KA24DET rich bogging/stalling on decel, not catching idle

[Chugpuppy]

Hey guys, need some help here

I've had this problem ever since I was N/A, although it was a LOT less pronounced than it is today. Basically, when the engine warms up and the idle settles at its normal operating rpm (around 800ish, with 15 afr), letting the rpm drop from anywhere above ~1500 rpm causes the engine to drop past 800 rpm and die. When it drops like that I'm getting readings of ~10 afr (maybe lower, the UEGO sometimes takes a while to register really rich conditions, and only reads down to 10). Sometimes it will catch itself, bounce up and down for a couple seconds, then even out, but nowadays it usually just bogs out and leaves my wideband reading a solid 10.

The second symptom is rich throttle transition. When I feather the throttle (just baaaarely giving it gas) it causes it to run really rich, again sweeping the wideband to a 10. It seems to hesitate when I get on the throttle also. If I'm in a parking lot or something, and have a jerky start (350z pp and 6 puck rated for 500hp, what) if my foot accidentally bounces on the throttle it will jerk VIOLENTLY, causing my foot to hit the throttle more, which makes it worse. I have to clutch in at that point, while also holding the gas so it doesnt die, then slip the clutch a little to get going smoothly again.

This also happens in second, and to a lesser degree in the higher gears. If i get off light throttle, then get back on in quick succession, it'll jerk roughly. Pisses me off. It especially likes to happen when I'm cruising at low speeds, but just barely need to touch the gas to keep myself going. Goes really rich when it does this, and will afterfire if I get back on throttle.

Everything besides throttle transition and idle is fine. Feels a little sluggish at wot, but pulls good afrs.

TL;DR: Once warmed up, car dies when clutch is pushed in and rpms drop, wont catch itself at idle. Throttle transition sucks, jerks around a lot. In both of these situations it goes really rich, with afr @ 10. Fine afrs under constant accel.

EDIT: car is also hard to start when warm. cranks fine, but doesnt catch unless i fiddle with the ignition and give it gas.

Now, mods and diagnosis:
S14 KA
S13 harness, coil, distributor, etc
Most of the Greddy 20g kit
Z32 MAF
440cc injectors
Enthalpy tune

What I've done recently to solve it:
Boost leak tested at ~25 psi, didn't hear any obvious leaks
Pulled codes, found 34, 12, 13
Cleared codes, 34 and 13 still showing up
Wired in a resistor to emulate a knock sensor, as my KS wiring circuit is bad. Resistor brings signal from ECU down to 2.05v, no more code 34.
TPS adjusted from .44v closed to .5v closed, currently reads .5v closed 4.35v open
Pinched and disconnected fuel pressure regulator vacuum line, no change in idle?
Disconnected MAF and started car. Idled lower, ~500, but still dropped a little when I let the rpms fall.

What I think may be wrong:

Bad MAF wiring/grounds - I'm not sold on this one though. The fact that it still did it with the MAF unplugged makes me think it isn't related.

Bad coolant temperature sensor - A possibility, although I wouldn't think it would cause this serious of a problem. Still have code 13, popping in a new one tomorrow.

Bad fuel pressure regulator - This is my new target. It worries me that it doesn't change the idle when I pinch or disconnect the vacuum line. I'm thinking maybe the diaphragm inside is sticking? or caught? Could be holding it at a pressure level suited for being on-throttle even when it goes back down to idle, causing extra fuel to be injected and it to bog down.

I can get pictures and video of my setup if that'd be of assistance.

I've been dealing with this for like a year now though, and any help would be appreciated so fed up with this car, missed a fucking awesome Dspot event with the Tuercks and Drift Faction guys today because I thought I could have it fixed once I pulled the codes, but nope...

[Chugpuppy]

54 views and not a single comment... cmoooon

[ultimateirving]

Kas have an iacv right? If that's the case test and replace. I had major issues with dying at decel and my idle would surge between 600-1300. Got a new iacv and it fixed all my idle decel issues

[Chugpuppy]

Originally Posted by ultimateirving

Kas have an iacv right? If that's the case test and replace. I had major issues with dying at decel and my idle would surge between 600-1300. Got a new iacv and it fixed all my idle decel issues

Took out IACV and cleaned it up, thing was spotless when i put it back in. No change :/

[drifting1two40]

i have a 93 ka24de with deleted emissions and egr blocked off. charcoal canister deleted. headers test pipe and catback. cold air with a 3 angle valve job all the valve seals replaced and arp head studs...ive been doing all this modification so that after i fininsh collecting my pieces im going ka-t.

but im trying to get my car running A1 before i boost so that i dont have the same problems transfer over once i turbo.

