Jump to content
SAU Community

M35 Stagea P0121 Throttle Problem

ONCE-NA
 Share

Recommended Posts

ONCE-NA Apprentice

ONCE-NA

Posted
Posted

So i've been having having problems with the car going into limp mode intermittently for a couple of months, some days its really bad and sometimes it wont do it for a week at a time.

My mrs drives it mainly, -taking kids to school etc and its really starting to shit her, and thus it impacts on me.

Since it started happening i've swapped out the pedal tps, the throttle body, (both with known working ones) put a new battery in and wiggled and unplugged shit etc, dit the pedal poition and throttle body relearn stuff, but still get the same problem.

I've searched a lot and it seems to be a common problem but had anyone found a definitive fix?

Oh yeah I've also cleared the drain hole under the battery and dried out all the stuff, (fuse box etc around there)

-Rod

Link to comment
https://www.sau.com.au/forums/topic/457051-m35-stagea-p0121-throttle-problem/
Share on other sites
scotty nm35 Grand Master

scotty nm35

Posted
Posted

So you have a TPS fault, something is wrong with the tps signal back to the ecu. There are two tps signals and they are both monitored/compared by the ecu constantly and anything that may throw the voltages out, even slightly will trigger the limp mode.

Do you have anything else hanging off the TPS wires? Such as a cruise control, piggyback ecu or something else aftermarket?

ONCE-NA Apprentice

ONCE-NA

Posted
  • Author
Posted

Yeah I punched out the drain tube.

However the error occurred 3 times again today.

After being good for a few days. I don't know what to do now!

I've got a whole other car for parts so I might just keep swapping things. Starting with that whole fuse box, and maybe the ecu.

ONCE-NA Apprentice

ONCE-NA

Posted
  • Author
Posted

My mrs said it seems to rev up more than it should just before it throws the error. And it's always after stopping at an intersection or something and when she gets back on the accelerator it does it.

It sounds like a problem with the throttle potentiometer going high or low just off closed but it's been swapped with one from the other car that was fine

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Plenty of times, either the throttle resistor on the back of the pedal, or the throttle itself is likely the issue, unless you have a wiring fault between them and the ecu.

What codes are the ecu throwing? Is it only the P0121? That seems to relate to the pedal sensor.

When the throttle goes into limp mode it almost disables the throttle. It will sit on 1200 revs, enough to drive out of problems and get off the road. You can actually get more throttle out of it if you push the pedal all the way to the floor, but it is quite dangerous, especially as it happens randomly.

ONCE-NA Apprentice

ONCE-NA

Posted
  • Author
Posted

Yeah that's the only code, and having tried the pedal assembly and throttle body from the other car that never had a problem I'm suspecting a wiring issue, corrosion, dry joint, or ecu problem, I'll swap the ecu and fuse box out over the weekend and pray that fixes it. It was strange that it worked flawlessly for 3 days after changing the relay so maybe there is a wiring problem in the fuse box.

What locally sold car has the same throttle pot? I vaguely remember reading it was a Maxima but can't find it again...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • PranK
      Are you an oil nerd?

      By PranK · Posted

      This is awesome.     
    • Borci88
      Borg Warner EFR Series Turbo's V 2.0

      By Borci88 · Posted

      Thanks for the quick replies guys its appreciated. A small extension was welded onto the standard 6boost external gate pipe which you can see where the pipe goes from black to stainless just below and to the right of the rear housing in the first picture. Overall I would say the flow is pretty good other than 6boosts choice to come straight off the collector at a decent angle.. Not sure why I went with two valves, I originally replaced the stock twin bovs with the GFB when I had the twins on. When I purchased the EFR it came with the Turbosmart Kompact BOV so I figured that would be a better option than the stock EFR Bov. I don't believe the Turbosmart BOV is adjustable? When I get the spike and then sudden dip in boost pressure, the turbo speed does drop as well. Stock head size wise however I believe it has Neo Turbo springs and a Neo Turbo intake camshaft and an aftermarket exhaust camshaft in the vicinity of 260 degrees. We didn't try a different MAC valve, we tried two different ways of plumbing it and we also tried removing the mac valve entirely and just having the boost source from the turbo directly connected to the wastegate and it still spiked / dropped and exhibited the same behaviour. Standard R33 GTR 5 speed tansmission. I'm running a Haltech Elite 2500 and can provide some logs if you. I understand what you're saying in that it looks like an auto plot however no, it's still a manual and it just has a lot of torque down low, for all intents and purposes it's a very impressive street car. I've attached a photo of the quickbitz dyno plot which was when the only difference is I was running -5 twin turbos with a mac valve. As you can see theres a decent dip in AFRs between 125kmh and 135kmh. Our problem now is not that the AFRs are dropping, just the boost pressure is dropping, however it is evident in the same RPM range of the map, coincidentally or not.
    • Lithium
      Borg Warner EFR Series Turbo's V 2.0

      By Lithium · Posted

      What transmission are you running?  It's a bit tricky with the scaling, but at face value the power "curve" looks more like a "line" which is a bit odd... basically a lot more like a dyno plot I'd expect with a highish (compared to a factory auto) stall torque converter type setup. If this is running an auto then this kind of boost control challenge is definitely a thing, the rpm scale on the dyno doesn't reflect what the engine is actually doing (unless the dyno has access to the engine's ACTUAL speed electronically) and what you'll get is a big rpm flare up as the engine torque launches past the converter pump's ability to resist torque at that rpm, then as the converter starts picking up rpm it will kinda even out again and the engine rpm will pick up more steadily. The trick with this "flare up" is if it's kinda near the boost threshold for the turbo then the engine's airflow requirements to maintain the previous boost level will outrun the turbo's ability to supply that boost - so you end up with a natural flattening off, if not dip when that happens.   If you are running closed loop, or even tune the "feed forward" wastegate duty cycle to deal with that rpm spike then when the engine starts settling to a more typical climb you'll actually have a situation where the gate is "too closed" and boost will run away for a bit, then have to pull down again.      It's not trivial to get this perfect as most boost control systems are generally expecting more predictable engine rpm rates of change, but if you *know* that's whats going on then you can at least "accept your fate" and realise getting that area perfect is kinda chasing your tail a bit, and assume that if the rest is working sensibly and the spike/dip isn't completely uncontrolled then you should be good. Sorry if I've gone off on a tangent, but the dyno plot and boost control behaviour look a LOT like what I've seen tuning autos in the past. What ECU are you running? Could possibly be convinced into looking at logs if I get too bored this weekend haha.
    • Piggaz
      Borg Warner EFR Series Turbo's V 2.0

      By Piggaz · Posted

      A few things that seem a bit off here. - why is there 2 BOV’s?  - the turbo smart BOV on the compressor housing, is it turned up ALL the way? I have seen this become an issue on old man Pete’s car. It would push open and recirc, turbo speed would rise and the boost pressure would do weird things. - stock head? Does that include springs? - tried a different MAC valve? Is it plumbed correctly?
    • GTSBoy
      Borg Warner EFR Series Turbo's V 2.0

      By GTSBoy · Posted

      Photo of manifold showing gate location? I mean, it's 6Boost, so we probably shouldn't be worrying, but always wroth knowing what the layout is. Plumbed back to atmosphere? Or into the dump?
×
×
  • Create New...