roi

Just installed my new Laskey motor (no turbo for now)
Fired up very fast only after 2 turnes of the starter.
Engine sounds very good and very clean working, although I have an idle
problem that I have to solve now.
It goes like this:
When I start it up (colled engine) it idles at about 1500RPM, after 30
seconeds trable starts, the RPM will go up to 2500 and fall down to 500 and
again and again, (when driving in gear every thing is great and air to fuel
is good)
My knock sensor is courrently not working as the demn thig broke and the
check engine light is on.
I realy don't think that this is the problem although I have ordered a new
sensor.
I checked for leaks and craked hoses but found nothing.
I tried disconnecting the idle valve and the problem pesisted although the
idel would go from 1300rpm to 1800 rpm very quicly (also A/F would go very
lean so I stoped doing this)

Any interesting ideas ???

ChefJ

what kind of ems or is it basically a stock motor? with stronger internals??

roi

[QUOTE=ChefJ,Apr 24 2008, 09:15 PM] what kind of ems

R3DS2K

check your coolant levels

roi

Why would you think that this would create such a problem ?

slodsm

If there is a big air bubble in the coolant, the IACV is getting intermittent signals of engine heat, like it's warm one second and cold the next. This will cause idle problems.

I would also check for vacuum leaks, maybe a swapped plug on something like IACV/Map sensor or so on.

I am unsure of what if any plugs can be switched around on an S2k. I am just going off general automotive troubleshooting here because I rarely ever even pop the hood on my s2000 and when I worked on cars for a living, they were one of the most rare cars you get with problems. Usually just upgrades so I have no 1st hand troubleshooting experience with them.

roi

No vacum leaks
Plugs can not be swapped
and coolant temp does not fluctuate on the cluster panel so I guss there is no bubble in the coolant (I filled it up by the book)

R3DS2K

temp gauge wont aways fluctuate if you have bubbles in the coolant system

in the morning when its cool... top of the radiator
start the car up with the cap off and let the car warm up till the fans come on.. and see if you have any bubbles come out.. once all the bubbles stop.. make sure the reservoir is over filled a little bit.. up the cap back on and turn the car off.. it may or may not take in more coolant from the reservoir when it cools off

if thats all good .. check your Ignition Timing

another thing you can do is performing a idle learn

http://www.xse.com/leres/efidiag/idlelearn.html

roi

the problem with the idle learn is that the RPM fluctuates between 500 and 2500RPM at a rate of about 1 second per cycle.

negcamber

I've had the same problem before and it did lead to the IACV.

When you had the intake manifold off, did you clean it? When you cleaned it, did you take the IACV off first or clean the whole thing? I found that if you leave it on when cleaning the manifold, crap would settle in the IACV. After I pulled th IACV off, cleaned it separately and oiled the gasket before re-installing, it idled fine.

And I agree with R3DS2K...our temp gauge is does not respond quickly enough to temp changes to be accurately used to diagnose a small air bubble.