Throttle Hesitation & Check Engine Light

[fishnyc22]

Hey everyone. I was hoping you can help me figure out how to solve a problem I'm having with my '90 (EDIT 2000) 4runner.

My father owned the truck before me. He had a small problem about 8-12 months ago where the Check Engine light came on. I also had a Check engine light on my former '97 4runner. It was the O2 sensor.

My father had his 90(EDIT 2000) serviced. They replaced the fuel and air filters, plugs and the check engine light came off.

I recently bought his truck and have had it for a few days when the Check Engine light came on again.

We took it to get looked at. The guy at the shop said that the code said that the fuel injectors were running LEAN though it might be the O2 sensors.

Another thing that I think is tied to this is that when I rev the engine, there is a hesitation that occurs (its almost as if it wants to rev, pulls back and then revs)

I noticed this the first time I drove it cause it requires much different timing when shifting (its a manual trans) compared to my old '97 4Runner.

My drives it fine as if it might have been like that all the time and he never noticed it.

Anyway. I really want to get rid of that hesitation. I've read online something about cleaning the MAF sensors and possibly replacing the O2 sensors.

I didnt get the exact code from the mechanic though I may take it to AutoZone this weekend to get looked it.

Anyone have any experience with this and can recommend a fix?

Thanks

Fish
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[mikes4runner]

There is no MAF to be cleaned on the 2nd gen. I would get the code pulled and tell us what it said before you start replacing and spraying things.


Mike

 

[fishnyc22]

Good to know...
thanks mike. I'll do that.

 

[fishnyc22]

Mike. I'm an idiot... I have a 2000 4Runner. Not a 90. I started writing 97 and realize thats the old one. and changed the 7 to a 0...

So its a 2000 not a 1990.

 

[fishnyc22]

Hey Guys spoke with my dad and wanted to give a bit more history on my situation.

My father got a new car and was preparing to sell the 2000 4Runner, but the check engine light was on. At the time the code told him it was the Fuel Filter that needed to be replaced.

The shop replaced the Fuel, air filters, plugs and gave it a general tuneup. Once replaced the light went (or at least they reset the computer) but the car sat and was not driven for about a month after that (since my dad had a new car to drive)

I got the car from my dad and drove it only a few miles before the Check Engine light came on. We took it back to the shop and the code told us it was the Right Bank was running lean (but that it was intermittent) (I don't have the exact code (but the I will have to go back to Autozone to get it ..but it was definately that one bank was running lean intermittently

The shop said it could be any number of things from something as expensive as the fuel injectors to the O2 sensors to something else. But even they recommended driving it for a while to see if it resolves itself.

They reset the computer and drove it only 8 miles before the check engine light came on again. I can definitly fell something weird going on, like a powerloss when accellerating (or maybe I'm crazy) and a hesitation when accelerating at the beginning of the rev.

As of right now, I think my options are:

1. Fix the fuel injectors ($$$$$)
2. Drive it as is and hope it resolves itself
3. Trade it in at Toyota and get the FJ Cruiser : )

Id really appreciate any suggestions to solving this problem.

Thanks

Fish
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[mikes4runner]

I would try cleaning your MAF since it is a 2000 and it has one has it ever been cleaned?

This is a comman cause of a CEL on my 01 MR2 if you don't perodicaly clean it...hesitates from stop,rough idle,CEL

Mike

 

[fishnyc22]

It has never been cleaned. I'll try again, but I was unable to get the screws off it last week when I tried.

Thanks for the advice.

 

[fishnyc22]

I was never able to get that MAF Sensor off, so I took it to toyota today to get an estimate. Waiting on a call from the.

Quick question:
With 126k miles, I was thinking of having them replace the Timing belt and Water Pump (and drive belt). If they are going in to replace the injectors, are they close the to timing belt? Should I expect a lesser labor rate for already being in there to replace it.

Thanks

 

[maine runner]

When I had my '99 LTD's MAF sensor cleaned at the dealer, it was $30.

This corrected a CEL and hesitation. Worked like a charm.

Do both the belt and pump at the same time, saves alot of $$$ . Ask for separate prices for each. then ask for a combined price for both.

 

[fishnyc22]

I ended up just taking my truck to Toyota since I could not get the MAF off. The screws were stripped from trying.

They wanted to replace the MAF as well as 2 Ox sensors, I told them to just replace the MAF.

PROBLEM SOLVED! No hesitation, engine is running great. Very happy to have my truck back!

It ended up running me $375 ($175 parts, $200 labor). Had I been able to get it off myself, I would have cleaned it, but since they were doing it, I just had it replaced.

I do still need to get the Timing Belt and Pump replaced, I just don't want to spend the $800 to do it. But will soon.

Thanks again for all the help with this.

Fish
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[Wintermute]

This fixed my 2001 4Runner hesitation problem.

This fixed my 2001 4Runner hesitation. I simply roughed up the contacts going to the throttle body. There is a 4-wire connector on each side of the throttle body. One is accessible by simply unplugging it. The other requires a little (but not much) work to get to it. This hesitation problem plagued me, off and on, for a year and a half with no one able to diagnose the problem. On a lark, I tried a little sand paper from my tool box and the problem left and has been gone for over a year now.

 

[noscgag]

This fixed my stumbling / hesitation problem with my 1997 too. I had previously replaced plugs, wires, and even coils, with no effect. Then I found this thread and figured cleaning the MAF sensor was worth a shot, and it worked great!

While waiting for the weekend to clean it I used the Torque app and a bluetooth OBD II interface to monitor the MAF sensor while driving around. I thought I would see a positive or negative spike in the graph when the engine stumbled. I had lots of stumbles, but the MAF graph showed nothing. The values were around 4 g/s at idle to a max of a little over 64 g/s while accelerating hard. On the Torque app the graph max is 590 g/s so it's possible I couldn't see a small spike, or it could be the spike is so brief it doesn't register, or maybe the value is being smoothed either by the ECU or by Torque, but it was disappointing not to get a confirmation that something odd was happening.

But in the end I am very happy that the problem is gone. Thank you everyone for posting this information, I don't think I ever would have thought to clean the MAF!