Well my ecu has the ECT code as well and a couple others. Basically my car runs pig rich and i have started to notice my oil getting black faster than usual and smelling of fuel lightly.

but two days ago i was looking at my ECT connector on the harness side and noticed theres was green corrosion all inside of it. also it didnt have the metal retainer holding it in place. so since i work at a nissan dealership i basically made a new connector with new metal contacts and everything on the inside and a new retainer now it seems im getting better gas milage and my exhaust doenst smell of fuel, or my oil. just my two cents about my ECT experience

[ultimateirving]

Originally Posted by Chugpuppy

Took out IACV and cleaned it up, thing was spotless when i put it back in. No change :/

Have you tested it to see if it functions? because this part specifically is designed to hold idle and catch the rpms from dropping too low and dying.

[Chugpuppy]

Originally Posted by drifting1two40

i have a 93 ka24de with deleted emissions and egr blocked off. charcoal canister deleted. headers test pipe and catback. cold air with a 3 angle valve job all the valve seals replaced and arp head studs...ive been doing all this modification so that after i fininsh collecting my pieces im going ka-t.

but im trying to get my car running A1 before i boost so that i dont have the same problems transfer over once i turbo.

Well my ecu has the ECT code as well and a couple others. Basically my car runs pig rich and i have started to notice my oil getting black faster than usual and smelling of fuel lightly.

but two days ago i was looking at my ECT connector on the harness side and noticed theres was green corrosion all inside of it. also it didnt have the metal retainer holding it in place. so since i work at a nissan dealership i basically made a new connector with new metal contacts and everything on the inside and a new retainer now it seems im getting better gas milage and my exhaust doenst smell of fuel, or my oil. just my two cents about my ECT experience

Going out to replace the coolant temp sensor now... I'll let you know if it changes anything

[silviaks2nr]

unplug your iacv from the harness and see if it runs any differently. My car runs 100% perfect with it unplugged so I just leave it off. Is your bov vented? if so can you stiffen it or recirc it? Shitty alternator/battery/grounds can cause symptoms like this as well. It would also be a good idea to change out the plugs if it's having warm start issues.

when you boost leak tested it did you open the throttle body?

[Mitsubayati]

I didn't read through the whole thread, but I had that same idle drop issue you had. It turned out that I needed to replace my distributor cap. The contacts were corroded. When I replaced it, the car idled perfect and I actually had more noticeable power as it had diminished.

[drifting1two40]

i would check the resistance on the sensor first before you just replace it. because mine wasnt the sensor . just the connector on the harness wasnt getting good contact

[Chugpuppy]

Coolant temp sensor replaced, getting code 55 on the ECU so electronically things are looking OK. Letting her cool off then taking her out to see if it made a difference.

[Chugpuppy]

Originally Posted by silviaks2nr

unplug your iacv from the harness and see if it runs any differently. My car runs 100% perfect with it unplugged so I just leave it off. Is your bov vented? if so can you stiffen it or recirc it? Shitty alternator/battery/grounds can cause symptoms like this as well. It would also be a good idea to change out the plugs if it's having warm start issues.

when you boost leak tested it did you open the throttle body?

I'll try unplugging the IACV next. BOV is atmospheric, but I dont think that's the problem. Only running like 7lbs of boost. I have a grounding kit installed, so grounds should be good, and I had the battery and alt checked out not too long ago, but it wouldn't hurt to double check. Just changed the plugs recently, so I'm gonna leave em in til I can get this figured out

[silviaks2nr]

Originally Posted by Chugpuppy

I'll try unplugging the IACV next. BOV is atmospheric, but I dont think that's the problem. Only running like 7lbs of boost. t

Even if you're only running 7psi if it's soft enough that it's open at idle you are going to basically have a very large vacuum leak and the car can idle down and run poorly under part throttle and when transitioning from vacuum to boost. I guarantee this is at least part of your problem.

[Chugpuppy]

Originally Posted by silviaks2nr

Even if you're only running 7psi if it's soft enough that it's open at idle you are going to basically have a very large vacuum leak and the car can idle down and run poorly under part throttle and when transitioning from vacuum to boost. I guarantee this is at least part of your problem.

It's not open at idle, spring's pretty hard actually. I still get a little flutter. Also, it's bogging down because it's running rich, if it was allowing air to get in it would be running lean afaik. I'll crank it all the way hard just to make sure though.

[Chugpuppy]

UPDATE: New engine coolant temp sensor in. Not getting any more codes. Car runs more or less the same :/ maybe a little less rich and more predictable while driving, but still exhibits the same symptoms as before.

I unhooked the BOV so it doesn't open at all, car still wanted to die when rpms dropped back down from revving it, so that isn't the problem.

When IACV was unhooked the idle dropped to ~400. Car still stalled after being revved to ~2500.

[Chugpuppy]

Bored at work bump. Thinking about replacing FPR soon.

[Chugpuppy]

Bump before I order a new FPR

[BryanS14]

I am having almost the same issue to a "t", I am thinking FRP too, mine is noisy at time. Not sure if I will have it replaced within the next week, so ill be looking to see if that fixed it.

