Galstaff

Wife was driving home in the middle of the night and broke down. She said she was driving and the engine started losing power then began to shudder. When she pulled over it died. I pulled the P0606, P0350, and P0300 codes using a scanner. I charged the battery and confirmed it was holding a charge both out of the vehicle and in the vehicle. I checked all engine fuses and they are all fine. I pulled the ECU and inspected the wiring harness with no visible damage. I'm guessing based on the codes the ECU has bit the dust. I'm planning on grabbing a can of contact cleaner and cleaning the connectors to rule that out before spending a lot of money. Any other suggestions for checks or troubleshooting? Anyone had their ECU rebuilt? Thanks in advance and Merry Christmas to everyone.

Max Blast

Does the engine core rotate freely?

Galstaff

Engine cranks freely but won't run.

BlownV8

Mileage?

Galstaff

168,000

Max Blast

If you’re using a generic obd2 scanner those codes can be misinterpreted. What scanner are you using?

Can’t hurt to pull both batteries and clear all codes, try starting. If unsuccessful, swap in a known good ECU and see.

Galstaff

I've got the iCarsoft i980 scanner. I pulled the main battery and charged it for 24 hours then pulled the connector for the smaller battery for 15 minutes when I was putting the main one back in. I cleared the codes but still no luck. I don't have access to another ECM/PCM unfortunately. Also from my understanding they are VIN coded correct?

BlownV8

At that mileage it is typically the fuel pump.

Galstaff

Any quick tricks to testing flow or a pre existing walkthrough thread?

Max Blast

If not I think someone with a WIS needs to chime in here, alternatively you can get a MB workshop subscription at startekinfo.com and read up on how to yourself.

Galstaff

I confirmed that the Fuel pump fuse is getting power when the ECU is in and the key is turned on. I've ordered a fuel pressure gauge to check if the pump is actually pressurising. If that checks out I'll check spark next. Thanks so far for the help.

Galstaff

Fuel pressure update. When the ignition is switched on there is zero pressure build up. I listened through the filler neck and under the seat and didn't hear the fuel pump kick on. The fuel pressure peaked at 50 psi while cranking but dropped to 45 psi immediately and then lowered slowly to 40 psi after about 5 minutes of sitting. From what I've read that does not appear to be normal operation of the pump. I think the next step is to remove the seat and do a voltage check at the pump. It sounds like I should replace the fuel filter since I'm already working in that area. Again, thanks for the help thus far. I am probably going to check spark as well just to cover all my bases.
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BlownV8

If you change the pump, you will need the MB fuel pump removal tool or, at least, an aftermarket one. I would spend the money on the OE version and they can be found on ebay and amazon. If your pump has not been changed, do it proactively since it won't last much longer.

Galstaff

So I checked for spark tonight and got nothing from any of the coils. With the P0606 code and no spark I'm thinking it must be the ECM that needs repaired or replaced. I plan to do the pump too because it seems to be wearing out at well. I'll have to give the wiring to ground a good twice over to make sure the wiring isn't the culprit and then I'll have to find a reputable place to send the ECM.

Galstaff

All the grounds seem good and I can't see any obvious wire harness damage. I think I'll have to bite the bullet and get the ECM diagnosed. I'm not a fan of computer failures. I can handle mechanical work but it's hard to troubleshoot when an ECM is the real culprit in your driveway.

Galstaff

Tonight I installed a new crankshaft position sensor and now I have spark on the driver side but no spark on the passenger side. I installed a new camshaft position sensor but still no spark. I'm working on getting the ECM serviced. I plan to go over the wiring again for the passenger side coils to see if there is anything I missed. Already checked the ground and it was corrosion free.

Galstaff

So I installed a new ECM, new fuel pump and filter as recommended based on my milage, and all new spark plugs. I got it to start and ran it for about 5 minutes. It ran rough and white smoke came out the exhaust initially. I figure there is oil in the cylinders from sitting for so long. Unfortunately the gas pedal was unresponsive while it was running. I could put the pedal all the way to the floor without any effect on the engine. The next morning it wouldn't start again. I've hooked it up to the iCarsoft and the throttle value is a fixed 15 %. The pedal does register on position D and E but doesn't effect the 15% value. Any suggestions how I should proceed. I feel like I'm right on the edge of having this fixed but can't seem to get all the dots connected. As always, thanks for all the help.

eric_in_sd

Are you sure you got the ECU mated to the VIN? This kind of super limp mode sounds like what it might do if the ECU is not coded to the vehicle. Like you can confirm the thing works but can't drive it.

Galstaff

I was wondering that myself. I paid to have it programmed but don't have the STAR equipment to determine if it actually worked or not. I just figured it wouldn't start at all if it wasn't vin coded.

eric_in_sd

Your i980 should be able to query most systems. Have you checked to see if there are any results in the BENZ section?