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View Full Version : Ka-t, Gas pedel stalls engine, Idles great! :/


Tantwoforty
03-14-2012, 04:58 PM
Alright, id been holding off on makeing this thread but eh, ill just throw it up and see if anyone can help me out
So Heres what i got going on:
95 S14 block and head
S14 upper manifold
S13 lower
S13 cams
BC springs/valves/retainers
head job /porting
new rings, bearings, gaskets, timing kit, ect
T25
370's
Rom tuned ecu
n62
S14 godspeed FMIC kit
HKS bov
3 inch all the way back, no cat
GP sports catback
ect ect

So my issue is this: I fire it up, it idles like a champ, smooth as butter..
But if i touch the gas pedal, it falls on its face and dies.. Like i cant let the clutch out because i cant add enough gas to compensate..
What i can do it gently press the pedal and it will slowly rev, pretty much keeping it right on the verge of dieing, i can get it to rev to like 3 or 4 k, it will actually build a little boost and blow off in this time.
But if i pass about 5% gas pedal it boggs and dies.. like you stop hearing combustion. if you remain past the 5% mark long enough, it will stall, if you releese it it picks back up and idles..

But so pretty much i cant touch the pedal or it dies, so i cant move it really ect.

Where im at:
When i had a emanage it showed me % of sensors and at that time the maf and TPS read great. but i havent checked them since switching to the new ecu but the emanage was sketchy so idk

I had a issue with leaky injectors, could it be flooding when i rev it and stopping combustion? Its my most likely option right now because i know it leaks form the bottom seal on all of them i think.

I checked the timing and its spot on

No Check engine light, code 55

Plugs are kinda old and crappy and may be fouled

It did this before i had the turbo hooked up awhile ago, changing spark plugs fixed it. i had a used set. but this time its not fixing it. but im thinking the injector leak is worse now and its putting the spark out there's a little smoke coming out the back... and it was way way worse before i hooked up the turbo.. im assuming the extra air is helping use up some of that fuel...

It ran great before, reved all the way and such, so this is kind of suddon and nothings really changed hardware wise

Anyway i was just wondering if someone could confirm its probably afr ( fuel drowning out spark) or if anyone else had has this issue and has found another cause like a sensor or somehting..
http://sphotos.xx.fbcdn.net/hphotos-snc7/s720x720/419189_10150666416674801_681149800_8948286_1472210 012_n.jpg
Hg15V9rEBzo
God thats sad to watch.. this is me staying in that 5% reving it and letting the clutch out alittle at a time so i could move it, then trying to get it to rev and failing.. i need to recirc my bov, hella Paul Walker right now lolz props to the gf for filming
wow, i just noticed my $140 pair of sunglasses on my trunk.. thank god for this problem! lol

di-devol
03-14-2012, 05:07 PM
You have a ka-t and no wideband?

702s13
03-14-2012, 05:07 PM
do you have a wide band? if so whats it say when its bogging? rich or lean, you can check the injectors by unbolting the fuel rail and turning the key to on, if you see any fuel then the seals are leaking and should be replaced... also who tuned the ecu? could be tuned for wrong injectors or something.

orion::S14
03-14-2012, 08:58 PM
Same exact issues can occur if you swap the #2 and #3 plug wires...i.e., it's 1-3-4-2 in the COUNTER-clockwise direction.

http://i34.tinypic.com/vec2nc.jpg

If you get #2 and #3 swapped (by putting them on in a clockwise direction, easy mistake), it will do exactly what yours is doing.

Start there. I hope for you it's that simple, because 2 minute fixes are awesome.

- Brian

cotbu
03-15-2012, 12:32 AM
You got to fix the leaking injectors or determine how bad they leak. The only thing the gas pedal controls is air. the ecu controls fuel. If anything is out of whack the ecu's calculations are going to be wrong.

I was also thinking timing, but again you say it spot on. Spot on what is spot on stock 20deg or KAT 15-13deg? IDK because you didn't tell me. If you don't have a cali or OBDII ecu, codes usually get stored (no cell) unless it a huge problem.

Tantwoforty
03-15-2012, 12:44 AM
I dont have a wideband yet. But the motor still needs to be broken in so i wont be flooring it for awhile anyway, Although yeah, it would be great right now.

The firing order thing is a good thing to check, Ill do that tomorrow.

Ill double check the timing tomorrow aswell.

I was told the tune was elapathy (spelling? idk) but theres no stickers or writeing or anything, but it ran good before on this ecu.. But yeah, with no markings idk wtf its actually tuned for :/

And ill try to pick up injector seal kits asap.
Thanks so far guys!

