tirkes

Hi guys, this is my first post. I am having frequent problems with my 2002 ML320 this month. It has 55,000 miles. Last week I had a crankshaft position sensor replaced which cost me $480 bucks. The dealer said the computer is reporting errors from fuel sensor which sometimes fails after refueling. He said he needs to replace the pump (to fix the sensor) and also it's time for a fuel filter change. Estimate was $750, fuel sensor normalizes after sometime and the car was running good before the CPS failed, so I walked away.

One week later, the engine sometimes running shaky and noisy when idle. And it hesitates to accelerate from idle. But once it is moving, I don't feel any problem. What is this? Do you think the dealer is right?

Please explain in simple terms since I am a newbie.

Thank you. This is a great forum.

GordonTse

it could be the fuel pump.. because if it hesitates when you push on the accelerator that means it's not delivering your fuel instantly.. the pump could be hesitating.. iunno... just a guess..

tirkes

I called another MB dealer and he said it sounds like a MAF problem. So one wants to change the fuel pump, fuel filter and spark plugs, and the other one wants to change the MAF sensor. Go figure the expences.

He also said that the error codes that the computer gives are very reliable. Just replace whatever the diagnostic codes says. Is this the right approach?

Mr Cheeks

if you have a scanner or can get the codes read post the codes

tirkes

Sorry, I don't have a scanner. But if I had a diagnostic software, I could hook up my laptop. I don't know which one would be better.

benzeboy

I don't think it's your plugs, sounds more like a fuel filter. Try cleaning the MAF it might help. Good Luck

tirkes

OK. I went to a Autozone and got these two diagnostic codes:

P0339: Crankshaft Position Sensor A Circuit Intermittent

P0600: Serial Communication Link Malfunction

There is still vibration at idle and also during driving.

Note: Since my first post, I unplugged and plugged the fuel pump relay and fuse (trying to reset the fuel sensor). The fuel level gauge is corrected (for now). It feel like it will come back on the next refill tough.

jbowen1094

I also have been having these same issues. I have changed the MAF twice, changed the plugs and changed the CPS. Maybe I need to change the CPS again..

tirkes

The problem is getting worse. The engine was running really shaky for a short time yesterday. I pulled over to a Autozone immediately. The error code changed from P0339 to P0335: Crankshaft Position Sensor A Circuit Malfunction and P0600 again.

mediasteam

I don't think it's your MAF, with maf problem you'll get "check engine light", must be fuel related.

If you try cleaning your MAF you'll kill it and would have to replace it for sure, that's what happened to me. If you MAF is really bad then common thing you'll notice is rpm going up and down.

tirkes

I took it back to the stealership to find out why I get the CPS error (they replaced it two weeks ago). He said error code is probably old. I think he erased the CPS errors during the test. But I need new spark plugs and cable set, estimate was $1,300. The shop forman told me I have to replace plugs every year. His manager said the same thing. This is happening in Park Place motor in Dallas. MB recommendation is 91K miles or every 5 years. I reported them to MB customer service as highway robbers!

I went to an independent mechanic and replaced all the plugs with two connectors for $660. The main problem was two of the the spark plug connectors that had broken insulation. Interestingly, there were no OBD codes anytime related to the plugs. I was told that plugs or connectors will not give any error code until it gets to the point that computer will shut the fuel injection to the cylinder.

The rough idle is gone!

mediasteam

I'm glad your car is running fine now. I hate stealership, that's why we have this forum where we can share our experiences and sometimes we can fix things ourself. You never need to change plugs every year. When you reported them to MB I hope you mentioned what they tried to do.

MIKE_ML430

i think im having a cps problem. i start my suv and sometimes it takes more then one crank to start and after it starts and i go somewear and it sits for a wihle it won't start. and now today it stalled it never did that befor. i would drive it and when it got warmed up it won't start againg till it set for 30-40 min. am i right is it the cps?