Ok.. since I've had my car boosted it's always stalled when stopping fast or letting up on the clutch quickly. Seemed like it just could not provide the volume of air through the IAC circuit. I *****ed about it alot but never realy tried to fix the problem.

Anyhow.. I spent about 30min on it today and figured it out.

1)You'll need to eliminate the "adaptor" peice that flows coolant through it or remove the small blade that looks like a throttle body.
2)Remove the three phillips head screws that hold on the IAC motor
3)Look through the large pipe that go's to the (after) maf and or up pipe tube. (where you took off the rubber hose)* you'll see that theres alot of small slices in a brass insert where the IAC valve Plunger go's in and out to controll idle.
4)Take a carbide bit or large drill bit and drill or grind the brass away through that opening to the same size as the tube/hole.
5) Make sure that there's no extra brass shavings or bent brass that will be able to stick the plunger!!!!!
6) The plunger hole and plunger should be cleaned and lubed with a light oil like WD40 or marvel oil before re-assembley.
7)Re-install the IAC motor (**it has a 6pointed end like a socket that needs to be alligned with the housing to go back together**) make sure that fits correctly and set it to full depth (closed)
8) lightly sand the housing and intake mating parts and RTV both peices.
9)You can use 3 of the stock allen head bolts but the other one needs to be shorter. you can cut a stock one or buy another that's shorter for the blind hole on the bottom left IAC position.
10) Let RTV set for a few minutes and your ready to start and check for leaks.

This allows the volume of air flowing through the IAC to be enough to not let the engine to die when the throttle snaps shut and chokes all the air off. With out this in stock fourm there's not enough volume able to pass though the restrictive port&the adaptor/blade assembly.

I did several throttle snaps there at the shop over 4-5000rpm where I KNOW it would normaly die and it cought it's self every time and stablized idle right away.
It would die all the time if you shut the throttle too fast coming up to a light and push in the clutch too quickly or doing a burn out and trying to push in the clutch ect.. anything that snapped the throttle shut quickly it'd be instant die. I can take pictures of the process and mods tomorrow and send them to Mark .. .if he's still willing to help me post info
~Scott

 

Very awesome info! That annoyed the hell out of me as well and I always figured there was just something wrong with my IACV. I'll definitely have to try that out and see how it goes.

You can send those pictures to me and I'll get them posted right up.

 

nice job ive had that problem without boost so i may try it in the near future

 

mine did the same thing scott... so i put a bov on it and it disappeared. What i think is happening is that it is pressureizing so much air in between shifts which of course takes more air through the airflow sensor which inturn dumps fuel into the moter...... but ya.... put a bov on your car... lol

 

actually i think a bov would make the situation worse unless you're recirculating the bov back into the intake piping and/or if you have the maf on the pressure side and have the bov before the maf.

 

yes.. i have a recirgulating one... my car stalled anytime i would let off wile boosting and press the clutch in. so i put a much better saab BOV recurlating now it NEVER dies.... before it ALWAYS died... letting more air go through the IACV would help because when the extra fuel is dumped into the moter after letting off it also gets a bit more air,.. helping the problem. Right now my buddys max that we just got running does not have a BOV and it dies in those circumstances. But hey, whatever works

 

thats a bypass valve. hehe. get it straight.

i was wondering if this was only a 3rd gen problem?

Scott, any plans of putting a bypass valve on that sucker?

 

aka diverter valve.. he

 

yeah, a recirculation valve would definitely solve the problem. mine is open atmosphere (which doesn't help) but i tried adjusting things using the safc (it has a setting that is supposed to adjust fuel when letting off the gas) but it doesn't seem to help out so most likely the iacv mod will solve the problem.

 

I'd do the deverter/recerc valve but that'd cost money! That was going to be my last thing to try but hadn't heard anyone having luck with that eather. (till now)
It's better to have a deverter/recerc on the car regardless... and if that solved the stalling problem fantastic. If you happen to do this mod with your car it can only help.
I'm taking the digital camera today and will take JPG's and send them to you tonight Mark... Thanks again,
Scott~

 

Would this happen if I put the maf on the non charged side of the turbo? I see alot of cars have been having this stalling problem with the bov and other reasons. But, my friend has the pfi kit on his 4th gen and doesn't have any stalling problems. Does this happen when the maf is on the charged side? Thanks.