Edit:
Wait, looking at the fireing order pic, maybe i put it right after #1 and not before?
When i first used the timing gun, it was WAYY off the marks, to the right i think.
So i spun the dizzy and got it over to the marks and put it to about 15 and no change except it idles a little lower (this was like a month ago)
Ill put it to TDC and redo it all..

But can timing randomly change though maybe something slipped? idk, off to investigate!

Edit again because i have a theory, maybe it didn't matter so much before i added boost because the ecu didn't sense boost and didn't try to adjust the timing to accomadate, but now that its seeing boost its trying to adjust it and its throwing it too far because i put the dizzy in on the wrong tooth?
I cant really work on it till tomorrow because its outside and its cold and dark lol anyway anyone think my theory could be it? mechanical timing is a little off so ignition timing's range is messed up?

EDIT AGAIN!?!?!?!
added video, its still processing to idk if it will work if not ill fix it tomorrow, good night zilvia

snafupossum
03-15-2012, 12:53 AM
sounds like ecu is tuned for wrong injectors

Tantwoforty
03-15-2012, 01:06 AM
sounds like ecu is tuned for wrong injectors

But it ran them ok before, but being as its not marked, ill definitely keep that in mind after i check all the cheaper things lol

brizanden
03-15-2012, 01:13 AM
try reseting your tps yet? mine did this cause my tps was way off

Tantwoforty
03-15-2012, 01:28 AM
try reseting your tps yet? mine did this cause my tps was way off

oh! no!
hot damn how do i go about that!
I mean, ill google it right now....
lol
http://www.240sx.org/faq/articles/throttle_position_sensor_adjustm.htm
I Seeeee
Alright cool now i have a list of stuff to do, re-timing the motor (pulling the valve cover and checking marks and lobes at tdc) and Reset the TPS
So the tps coulda gotten knocked loose and that could be the whole thing..

hOngsterr
03-15-2012, 01:36 AM
sad, reminds me of how i left my spy blox on my trunk and got ran over by the cars behind me....

Tantwoforty
03-15-2012, 01:47 AM
sad, reminds me of how i left my spy blox on my trunk and got ran over by the cars behind me....

dude im pretty sure i just picked em up off the trunk later like nothing happened, i didn't realize until now i drove it with them on there..
whew.. that was a close one, if the car ran right they would been gone forsure lol

Tantwoforty
03-15-2012, 12:22 PM
I followed the instructions on tps adjustment and my tps shows 0 restance on any pins I thought maybe I was testing it wrong so I checked the injectors and they all read 11.8.I'm pretty sure my volt meter is on the right setting.. So it must be bad right?
Makes sense why it idles nice and then dies from the throttle, ecus all fine and dandy making the engine idle and warm up and them bam boost air out of nowhere!
Anyway I hope its the tps, now I just gotta find one.

GroundPerformance
03-15-2012, 12:37 PM
Try unplugging the TPS and give it some gas.. See if it makes a difference. BTW Testing TPS requires testing the 12v power and 5v signal. with the throttle close you be at around .45 at the signal

Tantwoforty
03-15-2012, 02:30 PM
The tps makes no difference.. And im under the impression that you can OHM test it and it should show if its good or not, and OHM testing it requires me to unplug it form the harness.. your thinking of a signal test on the ecu side, well you can do it on ether side but yeah, no i havent done that yet. but givin that it has 0 restance and everything i found said it should under the same exact conditions then i gotta think its bad right?

<DOHC> Checking the TPS and Adjusting the Idle
<DOHC> TPS Testing and Adjustment

The TPS is there to tell the ECU how hard you have your foot on the gas. It isn't there to adjust for the idle. It's a sensor. It does have some adjustment of it's own and we'll try to give our version of what our Factory Manual says (though we won't even come close to doing it justice):

Throttle Sensor & Soft/Hard Idle Switch

The Throttle Sensor responds to the accelerator pedal movement. This sensor is a kind of potentiometer which transforms the Throttle Valve position into output voltage, and emits the voltage signal to the ECU. In addition, the sensor detects the opening and closing speed of the Throttle Valve and feeds the voltage signal to the ECU.

Idle position of the Throttle Valve is determined by the ECU receiving the signal from the Throttle Sensor. This system is called "Soft Idle Switch" and controls engine operation such as fuel cut. On the other hand, "Hard Idle Switch", which is built into the Throttle Sensor unit on the A/T equipped models, is not used for engine control.

