Problem:
It starts only if you give it thottle, and will only run if you hold the throttle at about 2K+ RPM, or keep revving it above 1K RPM. When I drove it home after buying the car, it runs fine, only dies with clutch in + no throttle.

Setup:
Stock lowport DE, stock compression, JWT ECU, 3 bar program, MSD 50lb on JGY rail, JWT S3 cams, adjustable FPR, J30 / Z32 MAF, TurboXS BOV, Tial wastegate, TurboXS dual stage MBC (currently not hooked up)

Intake air setup:
Filter>Turbo compressor>intercooler>BOV>MAF>TB.
There were no hoses/vacuum lines T'd in after the MAF, ** the TB, until the other day when I added one for a 3/16" i.d. vacuum line, used one of the hard vacuum lines (tried all three, none helped).

Vacuum to BOV comes the large hose connected on intake manifold to adapter for smaller hose, then to BOV.

Vacuum line from compressor goes to side port on tial external wastegate. Top port on Tial currently to atmosphere. TurboXS dual stage MBC not connected at the moment.

Timing was set before turbo install. Idle was not perfect before install, but did run.

Things I checked so far:
- vacuum leaks, found none so far
- TPS .48v at idle,
- fuel pressure ~36psi key on engine off.
- MAF = < 1v key on, engine off. Rev in neutral(no load) = ~1.4v@1.5kRPM, ~1.5v@2k, ~1.7v@2.5k, ~1.7v@3k, ~1.7v@4k
- MAF wiring:
J30/Z32 MAF-----------------------B13 wires
A) Not Used-----------------------Not Used
B) White (MAF Signal 0-5 V)-------Orange (MAF Signal 0-5 V)
C) Orange (Ground)----------------White (Ground) + Extra good ground
D) Black (Ground)-----------------White (Ground) + Extra good ground
E) Black/White (12V Power)--------Orange/Blue (12V Power)
F) Not Used-----------------------Not Used

(1) I checked the BLK/WHT-ORG/BLU MAF wire - key on/engine off = 18.x volts - supposed to be 12v!?!?

(2) Does the MAF voltage make sense? It's not under load, and it's a J30 MAF, but it peaks at 1.7v (in neutral, no load). My na '93 with stock MAF will hit 3v under the same conditions. Could the MAF be bad? Or is it just that the bigger MAF flows more so it sees lower voltage?

(3) Is there supposed to be a vacuum line for idle control to pipe between MAF & TB? If so, where does it come from? I added the smaller line, but didn't help. After searching other blow through threads with pics, it looks like the larger vac line has to be there for proper idle. Where does this line come from?

(4) To connect MBC, is it best to add a T to line from compressor to Tial, then go to MBC in. MBC out to top of Tial?

yes....there is a vacuum line in between the maf and the tb.....it is the big one that runs from behind the intake manifold....

Is the bov recirulated? MAF hooked up correct? Is the ECU programmed for the maf?

try running draw-through MAF, i bet it idles.

yes....there is a vacuum line in between the maf and the tb.....it is the big one that runs from behind the intake manifold....
I need to figure out which one - my other car NA w/highport has 3 lines going to the pipe between MAF & TB - one small, 2 larger. I already added the small one, but didn't help. On a lowport, where does the line come from? I thought it's the one from the IACV?

Is the bov recirulated? MAF hooked up correct? Is the ECU programmed for the maf?
BOV not recirculated. I thought it doesn't matter with blow-through, not metered air. I tried pinching the vacuum line to BOV to see if it was a vacuum leak - didn't help.

MAF wiring listed above. I checked it over at least 4 times. ECU is programmed for this exact setup - it's a J30 MAF = Z32 MAF. What bothers me is that the 12v wire is reading 18v, key on, engine off. Tomorrow I might try running a wire directly from the battery to the MAF to supply 12v. The multimeter reads the battery at 12.x volts, so I think the meter is OK.

try running draw-through MAF, i bet it idles.
Even without the idle control vacuum line to the intake between MAF & TB?
Maybe I'll try that.

Thanks to all for the suggestions!

Even without the idle control vacuum line to the intake between MAF & TB?
Maybe I'll try that.

Thanks to all for the suggestions!

I thought you had said that you already have it on the IC pipe between the MAF and TB. If you dont have it there, that is your problem. It will not idle without it at all.

I thought you had said that you already have it on the IC pipe between the MAF and TB. If you dont have it there, that is your problem. It will not idle without it at all.
I added the small 3/16" i.d. vacuum line, but that didn't help. I have to add the larger one, just have to figure out which one, where it comes from on the intake manifold. The intake piping is custom and does not have taps to hook up the vacuum lines. I had to drill a hole & weld a small tube on for the 3/16" line, and will have to do the same for the larger line.

What about question (4) above? To connect MBC, is it best to add a T to line from compressor to Tial side port, then go to MBC in. MBC out to top of Tial?

I added the small 3/16" i.d. vacuum line, but that didn't help. I have to add the larger one, just have to figure out which one, where it comes from on the intake manifold. The intake piping is custom and does not have taps to hook up the vacuum lines. I had to drill a hole & weld a small tube on for the 3/16" line, and will have to do the same for the larger line.

What about question (4) above? To connect MBC, is it best to add a T to line from compressor to Tial side port, then go to MBC in. MBC out to top of Tial?

BORNGEARHEAD helped me today.
Connected TB to <edit> Hotshot (AEM was too small) <edit> CAI intake pipe to J30/Z32 MAF to air filter (no boost).
Connected large line from manifold which comes from IACV air regulator, to intake pipe between MAF & TB.

