I drive a 2003 Tacoma 3.4L V6 automatic. For the past 3 years in the summer only I have had problems when accelerating from a stopped position. After hitting the accelerator the engine hesitates for several seconds and then will eventually begin to accelerate. It seems like the hotter and possibly more humid the weather the worse the problem. (I live in Georgia and summers can be pretty bad.) On the worst days my truck will hesitate for up to 30 seconds and will even hesitate while I'm moving.

I've had two dealerships and several small shops run diagnostics and everything comes back normal. The check engine light never illuminates. This is becoming kind of a dangerous problem.

Does anyone know what could possibly be causing this?

Try replacing the spark plugs with the same brand (likely NGK) and plug no. that came in the truck--no cross-reference plugs! Apply a light coating of dielectric grease to the porcelein and a heavier counting to the main electrode. If the problem persists, wipe down the spark plug wires with silicone spray or just replace them. Replace platinum plugs every 40,000 miles.

This link might help:

https://www.askmehelpdesk.com/cars-t...tml#post520809

You can try this yourself just for a test. Go to the electronics store and get some CRC electronics cleaner in a spray can.
Pull out your Mass Air Flow sensor. (MAF) 2 screws, one connector, located just after the air filter box.
Pull it out, spray the intake air temp sensor bulb, then look deep down inside it and look for the hot wire. Any dirt at all on that will give erratic maf readings so clean it good.
Dry it all off. Disconnect your negative battery cable 1 minute, and go drive the heck out of it so it will relearn and maybe get your fuel trims back where they should be.
If this 'test' brings better results, then the MAF really should be replaced. BTW, they don't like oil charged air filters like K&N. Good luck.

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Originally Posted by TxGreaseMonkey

Try replacing the spark plugs

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Thanks for the response to my question. I had the spark plugs replaced 15k miles ago at about 75k miles. This problem first arose the summer of 2006, before the spark plug change. I also threw a rod and blew a hole in my short block about a year after the hesitation problem started. The Toyota dealership did the repairs. I did, for a year or so, have a TRD oil-charged air filter, now I'm using paper filters (I was worried the oil would foul my MAF sensor).

Since posting my question I have replaced my MAF sensor(I bought a remanufactured sensor from Advance Autoparts with no real improvement. Please let me know if you have any more suggestions. Thanks

Quote:

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Originally Posted by kitch428

If this 'test' brings better results, then the MAF really should be replaced. BTW, they don't like oil charged air filters like K&N. Good luck.

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Thanks a lot for posting a response to my question. I had TRD oil-charged air filter for about a year before I started having this problem. When I read that they can foul MAF sensors I went back to paper filters. See my post above for info about my engine history.

I tried what you said about cleaning the sensor and thought it may have made an improvement, but started having trouble again so I bought a replacement MAF sensor and it turns out that did not help the problem. I had problems after replacing it and am still having problems after plenty of time for the computer to relearn. If you have any other suggestions please let me know. Thanks again.

Hi Afternoon Snack. Did you ever get this fixed? I have the Same truck as yourself and the Same problem.

Thanks

Hello

I also have the same hesitation as cporter and Afternoon Snack. Has anyone come up with a solution yet? The description of the hesitation is spot-on for what happens to my 2004 3.4L V6 w/Manual Trans.

-Only hesitates during hot and usually humid weather.
-Runs perfect during cold weather months.
-From a standstill, the truck does not respond for several seconds, even when hitting full throttle.
-While driving, the engine power sometimes pulses or drops off completely as if the throttle is being cut.
-Cleaning or replacing the MAF sensor does nothing.

If someone knows the fix, please respond. This really does get dangerous at times!

Thank you

Dog, have you tried installing colder running NGK spark plugs? Also, try filling up with higher octane gasoline. If the problem improves, colder running plugs and slightly retarding the timing should help.

Check the idle air control valve