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Engine Occasionally "hiccups"?

angusis2fast4u

By angusis2fast4u,
in Engines & Forced Induction

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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
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https://www.sau.com.au/forums/topic/449952-engine-occasionally-hiccups/
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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
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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

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