tires.

 

[evilunclegrimace]

I have had good luck with the United Motor Products Distributors and ignition parts in my trucks. My 1990 w/3.73 gears gets 17-17.5 on the highway w/265/75's at 72 MPH.

Rock auto has a discount code running right now for 5% off you order.

 

[studigggs]

This thread is not what you think.

I’ve put 4000 miles on my k2500 light duty in the last year, pretty solid 11 to 12 MPG but living where we do with mountains and canyons all around MPG sucks even in the best of cars. Best MPG has been 13. It’s all 55 or 65 MPH driving. I’m a little OCD about my vehicles and have tracked my fuel mileage and maintenance expenditures.

I’ve been slowly repairing and doing maintenance on the truck since I got it. Latest repair was all new front end components including a steering gear. My alignment was way out before I did the front end work as well. It also has all new AC Delco ignition components, excluding the distributor that has 214k on it. Truck has 3.73 years and 31x10.5r15 Michelin LTX tires on it and the front axle is permanently engaged with a Standard Motor Products TCA19. The engine is a Goodwrench L05 that was put in in 1998 and has 114k on it. Engine is filled with Valvoline Maxlife 5w30 and the 700R4 is filled with Maxlife ATF.

Took it out on its first real interstate run, 150 miles with 45 of those local highway and the rest interstate. Averaged 15.1 and shocked the hell out of me. I did 70-75 on the interstate and it just hummed right along. I’ll be doing the same trip next week and it’ll be interesting if the trend holds.

Intake gasket is weeping coolant on the front of the motor and my distributor cap is only held on by one screw because the other is stripped. I’ll be replacing the intake gasket, rebuilding the throttle body, and putting a new distributor in this summer.

Any thoughts on the World Power Systems distributor from Rock Auto?

If my highway MPG holds I may just keep running 31x10.5 tires.

Did you calibrate your odometer for the larger tires? if not, you may be doing slightly better than you think.

 

[PlayingWithTBI]

My 1990 w/3.73 gears gets 17-17.5 on the highway w/265/75's at 72 MPH.

Are you running with HLC (Hiway Lean Cruise) and/or EGR Disable in your ECM? If not, you should see another 10-15% increase in mileage, so I've been told. I'm almost to the point where I can verify it.

You must be registered for see images attach

 

[randomguy]

I have had good luck with the United Motor Products Distributors and ignition parts in my trucks. My 1990 w/3.73 gears gets 17-17.5 on the highway w/265/75's at 72 MPH.

Rock auto has a discount code running right now for 5% off you order.

Good to know! I noticed with my 1988 some of the part numbers are different than for newer trucks and the only AC Delco unit is a reman and I'm not too keen on that.

Did you calibrate your odometer for the larger tires? if not, you may be doing slightly better than you think.

I did not. I forget that 31's are larger than stock on these trucks.


Does anyone know what is different about a 1988 where a Delph CZ20001 wouldn't work??

 

[evilunclegrimace]

Are you running with HLC (Hiway Lean Cruise) and/or EGR Disable in your ECM? If not, you should see another 10-15% increase in mileage, so I've been told. I'm almost to the point where I can verify it.

You must be registered for see images attach

The engine is a .030 overbore with a cam for low end torque and a bump in compression. Fuel pressure is at 15psi. The only other mods are headers and high volume oil pump. I built this as a plow truck and I don't have any tuning capabilities.

 

[Schurkey]

Good to know! I noticed with my 1988 some of the part numbers are different than for newer trucks and the only AC Delco unit is a reman and I'm not too keen on that.

At least with a reman, you know that at one time it was actually designed and built properly. Cheap Chinese "new" products may not be designed or built correctly. Lots of aftermarket HEIs don't have any grease installed in the grease reservoir--because they didn't bother to drill the holes that lead from the grease reservoir to the upper bushing.

I'd rather have a properly-rebuilt OEM part than a brand-new Communist Crap product.

Does anyone know what is different about a 1988 where a Delph CZ20001 wouldn't work??

That distributor "looks" right, except maybe at the hold-down flange. Sure it's not got the oversized flange used on some of the "B" and "C" body cars?

 

[randomguy]

Managed 13.6 MPG on this last tank, ended up making a couple trips to town and one trip into the mountains in addition to 150 highway miles. Definitely a big improvement over the 11.5 MPG I was getting on similar driving. I suspect straight interstate driving is 16-17 now.

I may just tap the distributor one size larger. For now a zip tie is holding the cap tight haha.

 

[PlayingWithTBI]

Does anyone know what is different about a 1988 where a Delph CZ20001 wouldn't work??

Not sure but the older ones had the ESC inside the distributor, I think?

 

[randomguy]

Not sure but the older ones had the ESC inside the distributor, I think?

My ESC is external, and the only reason I know this is I had to run a new knock sensor wire from the ESC to the sensor.