Jump to content
SAU Community

Engine Occasionally "hiccups"?

angusis2fast4u

By angusis2fast4u,
in Engines & Forced Induction

 Share

Recommended Posts

angusis2fast4u Enthusiast

angusis2fast4u

Posted
Posted (edited)

So i've read around but not getting a straight answer, I'm believing it's CAS but coming here for a second opinion

So occasionally the engine will "hiccup". ill be driving down the road (usually I only notice it during freeway driving) and then the engine will like die for a short period of time, (it feels like when you lift your foot off the pedal for a split second)

I think I read somewhere it was CAS but can't since find that page to read up on it.

any help / confirmation / ways to troubleshoot it? Compression is good: 142, 150, 145, 145, 150, 150. New o2 and cleaned AFM.

is running a Power FC

RB20DET 1992 SKyline r32

Thanks for the help guys!

Edited by angusis2fast4u
Link to comment
https://www.sau.com.au/forums/topic/449952-engine-occasionally-hiccups/
Share on other sites
angusis2fast4u Enthusiast

angusis2fast4u

Posted
  • Author
Posted

I have splitfires, walbro 255 pump, brand new spark plugs (I forget if this issue was around before I changed them... Could that be it??) So i would hope it's not the coils or pump... Also the issue generally doesn't happen under power like usually just when im cruising along...

How did you check your CAS??

One of my old r32 did that
Checked cas, fuel pump, coilpacks etc
Ended up being dirty AFM

kaneryan Rising Star

kaneryan

Posted
Posted

i had an issue like this, but it only happened about like 5000 rpm. then it started to get worse and worse like 4000rpm then above 3000rpm. to the point i could hardly drive my car. ended up being my haltech has a safety cut when it leans out to much it will cut the engine every time its to lean,
ended up being a split hose pipe from my fuel pump to the top of my tank, so the full was getting sucked up the fuel pump then not even leaving the tank squirting out the hose then back down into the tank and then back into the pump again. only letting a little bit of fuel through at a time so was causing it to hickup so to speak, maybe check that, if it gets worse and worse maybe check this. also replace your fuel filter......... cost about $10 and is easy to do! and will rule it out, peace of mind

Ben C34 Grand Master

Ben C34

Posted
Posted (edited)

How does a dirty throttle bofy cause a hiccup?

And a car doesn't need tuning due to new coils. ...

Sounds like the power fc miss.

Just in case you missed GTSBOY ' S post

Edited by Ben C34
  • Like 1
Ben C34 Grand Master

Ben C34

Posted
Posted

i am aware of that, hence the "other mods" words in there..... clearly trying to sus out and get the most information to diagnose this issue.... you annoy me.

Ok cool. Seems odd you would mention it then.

Sorry that pointing out facts annoys you. I suppose I could just let it slide and let people think they need a retune due to replacing their coils, but hey, I'm not that kind of guy.

chiksluvit Experienced

chiksluvit

Posted
Posted

I have splitfires, walbro 255 pump, brand new spark plugs (I forget if this issue was around before I changed them... Could that be it??) So i would hope it's not the coils or pump... Also the issue generally doesn't happen under power like usually just when im cruising along...

How did you check your CAS??

Mechanic did back in the days

It was my first car 10+ years ago

Ben C34 Grand Master

Ben C34

Posted
Posted

Typically to check a cas you play swap tropics with a known working one.

Perhaps there's a way to check it with an oscilloscope, but as the issues tend to be intermittent it would be difficult and unlikely picked up like that.

angusis2fast4u Enthusiast

angusis2fast4u

Posted
  • Author
Posted

Typically to check a cas you play swap tropics with a known working one.

Perhaps there's a way to check it with an oscilloscope, but as the issues tend to be intermittent it would be difficult and unlikely picked up like that.

Yeah it like rarely happens like probably not even once a week, It probably only happens like once every 2 weeks

Ill look up the PowerFC miss.

Sparks were done like 600km ago

ill check out that throttle body as well

Thanks for the help ill report back when i've got an update!

Piggaz Grand Master

Piggaz

Posted
Posted

The power fc "miss" generally happens coming away from a set of lights, for example. Low rpm, generally low load. Well, mine did anyway.

There is a decent discussion on here somewhere about it.

Sarumatix Veteran

Sarumatix

Posted
Posted

I had this problem and it was a bastard to track down in the end for me it was the AFM pins getting a dry solder joint.

There is a guide on re-soldering in the DIY section. To diagnose I used CONSULT connected to a laptop datalogging all values. As soon as it happened I pulled over and spotted which value started it, AFM voltage dropping to 0.

Hope this helps

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

    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      Nah, that is hella wrong. If I do a simple linear between 150°C (0.407v) and 50°C (2.98v) I get the formula Temperature = -38.8651*voltage + 165.8181 It is perfectly correct at 50 and 150, but it is as much as 20° out in the region of 110°C, because the actual data is significantly non-linear there. It is no more than 4° out down at the lowest temperatures, but is is seriously shit almost everywhere. I cannot believe that the instruction is to do a 2 point linear fit. I would say the method I used previously would have to be better.
    • GTSBoy
      DeAgostini 1/8 scale BNR32 Nissan Skyline GT-R Nismo

      By GTSBoy · Posted

      That's hilariously putrid!
    • GTSBoy
      R33 Fuel Pump & Brakes after alarm swap

      By GTSBoy · Posted

      When I said "wiring diagram", I meant the car's wiring diagram. You need to understand how and when 12V appears on certain wires/terminals, when 0V is allowed to appear on certain wires/terminals (which is the difference between supply side switching, and earth side switching), for the way that the car is supposed to work without the immobiliser. Then you start looking for those voltages in the appropriate places at the appropriate times (ie, relay terminals, ECU terminals, fuel pump terminals, at different ignition switch positions, and at times such as "immediately after switching to ON" and "say, 5-10s after switching to ON". You will find that you are not getting what you need when and where you need it, and because you understand what you need and when, from working through the wiring diagram, you can then likely work out why you're not getting it. And that will lead you to the mess that has been made of the associated wires around the immobiliser. But seriously, there is no way that we will be able to find or lead you to the fault from here. You will have to do it at the car, because it will be something f**ked up, and there are a near infinite number of ways for it to be f**ked up. The wiring diagram will give you wire colours and pin numbers and so you can do continuity testing and voltage/time probing and start to work out what is right and what is wrong. I can only close my eyes and imagine a rat's nest of wiring under the dash. You can actually see and touch it.
×
×
  • Create New...