Car Stalling And Won't Idle

[AdamsR33]

here's how you check the temp sensor (courtesy of RB30-POWER). i did this recently.

Two ways you can check it.

Firstly by disconnecting the plug and using a multimeter measure the resistance across the two terminals at the different water temps.

Spec is

20deg 2.5k ohm

80deg 0.3k ohm

Mate just checked mine and it was .35k so slightly hotter than normal which explains the heat soak. and yes car was just used to go down the road.

[Cubes]

Replacing the motor probably wont even do it.

I had an issue where the car would all of a sudden idle a little rough and feel as if it was bogging on low rev's. Give it a boot full and it was ok.. Just partial throttle and idle. Then just as it came it would go.

Its been like this for years but hasn't bothered me until now.

With the stock ecu idle would drop low; since I installed the pfc in the car it holds a steady idle even when its playing up.

2 days ago its now always doing the rough idle and bogging partial throttle thing giving since 2 days ago.

Checking the new O2 sensor it tells me its going lean on idle and partial throttle its causing a rough idle and lean missfire when cruising. It also surges when taking off in first if you try to take of a little briskly until rev's get up over 2k. The o2 sensor now will not cycle until it hits 3000rpm, upuntil then it simply flat lines or sways between 0v and 0.2v.

and.. here's what I've replaced over time.

ECU (replaced with pfc)

ECU/Dash water temp sensor

Injectors (near new R34 GTR items that flowed 100% with no leaks)

AFM (With a bran spankin new Z32/Wiring checked)

Ran a direct feed feed from battery to fuel pump

REPLACED THE WHOLE motor. Not that this would be expected to fix anything anyway.

Coil Ignitor

TPS, IAC, AAC

Genuine O2 Sensor

Fuel pumps are AOK (std intank as a lift for the bosch external)

All sensors on the PFC screen are reading correctly.

All I have left now are coils and crank angle sensor.

So... don't bother replacing the motor it won't do ****.

Wiring loom... In my case most likely.

[mad082]

going to check the voltage to the temp sensor over the weekend.

going to give the aac valve another clean tonight. it hasn't been done for a few thousand k's.

nath: how hot is it where you are? if it isn't that hot then i doubt it is heat soak.

[Munkyb0y]

Mate just checked mine and it was .35k so slightly hotter than normal which explains the heat soak. and yes car was just used to go down the road.

as long as the results are roughly at those guides. mine came back at 0.31k.

if you go for a decent drive so you know ur engine is well and truly warm, and then you get a crazy high reading, then i'd look into it.

[Link]

What ign timing is everyone running??

Maybe advancing or decreasing it slighty may help too??

There has to be a fix because not every 33 does it - my mates certainly doesnt and his only has basic mods too

[Munkyb0y]

what is your idle rpm set at?

the other day i was at a tuner's shop, and he had a look on consult, no errors, everything was fine, except the rpm was 750 instead of standard 650. he put it down to 650. the car almost stalled when i drove out, then it was playing up alot on the drive home. i got home, set it back to ~750, no probs.

i'm sure your problem's not that simple. but i didnt expect it to behave like that just because of idle rpm.

[Link]

what is your idle rpm set at?

the other day i was at a tuner's shop, and he had a look on consult, no errors, everything was fine, except the rpm was 750 instead of standard 650. he put it down to 650. the car almost stalled when i drove out, then it was playing up alot on the drive home. i got home, set it back to ~750, no probs.

i'm sure your problem's not that simple. but i didnt expect it to behave like that just because of idle rpm.

Mine was hunting and used to stall so i ramped it up to around 850/900rpm just to be sure

Hasnt stalled untill we started to get really hot weather - today is a bit cooler so the car is fine

[AdamsR33]

going to check the voltage to the temp sensor over the weekend.

going to give the aac valve another clean tonight. it hasn't been done for a few thousand k's.

nath: how hot is it where you are? if it isn't that hot then i doubt it is heat soak.

mate i'm in Camden, near campbelltown.

fat33, no it doesn't happen with every skyline, but it would be the same as the ls1 pistons and burning oil in the commodores when they first brought out the 5.7l v8, not all motors had this problem but it still happened.

Also timing is stock, haven't been changed and either has the ECU, so whatever is stock is where my timing is set.

