Del

So as any of you who have read my posts in the mpg subjects know, I've got the worst mileage here. I'm hoping it's because the plugs and wires need to be changed, and was wondering if anyone can help me out on some names for mileage instead of performance, or should I just stick with Toyota stuff? Thanks.

Bumpin' Yota

out of curiosity, when was the last time you had the fuel filter or O2 sensor changed?

Del

I've never done it while I've had the Runner. I don't know if the previous owner did or not. Would that be a good place to start?

Chanson88

I just changed the fuel filter and pcv valve and cleaned out the pcv valve hose and went from 20 to 22 mpg, oh yeah they were both original with 80,000 miles.

Del

Alright I'll change those for sure. Any of that difficult to replace?

gwhayduke

If you've got a 22re, the plugs are easy and the fuel filter is a PIA.

If you've got a 3.0, the plugs and the filter are both a PIA.

I always take the 4Runner to a reputable shop when I want those changed. The banjo fittings on the fuel filter are easy to strip and the gas running down your arm and into your face is not aligned to my philosophy of longevity. Change the fuel filter first. I had mine changed last year when the 4Runner was giving me problems on a trip uphill to Albuquerque. It had more power and better gas mileage on the trip back and has been doing great ever since.

As for plugs, the dealer tells me my platinum Bosche are too hot a plug and tries to talk me into changing them whenever they see the 4Runner. Guys here on the board recommend the stock plug (NGK if I remember correctly...do a search for the part number). Few if any are getting the mileage that I get (17-19 city and 19-21 highway). And the Bosche have been in so long that I can't remember when they were changed (at least 3 years...60K+ miles).

I've never replaced an O2 sensor and the 4 Runner has 188K on it.

Once you do that, swap out to synthetic oils in the engine, tranny, rear and front differential, and transfer case. They helped me out about 1mpg. I use Mobil 1 in the engine and will swap the Castrol Syntec (not recommended) gear lube out to Mobil 1 this summer. Others swear by Amsoil, Royal Purple and Schaeffers. I think they are probably all pretty good choices. Mobil 1 is easier to find.

After you do that it comes down to driving technique. I drive it like a truck. Torque comes in at low RPMS so I tend to shift before 2500 unless entering the freeway at rushour.

Keep the stock tires size and swap out your auto hubs to manual hubs. A 2.25" cat-back with a Magnaflow helps as well.

Did I miss anything?

Victor

I also run Bosch Platinum plugs and I get 21-22 on the highway. I have Mobil1 synthetic in my tranny and transfer case and will be swapping out the rear gear oil sometime this summer. With my manual hubs I'll leave the regular gear oil I put in there about 6 months ago until later.

If you do change the O2 sensor I think stock Toyota is about the best you can get. People report that other brands aren't calibrated exactly to Toyota specs and they don't have as much power/economy. Lastly - what air pressure you running?

My truck is a real dog with the taller tires now if the A/C is on. Runs just like normal with the A/C off. I'm going to try switching my fuel filter to see if that is causing some power loss. The airbox mod helped a lot with my low end power (below 2000 RPM) but I need more oomph at mid-RPMs.

Bumpin' Yota

When my truck was completely stock I was getting 21-25 on the highway and 17-20 around town.

Stepped up to 235/75r15s from the stock 225/75r15s and saw a drop on highway to about 19-21 and around town to 15-18. This was with Bosch Platinum 4+ plugs. The dealer said "youll never get that thing to run right!" BS Things have been the same ever since till about 3 months ago. My 3.slow suddenly started getting 10-12mpg around town and 14 on highway. So the battle began to regain my gas milage.

1. FIPK - no change more power at top end though
2. Hi Flow Cat - 3mpg increase which was lost after 2 tanks and couldn't be regained?? no clue. WAY more top end power however.
3. Fuel Filter - 2 mpg increase, and waiting to see if I suddenly loose this gain too.....grrr

My O2 sensor is dead or dying because I have a soot in the exhaust indicating that the engine is running rich. There is also one hell of a rotten egg/sulfer smell when I stomp it. The injectors are also loud as ever, and the engine seems to bog at the bottom of each gear even when redlined. Idiot at the dealership said, "oh youve got a clogged cat, I'm 100% sure and it'll be 750bux to change it" He was wrong, my cat was fine and with the help of a retired mechanic, it cost me 3 cases of beer to replace.

4. New O2 sensor and new 2.25" exhuast are in the works next. Hopefully I can get that changed in the next 2 weeks.
5. MAF cleaning

gwhayduke

The rotten egg smell is usually associated with a lean mixture. My money is on the O2 sensor.

I've heard good things about cleaning the MAF sensor though. If it is dirty, it could be the source of your lean mixture. It could be misreading the amount of air flowing through because the dirt could be acting as an insulator.

