RB26 not idleing

[bulldog0690]

Not sure if this has been asked or answered or if anyone has ever encountered this situation yet. But I just swapped an rb26 into my 240sx, checked for vaccum leaks cleaned out the aac valve an air regulator. Checked the ohms on both they both check out good, no vacuum leaks nothin. The engine will not idle when I have my apexi power fc plugged in. It revs jus fine when u start it an flutter the gas, but let off an it dies. Stock ecu has one maf blown so it is unreliable in that area, but when its plugged in the engine will idle... Any tips, ideas, anything?

[Nesquick]

check the tune

[bulldog0690]

it has no tune. im still at the begining trying to get the apexi ecu to "learn" the idle process as the website directs.

[S-tec Motorsports]

Try turning off the o2 sensors, maybe one of them is bad. Sometime the stock tunes on them things depending on the version you have just plain suck.

[bulldog0690]

Yea I thought that too. Till I did turn them off. It didn't help at all. I did however read up on cleaning the itbs... I read it after I cleaned them. So I'm digging into that now will post if anything's changed.

[bulldog0690]

Anyone have any advice for a fix to the gaps between the throttle flaps an the body? Since I already cleaned them befor I read not to lol. Yes yes I know noob move, but help would be nice, all I can find is ppl trying to put blue silicone in there, I'm not about ta have silicone break off an float into my engine.

[J2fast]

Anyone have any advice for a fix to the gaps between the throttle flaps an the body? Since I already cleaned them befor I read not to lol. Yes yes I know noob move, but help would be nice, all I can find is ppl trying to put blue silicone in there, I'm not about ta have silicone break off an float into my engine.

you need to have the car tuned, that is why it will not stay on. trust me im a tuner on pfc, aem , haltech. everytime i check and everything else is in working order than it is the tune that needs to be worked. do you have aftermarket injectors, turbo, maps sensor, etc?

[SullivanRacing06]

are you using the oem mafs or are you running a map?

[bulldog0690]

No I'm running 300zx mafs, no o2s, and an apexi pfc. In the pfc I can select the 300 mafs an turn off the o2s which I did. An there was no change. It still would not idle. The only thing I can think of is the gaps in the itbs. But ur the second person to say tune. I have no idea what I'm looking at in the apexi hand controller as far as air/fuel mix an all that technical stuff. The only manual I have for it is half in Japanese, so I can't read it.

[J2fast]

You know what else you try is the screw that holds the throttle or closed for idle, open the throttle so the rpms are a lot higher like 1500 or so the it should stay on if it doesn't stay on then, your car is prob to lean or you have a leak somewhere

[bulldog0690]

Tried the screw, didn't work. Even having the throttle open didn't work still died. I checked for leaks everywhere I couldn't find any to save my life. I'm going to recheck the gaskets though.

[bulldog0690]

you need to have the car tuned, that is why it will not stay on. trust me im a tuner on pfc, aem , haltech. everytime i check and everything else is in working order than it is the tune that needs to be worked. do you have aftermarket injectors, turbo, maps sensor, etc?

Are you located anywhere near New Bern nc? And I'm just cautious about going in to get it tuned because I have done a few things to get rid of a hissing sound when I pressureize the intake, but its still there... I can't find it an Idk what it could be. But if you say that all it needs even though I still can't hold pressure in the system higher than maybe 2lbs then I will go for it. Because this is really getting on my nerves, iv got a major car show coming up at the end of this month that I want to get the car to. But I keep getting stuck with this thing. My brain is fried atm... Oh and now if I try to start it. It will idle for one second then die. You still think it just need to be tuned?

[Carl H]

good ol newbern.

have you checked the cold start regulator, sometimes they get stuck open and will cause it to idle weird.
cant believe no one asked this but is the PFC brand new?

if its not brand new you need to do a unit reset and disable the O2 sensors as well as the boost control kit, then set your mafs up in the airflow meter menu and make sure the closed throttle switch is engaging.

[bulldog0690]

Cold start reg is good, jus cleaned them the other week. No the pfc is not new, but I did reset it. Set up the mafs, an shut off the o2 sensors. didn't think or know about the boost control part, an I don't know how to check the closed throttle switch

[Carl H]

if you disassembled the itbs then the tps needs to be reset as well.
plug on the tps body (not the pigtail) should have two wires coming out of it, disconnect that plug and check for continuity against those two pins.
if no continuity then adjust the tps till you do and it breaks as soon as the throttle blades are cracked, if this is not set then the car WILL NOT idle.

[bulldog0690]

Yup adjusted that, its set at .4 or .04 whichever is the correct one I don't remember

[bulldog0690]

would making it a single turbo have a big difference u think? cuz im running a single holset hx40 turbo instead of the dual. An another thing I noticed, when I start the car an rev it to keep it running, my boost gauge doesn't read anything, an when I let off the gas, it dips down below zero.

[Carl H]

read what i said again.
and you have one very large vac leak if the boost gauge is not reading atleast -~20in/hg at idle with stock cams.

[bulldog0690]

ok, i will check that out tomorrow after work. Cuz I haven't herd that one. An that's what iv been figuring. I just cannot find it to save my life. and I don't have a fog machine so iv been using a bottle of soapy water an a bike pump lol. can't get everywhere wit the bottle. I will look at everything again till I'm blue in the face this week though. thank you very much for your help. ill post the news when I figure things out.

[Carl H]

you need more than a bike pump to find an air leak...more like 25psi of air.

[bulldog0690]

Well at the moment it starts hissing befor I even get to about 5psi.

[RRRRB]

Did you notice when you cleaned the itbs that the dowels are different some are longer than others... if not put in the right spot the itbs won't mount flush against plenum and or manifold... it will cause a severe leak.

[SullivanRacing06]

do you have a wideband on the car to see afr?

[bulldog0690]

What do you mean by dowels? Are you talkin about the shafts that the butterfly plates connect to? If so I didn't take those out. Just the plates. An I kept everything seprat so I knew what went where. An yes I have a aem wideband o2.

[RRRRB]

Did you take the throttle bodies off the manifold? The dowels go between the itbs and the manifolds..

If the car is misfiring or idling eraticly a wideband won't do much good.

[bulldog0690]

yes i did, an i didnt touch those. they are all in the same spot they were when i took them off, there is no gaps between the tbs. n no i know it wont. but thats why i have the pfc.

[bulldog0690]

Ok, well I found the leak, finally... Turns out it was a hose that had a slight hole, just big enough were soapy water wouldn't blow bubbles out of but small enough to hold about 1lb of preassure... But its fixed now. Thank u all for ur hints, advice, an help. Now to get this thing tuned!