Now it idles by itself when warm. Still idles rough when cold. Blip the throttle to 3k or so, let off and it drops to 400-500 rpm or so and stutters, eventually dies. Vacuum about 12-14, when idling at about 900 RPM, about 18 at 1200 RPM. With S3 cams, is that about right?

Tried adjusting timing a bit, without timing light, and it seemed a bit better. Will have to get a timing light to get it exact.

Fuel pressure at about 36psi at idle w/vacuum.
Plugs look good.
No smoke from exhaust, so I don't think it's too rich.

I'd still like to get a lowport car (preferably turbo) side-by-side, to verify vacuum lines. Anyone close to Madison willing to stop by?

Sorry man i totally forgot to get back to you. I would have come up this week end. It was a crazy week for me. Glad to hear you got it ideling. Maybe i can swing up next weekend if you need more help.

Sorry man i totally forgot to get back to you. I would have come up this week end. It was a crazy week for me. Glad to hear you got it ideling. Maybe i can swing up next weekend if you need more help.

No problem Russ! I've been overloaded at work too.
I might take this Friday off to work on it. Maybe work on it next Sat and/or Sun also.
Still has a cold idle problem.
Needs both outer CV boots replaced.
Gotta track down 2 oil leaks.
Should have intake pipe welded up for idle vacuum line early next week, so I can hook the boost up again.
Not sure if wastegate is opening, might need rebuild.
I'd like to get it going for the 9/24 meet, but if not no big deal.

This may or not help, but I've been told that with the MAF reading incorrect voltage that you have to turn the MAF until you get the right voltage or it will idle roughly. Checked that yet?

This may or not help, but I've been told that with the MAF reading incorrect voltage that you have to turn the MAF until you get the right voltage or it will idle roughly. Checked that yet?

I tried the MAF with connector towards pass. side, and also straight up.
I'll try rotating it a couple more times, after I get the intake tube welded up with the IACV-air regulator pipe connected. Most of the problem is from not having the IACV hose connected.

There's still a cold idle issue though. BKR7E plugs look good, gapped at 0.036".
Plug wires are fairly new, but Autolites. Will replace those with OEM. Probably should get a new cap & rotor too.

Well at least you got a warm idle. I couldn't get that.

glad you found the line.....i should have specified it....anyways....that big line that goes to the pipe needs to be pointed up....atlease thats how we got it on my brothers 200sx....it wouldnt idle right until that line was straight up and the maf turned to the right position.....forgot how which way the maf turned...

The intake tube is ready with the added AICV-Air regulator connection. Not sure if I'll get time to install it tonight though. I don't think I'll need the small one, so it'll probably just get capped off.

http://www.sr20forum.com/img/data/500/medium/IntakeTube1_P9132750.jpg

Had some 304 ss tubing the exact size I needed:
http://www.sr20forum.com/img/data/500/IntakeTube2_P9132746.jpg

Used 1018 for the small tube:
http://www.sr20forum.com/img/data/500/IntakeTube3_P9132735.jpg

Nice welds, unlike the welds that I had done.

Update -

Finally got some time to work on the car today - took the day off from work :D
BORNGEARHEAD helped a bunch.

Replaced outer CV boots.

Installed intake pipe between MAF & TB - now with the larger vacuum line from manifold.

Started & idled only with added throttle. Once warmed up, set the timing and idle. After awhile it seemed to smooth out. We're thinking the ECU was still learning, since it has very low miles with the turbo & ECU installed.

It still might have a cold idle issue - will check it tomorrow.

Found the oil leak. Leaking from the NISSport oil pressure adapter. Will try to get at that tomorrow maybe - make sure everything is tight.

MBC not conneted yet.

Plugged / disconnected some vacuum lines that weren't needed since EGR is removed.

Took a short test drive. Builds boost around 3-3.5k, pulls hard until 4.5k - 5k then falls flat on it's face, at about 8-10 psi - feels like hitting the rev limiter.

Checked for boost leaks - none.

Fuel pressure was at 36-38 at idle, w/vacuum. Bumped it up a bit. Same problem but with big backfire. Too much fuel pressure.

Adjusted it to about 36 at idle, but was 40 w/out vaccum, so turned it up a bit, to 39 idle - 44 w/out vacuum. Parked it for the night, will drive it tomorrow.

I plan to check vacuum lines with a gauge tomorrow. I'll try to pull slowly to higher RPMs (avoid high boost) and watch the MAF voltage & injector timing.

Anything else I should check? What would cause it to quit accelerating at about 5k RPM?

Thanks D.J. for all the help today!!!

I had major cold start issues before. Not it never dies when its cold or when I put the clutch in. Just give it time. My setup, 72lb, z32, 3 bar, blow through with s4.

I had major cold start issues before. Not it never dies when its cold or when I put the clutch in. Just give it time. My setup, 72lb, z32, 3 bar, blow through with s4.

The cold idle might be O.K. - will find out tomorrow.

I'm more concerned with it falling off at about 5k RPM, like hitting the rev limiter.
After searching a bit, might be plug gap. Will check that tomorrow. I think it's gapped at 0.036" or so, IIRC. Will try dropping that a bit.

In addition to the fixes for today, we also ditched the Autolite plug wires for OEM sumitomo wires. :)

*edit* - So maybe the ECU will learn over time & idle better when cold?
Is your setup 9.5:1 compression? What max boost do you run? Dyno numbers?
Thx - Josh

Id start at like .025 and work your way up. I ran too much of a gap an it did the same thing. I run 10 psi daily no dyno numbers. I still cant get it to run right either, dont have the time like I did before.