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Squeezing some more mpgs'

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Pookster

1/2 ton status
Joined
Nov 21, 2000
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Location
NYC, NY, USA
Im trying to squeeze a few more mpgs' out of the ol girl now that Im getting her back up and running.

Did a cap/rotor/wire/plug, New 2.5" true duals, long tube headers, no cats, and cheapo summit mufflers. Got a new 02 also.

Also got a 195 thermostat, I figure running cold doesnt help things along.

I have to have my friend help come and do the timing to make sure its still good.. I think its way off!
 
Is there a question here or are you just telling us the couple things you have done to try and increase mileage?

If you are looking for suggestions we will need a lot more info: year of truck, are you running TBI, tire size, motor, gears, etc.

Sounds like you pretty much have it covered from the motor side once you get it time right.
 
Since you said long tube headers and 02 sensor i'm guessing you have the 02 located in the collector? I would run a heated 3 wire 02 to make sure the 02 sensor is getting hot enough to keep the ECM in closed loop operation when it's supposed to be.
 
Keep it tuned well for the type of fuel you normally use
check operation of pcv and egr valves and charcoal canisters
sounds easy, but not many people check it; a clean air filter
synthetic oil and good quality oil filter
air up those tires, another one most people don't check enough
drive it easy

Sounds simple, right? Not many people keep an eye on those things.
George
 
Shouldn't affect it much, but then again, with most around 15MPG in these trucks, even a miniscule increase is impressive lol.

Charcoal cannister simply captures the vapors from the fuel tank, and dumps them into the engine while it's running, instead of just venting out the gas cap like in the old days. It's got a charcoal pack at the bottom that I'm sure is a regular replacement item, but no idea of the frequency.
 
A little off topic and yet the same...

I may have misunderstood something that was said to me many years ago, but it deals with the O2 sensors. I was told that if you have O2 sensors you need a cat because of the temp difference before and after the cat. I know the computer compares the two readings for fuel mixture. Is that something that is fixed with the heated O2 sensors 4X4HIGH mentioned?
 
The 02 sensor must reach a certain temperature before it will start reading. Having it further down the exhaust stream (long tube headers) or a high flow cat or no cat at all can affect the temperature that the 02 sensor is subjected to. Basically the more free flowing the exhaust system is the more likely you are to have an 02 sensor that won't get hot enough to work correctly. It doesn't matter if you have a cat or not if the 02 sensor doesn't get hot enough it won't give input to the ECM. A heated 02 sensor generates its own heat so it doesn't matter what you do at this point.
 
Cowboy_80 said:
A little off topic and yet the same...

I may have misunderstood something that was said to me many years ago, but it deals with the O2 sensors. I was told that if you have O2 sensors you need a cat because of the temp difference before and after the cat. I know the computer compares the two readings for fuel mixture. Is that something that is fixed with the heated O2 sensors 4X4HIGH mentioned?
Click to expand...

What you were told deals with newer trucks with OBD 2 ECMs They have an 02 sensor before and after the cat. The front sensor is used for fuel mixture. The rear sensor basicly just tells the ECM that the cat is functioning correctly and has nothing to do with fuel mixture.
On older TBI 0BD1 trucks. There is only 1 02 located before the cat. removing the cat has little or no effect on the single o2 sensor. Other than possibly making it go into open loop at idle sometimes. A heated 02 usually cures that problem.
 
Thank you gents. Now I'm smarter when I finally drop in something with an ECM. At the rate I'm going that will be before I get this motor ready to drop. And, I think you may have helped Pookster get more mpg. I feel smart now.
 
Ya,I think I was on track already, except for the charcoal canister. I've never replaced mine, though I didnt think they were supposed to be a repair item anyways.

BTW, I have a 87 350 TBI with a 700R4. Still running my summer motor oil in there (15w40) just to clean stuff out (diesel oil). Got Mobil 1 ATF in the transfer case and Mobil 1 in the diff.

I do have a throttle body spacer and injector spacer to install though, I'll see how that goes.
 
I'm lost here. You have a tbi spacer and injector spacers? I don't know what injector spacers are anyway, but I don't understand how you have a throttle body and injectors. I thought it was one, the other(mpi, efi), or a carb.
 
TBI is throttle body injection. It has a single (or dual, depending on year and what not) injectors that are electronically controlled.

It basically looks like a carb- but it is electronically controlled.

TBI is a type of EFI. But many things like TPI (tuned port injection) is also EFI (electronic fuel injection).

In the k5, 1987 was the first year with TBI; prior to that, the k5's had carbs.

Throttle body spacers are basically a chunk of metal that lifts the injection mechanism and throttle plates further away from the intake manifold. Supposedly, this extra space allows for better air/fuel mixture, which is supposed to result in more power/better fuel economy.

Injector spacer lifts the distance from the injectors to the throttle plate.

BTW, I think the first year for GM trucks to not use the TBI was 1996 or 1997 with the introduction of the vortec motors. everything between 87 and that year used it (on the SBC's). BBC's had a slightly different date range, but I dont know for sure.
 
Beings you are doing an injector spacer. You really should put on a salad bowl. AKA velocity stack.http://marine-performance-parts.com/hypertechpowerchargerforfullsizetruckgmtbi5057.aspx Cheap Mod That really helps TBI build more torque at low RPM which wil help MPG. It is a good power builder, espically with headers. Very good bang for your $$$$
Also help a little on the top end because you get rid of that stock air cleaner spacer can, that is pretty restrictive to air flow.
 
Well, you could always do what I am doing to increase MPG...

0703dp_01_z+duramax_diesel_engine_swap+detroit_65L.jpg
 
Pookster said:
Ya,I think I was on track already, except for the charcoal canister. I've never replaced mine, though I didnt think they were supposed to be a repair item anyways.

BTW, I have a 87 350 TBI with a 700R4. Still running my summer motor oil in there (15w40) just to clean stuff out (diesel oil). Got Mobil 1 ATF in the transfer case and Mobil 1 in the diff.

I do have a throttle body spacer and injector spacer to install though, I'll see how that goes.
Click to expand...

DO those spacer's work?? I have read several good and bad things with them. Some say waist of money other's say it does help:confused:
 
Thunder said:
Beings you are doing an injector spacer. You really should put on a salad bowl. AKA velocity stack.http://marine-performance-parts.com/hypertechpowerchargerforfullsizetruckgmtbi5057.aspx Cheap Mod That really helps TBI build more torque at low RPM which wil help MPG. It is a good power builder, espically with headers. Very good bang for your $$$$
Also help a little on the top end because you get rid of that stock air cleaner spacer can, that is pretty restrictive to air flow.
Click to expand...

wow, thanks, I didnt even know they had those.
 
redbeast24740 said:
DO those spacer's work?? I have read several good and bad things with them. Some say waist of money other's say it does help:confused:
Click to expand...

No clue. I know when I added it on my friend's truck, it seemed to have added a little seat of the pants power.

Im having issues installing the injector spacer, I got the TBI spacer in, but I still have to adjust the cables. I cant get the darn fuel lines separated. I can do the whole thing, but I cant seperate the two parts. Im soaking it in pb blaster, we'll see what happens. My flare wrench bent trying to turn this thing.
 
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