KA24E-T no idle, maybe missing? Looking for help

[Dantetris240]

Hey guys Im having some issues with my recently built KA-T. It's currently running but does not want to hold an idle (feels like its missing).

Here's the weird part:
If feather the throttle the car will stay running, if i hold the throttle in one spot (anywhere in the RPM range) the car will rev to that spot and stay there for just a moment, then drop down (i'm still holding the throttle). I have to take my foot off the throttle and then go back on it to keep it alive.

To simplify: car will not hold a steady RPM with throttle applied, regardless of rpm.



Car:
89 s13 KA24E w/ stock Comp forged internals
Freshly redone engine harness
550cc Deatschwerks injectors
Garett t3t4/ 38mm wastegate
Emissions deleted (only 2 vaccum lines left)
FMIC, no leaks.
Aeromotive fuel pump 250lph
Isr fpr
Battery relocated to trunk
Bov is blocked off (no planning on running one)
2 stages colder spark plugs (new wires, cap and rotor)
Jim Wolf tuned ECU
New MAF
TPS in spec
IACV and PCV retained

I've tried mostly everything i can think of but i'm pretty much out of ideas.

Ive checked the MAF and TPS and they are both reading correctly. IACV is clean, pcv is clean.
Plugs are BKR8E gapped at .34 (tried iridiums and platinums also, gapped at .34 and .45)

Before its suggested: yes ive searched and searched and followed solutions from other threads with no avail.

Thanks for your help.

[PapaSmurf2k3]

That sucks man. I hate it when you blow a ton of cash on a fresh rebuild and it isn't running correctly.

Do you know what your fuel pressure is? Do you think its running rich or lean or anything? Have you tried adjusting ignition timing? Did it improve at all?
Have you double checked the cam timing?

[Dantetris240]

Cam timing is on, timing was set after rebuild (the car ran fine after the rebuild (while NA).

Moving the timing forward or backward makes the car run very rough.



I have the fuel pressure set to 42psi, the one thjng i do need to figure out is if i am losing fuel pressure because i think that would explain it (the only problem is i can't get it to idle so its hard to monitor the actual pressure while running).

I think it may be running rich but the way it dies makes me think the fuel pressure is fluctuating (pedal can be depressed but revs drop anyway).

Thabks for your help.

[PapaSmurf2k3]

Yeah I would go old school and either take the intake pipe off, or induce a vacuum leak that you can feed fuel through while you're trying to run it. Basically you want to see if the engine will just run if you give it 2 of the things it needs for sure (fuel and compression).
If you can sort of "turn it off and on" based on the amount of fuel that you are manually spraying or pouring in there, you know you've got a fuel problem.

[Dantetris240]

Yeah I would go old school and either take the intake pipe off, or induce a vacuum leak that you can feed fuel through while you're trying to run it. Basically you want to see if the engine will just run if you give it 2 of the things it needs for sure (fuel and compression).
If you can sort of "turn it off and on" based on the amount of fuel that you are manually spraying or pouring in there, you know you've got a fuel problem.

That is a great idea and ill give it a shot aa soon as time allows this week, thank you!

[Dantetris240]

Yeah I would go old school and either take the intake pipe off, or induce a vacuum leak that you can feed fuel through while you're trying to run it. Basically you want to see if the engine will just run if you give it 2 of the things it needs for sure (fuel and compression).
If you can sort of "turn it off and on" based on the amount of fuel that you are manually spraying or pouring in there, you know you've got a fuel problem.

Thabk you for your help in determining that this is not a fuel problem.

Im wondering if the fact i still have butterfly valves with having the control solenoid is causing this? From what i understand though, they will stay open when the solenoid has no vaccum..


Edit: i also had my wife watch my fuel pressure gauge and while it is running while featherong the throttle the fuel pressure is 43.5 (42-45psi) when i hold the throttle (car revs up then rpms drop while throttle is still held open) the fuel pressure stays the same (42-45 psi.).