Dr. Zhivago

The 3.0 does NOT have a MAF. It has a Vane Air Flow Meter. Totally different devices. You can clean the AFM on the 3.0, but I don't see how it will make much of a difference compared to cleaning the hotwire on a MAF.

My .02
Dr. Z

Bumpin' Yota

Oh, I thought that the 3.0's AFM was also called a MAF. Thank you for that clarification that they are two different devices.

BTW - I see people talking about replacing their MAF on their 3.4L engines with a supra turbo's MAF. What pourpose does this serve and can any gains be accomplished with the 3.0 using an older supra's vane AFM?

Thanks in advance

gwhayduke

I learn something new everyday.

Hey Doc, I was looking into my 3.0 airbox the other day and I noticed that the opening into the "air vane" sensor really seems pretty small and restrictive. It appeared to me that it had a signicantly smaller cross section than the intake into the engine. Could this be why the airbox mods only add power up to about 2500 RPM?

Would it be possible or even reasonable to find a different airbox that would bolt in and use the same connectors and computer?

Dr. Zhivago

The reason they use a larger MAF is to accomodate more air being forced into the engine by the S/C and to equalize the A/F ratio with the addition of larger injectors. You can squeeze more torque and HP out of the engine that way. The stock MAF has a smaller cross-section and will restrict the maximum volume of air that you can force into the engine. However, I think it flows more than enough air for a normally aspirated engine.

As for the 3.0, you could probably use a larger AFM, but you would need to figure out if the stock ECU could deal with (and compensate for) the output signal of the larger AFM. It would be of benefit to open both the intake AND the exhaust side, not just the intake. Although, you would see some gains if you only did the intake. The Mark III Supra's have a Karman Vortex style AFM and not a MAF. They are less restrictive than the Vane AFM's, but more restrictive than a good MAF. A lot of Mark III owner's switch to a larger Karman Vortex AFM or even a MAF from a Lexus or newer Supra to allow more air into the engine so they can run increased boost. HKS also makes kits for these cars.

I think the ISR mod for the 3.0 is a good way to go while still maintaining the stock AFM and exhaust manifolds. If I had the money and one of those engines, I'd definitely do headers, exhaust and intake.

Hope this helps.
Dr. Z

Dr. Zhivago

See the answer above.

Dr. Z

livelarg

This may be a silly question, but how do I check the AFS on my 3.0?

Thanks
Kent

seafarinman

So if the Bosch Platinum +4 spark plugs are "too hot" as it were, could this be the cause of my engine running so hot out on the trail? I have an electric fan and it works pretty good, but when in 4 low and climbing, or just stuck in slow traffic it gets kinda hot. In fact it has gotten really hot (coolant boiling in overflow tank) and I have been lucky to not have blown the headgasket a few times now.:pat:

gwhayduke

A sparkplug's heat range determines how fast the plug gets rid of heat. A hot plug indicates that the plug does not get rid of heat well and may cause predetonation (pinging) because it's hot enough to light off the mixture in the cylinders. Sometimes if you have a lot of pinging on acceleration, you can switch to a cooler plug and stop the pingning.

As for your electric fan. I read an earlier post on electric fans just this last week that compared the CFM output of the stock fan vs. the black magic fan. In their comparison the stock fan moved more air. That may be the answer to your problem....or it could be something else, like a stuck thermostat. Try this link:

https://www.yotatech.com/forums/show...threadid=11057

At the very least you could put in a 165 degree thermostat that would open up earlier. But it could signal your EFI to keep the mixture rich longer than necessary causing lower gas mileage.

No easy answers here.

Bumpin' Yota

Ive already done the FIPK for my 3.slow and a high flow cat, and I have a new 2.25" exhaust is in the works. Personally Im terrified of trying to tackle headers in my "contortionist designed" engine bay. But that will probably the next step....*shudder*

In the event that the ECU couldn't deal with the new readings coming in from the AFM what would be the symptoms in the worst case senario and could engine or ECU damage result? If the ECU can handle it, would the fuel system have to be upgraded with the higher fuel demand?

Im just trying to get ideas right now....


ps - another idea, if i advance my BTDC timing to 12*, can I still safely do the ECT mod? Or will pinging give me that answer?
Thanks

livelarg

Allright, it is time for me to show how dumb I am.
I have been following this thread, but all of the abbreviations are throwing me off.
I know that the AFM is a air flow meter, but what is it and where is it?
I know what a ECU is.
But what is the FIPK that everyone is talking about?

Also Dr.Z
Would your reccomend the Magnacore wires, and the iridium plugs you have for a 88' 3.0?
Did thay make any difference for you?

Victor

The AFM is attached to your airbox and there is a tube that goes to the engine from it.

FIPK is Fuel Injection Performance Kit - K&N's kit that replaces the airbox with a cone filter.