[AdamsR33]

what is your idle rpm set at?

the other day i was at a tuner's shop, and he had a look on consult, no errors, everything was fine, except the rpm was 750 instead of standard 650. he put it down to 650. the car almost stalled when i drove out, then it was playing up alot on the drive home. i got home, set it back to ~750, no probs.

i'm sure your problem's not that simple. but i didnt expect it to behave like that just because of idle rpm.

Mate try cleaning the AAC valve, this usually happens when the ACC is dirty, when was the last time it was cleaned? also the AFM.

[Link]

mate i'm in Camden, near campbelltown.

fat33, no it doesn't happen with every skyline, but it would be the same as the ls1 pistons and burning oil in the commodores when they first brought out the 5.7l v8, not all motors had this problem but it still happened.

Also timing is stock, haven't been changed and either has the ECU, so whatever is stock is where my timing is set.

Yeah i agree with u there

MunkyBoy - Have u tried upping your timing at all??

Edited October 20, 2006 by fat33

[Craved]

15 BTDC is manual

20 BTDC for auto

[Cubes]

going to give the aac valve another clean tonight. it hasn't been done for a few thousand k's.

Check the solanoid is still working correctly.

I've seen one that was fine one day and dead the next.

What part, thats what everyone has been asking and all we get is "its heat soak, common problem" You only have to look in this thread alone to see that answer. And i believe SK over anyone as we know his knowledge of these cars is second to none.

Would love to fix it but if no-one knows which part or where to look then i ain't gonna spend hundreds of $$$ for a mechnic to try and find it.

Nath... I have a pretty good feel with Skylines as I've been fiddling with them for 5 years.

Besides.. You have misinterpreted SK's posts.

Disregarding SK's 'Try leaving the bonnet open between runs, heat soak is a problem.' post because as you say it also happens on the street. So your issue is not a heat soak from thrashing problem.

After that SK has pretty much said what I have... There's an issue, trouble shoot, find and fix it. hence his comments on checking fuel pressure, skyline disease etc.. Say what skyline disease............. age is whats common here. Exactly what SK has said. So it cannot be compared to the ls1 piston problem as that was at fault from manufacture.

If it were... I'm sure Nissan would have promptly recalled and fixed the problem.

[AdamsR33]

Check the solanoid is still working correctly.

I've seen one that was fine one day and dead the next.

Nath... I have a pretty good feel with Skylines as I've been fiddling with them for 5 years.

Besides.. You have misinterpreted SK's posts.

Disregarding SK's 'Try leaving the bonnet open between runs, heat soak is a problem.' post because as you say it also happens on the street. So your issue is not a heat soak from thrashing problem.

After that SK has pretty much said what I have... There's an issue, trouble shoot, find and fix it. hence his comments on checking fuel pressure, skyline disease etc.. Say what skyline disease............. age is whats common here. Exactly what SK has said. So it cannot be compared to the ls1 piston problem as that was at fault from manufacture.

If it were... I'm sure Nissan would have promptly recalled and fixed the problem.

Not to be disrespectful to you cubes, and i here what your saying, but if you have been working/fiddling with lines for 5yrs then how come this problem elludes you. You have tried just about everything to fix it but its still there. I thank you for your efforts in helping me with this problem and let me tell you if i/we could fix it then i'd do it tomorrow. Being an import how sure are we that nissan hasn't recalled these cars for this problem, and again the car was built for Japan, not Australia or Aussie conditions, so maybe the problem with heat soak didn't arise in Japan, but once in an AUS summer...

Yes it happens on the street, but as the topic states, only on very hot days, on cooler days its fine, i don't thrash my car on the street.

I've only owned my 'line for a yr so my knowledge is very limited, i welcome anyone who offers their help especially when i need it, so please don't take this post the wrong way. I also agree that age does have something to do with it, but still the part that is stuffing alot of us skylines owners up still sits there and laughs at us. I will try to fix/solve this problem, i doubt it will go away,atleast for summer anyway, and i urge anyone that finds the solution to post it up in big letters!!! as i will.

Actually you know what i'm gonna do, i'm going to replace all vacuum hoses, have you done that cubes??? i will let you know how i go.

[Cubes]

Not to be disrespectful to you cubes, and i here what your saying, but if you have been working/fiddling with lines for 5yrs then how come this problem elludes you. You have tried just about everything to fix it but its still there. I thank you for your efforts in helping me with this problem and let me tell you if i/we could fix it then i'd do it tomorrow. Being an import how sure are we that nissan hasn't recalled these cars for this problem, and again the car was built for Japan, not Australia or Aussie conditions, so maybe the problem with heat soak didn't arise in Japan, but once in an AUS summer...