[PapaSmurf2k3]

That's good. I guess it could always be an issue with too much fuel, but you'd probably smell that.

If you suspect the butterfly valves, you can reach back and activate them manually from the lever on the side, although like you said they are supposed to be wide open if they are broken.

You could always try adjusting your fuel pressure up or down to see if it makes a positive impact too.

You're positive your spark plugs are wired correctly, right?

[Dantetris240]

That's good. I guess it could always be an issue with too much fuel, but you'd probably smell that.

If you suspect the butterfly valves, you can reach back and activate them manually from the lever on the side, although like you said they are supposed to be wide open if they are broken.

You could always try adjusting your fuel pressure up or down to see if it makes a positive impact too.

You're positive your spark plugs are wired correctly, right?

I pulled the intake manifold off, the butterfly valves are indeed open woth no vacuum source (I am removing them and welding the holes anyway). Also ive found that where the fuel pressure currently is set makes the car run better (than higher or lower) but regardless of the fuel pressure setting the same patter persists. I have new gaskets for the intake manifold (upper set) and will be installing them once i get the manifold sorted out. Thanks again for your help thus far.

Intake runners where the butterflies are (you can see they are default open)

[Dantetris240]

Also yes i have the wires like this: (not my image)

[PapaSmurf2k3]

Good deal. Sometimes you have to just check stuff off the list

Have you tried running with the MAF unplugged completely? It should put it into a safe mode.

[Dantetris240]

Good deal. Sometimes you have to just check stuff off the list

Have you tried running with the MAF unplugged completely? It should put it into a safe mode.

Ive only tried that with the old MAF and it made a huge difference (car would hardly fire at all with the old MAF) but I've yet to try it with the new MAF. I'll get back to you as soon as ive tested it intake mani is still off the car.

[PapaSmurf2k3]

I'm just suggesting all sorts of general things to try to cut the deck to see what and where we need to focus... so if it seems like I'm all over the place, its because I am haha.

[Dantetris240]

I'm just suggesting all sorts of general things to try to cut the deck to see what and where we need to focus... so if it seems like I'm all over the place, its because I am haha.

Thanks for your help so far again, its great to get another opinion when it seems like you've tried everything. (plus I've posed this in 5 sites and askes some locals for help and you're the only one even bothing to try).

Should have the intake back on (with fresh welds) in the AM and I'll update this thread with my findings concerning the MAF.

[Dantetris240]

Okay, so I've got it back together again.

While it was apart here is what I did:
-New gaskets(oem Nissan not the FELPRO ones I was using)
-new PCV hose (fixed a vacuum leak I believe)
-new heater hoses (coolant through intake deleted already)
-butterfly valves removed, holes welded
-new hose clamps basically everywhere
-New coolant temp sensor
-Cleaned IACV and AAC
-cleaned EGR tunnel (It's still blocked)
-cleaned runners
-cleaned plenum and TB
-cleaned fuel rail and injectors
-added new grounding strap to intake side

The car is getting better, however it still will not idle and seems to be missing. The biggest change is that if I hold the throttle it WILL hold RPMs.


However it still seems to be missing bad (especially at low rpm) and will not catch an idle (though now it seems like it wants to a tiny bit more).

I've uploaded a video of it running: (MAF plugged in)
Https://youtu.be/NybbvfQjwWY

(sorry I'm not sure why youtube made the video sideways)

Now, as you said I tried it with the MAF unplugged, my findings:
-holds RPM rock steady at about 1850
-smooth. Very smooth.
-any throttle make it very very rough sounding (see video)
-smooth.
-while running, plugging in the MAF makes it die.

Please see video: (MAF unplugged)
https://youtu.be/EyL1y13G84Y

So since it obviously runs when the ECU is in safe mode, does this mean my fresh JWT tune is no good? Would I be better off with something like an SAFC? (considering one anyway but would like a decent base rune first)

Thank you for all your help so far, it's really coming along!

