Look here...

Hi all. This is my first post here. I used to read the old PPBB, but I never posted there.

I've got a '99 Boxster (non-egas). I fried the main bearings at the track due to oil starvation due to Gs. I got a replacement used engine from OK Foreign and put it in myself. I finished today. The engine does run, but it's got a couple of problems. It is blowing coolant, but I think I didn't bleed the coolant properly. After it cools, I'm going to do it again. When I initially started it, I had some nasty lifter noise. While going through the bleeding procedure (2500rpm for 5 minutes w/5000rpm revs every 30 seconds), that went away. The only other thing I notice is when I first start it - right when it starts cranking in fact - it makes a bit of noise like spark knock. It goes away after about 2 revolutions of the motor though, and doesn't recur.

This is all so you guys have some background for the real issue. Oh yeah. BTW, I did the IMS retrofit using the LN Engineering IMS kit. I followed the instructions to a "T" as I didn't want to have the timing jump. I was petrified of that.

So anyway, the problem I am having is that the engine idle is low. It idles around 600rpm. My old engine would idle around 800. It had a bit of fluctuation occasionally, but that was only once in a while. This engine fluctuates constantly. It's a bit better after it warms up. When it's cold, it will not idle on its own. After it warms up a bit, it will idle, but I have to ease off the power. Then it fluctuates between 600-800 constantly. While driving it, I have to keep power in when pressing in the clutch or it will die. Apparently, dropping down from a higher rev to idle quickly causes it to drop low enough to die. It always starts right up though.

FWIW, the MAF is about 15,000 miles old, as are the O2 sensors. I swapped the throttle body assembly from the old engine to the replacement engine, but that didn't change anything. I am also planning to swap the air/oil separators too, just to be safe as I know the old one is good. I also tried to carb cleaner thing to check for vacuum leaks and didn't get any results.

So what I'm asking you all is, what are the other possible causes for this problem? I'm just looking for a list of things to check.

Thanks!

Yippee38

It could be sticking or not connected properly. You can take it off and clean it.

I'm not sure where it is, but isn't it bolted to the side of the TB?

switched over to using E-Gas (drive by wire) and did away with the idle control valve.

From the symptoms I think Boxsterra is right on with his diagnosis.

Sincerely,

MarcW.

The only thing I can find is the "idle speed adjuster" in the parts list. It is screwed into the driver's side of the TB. In fact, in the first picture on this page (DIY from Pedro's Garage), it would be just to the right of the number 3. The dark grey thing between the numbers 2 and 3. So that is bolted to the TB. If you're talking about something else, tell me where to find it please.



Edited 1 time(s). Last edit at 02/16/2011 11:59PM by Yippee38. (view changes)

... for instructions.

[www.pedrosgarage.com]

Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

At least I think it did. I cleaned the idle control valve, but I also replaced the AOS as it had just a small amount of oil in the tube to the intake. It's running fine now. Now if I could get the damn air out of the cooling system. Bled it twice, but it still needs more.

Thanks guys!

I'd be surprised if that's the problem though. As I said, I swapped out the entire TB assembly from my original engine (basically, everything from the air intake tube to the manifolds). That engine idled fine most of the time. I guess I'll have to take it apart and clean it out since I didn't take it apart earlier. Hopefully, that will be the problem. I'll let you all know how it goes, though that won't be until next week.

Thanks!