S14 SR20 Lagging Problem

[95KA-Turbo]

Ok,

So I attempted to search for this for 2 days now and unfortunately the search function is not working on my personal computer, my parents computer, or my work computer.

Basically I just completed my S14 SR20 swap into my 97 240sx. The car starts and drives just fine. The car has a stock MAF, stock SMIC, stock bypass valve, megan elbow, 3" down pipe, stock cat, Trust DD exhaust, HKS air intake, and stock Silvia fuel pump.

When driving the car feels extremely slow from 0-4200rpms (like slower then my old KA). As soon as you hit ~4200 rpms the car feels like it gains a good amount of hp and pulls all the way to red line.

I checked the MAF, I am going to clean it out with some MAF cleaner tomorrow. I also checked the timing, it was really off - maybe 25 to 30 degrees advanced (the harness on the car looks to of had a AFC on it at some point so I wouldn't be surprised if it had some sort of tune in Japan). I am not sure if I did the timing correctly so I am getting that rechecked tomorrow by someone who 100% knows what they're doing. I attempted to reset it to 18 degrees advanced (as recommended by a local Nissan head) - I say attempted because I am not sure if I did it right (in between 3rd and 4th timing mark).

I am just looking for some suggestions, I am not sure if this is something common with S14 SRs...like I am not sure when VTC is supposed to kick in, I am also not sure if it hits as hard as VTEC or not...I was under the impression it was more similar to BMW Vanos in that it was for low end torque (ie starts early ~2000rpms and tapered off by ~5000rpms).

Any suggestions would be greatly appreciated. I can also mention I have 93 octane gas and a brand new 02 sensor.

Thanks in advance!

[renegade_ewok]

There is no way an SR should feel like a KA after 3,000 RPMs. Right around then it should punch you in the face when you hit full boost.

Check for vacuum leaks - do you actually hear the turbo spool at all? Check your exhaust manifold and hotside to make sure there isn't some massive leak that is preventing it from spooling earlier....

[95KA-Turbo]

I guess I should mention I can hear it spool and everything. I it makes and very audible noise when the bypass valve vents even around 2k. It is making all the right noises, it just seems to be missing a lot of torque.

I will be honest though I've never ridden in ANY car with an SR on only 7psi, haha.

[Z U L8R]

sounds like ur ignition timing is just retarded. if you think your vtc solenoid is bad you can just unplug it and go for a test drive, if nothing changes than it just may be. but before you do that, adjust your base timing. should be 15degrees advanced at idle. follow the procedure per fsm.

Dave

[slideways2004]

sounds like ur ignition timing is just retarded. if you think your vtc solenoid is bad you can just unplug it and go for a test drive, if nothing changes than it just may be. but before you do that, adjust your base timing. should be 15degrees advanced at idle. follow the procedure per fsm.

Dave

do what he said. exactly what he said

[95KA-Turbo]

Ok, so an update. The car feels much better today (yesterday it was ~85-90 degrees and today it is 65). I checked the timing it is just under 15 degrees, I did not have a means to change it where I was, I basically had a timing light and that's it.

The biggest problem I am noticing today is the motor will sort of hick-up/hesitate/sputter/whatever you want to call it. It is in any RPM range, under constant and wide open throttle.

I can just be cruising and it'll feel just like it does when you lift your foot completely off the throttle, except I haven't and if I push the throttle down it will either have NO response at all...like the gas peddle does nothing, or the car will sort of jar/hick-up.

Under WOT it just feels like I've let off the gas and the dead peddle seems to last longer. The longest it lasted was maybe 5 full seconds. Most of the time it will just cut off, then I try and give it gas and it'll be like on-off-on-off-on-off-on-off, then it'll be fine.

The car has cut off a few times while coming to a stop, and had a mildly rough idle a few times today. Again I'm running stock SMIC and stock bypass valve with the recirculation pipes and everything.


As far as vacuum leaks go, are you supposed to be able to hear the stock bypass valve really well? I can hear it very clearly, and the sound (when my window is down) sounds like it is coming from my driver side wheel well - which makes me think of the SMIC. I have not found any leaks anywhere but have not done the brake/flammable spray test yet.

One other thing to note is when I turn the throttle pulley by hand I can hear a clicking noise near the pulley. It sounds like a relay. It honestly sounded like the injector closest to the throttle pulley.

Sorry for the essay, I am trying to be as descriptive as possible.

[Grenade180sx]

my 14 sr had the BOV on the intake side of the piping. not on the smic. but the on of swtich seems like vaccum leak.

your car is already sending fuel for air that isnt there and then goes into WTf mode. when it lacks the air

[slideways2004]

also make sure you are checking timing right. the proper steps are listed in the fsm

cliff notes on timing.

put spark plug wire between coil and spark plug.
warm up engine
unplug tps
set light to 15
adjust from cas to 15. (each mark is 5 degrees and i think the marks start at -5)

[renegade_ewok]

Are you recirculating?

