Rb20det Idle Problems?!?!?!?!?!

[BlueRB240]

Ok here is the problem, I can't seem to get my car to idle unless I pull the big vacuum line off that goes to the break booster. If I leave it on and try to start the car it just won't turn over. The air fuel ratio while it's cranking with no vacuum leak is like 10ish, with it off it's around 14ish and when it fires up it's at 16ish. So when I fire it up with the vacuum leak that car will ilde high but it will stay running until I seal up the leak then the airfuel ratio shoots to the 10's and the car stalls out. I tried to unplug the maf to get it to idle and it just won't do it. Checked the ecu for codes but none all is good. I thought maybe my injectors were dirty and they were a little from the report I got back after I had them cleaned and balanced. I'm running 824cc Sard injectors with a Nistune Ecu and Denso 280lph fuel pump. I also reprogrammed my nistune and tried it another Rb20 and that car fired up like normal. I'm at a very big loss because I have never seen this before.

[payback21]

Mate i had this exact same problem with my wifes car recently and it took me a few days to nut it out.

After changing ecu, plugs, coilpacks, afm, fuel pump, checked electrical and intercooler plumbing but nup nothing. But after the few days of swearing and cursing i found it.

It ended up being the intake pipe that goes from the AFM to the turbo. It had wriggled off the front of the turbo and was just sitting in front of it. I couldnt bloody tell because as most know, the intercooler piping covers alot of the turbo so you cant visualy see it unless you look for it.

With the intake wriggling off the front of the turbo, it was sucking air in which was stuffing the fuel mixture ratio hence the reason why it wouldnt idle and it couldnt make boost.

Put it back on and now shes all sweat. I would also check the plumb back system if you have it as it may be sucking air from there somewere too.

Im not sure if this is going to solve your problem but check it out. Anything is possible. Hope you have some luck. Its a very annoying problem to find.

[BlueRB240]

Mate i had this exact same problem with my wifes car recently and it took me a few days to nut it out.

After changing ecu, plugs, coilpacks, afm, fuel pump, checked electrical and intercooler plumbing but nup nothing. But after the few days of swearing and cursing i found it.

It ended up being the intake pipe that goes from the AFM to the turbo. It had wriggled off the front of the turbo and was just sitting in front of it. I couldnt bloody tell because as most know, the intercooler piping covers alot of the turbo so you cant visualy see it unless you look for it.

With the intake wriggling off the front of the turbo, it was sucking air in which was stuffing the fuel mixture ratio hence the reason why it wouldnt idle and it couldnt make boost.

Put it back on and now shes all sweat. I would also check the plumb back system if you have it as it may be sucking air from there somewere too.

Im not sure if this is going to solve your problem but check it out. Anything is possible. Hope you have some luck. Its a very annoying problem to find.

I'm running a blow through setup on my car.

I did have to take my Rips manifold off to change my thermostat and thats when this all started to happen. I took it off again and didn't see anything and installed a new gasket. I'm going to start it again tomorrow and spay some brake cleaner around the flange to see if the idle changes might be a leak or something.

[blind_elk]

What fuel pressure are you running?

Considering that you are running injectors probably 4x standard flow rate, I'm surprised it runs at all. You have a programmable ECU - trim some fuel out of it at 'start' and 'idle'.

[BlueRB240]

What fuel pressure are you running?

Considering that you are running injectors probably 4x standard flow rate, I'm surprised it runs at all. You have a programmable ECU - trim some fuel out of it at 'start' and 'idle'.

I have it set to 40psi without the vacuum line. Nistune realtime board for adjustment.

[blind_elk]

Does the cold start valve work? Should be open at (cold) start, then closes off as the engine warms up.

[BlueRB240]

Does the cold start valve work? Should be open at (cold) start, then closes off as the engine warms up.

I am not sure, When I get a chance to get back to the shop (it's an hours drive for me) I'm going to check a few things like the IAC.

[rob82]

I am not sure, When I get a chance to get back to the shop (it's an hours drive for me) I'm going to check a few things like the IAC.

Good luck tuning it with the MAf on that bend.

[BlueRB240]

Good luck tuning it with the MAf on that bend.

It's on the bend it's on the a straight.

[BlueRB240]

Got it! damn K-constant didn't adjust automatically had to do it manually but it idles now! dyno time soon.