***Attention!!! 3.4 Owners with an Idle Problem***

[jhama78]

I just got educated on the importance of clean throttle bodies and IAC's on a 3.4 v-6... my neightbor has a 99 runner with a 3.4 and doesnt turn wrenches very much if at all.... his truck has 117000 miles on it and is bone stock.... Last week he was driving down the interstate at 65 mph and it lost power and cut off.... He was able to restart it and get home but It threw a check engine light and did not idle at all... He bought a scanner and it pointed towards a bad front o2 sensor (Ive never seen an 02 sensor make a vehicle not idle but whatever).... so that was replaced and it still didnt idle... I intervened before he had a breakdown and checked the tps and it ohmed out ok... also checked the maf and it showed that it was bad based on resistance... so he buys a new maf today and I install it this evening and still no idle... It runs fine if you open the throttle body a bit but does not idle at all with no foot on the pedal... I had done a little research on the topic and learned that this could be caused by a dirty throttle body assembly specifically a dirty Idle Air Control assembly... so I removed the TB and IAC and cleaned both up with Carb Cleaner and a toothbrush.... I Reassembled it and bolted it back on the engine and whaddyaknow the truck runs frikin great.... the thing is that the IAC wasnt really that dirty... So for those of you that have a 3.4 that wont idle.... BEFORE you buy anything for it... remove the throttle body, and unscrew the IAC from it and clean them both thouroughly!!!! This may solve your problem before you fall into EFI sensor HELL!!!!

take it easy doods

-j-rOd

[gnob]

the maf sensors on those rigs also cause similar problems.
it too can be cleaned with the correct cleaner (maf or electrcal cleaner)
the iac can be checked with scan tools as well. to active test it and make sure it is doing what it is supposed too.

[Revivalist]

Good info for possible future reference. . . . Thanks!

[jhama78]

ANother thing to note on this truck is that he has K&N air filter (cleaned in july) in the stock airbox... I personally have never liked these filters because I dont feel that they filter well enough. I have experienced this on my atv with the K& N, the intake boot on the carb would always have a little bit of fine dust in it whenever I would check so IMO its not filtering as well as it should. Since I put a UNI oiled foam filter on it I have had no dust at all on the carb side of the filter.

WHen I cleaned the TB and IAC last night there was a light coating of oil and fine particulate dust that resembled the dust inthe intake boot of my atv... so my thinking is that the filter let in too much dust which accompanied by the oil being pulled out of the filter contributed to the condition of it not idling... Agree/Disagree?

[jhama78]

ANother thing to note on this truck is that he has K&N air filter (cleaned in july) in the stock airbox... I personally have never liked these filters because I dont feel that they filter well enough. I have experienced this on my atv with the K& N, the intake boot on the carb would always have a little bit of fine dust in it whenever I would check so IMO its not filtering as well as it should. Since I put a UNI oiled foam filter on it I have had no dust at all on the carb side of the filter.

When I cleaned the TB and IAC last night there was a light coating of oil and fine particulate dust that resembled the dust in the intake boot of my atv... so my thinking is that the filter let in too much dust which accompanied by the oil being pulled out of the filter contributed to the condition of it clogging the IAC and not idling...

my .02

-j-rOd

[Pietro]

sshhh! Don't tell anyone this information. Proper maintenance keeps technicians from getting paid 2 hours for a 10 minute job because owners don't follow recommended maintanence

I wouldn't feel bad about replacing the 02 or MAF. Now the truck is ready for another trouble free 100k+ miles.

[pr0ject42]

Hmm that is interesting, but I'm not surprised. K&N or any other oil-based filter is not advised by Gadget or URD mainly for reasons of degraded performance and how quickly it dirties up the MAF.

I've been having some strange problems with my 3.4 getting SUPER lean on idle every once in a while and almost choking down. I'll have to clean all of that stuff out.

Thanks for the heads up dood!

[jhama78]

Heres a link that I found with some decent pics of what to clean and all that jive... http://www.yotatech.com/showthread.php?t=92286

and the part numbers for the two gaskets that you'll need to service it

TB gasket: 22271-62040
IAC gasket: 22215-62180

[ErikB]

Here's another great maintenance article, and it mentions cleaning the MAF and TB:

http://4x4wire.com/toyota/maintenanc...tenancep5.html