Jump to content
SAU Community

Recommended Posts

Yesterday, whilst driving my car and stopping at the lights, ocasioanlly the car would get into a sort of "rev Spasm".... It would drop revs almost to zero on the verge of stalling, then bounce back up to 1200rpm, and this would cycle over and over until I iether switched if the engine and started up again, or nursed the Idle( very hard to get idle back to normal by accelarating)

My AFM hasnt ever been playing up, however i am going to clean this tomorrow...

Is there anything else which can cause this? will the AAC Valve, be having an effect?

I also noticed on my boost gauge as it was trying to recover idle, the vacuum pressure would should up all the way up to zero, perhaps a little under. Which seems extremely wierd to me? does this signify a vacuum leak allong the lines somewhere??

Any help apreciated

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/
Share on other sites

before i got my car tuned my car did this, way to stop it havin a spazz, was to rev it so you got boost and vent the bov, and then it stoped serging, but it was really gay because at a set of lights you look like a tool reving ya car ahahah spechly if theres some shit hot car next to ya.... but thats how i solved my serge before i got the safc and tune so yeah....

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1729646
Share on other sites

I had the exact same problem yesterday, but it went away once I turned the air conditioner off.

It was really strange as the car drove fine with the air con on for about 5 mins, then it started to idle really rough and drove like a dog. Once I turned the air con off and gave the car a few small revs, it seemed to rectify the problem and the car drove fine again. I thought perhaps it was a bit of bad fuel or something, but when I drove the car later in the day with the air con on again, it did the same thing again.

Car's going back to the workshop this week for a few other things, so I'll be getting my mechanic to have a look at it for me while it's there.

Anyone got any idea what may be causing this?

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1729662
Share on other sites

Cleaning your MAF meter should help. If switching the car off and then on again fixes the problem I would point towards a faulty MAF meter. Try other things like cleaning the throttle body and AAC valve at the same time and see if these help.

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1730646
Share on other sites

Mine started doing this revving thing when i got my power fc installed

drives perfectly, but at idle just does this stupid down to 500 then to 1100 and yeah keeps going

it does look pretty stupid when ppl look at ya and they think you doing it. i just want to put the window down and say its the car ,

im takin it back to fist at wacol and they are going to have a look at it

let yas know what it is, if they do fix it.

Also on wednesday i turned my car off and when i went to turn it back on again, it just made a click sound and didnt start i had to wait abit till it would start again, a bit weird, but hopefully that will be sorted out too

and i went down the quarter last wednesday and the check warning light for the engine came on when the car is under load.

I'll post back on wednesday

THanks

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1730772
Share on other sites

Sorta. An AFM is an Air Flow Meter and measures Air Flow via air flap and needle.

A MAF meter is a Mass Air Flow Meter and measure Air Mass via hotwire.

They both virtually do the same thing and essentially achieve the same results but through different methods.

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1730960
Share on other sites

Yeah i have my car do that idle thing too.

Ive noticed its always on a hot and muggy day that when i start the car its idle rate will go up and down and some times even stall . But it seems to iron it self out after it gets running for a bit.

I will have to check my MAF. Good to hear that my car isn't the only one :D

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1736351
Share on other sites

i went to fist

had the hand controller hooked up on the car

idle was put up to 900 instead of 850

some base setting was low and , didnt catch the other thing he said

but it was high, so he made it so it equalled out .

i drove it tonight , seems to go pretty good , havent noticed the idle go whacko yet but let yas know .

I'll try and find out what the things on the hand controller exactly were

i think i might have to get one,

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1736465
Share on other sites

Hi Guys,

I had the problem a few months ago, not s much at idle but always before turbo's kicked in, it would cut out and gve a sharp jerk, its been fixed, the problem was that there was excess oil inthe airflow metres, got cleaned out, and works fine, but if the problem continues its time to replace air flow meters.

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1748766
Share on other sites

  • 2 weeks later...

Check your thottle position sensor. Tap it with a soft mallet while its running to check it's connections and internals are ok. Mine was fine when adjusted, but acted up after 5 minutes driving and drove all jerky and misfired and crap.

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1770880
Share on other sites

Another thing you could try is check your alternator is putting out the correct voltage. Make sure you check it at the terminal on the back of the alt...not just at the battery. If your output voltage is low eg...11.80V, the battery light will still not come on but the fuel pump and ignition may not have enough to run them properly as the computer will only see about 9.5-10V of that.

Your problem is probably elsewhere but it doesn't hurt to check as it will cause idle probs.

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1772701
Share on other sites

any way it could be an Idle port prolem on ur throttle body? it can have trouble switching from air going through the throttle body, to it switching totally to the idle port. If it gets blocked up with gunk or carbon it can make that car act a bit like that at times or eventually make the car stall. just a thought.

Link to comment
https://www.sau.com.au/forums/topic/95562-rough-idle/#findComment-1772866
Share on other sites

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


  • Similar Content

  • Latest Posts

    • Very decent bit of kit. Definitely black it out I reckon.  
    • Because people who want that are buying euros. The people with the money to buy the aftermarket heads and blocks aren’t interested in efficiency or making -7 power, they’re making well over 1,000hp and pretty much only drive them at full throttle  best way to way make money is know your customer base and what they want and don’t spend money making things they don’t want. 
    • It's not, but it does feel like a bit of a missed opportunity regardless. For example, what if the cylinder head was redesigned to fit a GDI fuel system? It's worth like two full points of compression ratio when looking at modern GDI turbo vs PFI turbo. I'm pretty reliably surprised at how much less turbo it takes to make similar power out of a modern engine vs something like an RB26. Something with roughly the same dimensions as a -7 on an S55 is making absolutely silly power numbers compared to an RB26. I know there's a ton of power loss from things like high tension rings, high viscosity oil, clutch fan, AWD standby loss, etc but it's something like 700 whp in an F80 M3 vs 400 whp in an R33 GTR. The stock TF035HL4W turbos in an F80 M3 are really rather dinky little things and that's enough to get 400 whp at 18 psi. This just seems unwise no? I thought the general approach is if you aren't knock limited the MFB50 should be held constant through the RPM range. So more timing with RPM, but less timing with more cylinder filling. A VE-based table should accordingly inverse the VE curve of the engine.
    • I've seen tunes from big name workshops with cars making in excess of 700kW and one thing that stood out to me, is that noone is bothering with torque management. Everyone is throwing in as much timing as the motor can take for a pull. Sure that yields pretty numbers on a dyno, but it's not keeping these motors together for more than a few squirts down the straight without blowing coolant or head gaskets. If tuners, paid a bit more attention and took timing out in the mid range, managed boost a bit better, you'll probably see less motors grenading. Not to name names, or anything like that, but I've seen a tune, from a pretty wild GT-R from a big name tuner and I was but perplexed on the amount of timing jammed into it. You would have expected a quite a bit less timing at peak torque versus near the limiter, but there was literally 3 degrees of difference. Sure you want to make as much as possible throughout the RPM range, but why? At the expense of blowing motors? Anyhow I think we've gone off topic enough once again lol.
    • Because that’s not what any of them are building these heads or blocks for. It’s to hold over over 1000hp at the wheels without breaking and none of that stuff is required to make power 
×
×
  • Create New...