Trouble Diagnoses:
1. Disconnect Throttle Sensor harness connector.
2. Make sure that resistance between terminal #1 and #2 changes when opening the Throttle Valve manually.
Looking at the "pins" of the connector w/ the locking tab of the connector pointing up, terminals #1 is the one on the LEFT. #2 is in the MIDDLE and #3 is on the RIGHT.

The results of the test should be:

Accelerator Pedal Condition Resistance in k Ohms
Completely released Approx. 2
Partially released 2 -10
Completely depressed Approx. 10
If test shows "No Good", replace Throttle Sensor.

Although this guy messes it up, still shows ohms and mine dosent show any anywhere at all ever...
V-Mwxicmpg4

Frank_Jaeger
03-15-2012, 04:01 PM
Yeah, he's got the pins wrong. It was 1&2 on mine. He asked me to send pics of my pins and I never got around to it lol.

cotbu
03-15-2012, 04:12 PM
FAIL!! XD!
Just do part 2 of his video, the voltage setting. If, after you set it, and the closed throttle voltage changes? call it bad!

702s13
03-15-2012, 04:46 PM
You say it ran fine on that ecu before? Before what? Before you turboed and installed bigger injectors? If so then this is def your problem, at idle the pcm can pull enough fuel out but as soon as rpm is raised its gonna flood out and die... Is try throwing in stock injectors and a stock ecu to see if it runs right just don't boost on it.

WESamiss
03-15-2012, 04:58 PM
honestly i want to guess its your fuel pump. my car did the same exact thing when it was going out. but i could be wrong.

Tantwoforty
03-15-2012, 08:20 PM
Yeah, he's got the pins wrong. It was 1&2 on mine. He asked me to send pics of my pins and I never got around to it lol.
Yeah i used 1 and 2. i diddnt really use the video i used the guide, still no OHMs

FAIL!! XD!
Just do part 2 of his video, the voltage setting. If, after you set it, and the closed throttle voltage changes? call it bad!
Yeah ill have to put my battery in and try that right now

You say it ran fine on that ecu before? Before what? Before you turboed and installed bigger injectors? If so then this is def your problem, at idle the pcm can pull enough fuel out but as soon as rpm is raised its gonna flood out and die... Is try throwing in stock injectors and a stock ecu to see if it runs right just don't boost on it.
It ran good on 370's and z maf with this tune and no intercooler pipes hooked up, but like i said ive had this issue before and that was on all the old stuff, witch makes sense why it could be the tps as i never changed that.. this kicked in like a day before i put my piping on.

honestly i want to guess its your fuel pump. my car did the same exact thing when it was going out. but i could be wrong.
Totally could be, ive seen them do stuff like this.. although it will idle untill the cows come home but that dosent mean anything really..


SO!
To clarify.
According to the internetz i can ohm test this bitch and it will tell me if its bad, but it seems people on here dont think that and think i have to volt test it, witch is fine ill go test the signal wire and see if its output changes with movement

and im off! :fruit:

champwho
03-16-2012, 04:43 PM
have you thought about taking it to someone local a good nissan person? im located in the city nxt to you and theirs a guy here who works on nissans and hes is good with his work hes located in perris

rynftw
03-16-2012, 05:02 PM
just to back you up on enthalpy tune, so you can get that out of the equation. i ordered my enthalpy ecu in January and now it's installed on my car, and the car runs fine and pulls hard, but has no stickers on the ecu. ka-t ftw :D

Tantwoforty
03-16-2012, 11:00 PM
have you thought about taking it to someone local a good nissan person? im located in the city nxt to you and theirs a guy here who works on nissans and hes is good with his work hes located in perris
Yeah, I have my old boss Alex, he owns a shop called Tek one autoworks. A shop in riverside that mainly works on nissans and turbo cars, I actually worked there for about a year..

just to back you up on enthalpy tune, so you can get that out of the equation. i ordered my enthalpy ecu in January and now it's installed on my car, and the car runs fine and pulls hard, but has no stickers on the ecu. ka-t ftw :D

Thanks for the support dude

So, I tested the tps with he ecu on and such and it actually seems to read good, it could have been off still, but whatever so I reinstalled it correctley, I re did all the intercooler piping so it's all sealed, mounted the bumper and added 2 gallons of 91
It started up, idled funny for a few seconds and then idled great, and I'm able to rev it freely and it builds boost and will drive normally!
As embarrassing as it is to say, I think it just needed gas.. Or maybe it had bad gas, i added some 89 a while ago... Anyway yeah so the issues all fixed!
Thanks everyone for your replys!!!

brizanden
04-01-2012, 05:57 PM
the reving was definitly the tps then. they need reset sometimes idk why they are weird. glad its all good