Milage issue

[montana4runner]

We've had our "04 V8 4runner (140,000 miles) now for a couple of months, and I'm a little confused as to the diminshing fuel milage that we are experiencing. The first few tanks of gas we were getting about 16.7 to 17.5 actual mileage, combined city/hiway. Had a Toyota dealership do belt, water pump, plugs, valve lash, change out all the fluids etc. Next tank was in line with previous milage. A few days after that, I cleaned the MAF and throttle body as per links on T4R. The TB was really dirty, probably never been cleaned. Used the CRC cleaner on the MAF. First calculated tank after that was 12.5, next one was 11.4. Cleaned the maf once more, Re-set ECU again, and now after several more tank-fulls we are making about 15.1 to 15.9. Same fuel, same driving habits etc. So I am assuming that mabe there is a problem with the MAF, although no CEL has appeared. Or, could I have done something to the TB to cause this to happen. Any ideas or help on this issue would be appreciated.
Regards, Rick

 

[Park]

could be engine build up try putting some of that engine cleaner

low tire pessure?

using A/C alot recently?

sometimes the octane of fuel your running can affect your mileage

fuel injectors

And this is a diagram of how bad poor mileage sucks...........:toilet:

 

[ghostridr]

We've had our "04 V8 4runner (140,000 miles) now for a couple of months, and I'm a little confused as to the diminshing fuel milage that we are experiencing. The first few tanks of gas we were getting about 16.7 to 17.5 actual mileage, combined city/hiway. Had a Toyota dealership do belt, water pump, plugs, valve lash, change out all the fluids etc. Next tank was in line with previous milage. A few days after that, I cleaned the MAF and throttle body as per links on T4R. The TB was really dirty, probably never been cleaned. Used the CRC cleaner on the MAF. First calculated tank after that was 12.5, next one was 11.4. Cleaned the maf once more, Re-set ECU again, and now after several more tank-fulls we are making about 15.1 to 15.9. Same fuel, same driving habits etc. So I am assuming that mabe there is a problem with the MAF, although no CEL has appeared. Or, could I have done something to the TB to cause this to happen. Any ideas or help on this issue would be appreciated.
Regards, Rick

I recently cleaned my TB too and noticed a drop from 24mpg to 17mpg afterwards, also noticed a "ruffer" idle (close to 1,000rpm) on cold starts while in parked. Leaning towards something to do with the TB/ECU not adjusting air/fuel ratio correctly post TB cleaning.

 

[ChaosStarter]

I recently cleaned my TB too and noticed a drop from 24mpg to 17mpg afterwards, also noticed a "ruffer" idle (close to 1,000rpm) on cold starts while in parked. Leaning towards something to do with the TB/ECU not adjusting air/fuel ratio correctly post TB cleaning.

If you don't disconnect the battery for a few minutes after you clean the throttle body, it won't learn it's new 'cleanliness'. These newer cars actually take carbon buildup into account over time. That's why they can be so gross, but it will still idle fine.

It can go both ways, if you disconnect the battery but have never cleaned the throttle body, it can idle pretty badly as well. We've seen it on a LOT of Corolla's when we do the ECM replacement under their recall they have going on. Plug in the new one and it idles like **** until you clean it.

 

[montana4runner]

I did disconnect the battery for about an hour the last time. Funny thing is that the on- board mileage monitor(?) slowly, over a couple of days crept up to 19.6 mpg. Now, my mpg gage is about 2 mpg optimistic now, prior to cleaning it was reading about 1 mpg positve. So, thinking mabe I will once again re-set the ECU, or replace the MAF. Hopefully mileage will increase a little. It's frustrating, knowing that it is capable of much better mileage than it's making now.
Rick

 

[montana4runner]

My wife took the 4runner to town today. I walked around the vehicle and checked for excess heat on the rotors, just to make sure I didn't have a brake dragging.......burnt my fingers on the passenger rear rotor. OK, I probably should have checked this earlier, but I had no other indication that the brakes might be hanging up. No hot brake odor, no pulling, chattering, squealing or unusual brake noise. I think once this issue is addressed, I will more than likely see my mpg return to previous levels. Must have been coincidence that this started to occur the same time I cleaned my MAF and TB
Regards, Rick