revs slowy crawl when accelerator is kept still

[Chirpstr]

When I rev the motor and keep the revs still, the revs slowly crawl up.
Sounds like a vacc leak yeah? Maybe the inlet manifold because I've checked all hoses and replaced vacc ball awhile ago.
Another thing I must say is the engine light flashed and it's code 13, O2 sensor open circuit. Now, I got this code a little while ago so replaced the 02 with a new one and also checked the wiring.
Could it be the TPS even though it didn't flash a code for it?

Cheers guys.

[hako]

Maybe its a dirty throttle body and/or a clogged IAC valve especially if your car has a lot of miles up.

[Chirpstr]

Yeah I cleaned the T/B and IAC awhile ago. Also gave the k&n filter a clean...

[hako]

Does this happen only when parked or also when driving?
I've had cars which had worn accelerator cables that would stick sometimes and give a similar problem. Shouldn't the IAC pull the revs back to where the pedal is...although if its happening at, say 2000rpm I'm not sure the IAC comes into the picture. Not the fuel pressure regulator or a partially blocked fuel filter?....charcoal canister blocked or a thousand other 'possibles'. Didn't over-oil the K&N?

[ephect]

does it splutter n cough whilst trying to get up to the rpm?

[Chirpstr]

Hako, I've already replaced the acc cable and it was doing this before I oiled up the K&N.
No it doesn't ephect, just slowly keeps going up it's strange... I must say as swell that when I put the clutch in when going slow (like approaching a speed hump) the revs dip a bit and want's to stall but then goes back roughly to around 700 rpm.

[ephect]

possibly faulty TPS?

so if you press the go pedel quickly to half thrott and hold it there, the revs slowly climb? taking say 3 secs instead of 1 sec? do you notice any difference when the engine is hot or cold?

[Chirpstr]

No, when I give it say half throttle the revs respond straight away, but when I hold it there and watch the taco the revs slowy increase and also I can hear it when foot is kept steady.

[ephect]

not so much responsiviness of your engine, but how long does it take to get to the rpm as per throttle position? i just making sure i have it right

so u instantly press the thottle from idle to half, engine responds, but it takes say 3 secs to reach 2500rpm (roughly half throt) instead of normally 1sec to reach 2500.. hope that makes sense

are we talking dash needle takes a while to get to rpm whilst engine its at the desired rpm as per throt posi? or does the engine slowly rev out when ur accelerator is press half way and held?

[Chirpstr]

The engine doesn't lack power at all.
The engine very slowly increases revs when the throttle is kept still but not at idle.
It sounds like a vacc leak maybe but like I said I've checked everything.

[Chirpstr]

Ok it seems to do it when she's warmed up.

[ephect]

cool, narrowing it down now.

so theres no other symptoms apart from the revs creap up?

[Chirpstr]

Not that I'm aware of. Could it be my inlet manifold gasket? Do they tend to leak when the motor's warm rather than cold?

[ephect]

yea could be the inlet manifold leaking, and you said you've checked all hoses for cracks so thats out. dont know if warm rather then cold affects it more

other thing possibly lies in the fuel system, pump, injectors or reg..

[Chirpstr]

pump, injectors, reg all new lol. And got a few good spare iac and tps's as well in the shed.

[ephect]

lol injectors????? ur killing me here lol

if its not a vacuum leak at the inlet manifold, the only thing left just checked my manual, is faulty engine control system. lol maybe grab a ecu from a wreckers n see if that sorts it.. clutching at straws here

[Chirpstr]

got 3 ecu's lol and the injectors sorry are exchange reconditioned ones (about a year ago). I'm thinking inlet manifold job.

[ephect]

yeap i agree, u've pritty much ruled everything else out

[delcowizzid]

sounds pretty normal to me apart from the near stall with foot on the clutch you will here and feel the ecu adjusting when you hold the revs there. most vn-vp's do it.

[hako]

I'd imagine that if it was an inlet manifold leak it would be most evident at idle when the vacuum is at its highest level whilst at say 2000rpm it will be lower and as its lower the possibility of it leaking is lesser at that RPM setting.
I reckon the clue lies in your statement: <I must say as swell that when I put the clutch in when going slow (like approaching a speed hump) the revs dip a bit and want's to stall but then goes back roughly to around 700 rpm.>
Dunno the connection but I think I've heard of this problem before but cannot remember the fix (damn beer). And you are sure the IAC valve is not sticky or misadjusted?
And lastly, are you running a manual ECU or an auto ECU?