This afternoon I cleaned the TB, IACV, and egr tube. After I got done I went for a quick drive and at a red light the tach was bouncing between 400-600 rpm's, the car was jerking, and it felt like it was going to stall.

Is there something I need to do now that these parts are carbon-free. I swear, the car ran better when everything was dirty.

Any advice is much appreciated. Thanks,
Ben

 

yah, you cleaned it too good. your car's engine was used to all the dirt. you do the maf as well?? try that that and a tank of 91 or w/e high octane you got in your area. let me know when your done.

 

did you tighten everything down? Did you get new gaskets?

 

I did not clean the maf, it looked good. I have to get gas tomorrow so I'll put 91 or 93 in it and see what happens. Thanks for the feedback, I'll let you know.

yes
no (I forgot to pick them up) The original one's looked fine when I took everything apart.

 

could be a vaccum leak due to a weak seal

GOOD LUCK!

 

thing about the maf is, you cant really see the dirt on the hotwires so a quick shot of crc would'nt kill it.

 

Worth a try if it acts up all day tomorrow.

Everything is pretty tight.....I realllly hope there isn't a leak.

Thanks guys.

 

try the CRC MAF cleaner, it wouldn't hurt anyway.

 

BANG: mistake number one: never re-use 2 dollar (or so) gaskets, i would not go ahead with the job if i have not received the gaskets yet, this MAY be the problem.

in general, any time u take apart anything in the car and have the chance to replace some parts with new ones (cost effectively of course) you should do it.

 

i hope u r not taking apart ur intake while the car is on and the maf is operating...cause thats the only time its hot and you should not be able to see it

 

aahhhhhh no, i don't think so dude. when its apart and wire is disconnected from maf..

 

Hindsight is 20/20 and I agree that I should have waited. I just got sick of the cel on due to egr flow being clogged. I am picking up new gaskets today to replace the old ones. I hope this fixes it. -Thanks

 

BTW, after cleaning TB and IACV should you do a Idle Speed/Idle Mixture Ratio adjustment?

 

^ no adjustments necessary, the idle may, should and will be high, mine idled at 900 rpm for about a week then came down to spec, its the time that the ecu needs to adjust.

i dont know a good way to explain it, but my theory is that the sampling rate the ecu uses is spread out quite good (anyone with digital electronics background knows what i mean) and thus it takes over a week to adjust itself. but in the grand scheme of things its not such a long time. Imagine what a car learns and relearns in 10 years...

 

What you said Andrei makes sense. I talked with a shop today and they said to disconnect the negative terminal of the battery for at least 30 minutes. When reconnected, the ecu should adjust to the new "settings" (no egr clog. etc. etc) They said that I drove with a clogged egr and dirty tb and iacv for so long that the ecu adjusted for these, now that everything is clean again, the ecu must re-adjust or "re-learn."

At least it makes sense to me....hopefully this will work. And I am still going to put new gaskets in. Thanks

 

worst comes to worse - all u do is adjust the idle screw thats located on top of the IACV, its a black plastic screw u cant miss it. just make sure the car is at operating temp.

 

Why to wait a week, if you can do the adjustment in 5 minutes without any special tools?

30 may be insufficient, FSM recommends to leave it for 24hours. But you can try to reset the ECU which will erase "self-learn" information also IMO.

 

because lets say u close the screw to lower the RPM and in about 30K Mi the IACV is mucked up by the oil coming from the PCV, then that dirt will clog the screw hole and the rpm will be lowered drastically and u may see the shaky idle or even rough spudering. thats why its best to leave the screw and let it adjust itself, rather then going back to the screw in a period of time adjusting it again and again

 

check ur mas

 

or try cleaning ur throttle body

 

Let me not to agree with you. When in "learning mixture ratio" ECU tries to adjust idle by IACV valve and generally you don't have to touch the screw. You have to touch it only if you have too high idle and ecu cannot compensate it by closing IACV. If later the hole got cloged, than knowing its idle volume mixture, ECU will open a little bit more IACV to compensate that clogging. And it can be seen on the consult clearly, that ecu opens IACV more when it is dirty.

 

thats also true, i do agree on the fact that the ECU is always adjusting and optimizing everything it can on the VQ30DE. There is definitely no harm in adjusting the screw, i did it to my car to perfect my idle just to get it as close as possible to the 750 - 650 rpm spec.

As far as i understand the workings of the ECU in the 4th gen is that it will compensate for the screw to adjust the idle to spec, and so far i have seen this in my case...

 

Agree with you. I'd say the screw's function is to make IACV to be opened 2-10steps on idle. So it is possible to have perfect idle while screw is blocking the air passage hole almost completly, but in that case IACV will be opened much more than it should be, which isn't a good thing.