Medevack1

well as expected the cel came back....

808Bill

But, it took a lot longer right? Something you did had a positive effect...

Macster

What are the codes? And obtain the codes then and there at the time the CEL appears.

Be sure to read any pending codes.

That the problem corrects when the engine turned off then back on again -- as you mentioned in a previous post -- does suggest a possible "electrical" problem.

One that comes to mind -- and one I dealt with in my Boxster -- is a bad VarioCam solenoid. The engine was running poorly, idle going up and down -- but no CEL but a pending code (P1341 IIRC).

After checking for codes and reading the pending code I shut off the engine then after a short time restarted the engine and the engine was just fine and remained fine for the 30 mile drive home.

The next day at the dealer when I mentioned to the tech how the fuel trim was going rail to rail the tech told me misfires can result from this solenoid (or actuator) failure as the DME adjusts the fueling in an attempt to get the #2 O2 voltage readings it expects but because the VarioCam isn't working right it never will get the readings and it goes too far and misfires can be the result. That just one cylinder misfires is not uncommon. There are differences between cylinders and it could be the #2 cylinder is the most sensitive to incorrect fueling of the 3 cylinders of the bank affected.

Also, the above doesn't mean I have abandoned the idea the low/high lift feature of one or both #2 cylinder intake lifters is acting up.

Unfortunately the above might read like I'm piling on one possible explanation for the untoward engine behavior after another but I have to stress at some point some diagnosis is going to have to be done to get to the bottom of this. Either you will have to do this or qualified/experienced tech.

Sure, it would be just great is Techron fixed the problem -- I was certainly hoping it would -- or something equally easy to do but sometimes that just isn't in the cards.

Howaboutthat

Sometimes MAF quirks can register with respect to a given cylinder. Easy enought to pop out and clean, and replace, if necessary (apologies if this already has been done or mentioned).

Medevack1

well Gents, I went ahead and replaced all the coils and sparkplugs. changed the oil and checked all fluids as soon as I turned the car back on the CEL came back now is every time I start the car and come to a complete stop i.e. idle. Once I get over 2k rpms the CEL goes away, once on the HWY the car runs PERFECT.

808Bill

Did you change your MAF?

Medevack1

no I didnt

Blue Chip

Idle control valve sticking maybe?

DBJoe996

1) Invest in Durametric and start logging the various parameters. Then use the engine activations to see if you can create the error code (such as using the VarioCam activation on Bank 1).
2) Unplug the MAF, clear the code(s) and run the engine. Take a drive. Performance will be down as the DME will default to "no feedback from MAF" setting, but it would not hurt to try. Clean the MAF sensor.
3) You said you changed the spark plug and coil on #2 (well you did all of them). What was the condition of the #2 spark plug? Reading the plugs will tell you a lot.

Medevack1

#1. I have an onboard Cel Reader
#2. I will try it on my way home and unplug the MAF
#3. Yes I replaced them all and the coils too, the condition of the #2 was darker than the rest.

DBJoe996

A recurrent error code P0302 (misfire on cylinder 2), and the darker spark plug (oily perhaps?), suggest something is wrong with cylinder 2. You have done the right things, now it is time to do a compression check, leak down test and boroscope cylinder 2. It could be a stuck lifter or valve seat problem. Not all that uncommon, but only those checks/tests will provide you with your next step.

AWDGuy

you need durametric to activate stuff, a code reader will....tell you the code. that's it.

if one plug is darker than the rest, i would assume oil or fuel is getting to it.

ditto

Do not assume that the cylinder identified as having a misfire by the code is the cylinder that actually has the misfire. It may be the adjacent cylinder that is the root cause.

After I typed that I started thinking that the sensors could be miswired too, like sparkplug wires going to the wrong plugs.

docmirror

I'll take a swipe. I would recommend not throwing any parts at it anymore.

Get something like this:

Which has recording capability. Connect the probe to the switching side of the #4 injector, and set the trigger to capture the injector pulse. You will have to fiddle with the settings for a while to get a good picture of the waveform.

Once you get a good capture of the #4 injector pulse, save to the buffer. This will be your reference. Now move to the #2 injector. Run the car, and induce the failure. Capture this pulse, and then use the compare function to look at both waveforms.

They should look identical. I mean they should look exactly the same, as they use the same pulse generator. If they don't match exactly, come back and share the results with a picture. If they are exactly the same when the problem is induced, I would then swap injectors(mentioned before) with #4 cyl and clear the codes, disconnect the bat for 10 min, then test again.

edit, I found an image online. Likely will look similar. Takes a bit to set up the scope, but make it look like this with the timebase, and set the voltage range a bit lower to capture more of the pulse transient.

Medevack1

ok its been 1 days and the cel hasn't come back....