weird s14 sr20det problems. PLEASE help!

[vboy720]

Fresh new s14 sr20det zenki swap. Has stock turbo, fmic, walbro, z32 fuel filter, tail bov, and new spark plugs (.030). Since the first day we swapped the engine, the zenki maf we got with our swap did not let the car run. It would turn over, bog and then shut off. But if we put in a s13 sr maf, the car would idle fine, but when driving, you cannot give more than 15-20% throttle. If you drive the car without getting on the throttle more than that, it drives fine. Even reving the engine when parked the car runs fine.

So i tried out another zenki maf i bought from a member on here which he states was working. With the new maf in, my car will turn over, idle like crap, rev like crap, and eventually bog and die during idle. checked my codes on ecu its a WC and reads 69f00.

I am lost here, because i dont know why my car would run better with a s13 sr maf, than a s14 maf. Is wiring for the maf different on a s13 harness than on a s14 harness?

[kanekoa28]

just to clarify you mean s14 maf from a blacktop sr20det maf right not the ka24de maf???

[GroundPerformance]

Your MAF or wiring could be bad. Also verify the PN# of your MAF it could be the S14 Kouki MAF which is not compatible with your WC ECU which is Zenki.

[vboy720]

Originally Posted by kanekoa28

just to clarify you mean s14 maf from a blacktop sr20det maf right not the ka24de maf???

s13 sr20 maf is the one that kinda works on my car. never used a ka maf.

Originally Posted by GroundPerformance

Your MAF or wiring could be bad. Also verify the PN# of your MAF it could be the S14 Kouki MAF which is not compatible with your WC ECU which is Zenki.

Maf# is 69f00 which matches up with my ecu which is "WC/69f00". as for the wiring, i dont know how i could trace it back to wiring if an s13 sr20 maf kinda works, but my zenki s14 maf doesnt. But i could be wrong, you probably know more than me.

[vboy720]

anyone else have any helpful tips please?

[Mr.Y]

Bump an older thread but I'm having the same problem. Haven't tried an s13 sr maf but I have a Zenki s14 sr with WC ecu and 69f00 maf and car starts and idles great, if you drive with very little throttle it drives good, soon as you apply more than like 25% throttle it starts breaking up and shaking. Very stumped. MOtor is stock, checked the maf wiring and its how its supposed to be.

I think both vboy and I can use the help

[DallasTXjdm]

I am experiencing almost the same issue right now with my BT SR. What was the outcome of your issue Vboy720 and Mr. Y?

[Mr.Y]

It seems to be a faulty fuel pump in my case. I put a pressure gauge on my fuel line and when i rev the engine pressure seems to drop instead of rise so i have a pump on order. Ill update once i install the pump

[Mr.Y]

Update. PUmp installed but problem still there. HAve suspicions bout the tps so I have one on order. Ill update once that comes in

[will_drift_4_food]

80% of the time, I don't think that the ECU is at fault. The problem is that most of the time, the ECU is separated from the motor at the time of shipping and you may or may not get the ECU that was originally mated to the motor(set). Most SR20 (S13) ECUs seem to be interchangeable if you have a MT.

You should all open up your ECU and make sure that it isn't chipped. Sounds like the ECU is chipped for either a different MAF or bigger injectors. My S13 BT ECU turned out to have a YellowHat Sports Maintenance daughterboard in it. When we took that out and desoldered the on-board jumper, the car ran damn near perfect. Just had to undo all the IAC and timing tweaks that we made during the troubleshooting process. If it's chipped for bigger injectors, obviously it will run really lean with the stock ones. I was actually running really rich and fouling plugs, but I assume that the ECU was setup for Z32 MAF. A couple of extra sets of plugs are a must for troubleshooting and tuning. Fouled plugs give erratic results.

Also, battery voltage plays a big part here. If you've done a swap, make sure that your alternator is charging at 14.4 and not 15.2 or 13.1 or something like that. A lot of people leave the charge light disconnected, and this will cause the alt to put out unregulated voltage. Go to Radio Shack and pick up a 100 ohm resistor and wire it between +12V and the charge light wire. Then check the voltage @ the MAF with the engine running and see if it matches the battery voltage.

[TFD]

MAF wiring:
Horsham Developments

Identify ECU:
Nissan S14 ECU types

S14 = Zenki
S14a = Kouki

Find someone with Nissan datascan or so to check your electrical stuff (tps/maf etc.)

TPS = 0.45 V
MAF = 1.4 V cold / 0.8 V warm
etc. (top of my head)

Good luck

[aww-shiet]

Im in the same boat as you guys. New member here, btw.

I have a 96 240sx SE with a s13 sr20 swap. Ever since the first day it got on the road, anywhere past 3200rpm it breaks up. It has a E5 ecu.

