do you have any idea how much boost you are running? got a gauge?

are your plugs wet from fuel? oil? coolant?

 

Nope no gauge, and I didnt get to check but I think I would have noticed if it were oil. But again not sure it could have been, it was dark. To answer question though no I don't have any idea how much boost I'm running.

 

Your plugs are wet because the cps is bad. Good luck, Tuna out.

 

Is the misfire on all cyl? One side?

If you find it is on one side, don't overlook a partially clogged cat that can't pass the extra volume being forced through the engine

 

I'm geting a random misfire code. I changed all 12 plugs, but it didn't help much. It rides smoother while it misfires but its still shakes and jutters at a stop after driving it for a litle while. I am going to try the cps, but any other sugestions, ideas,or anything are still needed.
If it's not the cps I'm completely stumped.

 

I don't see a code in the list for "random" you should be able to pull the code and it will point you to which bank and cyl has the issue. Once you have those codes i.e. P300 (multiple missfire) + the codes to tell you where to look 301 = cyl1 302, 303, 304, 305, 306 then you can narrow it down.

CPS will give you issues in fits and starts until the car won't start at all (it will crank).

Clogged Cat will start with a mild miss and then eventually work its way to having to nurse the car to a shop as there will be no power, violent shakes, and in some cases stalling.

You may find out that with the extra boost you are blowing out the spark as it tries to jump the gap, or that one of the coil packs have issues.

 

Im sorry the codes where 303 304 and 306 but none consitantly, and the way that you discribe the clogged cat sounds nearl exactly how it acts.
How would I go about unclogging it for a lack of a better term?

 

Well based on the codes you have issues on both banks of the motor. 303 is cyl 3 on the passenger side with 304/306 on the drivers side.

Some will tell you that removing or loosen the o2 sensors and run the motor and see if the codes pop up again...i don't see that as a safe way but I guess if one is careful then allowing some flow out of the openings may provide enough additional flow for things to run smooth. If you start with the rear sensors and all checks out ok then you can assume the plugged cat is the rear cats not the ones near the engine block. If you sill get the codes then you have to assume the blockage is in the upper cats and that they have melted.

There are some catalytic converter cleaners you can run through the fuel system which are about 30.00 and some claim they work, but if the cat is begining to melt down they will not do anything for you.

Now for the big news...exhaust parts on this car are over the top. Mercedes was the lest expensive with rebuit oem units with front and rear cats and pipes as 1300.00 per side...2600 for a full set from header connection to h-pipe connection. I chose to have a local muffler place here in town replace the cats only and that ran me 1000.00 for all four including labor.

If you don't have high milage on the car (80,000 or less) they will be covered under the factory emissions warranty by the dealer. Mine went at 130,000.

 

I believe that is 8 years or 80,000 miles on the warranty isn't it? If so and SRT6 (05 model) was sold late 04 that puts you at the 8 year mark doesn't it?
Might check those dates before telling a dealer fix it...it's under warranty.

 

Before blaming the cats, waiting to see if the CPS (or a combo of CPS/cats) is causing the issue. If rings were bad, just warming the car up under no load and then doing a compression test should show that, especially in the affected cylinders that code-out often. Resetting the ECU/battery making it better sure doesn't sound like a mechanical problem going on, or even the cats. I am leaning toward the CPS being at issue.

 

I'm going to go against the notion of it being the CPS, your symptoms don't match the diagnosis I personally had, not saying my experience is the end all be all. However, your symptoms do mirror an issue a fellow forum member expressed to me and a key characteristic I personally have.

 

Had a similar situation a while back - mine was the CPS. However the issue did not go away until I changed the CPS AND plugs.

 

The issue was that some where along the line somthing caused my number 4 piston to have damage. The guy M-Tech said it was likely due to water flooding the engine, but he was unsure. The engine is currently undergoing a rebuild rather than an engine swap. SInce the cost of repairs are so expensive and I have already put so much money into the car after all work is completed it will be up for sale with all extras included...

It has the works as far as aftermarket, but if any of you think that with an EC S/C pulley and Tune as well as a TCU tune, aftermarket intercooler, pulley saver kit, new altenator, new plugs and wires,new tires and rear drivers side rim, and the rebuild at 52,000 miles is $18,500 too much to ask I have put in far more than that for the price of the car and part and labor but would really like to hear your opinions.

 

wow, really sorry to hear that!!

 

Thanks, it really sucks because this financially means the end of me and this great car.

 

If water flooded the engine, damage or remnants should be visible elsewhere and not just piston 4. Could you prob your M-Tech for additional information on this? I never though this could be your issue, I wish it was only a faulty CPS . Good luck with the future sale.

 

Well having read your statement in the beginning. If the car ran fine before a tune and bad after a tune. I would have to look at the tune. But it looks like you have it under control....
Lean conditions do wonders to pistons...