Engine Hunt at Idel - 986 Forum - The Community for Porsche Boxster & Cayman Owners

aussieboxy · 03-13-2007, 02:52 AM

I gave a 2000 2.7 that hunts at idle. What I mean by that is that the idle speed will drop to about 400rpm and the jump up to about 1500 rpm. It does this constantly. It's not quite as bad one you put the aircon on but it's still annoying.

Any idea's on how I can fix this problem.

Thanks guys.

insite · 03-13-2007, 05:20 AM

clean the idle air control valve

aussieboxy · 03-14-2007, 05:17 PM

Thanks and how do I do that?

insite · 03-14-2007, 06:26 PM

it's bolted to the driver's side of the throttle body. remove it (2 screws) and clean it out with carb cleaner. make sure the flap operates easily. re-install it.

while you're there, remove the intake hose from the throttle and look in it for oil. if you see oil, you probably need a new oil separator; this causes a vacuum leak that can cause your unstable idle.

also check for other vacuum leaks while you're in there. do this with propane or carb cleaner. wave / spray it around and see if the RPM's jump. if they do, you have a vacuum leak in that area. any of these can cause your issue without throwing a check engine light.

aussieboxy · 03-17-2007, 02:36 PM

Thanks I'll try that

blinkwatt · 03-17-2007, 04:21 PM

Quote:

Originally Posted by aussieboxy

Thanks I'll try that

If that doesn't work you may want to smoke test the intake for leaks.

aussieboxy · 03-17-2007, 10:48 PM

Hi,

It's my 1st time workin on the Boxster. I had a bit of a look but was unable to see the throttle body. Do I need to take off the black induction pipes to get access to it. I got a Mitchells manual on CD and it's absolutely useless

Thanks for your help

blinkwatt · 03-17-2007, 11:17 PM

Quote:

Originally Posted by aussieboxy

Hi,

It's my 1st time workin on the Boxster. I had a bit of a look but was unable to see the throttle body. Do I need to take off the black induction pipes to get access to it. I got a Mitchells manual on CD and it's absolutely useless

Thanks for your help

The black induction pipes(intake system) should lead up to a shiny metal thing,that's the throttle body. You should only have to loosen up the intake tubing to get the throttle body out. Before you do that and take a couple hours I would suggest just smoke testing which takes only a couple of minutes, if there is a leak then you saved a bunch of time.

aussieboxy · 03-18-2007, 11:05 PM

Ok I found the throttle body, although it seems different from what you described and the pics I found on the forum. By boxster is the 2.7 with the electric accellorator actuator rather than the cable.

aussieboxy · 03-18-2007, 11:06 PM

How do I do a smoke test?

Thanks I really appreciate your help

blinkwatt · 03-18-2007, 11:34 PM

Get that K & N air filter out of the car. When I had one it cost me $240 for a new MAF.

aussieboxy · 03-19-2007, 04:29 AM

What's a MAF & how do I do a smoke test

aussieboxy · 04-07-2007, 12:35 PM

Can anyone help me on how to do a smoke test to check for vacume leaks?

Thanks

Rodger · 04-07-2007, 01:04 PM

First you need something that makes smoke but not fire.....I use a thick rope with a smoldering end. You can also use a cigarette or cigar if you can tolerate the smoke. With the engine running, move your smoking instrument near the various pipes and hoses in the intake system (throttle body, vac lines, air-oil seperator, etc.) and see if any of them start sucking up the emitted smoke. If so you've found your leak.

The MAF (mass airflow sensor) is mounted in the intake pipe near the air filter housing. It has an electrical connector and it measures the amount of air entering the engine so the proper amount of fuel can be measured. An over-oiled K&N filter will contaminate the sensor, ruining its readings.

insite · 04-08-2007, 04:14 AM

or you can just use propane (seriously). auto shops wave an unlit propane torch around the engine bay. if the idle jumps, you found the leak. the propane is sucked into the engine through the vacuum leak and burned in the motor. it temporarily increases the idle.

aussieboxy · 04-14-2007, 04:08 AM

Thanks guys I'll try that.

aussieboxy · 04-14-2007, 04:09 AM

Thanks guys I'll try that and see what I can turn up.

aussieboxy · 04-25-2007, 12:59 AM

Ok I did the smoke test and was unable to find any leaks. Tired both ways with smoke & carb cleaner.

Any other idea's. I really apprecaite your feedback.

aussieboxy · 07-18-2007, 05:53 PM

I thought I would revive this thread. I still have the same problem. Not really a major issue as the car doesn't cut out & I mostly do country driving so you don't notice it, but I would like to get it resolved.

Any other idea's, I had thought of cleaning the MAF although I did pull out the sensor a while back & clean it with no effect.

Thanks for you input guys.

insite · 07-18-2007, 06:29 PM

Quote:

Originally Posted by aussieboxy

I thought I would revive this thread. I still have the same problem. Not really a major issue as the car doesn't cut out & I mostly do country driving so you don't notice it, but I would like to get it resolved.

Any other idea's, I had thought of cleaning the MAF although I did pull out the sensor a while back & clean it with no effect.

Thanks for you input guys.

unplug your MAF to see if the problem goes away. most common causes for a hunting idle are MAF, oil separator bellows, and oil fill tube in that order.