Critter

Tech guy, he states that the spark became more rapid as the car tried to start, I take it he removed the wires from the plugs in the engine and put on old plugs to check for spark. So now when cranking the injectors are still firing but there is no wires attached to some cyl so he has gas smell. I personally would remove one plug from every cyl, then as the engine cranked one person could follow the spark to ensure each and all are working. Then the next would be fuel supply, pressure gauge on injector feed tube. Also as stated try another Crank Position Sensor CPS if you see intermittent spark.
AMG55tech What is your view on it being a TPS Throttle position sensor issue?

03'55AMG

I used an inline spark tester to test spark. And I dont have the old CPS to throw in, but I will check for crank signal through STAR

Critter

Are you positive you have the fuel pressure required to run, recheck with meter off Schrader valve for pressure when cranking. Recheck connections on fuel pumps under rear seat. When ignition is turned on can you hear pumps running when the rear seat is removed?

03'55AMG

Yes, I hear the pumps prime. I will test pressure during cranking to verify pressure. Just to add, both pumps and sending units are new.

AMG55TECH

A throttle position sensor is not out of the question, but very unlikely. Has anything with the throttle body been changed or modified? If yes, then that may make it much more likely for there to be a throttle position issue... this is something that can also be checked using STAR. Also something to keep in the back of your mind is a bad camshaft position sensor. This engine relies greatly on the crank position sensor, but occasionally i have seen camshaft position sensors cause issues.

E55Greasemonkey

After 3 months, a lot of time wasted, and throwing parts at it, it's time to take it to someone who knows what they are doing, whether it's a dealership or competent MB independent shop. An experienced tech should be able to diagnose this in a couple hours.

03'55AMG

I wouldn't call it time wasted over the last few months. Added up, I've probably only spent about 5 hours working on it, I just have had no time lately. And eventually I would like to be a Mercedes master mechanic, so that's why I don't let others do the work. I ask for help rather than lose the chance to find out what's wrong and possibly fix it again in the future on another car. Just my $0.02.

03'55AMG

If it's of any help to anyone, this issue developed RIGHT after the burnout. Tires spinning running great to let off the throttle and bam, rough running.

AMG55TECH

I would like to see what would happen if you flash the M.E. back to stock. What mods do you have to need the Eurocharged tune....headers, throttle body, pulley? I know it would be a little off the wall, but I have seen tunes cause some issues. Worked on a moded C63 a while back with random missfires and in the end, it was a tuning issue.... maybe not necessaraly a tuning issue, but possibly more of just a M.E. confusion issue. Unfortunatly im not there and cant get my hands on your car, so im only able to just throw some Sh*t at the wall and see what sticks. But because of the way your car sounded in the video when cranking...Im still leaning towards either a wiring harness issue or a M.E. issue.

Speedriven1

Keep it simple. Test compression on each cylinder.

gaspam

did you check for oil in coolant? happened to me on one of my motorcycles after a giant burnout = i blew the head gasket

WANTED!!

Without having read your original thread, two thoughts come to mind. First, I saw you did compression testing, but what about cylinder leak down? Tends to be a little more revealing if a mechanical issue does exist.

Second, did you check all of your other plugs? Could it be possible that something else got knocked loose that affects ignition timing?

03'55AMG

No coolant in oil or vice versa, and no exhaust gas in coolant. Compression was good on all cylinders as well. Currently, the only engine related mods in the car are K&Ns. Tune is not installed yet, wanted to get better cooling mods first. My fuel pressure tester had a split in the hose, so I might just go buy one from auto zone rather than wait 2 weeks for my snap on guy to get back from vacation. Will check all physical connections again, as well as relearn the throttle body. Then check crank signal and cam signal in STAR.

211.070

How old are your sending units? You stated that they are new, but how new? If one of the lines from the pumps to the filter came off it can cause this issue. I have seen it more than once.

211.070

Fuel pressure and volume are one of the first checks. Fuel, fire, air...

If The coils are firing you have good CKP and CMP signals. They don't fire without those.


What were your RPM's during this burnout? This is an unlikely scenario, I have seen weak valve springs cause misfires.

03'55AMG

Pumps were installed maybe a month ago. RPMs during burn out were probably around 6,000 or so.

03'55AMG

Update. Had some more time to mess around today, and I figured I would keep it dead simple. Check ALL connectors (coil packs, injectors, ECU, TB, etc), and make sure the car can get its big 3 ingredients (air, fuel, spark) as best I can with what I have at home to use. Left my STAR and snap on scanner at work so no diagnostics unless I use my cheapo $90 generic one or my Torque app. After checking all connections and verifying fuel was at the valve on the rail, I tried firing it up. It fired right up for a split second then almost died then went again. I shut it off and took a video, and fortunately I could replicate it on film for you guys to see.

Ignore the bulb light, it is because my bumper was off for H/E install and it popped out. SRS light popped on after disabling the SOS malfunction light through STAR. The first part was what it did when I first started it. Second part has never happened before. Almost sounds like it isn't getting enough fuel to run. I will pick up a can of starting fluid Monday and shoot some into the TB and see if it fires up, if so, maybe one of my hoses in my tank fell off. Then its back to the misfire... At least with all the money I have saved in gas I can hopefully fix this..

novae500

wonder if a hose/connection of the sending units you recently got done came loose during your burnout??

ahmad0658

There is one sensor close to the S/C pulley a little to the left, I had similar issue to you where the car starts for few seconds and then stop and doesn't want to start again, then start for few seconds and stop again, It was a cable not plugged on a sensor near the Supercharger pulley to the left when you face the engine front. Check it, it could be damaged sensor, I don't know what is that sensor really, if any one can give us some information that would be good.

E55Greasemonkey

Before anything else, you need a fuel pressure gauge attached at the rail. They're only about $25 at autozone. That's where you need to start.

shardul

iTrader: (1)

it is called the camshaft positioning sensor

Critter

E55greasemonkey is correct you must verify fuel pressure at cranking speed. You may also be correct in the line off scenario at the fuel pumps within the tank, but the gauge on the fuel rail will resolve this. Do not put starting fluid in this engine, if you want to be a scientist the take a small squeeze bottle with a little gas in it and squirt some fuel into the throttle body and then try to start, the car will probably start right up then stall as you have shown now. NO STARTING FLUID!!!

03'55AMG

Got a fuel pressure tester today. Will test it here soon. Also going to try some gas (no ether) into the TB and see how that does. I will also check for the cam position sensor too.

03'55AMG

Fuel pressure when primed is about 72 PSI, and bounces between 70 and 80 PSI when cranking. Cam sensor plug was in all the way also.

Quadcammer

be careful squirting fuel into the intake. You don't want fuel puddling in the intake.