[s13drob]

I saw your link in another similar thread. I think you should do the same as i suggested on his issue. Check base timing/idle...
KA-T.org - The Home of 1000+ whp/7 sec Turbo KA's

[Chugpuppy]

Originally Posted by s13drob

I saw your link in another similar thread. I think you should do the same as i suggested on his issue. Check base timing/idle...
KA-T.org - The Home of 1000+ whp/7 sec Turbo KA's

First thing I did. Right on the money.

Ordering a new FPR today when I get home from work. *pretty* sure that's what it is. All the symptoms point to it. Just not sure whether or not to just get a replacement stock or go adjustable aftermarket...

[Chugpuppy]

New Borg Warner stock replacement FPR installed along with new Z32 fuel filter. No change. Checking MAF voltages again tomorrow and adding a chassis ground. Running out of ideas.

[tayloray]

holy shit this is a though one. Have you checked you're tps voltage? Granted that would be cutting fuel rather than adding, but i've had issues with mis-calibrated tps's, and it does that on-off throttle bobble. The tps was still reading 0 at part throttle. Not sure if it'll help, but just throwing an idea out there.

[Chugpuppy]

Originally Posted by tayloray

holy shit this is a though one. Have you checked you're tps voltage? Granted that would be cutting fuel rather than adding, but i've had issues with mis-calibrated tps's, and it does that on-off throttle bobble. The tps was still reading 0 at part throttle. Not sure if it'll help, but just throwing an idea out there.

Yeah, I'm trying to cover everything. TPS has been checked and adjusted to spec, was .44v closed, increased to .5v closed with no change. 4.35v WOT.

[tayloray]

Have you checked your injector o-rings? I had issues with them going out and causing vacuum leaks. As well as them causing fuel to pour past the injector into the cylinder.

[Chugpuppy]

Originally Posted by tayloray

Have you checked your injector o-rings? I had issues with them going out and causing vacuum leaks. As well as them causing fuel to pour past the injector into the cylinder.

I have a top mount injector setup and Greddy rail, so that can't really happen afaik... My engine is bogging because of a rich condition, not a lean one that could be caused by vacuum leaks.

Checking voltages and rechecking timing when I get home from work. Could it be possible that the distributor is off a tooth, and even though it's at the stock 20 degrees it could actually be advanced or retarded?

EDIT: I shot it with a light and the timing was at 20*... so it should be perfect correct? If the dist was off a tooth, therefore skewing timing, shouldn't the light catch that?

[tayloray]

Originally Posted by Chugpuppy

I have a top mount injector setup and Greddy rail, so that can't really happen afaik...

Checking voltages and rechecking timing when I get home from work. Could it be possible that the distributor is off a tooth, and even though it's at the stock 20 degrees it could actually be advanced or retarded?

Oh yeah duh. Forgot ka's where top feed. You could still get and injector leak but you would definitely hear it.

If timing was off it wouldn't run well at all. It would still idle alright too.

Checked your intake manifold gasket?

[Chugpuppy]

Originally Posted by tayloray

Oh yeah duh. Forgot ka's where top feed. You could still get and injector leak but you would definitely hear it.

If timing was off it wouldn't run well at all. It would still idle alright too.

Checked your intake manifold gasket?

KA's are side feed stock. I converted mine to run RC Engineering 440cc top feed injectors.

Intake manifold gasket was recently refreshed with a new Felpro one, which resulted in no change. The intake system from the turbo to the block has also been tested to 25lbs of pressure and no obvious leaks were present. Again, the car is dying due to a rich condition, not leaning out as would indicate a vacuum/boost leak.

[tayloray]

Originally Posted by Chugpuppy

KA's are side feed stock. I converted mine to run RC Engineering 440cc top feed injectors.

Intake manifold gasket was recently refreshed with a new Felpro one, which resulted in no change. The intake system from the turbo to the block has also been tested to 25lbs of pressure and no obvious leaks were present. Again, the car is dying due to a rich condition, not leaning out as would indicate a vacuum/boost leak.

Have you tried letting it die then checking your plugs? Could have a bad injector that's sticking open. Flooding out one cylinder.

[Chugpuppy]

The plugs don't really change color, but I can see a little puff of black smoke when it dies. If one injector was sticking open it'd run weird during accel and also idle weird. It idles perfectly, but dies if it's revved and then not given gas after.

[tayloray]

Originally Posted by Chugpuppy

The plugs don't really change color, but I can see a little puff of black smoke when it dies. If one injector was sticking open it'd run weird during accel and also idle weird. It idles perfectly, but dies if it's revved and then not given gas after.

I know someone already mentioned this. But I had the same problem with my old rb20 setup. Turned out to be a leaky bov. Which may make sense because if you rev, start to build boost then release, you loosing metered air. Causing a rich condition. Have you tried a new maf?