[95KA-Turbo]

Yeah my bypass valve is under the fuse box in the engine bay and it connects to the recirculation piping that goes back into the intake (on the other side of the motor).


The timing lights I used were kind of old school and did not allow for an setting to be selected.

To check the timing I just put the timing light loop on the wires for the 1st coil pack. Upon reviewing the FSM I can also use the black wire that sticks out of the coil pack wiring harness (this I did not know). The car was warmed up and the TPS was unplugged.

[WTFaNG]

how long is your vacuum line to the wastegate acuator? and check for gasket leaks before the turbo.

S14 sr doesnt really have a kick in the face boost like the S13 sr's. oh yea that clicking noise near the throttle when you blip the throttle is the vtc solonoid clicking on and off.

[shame_16]

Have you changed the fuel filter?

[95KA-Turbo]

how long is your vacuum line to the wastegate acuator? and check for gasket leaks before the turbo.

S14 sr doesnt really have a kick in the face boost like the S13 sr's. oh yea that clicking noise near the throttle when you blip the throttle is the vtc solonoid clicking on and off.

The vacuum line is roughly 2 feet long from the wastegate to the piping.

I need to change my fuel filter.


Another note to make is the car will backfire on occasion as well.

[renegade_ewok]

If your car had some massive vacuum leak post MAF and pre-engine, the car would richen out massively when you hit boost as metered air is escaping. Check it with a wideband to make sure. If it goes rich, metered air is escaping. It shouldn't go lean unless you boost past injector capacity (you said 7 psi so this is out the window)

If you hear it spool then obviously there shouldn't be a leak on the manifold/hotside. You said the car had an SAFC on it at sometime... If there is a way to check the ECU for a reflash/chip try that. Maybe the ECU was the safety fall back if something in the car failed (like another piggyback, etc) and has an ultraconservative timing map with extra fuel to keep it safe.

Check your A/F trims and that should give you some insight.

On the backfire thing, I have a cammed S14 SR and a full 3" catless turboback and I backfire every now and then randomly but not often. How often is it? It only happens a few times on trips but since you said you have a cat I would think it should muffle it a little more/prevent it. If it happens often then it could be superheated fuel (from going through the cat) undergoing combustion when it hits the air. Which could be evidence of a rich condition.

[phoenixheat_2002]

I'm going through the same headache right now but in an S13. My timing sucks b/c the timing light i was using isn't the greatest. I also think that I have a boost leak somewhere. I have yet to put a wideband in but I do know that my car is running super rich (thanks emissions).

[renegade_ewok]

running super rich will make your car bog and run like crap - go to a shop that has a dyno and they should have an A/F sensor (the kind they stick in the exhaust pipe) and just have em slide the bitch in and see what it says.

[Z U L8R]

if your car is breaking up under load you could have a bad coil pack or two. yesterday i just fixed a customer's rb25 car that would have a studder under load. i adjusted his timing, cause it was off, put in bcpr7es gapped at .028 cause he had his bkr7e's (which are just as good) gapped at .039 which was too big, and adjusted his tps cause his safc2 would say 93% throttle at wot. after that the car wouldn't skip on low boost, but would above 10psi, i swapped the first 3 coil packs with another set, still did it, swapped the back 3 and it went away. car came in making 290rwhp@11psi and left after i tuned it making [email protected] running smooth as a baby's ass with 11.9 air/fuels :P

gl man
Dave =]

[95KA-Turbo]

I really appreciate all of this help guys. I bought a new fuel filter today, and am checking my TPS tomorrow as well as correcting my timing and checking my spark plugs.

Will the coils check as bad if I use a multimeter? I don't have a way to replace them just to test it.

[Z U L8R]

it's kind of tough to test em if they're arching under load. you could maybe spray some soapy water on em while it's running and see if you see them arching, but u still may not see anything and they still may be bad. it's just one of those things. intermittent problems sux. you could put your car on our dyno and i can put load on it while you check them lol :P gl brotha, u'll find the problem. i see u posting wise things on other ppls problems so you're not a dummy.

gl
Dave

[95KA-Turbo]

Thank you, I'll be sure to post up when I find something out. One of the coil packs has a little scrape/cut in the plastic around the clear part - I think from shipping. S13 and S14 coil packs are the same if I'm not mistaken? I may be able to borrow some S13 coil packs tomorrow.

[95KA-Turbo]

Ok, well I changed my fuel filter (which was old as fuck), cleaned the hell out of my MAF, corrected my timing, and checked my TPS (which was 0.44 - so nearly perfect).

It has much better pick up now, but is still kind of slow before ~4k - which I think just may be because I've never ridden in a completely stock SR before, haha.

I checked for vacuum leaks with some MAF cleaner but had no luck in finding any. I am going to replace all the lines anyway because there are not that many and it would 100% remove any question. I completely doused my SMIC and no idle change occurred...but again I was using MAF cleaner not really an appropriate method.

