Boxster 1999 2.5 986 idle problem

[darren_r]

I have been having problems with this 986 for over 14 months now. So far I have replaced the following:

new MAF

new AOS and all bellows/tubes

new coil packs

cleaned throttle body, ICV and new gaskets

O2 sensor

oil filler pipe (due to a crack)

The problem I still have is erractic idle 800-1000 rpm and a slight misfire. I have followed this forum all this time trying to resolve this problem with suggestions from other users posts

I scanned with durametric and have the following error codes (actual values shown below): Note that I am most concerned about the camshaft errors as these have never shown up until now (from what i have read 6 degrees is valid range and as you can see mine is well beyond this). I still suspect that i have a vacumm leak somewhere as I do hear a howl from the fuel filler on occasions. I am at my witts end now after all this time and any help will be much appreciated.

Motronic 5.2.2

Current Fault Codes

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P1124

Factory Fault Code 27 - Oxygen sensing adaptation range 1 (cylinders 1-3)

Enrichment limit

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P1126

Factory Fault Code 35 - Oxygen sensing adaptation range 1 (cylinders 4-6)

Enrichment limit

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P1531

Factory Fault Code 174 - Camshaft adjustment, bank 1

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P0150

Factory Fault Code 18 - Oxygen sensor ahead of catalytic converter (cylinders 4-6)

Short circuit of wires or limited voltage increase

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P1340

Factory Fault Code 322 - Timing chain out of position, bank 1

Below lower limit or above upper limit

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P1319

Factory Fault Code 62 - Misfire, emission related

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P1313

Factory Fault Code 50 - Misfire, cylinder 1, emission related

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P1314

Factory Fault Code 51 - Misfire, cylinder 2, emission related

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P1315

Factory Fault Code 52 - Misfire, cylinder 3, emission related

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P1585

Factory Fault Code 8 - Misfire with empty fuel tank

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Below is the Durametric scan actual values (engine cold):

Sensor Value Units

IATS 7.5 ;deg;C

ECTS 42.0 ;deg;C

Ignition timing 6.0 crk

Range 2 Cylinder 1-3 (FRA) 1.01

Range 2 Cylinder 4-6 (FRA2) 1.01

Camshaft position 1 deviation 21.0 crk

[darren_r]

I should note that this car seems to rev fine and pulls great above 2500-3000 rpm

[logray]

This sounds like a stuck variocam actuator. It is stuck in the on position, which accounts for the cam deviation, erratic idle, and smooth running above 2500 rpm.

[darren_r]

Thanks for your reply. How do I test this and is it an easy job?

[darren_r]

would this also account for the 1124 and 1126 errors?

[logray]

Codes 1124 or 1126 could be old or directly related, if cam timing is off signifigantly fuel trims can go out of whack. Most if not all of the codes point towards a problem with a faulty actuator, especially P1531.

Sorry it's not an easy fix. Have a read through these threads for details on the repair:

http://www.renntech....-on-with-p1524/

Edited February 19, 2012 by logray

[Loren]

would this also account for the 1124 and 1126 errors?

I would clear all of the faults reported and re-test.

That way you will narrow down current active faults.

[logray]

"P1531 Factory Fault Code 174 - Camshaft adjustment, bank 1"

"The problem I still have is erractic idle 800-1000 rpm and a slight misfire."

"Camshaft position 1 deviation 21.0 crk"

Definately agree with Loren, clear the codes and see what comes back.

However the above statements lead me to believe they are not going to go away. The poor idle, misfires and timing chain out of whack due to actuator control stuck on. Lots of good info in those links above.

[darren_r]

Many thanks to all. I will have a read and keep you updated. Just for info all codes except for cam related have been regularly occuring for the last 10 months or so Cheers

[adonkin]

I just was reading recently (Excellence, Panorama?) that erratic cam timing strongly indicates imminent IMS failure. I think that I'm hearing the death rattle starting in my 2000 986 base.

what a drag!

[logray]

Have it properly diagnosed, could be something else, example crank position sensor, intake leak, fuel problem leading to rough idle and excess chain noise

[darren_r]

Right, quick update.