[PapaSmurf2k3]

Yeah it could be the tune... but could also be a bad MAF.

Does your idle air control valve had an adjustment screw on it? You may just need to tune that.

[Dantetris240]

Yeah it could be the tune... but could also be a bad MAF.

Does your idle air control valve had an adjustment screw on it? You may just need to tune that.

So I doubt the MAF is the problem, as the MAF is brand new and DID CHANGE the way the car ran (I could not even keep it alive before). Adjusting the IACV screw all the way in or out does not change the way the car runs.

A note: I tried moving the MAF after the turbo, I also tried putting it directly onto the hot side intercooler piping (without the turbo feeding into the piping.

[PapaSmurf2k3]

Yeah, if you can, take the turbo out of the equation for the moment. If your MAF is on your turbo intake side and you've got any boost leaks or anything, it'll throw all of that off.

Really your best bet would be to try the factory intake tube (or similar) until this gets squared away.

[Dantetris240]

Yeah, if you can, take the turbo out of the equation for the moment. If your MAF is on your turbo intake side and you've got any boost leaks or anything, it'll throw all of that off.

Really your best bet would be to try the factory intake tube (or similar) until this gets squared away.

I switched back to the stock intake tube last night, problem persists. I also added a ground to the MAF (from the harness side ground wire) no change.

Next I am going to add more grounds to the engine for good measure. But I'm really thinking it might be an engine control issue. What would be the best way to narrow that down?

Thank you

[PapaSmurf2k3]

Swapping back to stock size injectors and running a stock ECU.

[Dantetris240]

Swapping back to stock size injectors and running a stock ECU.

Ill give it a shot if I'm able to find an ECU.

[Dantetris240]

*update*

I have yet to find an ECU that is reasonably priced.

Installed some new grounds
Checked MAF harness
Got another new MAF (was under warranty, no questions asked)

Car had same issues.

Adjusted throttle cable (to slightly open TB with no pedal action)

Car "idles" at 1200 to 1700 rpm.
Runs very rough under about 2500 rpm.
Still seems to be missing.

I have read about people retarding the timing by pulling the distributor and moving it a tooth off (for turbo applications) but JWT said i can run stock timing when i picked up the ECU from them. Any comments or ideas on this note?

Thanks,
D

[PapaSmurf2k3]

Realistically you should only put the dizzy a tooth off if you adjust it fully one way or the other, and that's where it runs the best.

[Dantetris240]

I see, currently turning it to full retard *phrasing* seema to make it run the best. Maybe I'll mess woth it if i get the chance this evening.

[Dantetris240]

Adjusted the timing (a tooth off) and got it running a bit better. It will move itself under low rpm (rough) but when throttle is applied it begins to feel like it has power, but the rpms quickly drop and it feels like it wants to die (a light rev and it goes back to 'idle').

Keep in mind the throttle cable is still set to keep the throttle open a touch when to pedal is applied.

Adjusting the idle screw (all the way in or out) changes nothing.

Where would you guys go from here?

Thanks,
D

[PapaSmurf2k3]

Can you check the ignition timing?
Might want to try closing the throttle all the way too.

[Dantetris240]

Can you check the ignition timing?
Might want to try closing the throttle all the way too.

I'm going to try to check it tonight, but the car will not stay running with it closed.

[PapaSmurf2k3]

Did you ever replace/clean the idle air control valve?
Are there any check engine lights?

[Dantetris240]

Did you ever replace/clean the idle air control valve?
Are there any check engine lights?

Yes, the IACV is clean (replaced it aboit 2k miles ago).
There are no check engine lights.

[Dantetris240]

Solved.

Jwt re-mapped mu ecu and the car runs perfect!
Made 385hp and 376tq on 14psi.

Thanks for all your help nico!

[PapaSmurf2k3]

Damn those are some good numbers!!!