Anyone want to help troubleshoot?

Rough idle that gets worse after the car warms up. It's almost unnoticeable when the engine is cold, but definitely not perfect. After driving a block, it gets very rough. It actually used to die a at idle, but doesn't do that anymore. When you give it any gas, it's very smooth and feels as if it has all its power. See codes above.

Recently had a cracked cylinder head replaced on bank 4-6 after a water pump failure. Mechanic swears timing was perfect and he checked both banks. However, I do think he might just have been intoxicated during a majority of the work.

Could a vacuum leak cause this? Air oil separator? or is my timing really off? My code reader data tells me it varies from 3-20 degrees at idle (supposed to be less than 6).

When the engine was out, the IMS was checked and the variocam actuators were replaced along with the chain guides.

Any input is appreciated! I really don't want to take this to the dealer.

 

It's 2am and I have cleaned out my intake. The idle control valve was completely covered in black soot. I hosed it with brake cleaner.

Question: with the valve disconnected from, should one side be partially opened? It can completely close or open with a little pressure. I'm just wondering if I cleaned it well enough or if I need a new part. Any way to test if it's working?

I'm going to take a quick drive to see if it's working any better.

 

I bet your CEL is flashing. Don't drive a car with a flashing CEL.

Cleaning the intake and IACV will probably not help this situation. Yes one side of the IACV should be slightly open. You can ohm out the IACV. It can also be further disassembled by pulling out the lock pin and twisted apart, then cleaned internally.

The p1531 indicartes that your bank 1 variocam actuator could be faulty, and would explain the rough running at idle, but smooth power above that.

Interestingly p1539 indicates the passenger side variocam actuator could be faulty as well.

The misfires (p1316-19) indicate the timing is not right or a variocam actuator has failed.

Usually they both don't fail at the same time, so this could mean the timing is not set correctly.

What's a little suspect here is that you are also popping a p1340 which indicates the cam allocaiton was done incorrectly (timing is not right).

Only possible cause of p1340:
– Allocation of outlet camshaft to inlet camshaft incorrect
Note: This fault can be stored only if the engine was disassembled and the allocation of the outlet camshaft to the inlet camshaft was incorrectly set.

P1341 Camshaft Adjustment, Bank 1 – Below Limit
P1341 Camshaft Adjustment, Bank 1 – Above Limit
P1341 Camshaft Adjustment, Bank 1 – Signal Implausible

Possible causes:
– Short to ground
– Open circuit in triggering wire
– Open circuit in B+ supply
– Actuator faulty

I suggest you take it back to where they worked on it, have it towed if necessary.

I would a.) not run the car and b.) verify and correct the timing (might require removing the cam covers if the cam allocation was not done right), c) clear the codes and see what comes back.

Also you said: "My code reader data tells me it varies from 3-20 degrees at idle (supposed to be less than 6). "

Is this "actual angles" or "cam deviation" you noticed this with?

 

You were right, it didn't improve... maybe a little less variability of rpm at idle, but still rough.

I don't think I'm going to send it back to that mechanic. I did a lot of the work on the car myself, but left the more specialized stuff him. To work on the timing, can it be done through the cam covers or does the head have to come off? Think I should tackle it myself or bite the bullet and send it to the dealer? I can easily take the covers off and check if it lines up with the markers.

 

The first thing you can do is just remove the plastic green cam end caps with the engine in car, rotate the crank by hand a couple revolutions and verify the timing is correct or incorrect.

If it's off, and the cam to cam chain allocations are right in both banks then you can just remove the oil scavenge pumps and fix the timing, no need to remove cam covers or engine from car.

If it's off, and the cam to cam chains are done wrong you need to pull the cam covers and remove the camshafts and correct the allocation (correct number of teeth between sprocket marks).

If the timng is right, then you have bad actuators and the cam covers have to come off to replace them, but again highly unlikely both are bad, unless you bought second hand parts.

 

Thanks Logan! Sounds like I can do it relatively easily.

I did get a used part for bank 4-6. Bank 1-3 is brand new and cost $1k! Ouch! That one was obviously bad; the mechanism was very sloppy. I had a box of two or three others for 4-6 and picked the most solid one. I'll admit that I didn't put a 12v source to check the actuator.

 

Along with the work shop manual instructions to verify timing (I suggest you follow those word for word), here is another good link:

http://986forum.com/forums/performan...iming-m96.html

Since you want to verify cam to cam chain allocation as well you need to look at the slots on both cams on both ends.

 

Looks like a great writeup. I have the shop manual, too. Does it matter that I do have variocams and the other writeup is for a boxster without variocams? My car is the '99 with cable drive and it has one variocam per bank. (I think the later cars have 2 per bank?)

Forgot to mention that during hard acceleration, the exhaust is very loud and sounds like a harley davidson on passenger side only. Assuming this is misfire with combustion every other cycle?

FYI, the measurement was degrees of ignition advance at idle. It's still between 5.5 and 13.5 degrees with too much variability.

 

The write up is for the same engine you have.

Yes your timing sounds like its off or variocam actuator is bad.

Ignition advance should be stable. Ignition timing is controlled by the computer.

For mechanical (cam) timing, you can read out your "cam deviation" without running the car, that would be a good place to look even before you pull the cam plugs. I would still pull the cam plugs and verify.

 

logray, i tried to +1 you for rep since you're always so helpful but it said i couldn't until i spread some love...

 

Going to work on it tonight. I'm guessing that bank 4-6 wasn't torqued to spec and I can guarantee there's no locktite on the cam bolts. Ouch! I hope I haven't been driving it with the camshaft sprocket loose.


Not my picture below... I'll see if I can get some good pics tonight.