99 CLK430 Misfires, and poor acceleration above 1/2 throttle or 3000 rpm.
Thread Starter
Junior Member
Joined: Feb 2009
Posts: 19
Likes: 3
1999 CLK430
99 CLK430 Misfires, and poor acceleration above 1/2 throttle or 3000 rpm.
I have a 99 CLK430, about 120,000 miles on it. I have been having trouble with hard starting, misfires, and poor or no acceleration. I have run a couple of fuel system cleaners through it including BG44K with no luck. It has a brand new Bosch Fuel Pump, new fuel filter, and clean (lightly oiled) K&N's. I have also checked the filter housing and ducts for obstructions. I have a brand new BOSCH Air Mass Sensor from AZPartshauz that I have tried swapping out with the original, but it has no effect. Today it would barely run, and finally triggered the CEL. I looked under the hood and noticed the vacuum line, connecting what I believe are called "EGR Shut Off Valves" on the front of the manifold, was rotted away so I replaced it. Started it up and it ran better but not great. Next I hooked up OBDWIZ and looked at the trouble codes and PID readings.
P0300, P0301, P0302, P0303, P0305
It's also showing for O2 Sensor 1, Bank 1: "Minimum Sensor voltage for test cycle: fail" and also "Maximum Sensor Voltage for test cycle: fail" I was also concerned about the timing advance reading, as it is reading negative "-" before the value, every other vehicle I've hooked this up to does not read negative.
I used OBDWIZ to clear the codes, started it up, and it was running much better. But still poor, unpredictable acceleration especially above 1/2 throttle and above 3000-3500 rpm. I recorded the logs for about 45 minutes at idle, low speed, and highway speed, and attached them to this thread. I also included the overall stats for all the PID's. I got back to the house and idled in the driveway for a few minutes while I looked over the logs. Then I decided I would drive it again. It started almost normal, and within a 1/4 mile the CEL came back on and it began stumbling hard. I cleared the codes again and it returned to the same condition of running better, but stumbling above 1/2 throttle, or above 3000-3500 rpm.
Sorry for the lengthy description, but I figured it's best to state everything I know about the problem. I would greatly appreciate any help that you all can offer, I can't figure this one out.
P0300, P0301, P0302, P0303, P0305
It's also showing for O2 Sensor 1, Bank 1: "Minimum Sensor voltage for test cycle: fail" and also "Maximum Sensor Voltage for test cycle: fail" I was also concerned about the timing advance reading, as it is reading negative "-" before the value, every other vehicle I've hooked this up to does not read negative.
I used OBDWIZ to clear the codes, started it up, and it was running much better. But still poor, unpredictable acceleration especially above 1/2 throttle and above 3000-3500 rpm. I recorded the logs for about 45 minutes at idle, low speed, and highway speed, and attached them to this thread. I also included the overall stats for all the PID's. I got back to the house and idled in the driveway for a few minutes while I looked over the logs. Then I decided I would drive it again. It started almost normal, and within a 1/4 mile the CEL came back on and it began stumbling hard. I cleared the codes again and it returned to the same condition of running better, but stumbling above 1/2 throttle, or above 3000-3500 rpm.
Sorry for the lengthy description, but I figured it's best to state everything I know about the problem. I would greatly appreciate any help that you all can offer, I can't figure this one out.
Thread Starter
Junior Member
Joined: Feb 2009
Posts: 19
Likes: 3
1999 CLK430
Here are the other screenshots...
One more thing, it does not seem to kick down reliably, even when going to the manual kickdown at full throttle. Yesterday I was thinking about the TPS, until I saw the O2 readings today. Also, I have pulled a few spark plugs and looked at them. Also, I pulled the plugs on cylinders 1 & 5, they aren't great so I ordered a new set, but they don't look bad enough to be causing these problems by themselves.
One more thing, it does not seem to kick down reliably, even when going to the manual kickdown at full throttle. Yesterday I was thinking about the TPS, until I saw the O2 readings today. Also, I have pulled a few spark plugs and looked at them. Also, I pulled the plugs on cylinders 1 & 5, they aren't great so I ordered a new set, but they don't look bad enough to be causing these problems by themselves.
Thread Starter
Junior Member
Joined: Feb 2009
Posts: 19
Likes: 3
1999 CLK430
Problem Solved, I wrote a novel about the solutions here:
https://mbworld.org/forums/clk-class...ml#post4589588
https://mbworld.org/forums/clk-class...ml#post4589588
Super Member
Joined: Apr 2010
Posts: 665
Likes: 1
From: springfield,mass
2001 clk 320
Great write up and pics.will have to do a nice check up on my car.I know at times when I push the car wot my check engine pops on and gives me the code for the egr valve.ima have to check the hose for any cracks cuz I surely don't need any sand in my manifold.this forum is great thanks to guys like u that inform us of your problems and showing us how to solve them.I've saved tons of money by (switching to geico) lol.no really I've saved a lot of money by joining this forum.thanks senorking and to all that help us out.
Super Member
Joined: Feb 2008
Posts: 618
Likes: 3
From: orlando
Sold 2003 CLK 500,2003 SL 500,2006 Acura MDX,1998 BMW M3 convertible
Great write up and pics.will have to do a nice check up on my car.I know at times when I push the car wot my check engine pops on and gives me the code for the egr valve.ima have to check the hose for any cracks cuz I surely don't need any sand in my manifold.this forum is great thanks to guys like u that inform us of your problems and showing us how to solve them.I've saved tons of money by (switching to geico) lol.no really I've saved a lot of money by joining this forum.thanks senorking and to all that help us out.
Last edited by jbenz99; Mar 25, 2011 at 12:25 AM.