Things that were changed:

Fuel Pump upgraded to a Walbro 255
Spark Plugs changed to BKR7E
Went from a KA SOHC Maf to CA18 to now S13 SR20 Maf
CAS Was also changed

Problem still remains. I think its one of the coils going bad in boost.

[fufanu180]

I have the same problem. I ended up ordering that consult cable for the car and installed datascan on my laptop and everything seems to be fine but the throttle isn't smooth past 25%.

I later figured out that if I turn up the air/fuel ratios richer then the car actually runs fine. Idles at 16.1 on the wideband, cruises at 14.8, and drops down to 11 or so in boost. Without turning up the fuel the car would idle like It's cammed out, would be very sluggish, and wouldn't even give a reading when at idle and cruising on the wideband.

Weird shit. I still haven't figured it out but I definitely take my laptop with me everytime I wanna drive it though....which is ridiculous. I just wanna hop in and go.

CenTex240

[Couped_up'd]

I have had this same problem. It was my Throttle Position Sensor (TPS)

Please check your TPS. Make sure you have a good working TPS before going to the MAF as the faulty unit.

In Order I would check:
1. Check TPS
2. Make sure your car is in time
3. Boost leaks
4. Maf
5. Maf Wires.

[aww-shiet]

Originally Posted by fufanu180

I have the same problem. I ended up ordering that consult cable for the car and installed datascan on my laptop and everything seems to be fine but the throttle isn't smooth past 25%.

I later figured out that if I turn up the air/fuel ratios richer then the car actually runs fine. Idles at 16.1 on the wideband, cruises at 14.8, and drops down to 11 or so in boost. Without turning up the fuel the car would idle like It's cammed out, would be very sluggish, and wouldn't even give a reading when at idle and cruising on the wideband.

Weird shit. I still haven't figured it out but I definitely take my laptop with me everytime I wanna drive it though....which is ridiculous. I just wanna hop in and go.

CenTex240

hmm thats some werid shit. my wideband reads 10.0 in boost which i know its in the 9's. I might try and turn up the boost and see what happens. Also ill check for boost leaks.

[fufanu180]

I wonder if it could be the wiring to the tps, o2, or mafs?

I know it should read .45 when closed but what else do you look for?

I thought it was the tps as well so I got another one from a buddy(a whole different throttle body since the tps can be very flakey once dismounted from the tb) and I still had the same problem.

CenTex240

[will_drift_4_food]

Originally Posted by fufanu180

I wonder if it could be the wiring to the tps, o2, or mafs?

Very possible since they are usually interconnected in some way. Maybe a bad ground? Always a possibility.

Originally Posted by fufanu180

...since the tps can be very flakey once dismounted from the tb

They are "flaky" because they are often not adjusted properly. Even a tiny bit off can make a huge difference in drivability, even more so than timing and AFRs.
It is my experience that an analog meter is the key to adjusting a TPS. Most of the time it is an "insert feeler gauge, turn TPS until the needle deflects, and then back to the point of deflection" thing. Very easy when there is a needle to watch. The display on the digital meter doesn't react fast enough, most of the time this is a feature to prevent inaccurate readings. I am not a Nissan expert by any means, so please also consult the FSM.

[fufanu180]

Originally Posted by will_drift_4_food

It is my experience that an analog meter is the key to adjusting a TPS. Most of the time it is an "insert feeler gauge, turn TPS until the needle deflects, and then back to the point of deflection" thing. Very easy when there is a needle to watch. The display on the digital meter doesn't react fast enough, most of the time this is a feature to prevent inaccurate readings. I am not a Nissan expert by any means, so please also consult the FSM.

You use a feeler gauge to adjust your tps? When I've had to mess with my tps before I just used a volt meter that taps into the ground and the voltage return on the tps. I would adjust it until it's exactly at .45, then I'd lock down the screws but still checking while I'm tightening the screws to make sure that the value doesn't change at all.

What is this feeler gauge method you speak of?

[scumbag]

sorry to intrude but i have a zenki sr20det and im having trouble finding mafs and a harnes can any1 help ?

[fufanu180]

Zilvia fs section. And I have a 14 mafs and housing if you're interested. Pm me.


CenTex240

[atpena]

I'm having the same problem I did some research and figured out my engine was an automatic so the throttle body and tips all that stuff was different I had to desire it, but now I. Having problems with my maf I can put my hand in front of it and the engine wants to shut off or low air into it and the engine sputters to shut off.... Any ideas??

[aww-shiet]

I found out what my problem was when I sold my s14, head gasket cracked. That's what caused all my sputtering. It's a shame I got rid of it