Idle Issues

[No Crust Racing]

Morning Gents,

I've got two different idle issues but only one occurs at any given time.

1st: A very small hunt, like 50rpm hunt, it just bounces back and forth a little, only just registers on the tacho but you can hear it in the exhaust.

2nd: If it's not doing that at idle then when gearing down to a complete stop when I put the clutch in and engage first the idle will jump to say 1100rpm then after maybe 1-2 seconds, return to normal. It will do this any time I am coming to a stop and it happens when I engage the clutch.

Background, I've searched about these issues and have removed and cleaned the AAC and AFM. The AAC did have a fair bit of build-up on it and I did my best to clean it, it was literally swimming in carby cleaner For a period the idle hunt (which at the time was a bigger hunt) went away. The idle increase on clutching has not gone away. The AFM was cleaned with Electrical contact cleaner and the mesh was wiped over carefully, no change.

For reference, car only has a POD with a mr_crust airbox, cat back, low boost bypass on the solenoid and a boost guage as far as mods that could interfer with air flow characteristics, these problems were evident before these mods and have seemingly not been affected by them for the better or worse.

Thoughts? Otherwise I might take the AAC valve off again and totally dismantle it so I can really clean it properly but I'd like to hear other peoples thoughts on the matter.

Cheers

[mad082]

could be a dodgy o2 sensor. it could be causing it to run a bit rich.

[No Crust Racing]

The sensor is no more than 1yr old as I replaced it when I got the car (it was shagged) and my rego is due next week The car does smell a bit rich on start and despite checking the seals I still see fuel vapour from the filler cap so I assume the smell is coming from there. The car returns around 12.5-13L per 100 around town so that's acceptable as I understand it.

[No Crust Racing]

Update: The idle jump issue appears to happen when I'm coasting towards an intersection, clutch in and then engage a gear, it jumps up to 11-1200 as soon as I engage 1st or 2nd... ideas?

[RB30-POWER]

Has it always done this or just started to play up?

[No Crust Racing]

It's been intermittent since I've had the car and I've tried the things above that I mentioned and haven't really gotten far besides when I cleaned the AAC valve which seemed to stop the hunt issue. The hunt comes and goes but the idle jump on engaging the clutch and putting it into gear when approaching an interesection is pretty consistent.

[Godzilla32]

Does the 25t use a clutch booster like the gtr?

[No Crust Racing]

No idea sorry =\

[Godzilla32]

have a look, cuz if it does theres your problem, its a vacuum leak. Well it will deffinetly solve the clutch in problem...

Edited October 7, 2006 by Godzilla32

[RB30-POWER]

Only time I have really seen what you describe is when you put an Auto ECU into a manual car.

The Auto ecu looks at the neutral position sensor on the gearbox and goes ok, you just put it in gear, lets idle up for the load the auto puts on the engine when in gear.

But if you have a manual just because you change out of neutral doesn't mean there is any load on the engine because the clutch is still dipped.

The manual ecu doesn't have this extra idle up because it isn't needed.

If the ecu is the correct item for the vehicle then maybe the clutch is not releasing properly and putting slight drag on the engine when the gear is engaged, does the clutch release fully when dipped?

[No Crust Racing]

I've had the ECU out before and it 'seemed' normal but I couldn't honestly say if it was right or not, the problem is intermittent thoguh so if it was ECU I doubt it would be behaving this way. As for the clutch booster, how di I tell.

[Godzilla32]

if it has one it will be a smaller version version of the brake booster behind the clutch master cylinder

[No Crust Racing]

Ok, well here's a pic showing the clutch fluid reservoir, doesn't appear to be a booster in the same way that the brakes have one. Or am I looking in the wrong spot?

[LatinR33]

I had a similar prob with idle being abit wierd and getting stuck and going up to 1,100rpm by itself. Ended up being TPS cleaned the contacts and all good Not to sure if it would help but atleast its something else to look into.Another person I know had a pod filter changed it back to stock ecu reset and good. RB25's r mysterious sometimes good luck mate!!!!

[No Crust Racing]

I'll try cleaning the TPS contacts, I have some cleaner handy - Cheers for the tip, interested to here more info on the vacuum leak idea.

[RB30-POWER]

Did you see these threads from last week.

Slightly different problem to yourself, but you might as well check the air regulator if you are still hunting for the problem.

http://www.skylinesaustralia.com/forums/in...=135917&hl=

http://www.skylinesaustralia.com/forums/in...=136269&hl=

[No Crust Racing]

Tried cleaning the TPS plugs and contacts, no change. I'm leaning toiwards thinking it may be a vacuum issue, easiest way to tell? Go to hose joins and spray with brake cleaner?