Yes it happens on the street, but as the topic states, only on very hot days, on cooler days its fine, i don't thrash my car on the street.

I've only owned my 'line for a yr so my knowledge is very limited, i welcome anyone who offers their help especially when i need it, so please don't take this post the wrong way. I also agree that age does have something to do with it, but still the part that is stuffing alot of us skylines owners up still sits there and laughs at us. I will try to fix/solve this problem, i doubt it will go away,atleast for summer anyway, and i urge anyone that finds the solution to post it up in big letters!!! as i will.

With regards to your problem... The only way to know with an issue like yours is to check it when its doing it.

It could be many things. Yes its a heat problem.... It appears this problem you are experiencing is common as only the people who have an issue tend to post in such threads. Those who are not couldn't care less half the time.

Maybe your AAC Solanoid descides not to play when hot, maybe an issue with fuel supply when at idle as the fuel pump will be in low volt mode. Tap the throttle and it buzz's up on full volts. Both very easy to check and rule out. Maybe a faulty fuel pump? Did it do it before the fuel pump? Rule things out one by one. Thats what trouble shooting is all about. Unless its a rather obvious symptom.

and mine...

EDIT: Who cares about mine.

EDIT: Yep all hoses have been replaced, there's really not that many.

Hoses on mine off the top of my head:

2 x FPR's, 1 x std boost guage map sensor, 1 x brake booster, 2 x carbon canistor, 1 x Bov, 1 x wastegate, 2 x IAC, 1 x AAC... I think thats it.

[J_Red33]

Replacing the motor probably wont even do it.

I had an issue where the car would all of a sudden idle a little rough and feel as if it was bogging on low rev's. Give it a boot full and it was ok.. Just partial throttle and idle. Then just as it came it would go.

All I have left now are coils and crank angle sensor.

So... don't bother replacing the motor it won't do ****.

Wiring loom... In my case most likely.

Interesting that you mention the crank angle sensor hasn't been changed Cubes, I'd suggest you get a lend of one to give it a try.

The Mitsubishi optical crank angle sensors that skylines use (all the way back to the R31's as well as being used in Z32's, Lancers', Pajeros', Magna etc) are known to go faulty from time to time. I used to rebuild dozens of them (specialist job, don't try it yourself) & they most commonly failed under heat.

The other interesting thing too was that some times when they failed under heat (we performed testing with a heat gun & an oscilloscope on a special test bench), they would actually loose signal at low rpm rather than high rpm, or with higher engine speed the ECU could process out the errors & figure out what exactly the engine was doing depending on how bad the signal was.

There were other conditions they could fail under too (dust masking the optical sensors was always a good 1) & it could sometimes be dependant on the specific engine management they used.

This would also be a strong suggestion for you too nath95, they're not hard to swap over & all you need is a screwdriver/spanner & a timing light to double check the setting & your away. Would know if it's the problem as sessions end.

Edited October 20, 2006 by Cubes

[Cubes]

Thanks Jazza.

I will swap one out with a known working one when I do the PFC swap tomorrow.

Jazza.. I ripped my swear word out of the quote.

[J_Red33]

No worries. Not saying its a guranteed fix (but then what is), but since you've done nearly everything else it's more than worth the small amount of effort to try it.

Let us know how it goes.

Didn't actually take notice the swear word before, just threw in a few extra lines of the story, thought that was a good quote

Edited October 20, 2006 by JazzaR33

[AdamsR33]

cubes, did it before fuel pump was replaced and now when new one in.

Jazza, good suggestion, cubes keep us posted please.

[Munkyb0y]

MunkyBoy - Have u tried upping your timing at all??

i dont need to touch my timing. the car runs great. idles happily at 750, doesnt miss or flatspot (knock on wood), and is already advanced slightly, probably due to the tune on the unichip which came with the car.

i might clean the aac when i get a chance. i came across the DIY just the other day.

[mad082]

well i think i may have found the source of my problems..... #crosses fingers#

i have a cracked oil breather hose on the head (the one from the intake pipe to the passengers side rocker cover). this would've been broken when i got my manifold studs replace a few weeks back. so i've replaced that, and then i also found that my pcv valve grommet was split. so basically i had 2 vaccum leaks. getting a new grommet today, so hopefully that will be the end of my issues.