BIG Hesitation Issues/Problems

NYSpeed Automotive
1

So i’ve been experiencing some serious spark cut recently. I thought it was fuel cut, until it started to occasionally backfire and smell like it’s just throwing raw gas out the exhaust…it’s getting fuel, but not igniting it. Also, it ONLY occurs once the car reaches normal operation temperature…sometimes i have to drive it a mile or two for it to start acting up again.

I found a couple FAQ’s about hesitation in these cars, and have come to a few conclusions…:

it’s not the plugs or fuel filter, both are less than a year old…and if it were either of these, the problem would occur all the time, not when the car is fully warmed up…

It’s not the air filter, it’s brand new…

not the ignitor chip/PTU, it’s also less than a year old, and it’s the newer upgraded style (nissan did a big recall back on the old ones, and in the US they didn’t do the recall i think…so i took it upon myself to get a new one while doing the swap)

on the one faq i found, coolant temp sensor could be a possibility, but another symptom then would be the temp guage flying up and down…and i dont have that, so scratch that theory…

i’m about to order a new sub-harness for my PTU to eliminate the possibility of it being the problem because it’s old, and old things tend to stop working right…

the only other things i read about that could be the problem are the CAS or the TPS…both of which have easily accessable connectors that i’ll be checking soon…

but what i wanna know is if anybody knows which of the two (CAS or TPS) would cause it to only behave like this when warm…i would think that if it’s the TPS, the problem would be ALL the time…from start to stop…

Also the hesitation is very violent…feels like i’m tapping on and off the gas…and at idle, it goes from normal (900 RPM or so) all the way down to 300 RPM sometimes…eventually just stalling itself out…

Any ideas?

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Leaky injector?

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does it do when your driving or is it only hesitating at idle?

4

meh doesn’t feel like a leaky injector…why would fuel not be igniting due to a leaky injector? and this isn’t a consistant/steady problem…it’s very randomized…

and yes dave, once the car is warm, it’s all the time, i have to keep giving it gas at idle so it doesn’t drop enough to just stall itself…

i get out of work in an hour, gonna go home and check the connections on the TPS and CAS and brillow pad clean them/spray them with electrical connection cleaner…see if it makes any difference…

i have a spare of each too from my old NA engine i remember…i’m fairly positive the part numbers are the same for the TT and NA engines, so that’ll save me a shit load of money if one or the either, or both need replacing…the CAS alone i think is like $350.

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Because a leaky injector dumps infinite amounts of fuel more than can be burned off. When it happened to me it caused the car to stumble and die…same happened with woody.

6

my Z has done that before. Was the CAS sensor, just clean it and hit it with some dielectric grease too. My buddy has the TPS do the same thing. Also check your injector plugs and grease them. Thats the thing i hate with Zs is the wiring nightmare

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Pull the codes off the ECU and tell us what they are first.

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i pulled codes off of it a while back when it did the same thing, i immediately pulled over, shut off, and checked codes…and got a 55…aka no problem…so i was really confused at that point. i’ll warm the car up and go around the block once when i get home…in like 20 minutes…and then once it starts doing it again, i’ll check for codes. i’ll then check the injector clips, CAS clip, and TPS clip…anybody in the area with any experience is more than welcome to stop by and lend a hand…

cough…kyle…cough…

it’s the least you owe me since i let you beat me :wink:

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LOL…or you could just bring it to my house…not that I have tools here but I will give it a look…I am too busy doing paperwork to leave at the moment…but if u wanna swing by…feel free.

10

PM me your cell, i leave work now, will be home in like 20 minutes tops, and can pack some tools in the z, and drive it to your place…by the time i get there it should be half way warmed up…meaning i’ll be able to make it there without it starting to act up…or better yet, since i’m just leaving now, call my cell and let it ring once or twice so i get your number, and i’ll just call you back when i’m home and ready to swing by, if you don’t mind…949-1461

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HMM MAYBE UR INJectors r staying open. a ignition stethoscope would help diag this problem

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so i got to kyles…and of course, the car was fine…completely…we looked at some stuff, i cleaned the TPS clip, he checked out the MAF, etc…everything looked pretty good, and she sounded like she was running great…and for once, this was what i didnt want to happen…hard to fix a problem when it’s not occuring.

i told him i’d go for a quick ride to beat the shit out of it a bit, and sure enough…i get about 2 miles away, and it starts up…luckily not as bad as it’s been in the past…but still there…call kyle, let him know i’m on my way again…

it was moderately bad on the way, every now and then fixing itself…very wierd…i get there, and we start playing with what has been my first guess all along, the sub-harness for the PTU, and sure enough…by moving the wires around a bit, he is able to somewhat control/adjust the idle…and it becomes consistant/develops a pattern…it starts to go bad and bog, he straightens out some bent wires, and it smoothens out…

needless to say i’ll be ordering that new sub-harness this week, probably will have the wiring in it lengthened a bit so i have some extra wiring/room to mount it properly somewhere so the PTU isn’t just sitting in the bay, and i’ll have to go from there…

:tup: to kyle…thanks for jiggling my broken shit…

PS:

InB4SomebodyPutsThatInTheGayUnderTones

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Put this in the undertones…thanks for paying me with the rusty trombone…its soo cool of you to have used listerine before to cool off my balloon knot! yummmmmm

Ok…back to reality…

Yeah I still have the Z magic :stuck_out_tongue:

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word…>VGs are known for bad injectors that cause the sypmtoms u are having andy

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UPDATE:

talked to a few people that sell z parts…and it turns out that when Nissan did their PTU recall, the kit they put out came with the new ptu, mounting bracket, and harness for it. All together it costs about $175, but you can get it new from nissan if you check your vin and it wasnt replaced…

the problem…

NOBODY carries the harness on it’s own…which is only a $20 or $30 part…i’m not paying $175 for something i dont need, but nobody has it separate, and nobody is willing to break up a package…

i was told i can just eliminate the harness and wire the main EFi harness directly to the ptu…and i’m sure i’m capable of doing it, but i’m the suck when it comes to wiring custom shit, and it would take me forever. I’m gonna buy soder (sp?) and some different color wiring today on my way home and look at it to see if i can figure it out…but if anybody is good with this type of work, or knows somebody that it, and wants to take on the job for me for a certain price, give me a name, and name me a price…

this is a link to the kit…there’s a picture, you can see the harness i’m talking about…

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i bet i know where i can find one

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i bet you’d feel great telling me where i can get one…

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call or text me later, ill help ya out

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i gotta call and ask him…what exactly is it called that u are looking for…no acrynyms

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it’s called the PTU harness, or PTU subharness…