sqzdog

When I hit the gas, its like it hesitates and then goes. It runs fine otherwise. This just happens when I am at lower speeds and hit the gas. I removed the throttle body and cleaned it, checked the plugs, checked all vacuum lines. Everything is intact. What can this problem be? My last resort is to go to the $tealership. I'm hoping that you folks can offer some advice. This has 79,000 miles on it.

Thank you

MTL_4runner

Make sure to do the fuel filter and air filter too.
.....also clean the MAF sensor for good measure.

sqzdog

Ok, I unplugged the TPS and plugged it back in and it triggered my check engine light. How do i reset the light?

sqzdog

Just cleaned the MAF sensor. Problem still there. Also, the light reset itself...

BruceTS

How many miles on the plugs? Did you actually pull the plugs to check them? Are you using the dual electrode plugs?

Since the check engine light wasn't on, I doubt there was any problem with the MAF sensor.

Mohamed

Hesitation upon acceleration can be a number of things, but the most common is carbon buildup. Sometimes cleaning the TB just isn't enough, try cleaning the upper head with seafoam. Stuff works absolutely excellently!!!

Here's my post on how I used in my Honda but should be the same principle, use the brake booster line to inject into the system since it is the biggest draw on the system. Like everyone said otherwise, check your sparks plugs, air filter, fuel filter, and heck dump a can of injector cleaner into your gas tank (like BG 44K or Seafoam).

apc

I had the same problem a few years back. Cleaning and regapping the plugs did the trick. The gap actually widens over the years as you drive.

sqzdog

Not sure about the # of miles on the plugs. I did pull them and the looked to be in good shape. They are dual electrode plugs. My next plan is to replace the fuel filter if you guys really think this may be a possiblility.

BruceTS

Try replacing the plugs........

MTL_4runner

If you have not replaced them, it is cheap insurance to put in new plugs.
Just put in some new ones, should be less than $30 for OEMs.

butnut

Been meaning to post...I got the same thing, seems to happen more often just reversing??? It does'nt happen everytime which is wierd. I got close to 130k and changed plugs a few months ago..maybe the fuel filter? Also used BK44 in Jan before I changed my oil, throtttle body was cleaned last year...checked vac lines. Sometimes it just feels like a bump-bog...thanks.

yoda-g2

My '99 (3.4L) did the EXACT same thing, when I pulled the codes it was showing a misfire on cylinders sharing a coil. First I checked plugs and they "looked" fine, so I bought a new coil and decided to replace the plugs and wires anyways while I was at it.

Turns out when I compared the old plugs to the new ones I could tell then that the plugs were VERY wasted. The gap was at least 2-3 times what it should've been on all of them. So being the cheap a$$ I am, I did the plugs and wires first and fired her up. Took a spin around the block, and she ran like a champ. So I returned the coil. Haven't had problems since.

Make sure you get the dual electrode plugs, only $2.25 each at the $tealership. Ans IMHO, the OEM wires are the best way to go.

Hope this helps you out, I was plagued by this problem for over a week. If it still doesn't work, getting a REAL injector clean done can help, did wonders on my '91.

MTL_4runner

That hesitation is almost always spark related. If you replaced all the plugs and the fuel filter yet still no go, then pull the injectors out and send them out for a complete cleaning. The fuel treatments are very good but they still don't tell you if one injector has a bad spray pattern or flows much less than the others. I recommend the treatments for ongoing maintenance not when troubleshooting a problem.

Xpresident

I had the same problem with mine a few weeks ago. Took it to the dealre, and they did a throttle body I.V. It cleaned out the carbon buildup inside the throttle body. It purrrs like a kitten now. Only drawback was that it took them 2 hrs and cost me $135.00

sqzdog

Ok, the dealer charged me $70 today to tell me that i needed a TPS and a Mass Airflow sensor. I have the TPS on the way but am looking for a good deal on the Airflow sensor. any ideas?

Mohamed

MAF is bad? Really? Oh well.

According to what I remember about cleaning mine it's just a wire band across a housing atop the airbox. Can't you just go to a junk yard and pick one up for cheap? You can then clean it like I did to mine and that's with a q-tip and alcohol, and gently stroking it, be gentle with it is the key here.

sqzdog

What actually goes bad on a MAF sensor? I am picking one up from a junk yard tomorrow for $50. They are about $150 from the $tealer.

3.4v6

call me stupid ... but how do you clean the MAF sensor? thanks

sqzdog

FOLLOW-UP --

The Thottle position sensor fixed the problem. I bought it from a Toyota dealer out of Texas who sells parts much cheaper through the internet. Hoy Fox Toyota. You might want to check them out before you buy from your local dealer. Thanks to everyone who helped me with the problem.

Unhappy99

cleaning the MAF

My 99 started throwing P0171 code again two weeks ago. Took out the MAF, cleaned it with Berrymans FI cleaner, dried and reinstalled, all in under 10 minutes. No more codes.

Probably should become an item of annual maintenance.