 

you need to recirculate the air after the maf and before the compressor in order for it not to stall. its not as loud as a bov, but it still makes a whoosh sound.

 

I plan on putting the maf on the non charged side/intake side of the turbo. So I shouldn't have to worry about stalling right?

 

you need to recirculate the air to after the maf and before the compressor and you will not have to worry.

 

Brad92SE had it on the charged side by a bend and it caused all kinds of problems. He moved it to a part of the charged side that was streight and it solved the problem.
I've always had mine on the non charged side of my system but don't use a BOV or Recerc. (tight wad)
Pic's are on the way to Mark...
Also.. I grafted a late 80's early 90's caddy 3'd brake light into my decklid. After being rear-ended 2weeks ago I thought I should blind the person in back of me when I'm stopped now Pic's included
~Scott

 

Those guys with the pfi kits dont seem to have any trouble, so I will be good because im basing my setup like that.

 

Problem with our VG's is no one makes "kits" or solutions for our problems so we've just gota figure them out for our self.
I sent the pic's to Mark if his e-mail is still at yahoo.com
I've got two more pictures of the IAC motor and housing to take.
There must be two different styles (internaly) in the IAC. I took one off the parts car today to do the same mod and it's different. 89-90 must be one style and 91up another. Not sure on the dates for the changes. Mod will work on eather one in the same manor.
~Scott

 

Yeah I know, no one makes a kit for my vq35 thats why im going custom. But to save yourself the headache, why not just put the maf on the intake side of the turbo.(like the pfi kit does) Or is there no space?



Why not just do it like this? I don't understand.

 

boostedmaximas maf is on the intake side. heck its still bolted to the stock airbox..... hehe

 

LOL, but yeah im just going to put it on the intake side of the turbo, will save alot of headaches.

 

I know for sure the auto and manual cars use different iacv's.

Sorry it took me so long to get the pictures up, I was working on the 85 300ZX Turbo... that has melted pistons/pistons missing some metal.

 

I like that brake light. Nice work.

 

nice... i also like the light

 

thats what i thought when i first saw it. scott showed it to me the other day.

 

It's actually only a VG problem

Scott, glad to hear you got that taken care of. That brake light looks awesome! I need to come check that out sometime in the next couple weeks.

 

Ok.. Update....

Enlarging the slot there where the tube is helps ALOT but it's not a 100% cure on my car so far. I'll keep working with it till I can resolve it completely.
Taking too much material out of there will result in high idle. I've been playing with this more. Got a few more pic's of what I'm talking about and will send them to Mark.
Thanks again Mark!!
~Scott.
outside 3d brake light pic included car all back together too.
Thanks for the comments about it.. Just hoping no one else hits me again!

 

well reading your posts you guys have a fair amount of know how i have a vg20et and it running like its on the choke i have take it to auto elec and he said oxygen sensor so i got a unervsial one but it is just flat down the highway put your foot flat and black smoke and no accelerationit has about 4pounds of boost i can hear it bossting and see it on the dash gauge it all seems to work but its like the chokes on is there a fuse a wire or vacum hose i can pukk off to get some hp out of it any help would be good its nissian maxami 1988 auto turbo pu11

 

mango, it sounds almost like there's a leak around the maf (not getting the correct signal) which will cause it to run very rich. are the rpm's limited at all (will it only rev partially or till redline)?

also, are the fans constantly on at all? if they are that could be a sign of the ecu not getting a good signal from the coolant temperature sensor which could also cause it to run very rich.

Pictures!

 

thank you for the come back!!!! you a right when you ask about the rpm it dose have trouble reveing to redline but if i pull the vacum hose to the fuel regulator it will reve sweet but still a **** load of fuel out the back but i took it to a fuel injection joint and had the fuel pressure checked ok well i will go and have a really good look at the air flow meter and on this car it seems to only have a coolant switch in the front side of the block which tells the car when it can go into overdrive once the car has warmed the maf that you were talking about is the air flow sensor isnt it im only new to fuel injection at this point give me a holly any day

 

Good find scott hope it works for mine.