It still hickups a little bit. I am going to swap them out with my friend's coil packs tomorrow and see if it is any better. I didn't really drive it long enough today after the changes to tell if what I've changed effected the hickuping because it occurs sporadically and I just ripped on it up and down the street a few times to check for power increase.

I will continue to post any updates I have! I really appreciate all the help.

[lordofthemiasma]

sounds to me like a bad maf..... based on your description. im curious. wtf is the "brake/flammable spray test".:tweak:

[95KA-Turbo]

You just use carb/brake/maf cleaner to check for vacuum leaks. If the idle changes when you spray it on something particular you have a vacuum leak there. It is not a great method, but it is cheap and can give you an area to concentrate on for fixing vacuum leaks.

[slideways2004]

use the right type of timing light and also the proper method. using the "loop" is not accurate. on my car it was 15 deg off with that. i have heard upto 30 degrees off with the loop. use the spark plug wire method to time

[Forge_55b]

take off the bypass valve, and cap off the related hoses, sounds to me like if you have no vacuum leaks the bypass valve might either be on backwards, or just stuck open

[Z U L8R]

blow off valve leaking could be a possibility.....but a lot less likely than a bad coil pack or two. and you are correct that s14 uses the same, it's the s15's with the little itty bitty splitfire looking joints. gl bro, u'll fix it
Dave =]

[95KA-Turbo]

Ok, so a mini update. Upon further searching on the car I found my fender harness was trashed. I rewrapped each individual wire and got it tucked up real good. That did not fix the problem.

I finally got my gauges in so I can better describe what happens when it starts hickuping. According to the boost gauge vacuum is remaining the same, when I push the throttle when it is hickuping (when the car feels like I have taken my foot off the throttle and even when I push it it doesn't do anything - the symptoms usually last a few seconds) the gauge shows the appropriate vacuum (in other words no major vacuum drop or anything).

I have the boost gauge Ted off at the fuel pressure regulator hose.

I am waiting on some extra coilpacks to show up in the mail. Just giving an update before then.

[Z U L8R]

cool. i would advise not having anything T'd off the fuel pressure hose unless it's a boost controller that specifies to. you don't want to have any interuptions in the fuel pressure rising. gl man, keep us posted

Dave =]

[95KA-Turbo]

Ok, so I have since replaced the coil packs and the coil pack harness. This made the car feel a thousand times better! It was seriously like I gained 20whp. I now am having a slightly different problem.

Intermittently, when I take left hand turns (they can be very very slight or sharp it is really variable) the car will flat out cut out (like I removed my foot from the gas petal) or kind of sound like it is hitting rev limiter but much more quiet. It is very particular and does not do it all the time, usually on wider turns were I am going a little quicker in any gear (1st-5th). This includes from a stop making a 45 degree left, to me being on the interstate making a very slight left in 5th gear while cruising. The car will also randomly cut off while at stop lights - this is also not constant and happens sporadically.

I went over the car with a fine toothed comb and only found one thing. There was a ground that was not grounded connected to the alternator harness. I grounded that and the problem still exists.

While the car was running I tugged, pulled, wiggled, yanked, etc on each sensor and harness I could find and nothing caused the idle to change, let alone cut off. I even took the ECU and shook it around to see if I had a loose connection and that was no luck.

I also looked into my gas tank to make sure my fuel pump was alright (as I replaced this when I did the swap). That all checked out fine.

I am doing a drift event tomorrow and hope that I don't have too much trouble at it. I will report back from that to explain anything else.

Please someone give me some ideas! I am pulling my hair out now. I am able to drive the car just fine it is just really annoying! I need this taken care of so I can drive a normal car again! Thank you in advance.

[renegade_ewok]

I don't know if 240s have this issue, but in the suby world RSs sometimes have an issue where the fuel will shift around in the tank causing fuel intake to get screwed up dropping fuel pressure. Given this is usually under harder driving conditions... Don't know if this is an issue with these cars just throwing it out there.

[95KA-Turbo]

Well, at the drift event it only acted up a few times. The strangest thing is that if I turned my headlights on (which raises the RPMs at idle just slightly) the car wouldn't have any problems really. The couple of times it did mess up it stalled out completely and was hard to start afterwards (leading me to think of fuel because it was just like when you take the fuel pump fuse out to depressurise the system). I am leaning toward something messed up wiring wise for the fuel pump. I will update things as I figure more out - in the mean time any other suggestions are appreciated.

[95KA-Turbo]

Just an update because I hate it when I search and find a thread that has similar sounding problems I'm having with no solution.


I am 99.9999999999999999% sure I've fixed the problem. I took my fuel pump out to inspect it and everything looked good, I gave it a jiggle just to be sure nothing was loose and put it back in. I am pretty sure I had it sitting in there incorrectly before, the car feels awesome now! It doesn't cut out at all even on extremely sharp turns and it idles MUCH better.