Power FC - Idle problem at certain water temperature

[poyz]

Hey all,

I have this continuing issue with my idle.

Here's the relavant hardware. PowerFC, standard MAF, standard injectors.

As water temperature approaches 80c the idle will go up to ~1300 and down to ~900.

It only does it when water temp approaches 80c. Under ~75 or so it's fine (as in it doesn't hunt - its constant). At 90c the fans come on and idle once again stabilises (constant).

When I play with the water temp correction values at 80c I can get it to hunt faster (it goes up and down faster) but I cannot get it to stay at one place.

Ideas/Suggestions?

P.S. I've seen a few post with people with similar type of problem. The difference is, mine only happens when it hits a certain temperature.

Thanks.

[Beer Baron]

Mate, it's cause you drive a GTI-R!

lol.

:jk:

I've have never heard of that happening at just one small temp range. Maybe take it in to a good PFC tuner?

Best of luck - unstable idle is a pain in the ar$e.

Richard

[R31 POWER]

Yer I found out the same to,when it was under electrical load eg lights heater etc it would hunt.Go into the idle setting and put the idle setting thats under the rev limit to 1270.it might be different for your car but I've played with all those idle settings and have mine idling perfect.

[poyz]

Richard, I did take it to a good PFC tuner to get tuned. I suppose they never picked up on it. How's the R and when's the R32 coming down?

R31 Power, I'll give that a go. I'll post what I find.

For those interested, while driving into work this morning stuck in traffic on the corner of LaTrobe and Spencer I turned O/2 Feedback "OFF". That fixed the hunting.

Go figure? I guess I could always switch between closed loop on/off with the hand controller depending on the situation.

[Beer Baron]

  poyz said:

Richard, I did take it to a good PFC tuner to get tuned. I suppose they never picked up on it. How's the R and when's the R32 coming down?

R31 Power, I'll give that a go. I'll post what I find.

For those interested, while driving into work this morning stuck in traffic on the corner of LaTrobe and Spencer I turned O/2 Feedback "OFF". That fixed the hunting.

Go figure? I guess I could always switch between closed loop on/off with the hand controller depending on the situation.

Hey Dandin,

It sounds like you may be on to something there. Possibly a faulty O2 sensor making the car not run nicely in closed loop? Does it exhibit any problems under light load cruise? or just idle?

Mate, the IR is better than it's every been, so of course I'm selling! All jokes asside, I'm really enjoying it at the moment - everything working as it should I am going to miss the little fella but the GTR should help ease the pain a tad!

Already buying up for the new car (just bought a PFC for it too). But it won't be here until december/january

It's a hard wait...

Richard

[poyz]

Actually, on cruise the O/2 sensor does it's job well. Cycles up and down nicely and frequently at highway speeds. And once again, the hunting only happens when temperature approaches 80c.

Enjoy the R32 mate. You owe me a spin next time I'm up your way.

[Beer Baron]

  poyz said:

Actually, on cruise the O/2 sensor does it's job well. Cycles up and down nicely and frequently at highway speeds. And once again, the hunting only happens when temperature approaches 80c.

Sounds like deffo a tunning prob then. Most likely not hardware.

  poyz said:

Enjoy the R32 mate. You owe me a spin next time I'm up your way

thanks, and for sure mate you are most welcome anytime Only problem is you may find it a bit tame after stepping out of the pul-sah! Let me put the PFC I bought in + the neon cup holders, then we're cooking!

Richard

[The Alchemist]

Hi there, your problem could well be the O2 feedback...not that its not working properly but because your car may not like a AFR of 14.7:1 when at idle during warm up .....My GTR does the same thing and got even worse when I put cams in .....I leave it turned off all the time now as I have done a lot of work on Light throttle cruise settings and have a constant 15:1 now on light throttles.

The o2 feedback, if switched on, comes into play once the engine temp reaches 70C on the GTR and this is when it starts the hunting. The temp for a GTI-R may be slightly different at which this occurs. During the 70c to 90c period the engine cylinder head is still coming up to operating temp during which time the engine would still be sensitive to a lean AFR of 14.7:1 and cause the symptoms you accurately described.

Once over 90C the fuel is atomising properly, instead of partially condensing on the back of the valve head and the idle will smooth out. One way around this is to increase the cold start temp compensation on the PFC at the 70C bracket and increase it gradually until the idle smooths out during this transition period. Or , as you;ve found, leave the O2 F/B turned off but if you do you had better make sure your tuner did a good job of the light throttles or expect fuel economy to go out the window

Hope this helps

MIke

[poyz]

R31 Power, I did as you suggested. No more hunting (even with O/2 feedback on). However, idle is now higher (something I can live with).

Mike, I will try what you have suggested and post up the results.

Thanks for the input people.

[R31 POWER]

Good to hear but do still fiddle with those 4 settings,I always did it waiting at traffic lights.

[R33vit]

I had this same problem when I first installed my PFC. I found it was because I did not run with the A/C on for 10 min then headlights for 10 etc when I first started the car after installing the PFC.

Do you by any chance have an electric thermo fan. This could be your problem.

[Russco]

Do you by any chance have an electric thermo fan. This could be your problem.

R33vit, what dramas did you have with your thermo fan? Got one on my R32, when it kicked-in the Power FC started reading in the middle of the map, went bonkers? Is this what happened with yours? Still trying to rectify the problem.

[R33vit]

No I dont have thermos but I had a electical load on and it would hunt. After I re initialized my PFC I followed the install manual step by step. If you do this you will lose your tune so take note of ALL the settings.

If it's been tuned with the FC Datalogit software then there may be other setting's you cant see and you'll lose them.

[R31Nismoid]

  poyz said:

For those interested, while driving into work this morning stuck in traffic on the corner of LaTrobe and Spencer I turned O/2 Feedback "OFF". That fixed the hunting.

Go figure? I guess I could always switch between closed loop on/off with the hand controller depending on the situation.

if that fixed it, your O2 sensor is rooted.

just change it.

Mine does exactly the same thing, once it gets hot. So we've turned off the O2 till i buy another. It will only hurt economy, nothing else in the mean time.

-ash

[poyz]

  R33vit said:

Do you by any chance have an electric thermo fan. This could be your problem.

Yep, sure do have a thermo fan (as with all east/west) SR20's.

They kick in about 90c.

[poyz]

Ash, thanks for the tip.

But here's something. Hwy driving between ACT/Melb I was getting close 600km per tank (on a 50 litre tank). I get about 350-450km per tank city driving with the occisianal heavy right foot (pending on how heavy my foot gets).

Either way, I'll think about changing the O/2 sensor down the line.

Mike (The Alchemist) - Where in the PFC menu do I change "cold start temp compensation"?

[The Alchemist]

settings "2" on the datalogit software, otherwise under "etc" or "settings" I think on the PFC commander, been ages since I've used it ....will check and get back to you.

regards, Mike.