Hi there I just found this bb and looks like a great place to get good info, anyway Ive got a 93 runner with the 3.0 V6. The motor has a surge to it. It does this more so when its cold but still noticeable at full op. temp. It happens at around 2100rpm and goes away at about 2500 and starts surging as if it were carburated(remember those days)I have replaced the fuel pump, fuel filter, had it scoped at the dealership(nothing wrong with it they say)they adjusted the timing at the same time. I changed the fuel pressure regulator, air filter, spark plugs(gapped them too) cap, rotor, wires, have ran numerous bottles of injection cleaner through the tank, pulled the throttle body off and cleaned it up. I dont know what im missing? Its driving me frickin nuts!!!:mad:
Now while your driving it feels like it has a slight miss as well, and the last thing it does is at slow speeds especially when your wheelin in 4low coming down hill and you have slight throttle on it is like your giving it fuel then letting off then giving it fuel then letting off all while my foot is steady( This can be done from under the hood while holding the throttle cable slightly on )just another thing that is pissin me off. Now im assuming all these symptoms are probably all related to something im missing(I hope) The mechanic at the dealer mentioned that the throttle body might be wore out because when he tried to adjust the idle it took a few turns to start changing, but when I talked to the parts guy he said they couldnt get me a price(would have to get back to me) because there comp. didnt list a parts # on one because they have never sold one and said its highly unlikely the tb is wore out. Well is this a characterisic of the V6? This is the first v6 ive had and im starting to think I should have gone with the 22r cause I never had a problem with them. Thanks for any info and sorry bout the length of the post but figured I should describe the full symptoms.

 

you may have a bad fuel injector.try getting a scan tool to read the codes from the computer.aslo the tool will show the injector perforamce, atleast the one my garage guy has.hope that helps

 

I had similer issues like you describe. My problem turned out to be a bad exhaust valve requireing " a valve job". Has a compression check been done? Mine started ever so slightly then got worse. Upon compression check I found 0ne cylinder only had maybe 20 lbs of compression.

 

Thanks guys

Ill check into the injector issue, and I never even thought about a bad valve but Ill do a compression test tomorrow and see what turns up. Just out of curiousity whats the milage expectancy out of a v6 mine has 200,000 km on it?

 

Sounds exactly what my Runner did a few years ago.
When cruising on the freeway, and then when you slow down a bit, it would buck.

It turned out to be 2 bad injectors. They were not spraying correctly, and that caused the surge.

The fix? $480 at the dealer. Dropped it off in the afternoon.
In the morning they pulled the injectors out and sent them down the street to get ultrasounded.

Dealer reinstalled them, replaced a bad PCV hose, and the rig has run well ever since.
I have a printout of the injectors and you can see on the sheet how they were bad, and then retested after cleaning.
I'll have to upload it later.

When they were dirty, the exhaust sputtered too. After being cleaned, the exhaust note sounded right on.