I have ohm'd out both solenoids (bank 1 and 2):

bank 1 = 12.5 Ohms

bank 2 = 13.1 Ohms

I also applied 12v directly to each one, both made slight tick noise, tbh I was expecting it to be much louder. Also, I was expecting the bank 1 to not react at all or at least hear a noticable difference between them.

I also checked that 12v is getting to each one with the ignition on, all ok.

Do you think that this suggests a failed actuator? I dont really want to replace the solenoid just to have to go back in again to do the actuator, but on the other hand I dont want to replace the actuator if there is no need especially given the cost!

Any suggestions, do the ohm readings suggest a ba solenoid? Can you service/repair the actuator without replacing it?

Also, I monitored the camshaft deviation for some time, it is dead steady at 23 degrees and never changes.

Cheers

[logray]

If you activate the solenoid manually and don't hear the engine idle change, then chances are the actuator is toast. The engine should be warm and air conditioning on when you try this. Try both banks to make sure activating the solenoid does in fact change the engine idle.

There is no way to service an actuator, they are sealed/welded units that get "tired". Similarly, you don't want to buy a used actuator because there is no way to know it's condition just by looking at it, unless you are a gambling person.

The 12.5 ohms seems low, normally I see/get around 13 ohms or higher.

Yes if you are going to open the camshaft covers, I would replace actuator and solenoid ($700 USD together) part instead of just the solenoid ($150 USD by itself).

"Also, I monitored the camshaft deviation for some time, it is dead steady at 23 degrees and never changes."

This might be worth a quick sanity check of the current mechanical timing of the car. Perhaps the cam sproket slipped and timing is off and needs to be corrected. Variocam will not actuate if the mechanical timing is off. This can be done relatively easy with engine in car. Details here:

http://986forum.com/forums/showthread.php?t=26418

[josellama2000]

I had a similar problem, which i solved when i replaced the titanium spark plugs and a cheap air filter i installed before with a correct spark plugs and filter.

[darren_r]

thanks logray.

I just tried activating the solenoids with the engine running a you suggested. When activating bank 2 idle gets worse however activating bank 1 there is no change. I guess that this confirms that bank 1 actuator has failed in the open position.

With both solenoids disconnected and engine running it did seem to idle better.

Whilst investigating today I have also found that spark plug 5 has an oil leak but i guess that this shouldnt have any effect on the solenoid error being thrown. Also, possibly unrelated I appear to have to top up my coolant every couple of weeks as the light keeps coming on due to being low. I am hoping that I jut created a small leak somewhere when I replaced the oil filler tube a few months ago.

Josellama - were you getting P1531 error code also?

[logray]

Yes this sounds like a failed actuator to me.

Oil leak in spark plug might cause a mis or slight mis, unrelated to variocam issue.

You might have a leaky hose or coolant tank somewhere. Usually if you get under the car and fish around with a bright torch you can see tell tale "whiteish" fluid/residue from the source of the leak.

[darren_r]

Thanks again logray. Looks like I need to shop around for a few quotes as I dont fancy doing this one myself, solenoid would have been Ok but this is a bit to far out of my comfort zone. Maybe it is time to cut my losses and get rid of it!

[darren_r]

Just another thought and probably clutching at straws.

Is there anyway that the solenoid has failed open? Therefore even though it makes a noise it is not actually closing? The low Ohm reading is still bugging me a bit, but maybe this just suggests that this is on its wy out also.

[logray]

Well either way you have to remove the camshaft cover to replace the solenoid and/or actuator.

So if you are opening up the cam cover, might as well replace both, otherwise if you replace the solenoid and it turns out to be the actuator you have to remove the cam cover again (read, major waste of $$$ on labor).

[mattatk]

Guys,

When the variocam solenoid is activated with the car running at idle (with Durametric), the RPM should surge up momentarily& then return to idle. What do you reckon is wrong if, on one bank, the RPM surges but doesn't increase as much as the other (approx. 600RPM vs 1200RPM on good side)??

I am guessing that the variocam system is trying to work but something is stopping the full actuation??!?

Thanks in advance