low rpm slowness on 22re

[inacoma]

I thought I would update everyone with what I did to fix the problem.

first...the mechanical timing of the truck was spot on.

I got to thinking that my MAF might need adjusting....so I googled in and low and behold...it turns out if you add a bigger intake (late model air intake for me) and headers (DT headers) you need to trick the MAF to run "richer"...more air in = need more fuel. this issue occurs at mid-RPM where the truck WANTS to lean itself out....EXACTLY my problem. So took the MAF apart, adjusted it 3 notches (might go to 5 to open it more since I"m at 6k feet) to fool the computer thus making the mixture ritcher...and viola!!!! she's running strong now! so happy. might not even sell it now!

 

[KY854RUN]

Ktp,

When I added the Thorley header to my truck I had similar issues. I also installed a fuel/air mixture guage to use to adjust the MAF. Before making any adjustments I could tell that I was running lean just from the smell of the engine running hot from the lean mixture. I initially went 5 notches and this was way too rich. I have sinse backed it down to 3 notches and I think that I might try it at 2 notches to see how it does. Every write up on this that I have read, says that you only need go 1 or 2 notches. But, I know that each truck is different. I'm trying to get my mileage up.

 

[inacoma]

Ktp,

When I added the Thorley header to my truck I had similar issues. I also installed a fuel/air mixture guage to use to adjust the MAF. Before making any adjustments I could tell that I was running lean just from the smell of the engine running hot from the lean mixture. I initially went 5 notches and this was way too rich. I have sinse backed it down to 3 notches and I think that I might try it at 2 notches to see how it does. Every write up on this that I have read, says that you only need go 1 or 2 notches. But, I know that each truck is different. I'm trying to get my mileage up.

I'm going to run 5 notches to see what happens. So far the truck isn't running rich. I DO know that my truck WAS running lean..damn thing got hot hot hot...vapor locked, etc. If I was closer to sea level, I probably would stop at 2 or 3 notches. I just love the way the truck drives now.

...oh, and I have a lot of "big air" devices...late model intake (larger plenum), engnbldr oversized head with torquer cam, and DT headers. Next is a larger cat back...I'm thinking 5 notches will match my system pretty well. Driving it for a while will be the "tell". Heard it takes a while for these computers to re-learn...even if the battery is disconnected.

kumar

 

[KY854RUN]

I'm going to run 5 notches to see what happens. Since I live at altitude, I need all the air I can get. Turning the notches allows more air to enter, if I understand it correctly...i.e. opens the "gate" up more

kumar

Kumar,

You are wrong, the MAF measures the amount of air that enters your engine. It does not control the amount of air entering the engine, the throttle body is what controls how much air enters the engine.

Also, what you are calling the MAF is refereed to in the service manual as the AFM (air flow meter). It tells the computer how much fuel the engine needs based on the amount of air that it measures. When you make changes to the engine to make more power, the engine will need more fuel. Even though there is more air moving through the AFM, the computer will run the engine lean (less fuel) because the computer is not programmed for the changes that were made to the engine. By making adjustments to the AFM, you are basically tricking the computer to give the engine more fuel. This is just recalibrating the system to match the modifications that were made to the engine.

This article on 4x4wire.com explains why you might need to do it and how to do it. Adjusting the Air Flow Meter I know that you have done this, so this is posted more for those that have not done this modification.

If you go to 5 notches, I think that you will be running way to rich and see a drop in you fuel mileage.

 

[inacoma]

Kumar,

You are wrong, the MAF measures the amount of air that enters your engine. It does not control the amount of air entering the engine, the throttle body is what controls how much air enters the engine.

Also, what you are calling the MAF is refereed to in the service manual as the AFM (air flow meter). It tells the computer how much fuel the engine needs based on the amount of air that it measures. When you make changes to the engine to make more power, the engine will need more fuel. Even though there is more air moving through the AFM, the computer will run the engine lean (less fuel) because the computer is not programmed for the changes that were made to the engine. By making adjustments to the AFM, you are basically tricking the computer to give the engine more fuel. This is just recalibrating the system to match the modifications that were made to the engine.

This article on 4x4wire.com explains why you might need to do it and how to do it. Adjusting the Air Flow Meter I know that you have done this, so this is posted more for those that have not done this modification.

If you go to 5 notches, I think that you will be running way to rich and see a drop in you fuel mileage.

so that big flap inside the AFM isn't really mechanically controlled to open and shut? I guess not. that thing has some serious amount of resistance if it is opening based on the draw of the engine. No wonder they went with the non-mechanical version in late model engines (not late model 22re, but new cars/trucks). I'll keep an eye on my gas mileage and see what happens. Been running about 19 or so mpg before the adjustment ...granted there was ZERO power in the mid range so that 19 was unbearable. I'll run through a tank of gas and see what happens and report back.

ktp