stilov

If it's a miss, its slight.

had Porsche plugs and coils done 12k miles ago
NO CEL
No codes on durametric

logged misfires, shows none

logged engine roughness, and it does fluctuate, but I don't know what is normal.

Any ideas?

Thanks!

Basso

My 2000 s was the same prior owner had replaced the MAF, there is a cut off on this year for which MAF to use there are 2 for the same year.
He used the wrong one made the idle hunt (I have a used MAF with 3k miles on it for sale fits early 2k cars) is your early or older 2k car do you have a part #.

trendy996

How do you know if its a earlier or later 2000?

flyingpenguin

If you want to know for sure, take of rear bumper cover. Chassis has a sticker with production date (Euro dd/mm/yy format if I recall correctly).

Not sure if a VIN decoder somewhere online would give you production date..

Macster

Unless the AOS is new I'm going with AOS as suspect #1.

The 1st one to fail in my 2002 started out with a mild hesitation off idle and a fluctuating idle speed. Nothing gruesome just a mild lazy up and down idle speed variation that was out of character. Oh the car had about 80K miles on it when this started.

I futzed around trying to diagnose what was wrong, tried the MAF cleaning, some Techron in the tank. The engine started running worse and at some point I unscrewed the oil filler tube cap and tried to remove it but couldn't against the pressure difference between the crankcases and atmospheric pressure.

(BTW, this symptom is a latter stage failure symptom so if you are able to remove the cap this does not let the AOS off the hook.)

At this point I was thinking a bad (somehow) oil scavenge pump was the culprit but when I called the dealer service manager to make arrangements to bring the car in after listening to the symptoms he told me it was the AOS. He urged me to avoid driving the car running the engine so I had the car flat bedded in and after the AOS was replaced the symptoms were gone.

Macster

The build date is stamped on a metal plate that is riveted to the driver's side door jam. The build date is the month/year.

The proper MAF to use is tied to the car's VIN, though. If you feel you need to replace the MAF you need to get the proper MAF based on the car's VIN. Be aware that early Boxsters (the 2.5l Boxsters) can require a DME upgrade to use the proper MAF as the MAF was changed for these and the new MAF is not compatible with the older (not updated) DME. The older style MAF which is compatible may not be available or the newer MAF may be picked out of stock without the parts person knowing the MAF requires a DME upgrade.

stilov

I did the aos last summer about 4000 miles ago. When I did it though there was a decent amount of standing oil in the manifold. I thought maybe it fouled the plugs.

I don't get much of a hunting idle, it just feels and sounds stumbly like a miss. But nothing in the cel department.

Macster

Are there any pending error codes?

stilov

Nope but I do have a row flash.

I guess it did have O2 sensor codes but I have no cats so figured that was it.

Macster

IIRC among other things the ROW flash is for cars with no #2 sensors (sensors after the converters).

However, the engine should still operate with no drama and this includes no misfires or stumbling, etc.

If you were seeing O2 sensor codes these were almost certainly for the #1 sensors, so something is, pardon the expression, amiss.

If you have removed the converters, or in some way changed the exhaust in some major way this can upset air flow through the engine and this can cause problems. This could account for the behavior you report, are experiencing.

stilov

None of these thing were done recently...ROW flash and cats removed were from more than a year ago.

The miss or stumble, a little popping at idle (and I mean a little) has just seemed to be a degrading issue, not a result of something else.

I suppose I am making this more complicated than it needs to be. I'll probably start with plugs, clean the MAF and TB and see how its running then.

If what you say is correct about the front O2 sensor codes...than I would guess it's an A/F issue since both banks threw codes.

Its the type of thing where my wife would never even notice driving it...

I'm nitpicky, so i do notice it has gotten gradually worse, and again my thought was the extra oil in the intake from the past bad AOS probably took some life away from the plugs.

Macster

Not sure what it is worth, but generally if the engine is popping (backfiring or spitting back) through the intake the mixture is lean.

If the engine is popping (backfiring) through the exhaust the mixture is rich.

You can pull the throttle body. If it needs cleaning this can be a sign the AOS is acting up, even if the AOS is relatively new. Really the throttle body (and the MAF) should never need cleaning with a properly working factory engine intake air filtration system and a properly working AOS.

If the CEL ever comes on read the active and pending codes ASAP. Write these down.

Idle speed is around 740 RPMs +/- 40 RPMs. My experience with my cars is the DME keeps the idle speed pretty constant. There is some fluctuation but it is really only noticeable when monitoring the RPM using an OBD2 code reader/data viewer in real time.

The only times my Boxster has manifested a fluctuating idle -- the idle speed was going up then down -- was with a failing AOS (the 1st one -- the idle was not affected when the 2nd and 3rd AOS were going out) and when a VarioCam solenoid/actuator went bad.

In the case of the VarioCam solenoid/actuator there was no CEL but there was a pending error code that pointed to the VarioCam solenoid/actuator.

stilov

Cool...I'll drive it a bit more (have to...996 is still under the knife) I cleared those O2 codes, so if anything comes back maybe it'll give me better direction.

Also have new suspension waiting to go on and some plasti-dip orange wheels...getting crazy around here.