03 hesitation from a stop?

[adventureman73]

Fuel injectors are toast!

Hey, this is my first post, so bear with me, please.

I've got an early '03 4Runner with about 56,000 miles on it. Within the last couple months, I've noticed a hesitation and shuttering when starting from a dead stop.

I've tried different fuel grades (I'd been putting premium in in since I bought it back in '03), had an injection cleaning and have done all my regular (5k interval) maintenance. None of that helped. Runs fine once you get out of the gate, no problems downshifting to pass or climb hills, no issues in 4WD or anything else...except for this, the truck is rock-solid.

It'll even do it when stopped and in Neutral, so I don't think it's a tranny problem. It was in the shop yesterday, and the dealer is stumped; they were gonna call the Toyota Tech (?) line and see if they had any clues.

Anybody have a similar problem, or know of a possible cause/solution? I read on another post that someone had a '99 with a similar issue and the spark plugs and wires were bad...could this be causing it?

----

So I've been having some hesitation issues, as noted above, and it turns out that my injectors (all 6) are shot. They're plugged full of crap and have to be either cleaned or replaced. On top of that, my sparkplugs got crispied because of the fuel injection problem. The culprit: bad gas. Anbody else have this sort of issue? I live in Corvallis, Oregon (about 2 hours south of Portland). Not sure if it's a regional thing or not.

 

[greasefingers]

The spark plugs are just approaching their half-life. But the wires could be in question. I do not remember if the service manual states a specific replacement schedule. Spark plug wires that I am familiar with do not last as long as the iridium plugs (120 k miles). Maybe Toyota uses something superior to the norm.

I tend to think that it is a fuel delivery issue, but with so many sensors today it could be anything. I wonder if the dealer can examine fuel flow/pressure with their Scan tool.

You could inspect the MAF sensor. It would also be nice to examine the movement of the butterfly, in the throttle-body, with respect to the gas pedal movement. Sorry if I appear to be brain-storming but I am trying to think of things that a DIY-er can do.

 

[adventureman73]

The spark plugs are just approaching their half-life. But the wires could be in question. I do not remember if the service manual states a specific replacement schedule. Spark plug wires that I am familiar with do not last as long as the iridium plugs (120 k miles). Maybe Toyota uses something superior to the norm.

I tend to think that it is a fuel delivery issue, but with so many sensors today it could be anything. I wonder if the dealer can examine fuel flow/pressure with their Scan tool.

You could inspect the MAF sensor. It would also be nice to examine the movement of the butterfly, in the throttle-body, with respect to the gas pedal movement. Sorry if I appear to be brain-storming but I am trying to think of things that a DIY-er can do.

Braintstorming is good. I'm not much of a DIY-er, I can change my air filters but that's about all I've ever delved into. Prefer to have "professionals" do most of the work. But anything I can tell them is a plus; the service dept. actually listens to me (because of the fiasco of my last vehicle).

 

[greasefingers]

Do you have the V6 or V8 engine?

 

[adventureman73]

Do you have the V6 or V8 engine?

V6, 4-speed auto.

 

[adventureman73]

An update for those who care (late in coming, sorry):

So I took my 4Runner in in 23 August and they determined that my injectors and spark plugs were shot. The injectors were clogged beyond belief and the spark plugs were crispy as a result (mis-firing because of not enough fuel). So I had 2 options:
1) Get the injectors cleaned and reinstalled and replace the plugs. This would have been about $600 but with no warranty on the work (the place that does the cleaning doesn't warranty there work because the wiring could go wrong the next day, etc).
2) Replace the injectors completely, along with the plugs. Cost $1200 (and change). Little buggers are over $160 a piece and there are 6 of them.

I voted for Option 2, as painful as it was, because this was getting dangerous (I went to pull out from a stop a couple days before this and it almost stalled in the intersection...I had to slam on the brakes and back up real quick!).

So I had it done on 26 August and my 4Runner is now running better than it ever did! Nice smooth acceleration and good response. I'm glad I'm back in action, it really hurt having my Beast in that sort of shape.

Thanks for listening!

 

[toybox]

Wow! That is good to know. May I ask ( and I know this will stir the pot) what gas you were using prior to this work? Was it no-name gas or a known brand? Premium or regular?

 

[adventureman73]

Wow! That is good to know. May I ask ( and I know this will stir the pot) what gas you were using prior to this work? Was it no-name gas or a known brand? Premium or regular?

I've been using almost exclusively Shell VPower, with the occasional Chevron Supreme thrown in when I can't get to a Shell station. Apparently there's been some "bad gas" in our area, according to the dealer, but they had still never seen anything quite like this.

 

[toybox]

I've been using almost exclusively Shell VPower, with the occasional Chevron Supreme thrown in when I can't get to a Shell station. Apparently there's been some "bad gas" in our area, according to the dealer, but they had still never seen anything quite like this.

I was hoping you would say no-name regular gas.

So much for that Top Tier gas, eh. (btw I use Shell Vpower)

Looks like I'm just going to use the cheapest gas I can find from now on and just keep putting in the injector cleaner every so often.