'99 4Runner 6cylinder has 124k on it. I replaced the plugs with Bosch platinum (correct type for the engine...2 "prong"), cleaned the carb body, oil, tran fluid and air filter. Mpg has dropped 3mpg. Any ideas why? I'm suspecting plugs....anyone else experience this? I'm quite sure I put it back together correctlyu.
lower mpg after tuneup
- Thread starter kbeeson
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CJ3Flyr
Super Moderator
kbeeson said:
I am assuming you've double checked your work on the air intake and there are no leaks; air filter housing is sealed correctly etc.I may get :bash: for this next one: I have never had Bosch plugs run well. If it were me I'd be looking for some Denso's or NGK's. That's my 2cents...
:cheers:
Good question. I used 5w/30 which is what the engine says in the oil cap. I did change the trans fluid (about 5 qts of it) and NAPA said to use "Dexter".... NAPA ATF Dexron III Mercon. I questioned him on this as I heard it needed typ "IV" but he confirmed that is what it is generically. I made sure it was filled to the right level (middle of the cool lines). Is this stuff ok to use?
other thoughts
Just in case anyone was wondering: I did the following along with the spark plug change:
Clean Throttle Body. I did make a mistake and instead of puttinga rag to protect the holes in the carb body, I had it too far outside, so maybe som throttle body cleaner got in there? I didn't saturate it and used a rag to wipe it up quickly.
Rotated tires
Changed oil (5w/30) and 5q of new trans fluid
Just checked my tires and they are up to pressure
Could it just be due to increased cold and now? Where is the other posted who did the 90k mile located (is it in a cold spell). what kind of plugs did they install? I had driven before that and every week was getting 18mpg+.
Initial test afer the first run on the NGK's is 16mpg, slight improvement, but 2-3 shy of where I was (albeit have been driving 4wd in the snow lately, so that does drink more gas.
I've been using Sam's club gas 87octane...wonder if anything there, I may switch for a while and see what happens.
Just in case anyone was wondering: I did the following along with the spark plug change:
Clean Throttle Body. I did make a mistake and instead of puttinga rag to protect the holes in the carb body, I had it too far outside, so maybe som throttle body cleaner got in there? I didn't saturate it and used a rag to wipe it up quickly.
Rotated tires
Changed oil (5w/30) and 5q of new trans fluid
Just checked my tires and they are up to pressure
Could it just be due to increased cold and now? Where is the other posted who did the 90k mile located (is it in a cold spell). what kind of plugs did they install? I had driven before that and every week was getting 18mpg+.
Initial test afer the first run on the NGK's is 16mpg, slight improvement, but 2-3 shy of where I was (albeit have been driving 4wd in the snow lately, so that does drink more gas.
I've been using Sam's club gas 87octane...wonder if anything there, I may switch for a while and see what happens.
Agree, it seems extreme, but our experiences are consistent. if it was a dealership, maybe you could call them and see their thoughts. I'll ask my mechanic friend as well. what else did they do to the truck... timing belt, clean throttle body, etc.. ?
One might think...maybe a wire was switched, but I did the work myself one at a time, no way that is the case.
One might think...maybe a wire was switched, but I did the work myself one at a time, no way that is the case.
Have you folks reset your computers in your tucks? When I replaced the plugs in my previous 4Runner the mileage decreased 2-3 MPG until I reset the computer. within a week the mileage was back up to where it had been (and a little higher) before the tune-up.
I'll do the same thing when I replace the plugs in my 2008 T4R.
I'll do the same thing when I replace the plugs in my 2008 T4R.
CJ3Flyr
Super Moderator
pook187 said:
No. The only thing that is in question is time... Some say disconnect the battery for 5-8minutes, some say longer. If you disconnect the battery for 20-30minutes that'll do it. You'll have to reset auto windows and the radio. If it's a 4th gen you can pull the fuse instead of the battery and not mess with radio/windows. I don't know if you can do that on a 3rd gen.
:cheers:
Toyota's answer
I called Toyota. They said they get this issue quite often and to run two full tanks of high octane fuel and that should clean it out. I've always run 87 octane. I'm on my first tank of premium. I may also try one of the purported Top Tier gasolines as they are reported to have more detergents in them. I've been running sams club and speedway gas for a while and was getting 18-19 most of the time before the tunup and went down to 15-16.
http://www.toptiergas.com/retailers.html
Will let you know if this does the trick. been consistently at 15-16 for two months now since last tuneup.
I called Toyota. They said they get this issue quite often and to run two full tanks of high octane fuel and that should clean it out. I've always run 87 octane. I'm on my first tank of premium. I may also try one of the purported Top Tier gasolines as they are reported to have more detergents in them. I've been running sams club and speedway gas for a while and was getting 18-19 most of the time before the tunup and went down to 15-16.
http://www.toptiergas.com/retailers.html
Will let you know if this does the trick. been consistently at 15-16 for two months now since last tuneup.
wolfgang
New member
Bosch plugs are affectionately called Botched by yota owners! Use ND/Denso or NGK. I haven't heard of a "tune up" since the '60's - hope you only paid for swap out of parts as there are no carb, valve or timing adjustments needed like in old cars. Not even any points any more. Saying you want a tune up is asking for big bill. Best "tune up" is a bottle of Chevron Techron FI cleaner every 6 months.
