Idle Rev Malfunction - Help

[Jaydous]

Ok, I get in my DC5R today after being away for a week and start it up. Everything seems to be running fine until the car has done it's initial warmup (2k revs for around 30s-1min). After this every time I idle the car it consistantly revs from 1k - 2k over and over again in intervals of around 2 seconds.

Since I have been away it has rained in Brisbane pretty hard and it was only sitting half undercover which leads me to believe it is a water issue. I thought it could be something to do with fuel or the fuel line but the revving seems way too consistent for that. I took it for a lap around the block and a little rev and still no change, every time it comes back to idle it jumps up and down - apart from that it drives very normally.

I have a Hondata K-Pro and I was thinking maybe if I re-mapped it or uploaded the same mapping again it might fix it (also idle is set at 800rpm). Anyway I havn't done anything yet and just wanted ideas before I touched the thing. Thanks in advance, Jayden.

[daz]

You could try resetting the ecu. If that doesn't help then there could be moisture build up on the idle speed control sensor.

[Mashi]

hey jaydous.
i had the same problem... however the problem didnt go away whlist i drive
so it was VERY scary just driving it to the mechanics. ><
you need to replace the air control value, its a malfunction...
apparently this rarely happens???

well i hope that is what the problem was, simple to fix.

[Jaydous]

hey jaydous.
i had the same problem... however the problem didnt go away whlist i drive

Ok this sounds like the best answer as my mate who is pretty cluey said it could be something to do with an air sensor. But honestly.. how often do you keep your car at 2k rpm haha, when I'm driving, say at 3k rpm it doesn't do the same thing and go to 4k rpm consistently, only and idle problem. I looked like a complete cockwang at the traffic lights though when i took it for a spin this arvo haha. So I sat there with the revs at 2500.

[Mashi]

well i hope that is the problem for you.
anything else i would be worried. hehe

if so... get the part 2nd hand, mechanics told me it was pretty pricey to replace brand new and not worth it.
gl

[vippy84]

whatever sensors that honda has, they are pricey.. i replaced both of my o2 sensors and knock sensors.. cost me over 1k

[Jaydous]

Turned the car on today and went for another little drive and it has stopped doing it. I wonder when or if it will start again, makes me scared of the wet now

[kookie]

I had the same issue after the car was at the smash repairs. I just did a couple of vtec runs and the problem went away itself.
I know what you mean your at the lights and the car revs on its own.
I too also had the k-pro.

[TODA AU]

Check - set TPS values in K-Pro.
Also reduce idle speed motor response value.
Check temp vs idle speed values vs base idle speed value for conflict.
Check fast idle (moving) vs temp values for conflict.
Check (in Advanced) the over run fuel cut values, issue could be here too.

(The other thing it can do is ride the ignition timing on the zero map on the way back to idle.)

K-series Idle spped motors rarley stuff up.
However the TPS sensor on K-series is a piece of crap.
Chances are it's on it's way out.

[45SET]

Jayden... I think you should revert back to the OEM ECU...

Listen, I'll GIVE you my ECU in exchange for your Hondata...



But if the problem happens again, and the car keeps changing revs, and someone asks what its doing, just say it has a REALLY lumpy cam

[Didz]

lol

[wpg81]

I had this problem yesterday!

The car would idle up to 3000rpm and down to 1500 and up and down,turn ac on and it would stablise at 2000rpm for a fue seconds and than return to hunting up and down again. So i cheaked the ecu for codes but nothing. Removed and cleaned the throttle body and iac port,cheaked the tps and iac motor with multimetre. Refitted but still the same!

After much head scratching i found a vacum port block off that was old and cracked. The block off was leaking a very small amount. Replaced and all fixed!

IN MY CASE it was the port block off at the front of the engine end of intake manifold. (up close to alternator/power steer) not ecu adjustments,not tps,not iac motor or map sensor.

Hope this may help others