W163 ML430 1999 - Crank but won't start
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ML430
W163 ML430 1999 - Crank but won't start
Hello everyone,
I'm having trouble with my SUV and hope I can get some help troubleshooting further. I hope this isn't too verbose, but I'll walk through the problems that led me to this point.
First off, the water pump bearings failed taking the belt and front main oil seal with it. I replaced the water pump, front main oil seal, and belt. About a week after that, the engine didn't run smoothly. It would idle roughly and I had a few misfires. So I removed the air intake, cleaned the TB as best as I could, and cleaned the MAS. It ran ok for a few days, then died while driving and would crank but not start.
At this point, I cleaned the throttle position sensor and made sure it was moving correctly. I also took out the throttle body, cleaned it, and reinstalled it.
I checked for error codes and got: P0341, Camshaft Position Sensor (CPS). So, I replaced the CPS and cleared the codes, but the SUV still won't start and the same error code came back.
I also checked the fuel rail pressure, and it's ~45-48psi. I don't know if that is low enough to have zero ignition, but I suspect not. So I'm guessing the fuel pump, filter, relay, and fuses are probably okay.
I'm worried I might have messed up something with the O2 sensors, the throttle body, or the MAS when I was working on them. But everything seems to be reinstalled correctly. And I don't know what, if anything, in those loops would prevent ignition.
I'm thinking the next step is to check if I'm getting a good spark. I need to figure out how to do that for this engine.
Recap:
If anyone has any ideas on what else I can look into or if you need more details to help me troubleshoot, please let me know. Thank you for any advice you can give!
I'm having trouble with my SUV and hope I can get some help troubleshooting further. I hope this isn't too verbose, but I'll walk through the problems that led me to this point.
First off, the water pump bearings failed taking the belt and front main oil seal with it. I replaced the water pump, front main oil seal, and belt. About a week after that, the engine didn't run smoothly. It would idle roughly and I had a few misfires. So I removed the air intake, cleaned the TB as best as I could, and cleaned the MAS. It ran ok for a few days, then died while driving and would crank but not start.
At this point, I cleaned the throttle position sensor and made sure it was moving correctly. I also took out the throttle body, cleaned it, and reinstalled it.
I checked for error codes and got: P0341, Camshaft Position Sensor (CPS). So, I replaced the CPS and cleared the codes, but the SUV still won't start and the same error code came back.
I also checked the fuel rail pressure, and it's ~45-48psi. I don't know if that is low enough to have zero ignition, but I suspect not. So I'm guessing the fuel pump, filter, relay, and fuses are probably okay.
I'm worried I might have messed up something with the O2 sensors, the throttle body, or the MAS when I was working on them. But everything seems to be reinstalled correctly. And I don't know what, if anything, in those loops would prevent ignition.
I'm thinking the next step is to check if I'm getting a good spark. I need to figure out how to do that for this engine.
Recap:
- Replaced water pump, front main oil seal, belt
- Rough idle -> abnormal throttle/power
- Removed air intake, cleaned MAS/TB as much as possible -> ran ok for a few days -> died while driving -> crank but no start
- Removed TB (had to remove O2 sensors), fully cleaned it, reinstalled everything -> still crank but no start
- Saw the CPS code at this point -> replaced CPS -> tested fuel rail PSI (~45psi) -> no change
If anyone has any ideas on what else I can look into or if you need more details to help me troubleshoot, please let me know. Thank you for any advice you can give!
Last edited by getDown; Apr 1, 2024 at 11:14 PM.
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