98 E300 DT shut off delay - PeachParts Mercedes-Benz Forum

chiwanga · #1 02-01-2017, 08:42 PM

I have replaced the shut off valve twice along with all of the plastic fuel lines. The engine takes and extra 1-2 seconds to shut off and usually revs up a bit before the shut off occurs. The problem with this is that it throws a CEL and won't pass California smog. I'm wondering if the lift pump may be weak and causing this problem. Any suggestions?

tjts1 · #2 02-01-2017, 09:11 PM

My 97 has a similar problem intermittently. It triggers code P0200. I would just delete the code and immediately smog it.

tyl604 · #3 02-01-2017, 09:35 PM

I think you must drive around long enough for codes to reset first.

Diseasel300 · #4 02-01-2017, 09:46 PM

What is the shutoff system in this car? Is it a vacuum pod like the older ones, or is it a solenoid?

If it's a vacuum system, have a helper shut the key off and see if the stop lever immediately pulls down (if there is one). If it's slow or lethargic, it might be time to check the vacuum system out for leaks.

Could be barking up the wrong tree - I'm not familiar with the later cars.

chiwanga · #5 02-01-2017, 10:43 PM

I have to drive the car long enough after CEL reset to clear the EGR monitor, and that can take a while. The CEL will come on after 1 day of driving. It has an electric solenoid that cuts fuel. The solenoid has 3 lines attached to it. My understanding is that the lift pump provides negative pressure once the valve closes, in order to shut fuel more quickly. I may be wrong on this, but I'm going to take a $130 gamble and replace the lift pump. I'm not sure what else it could be.

tjts1 · #6 02-01-2017, 10:44 PM

Quote:

Originally Posted by tyl604

I think you must drive around long enough for codes to reset first.

The CEL resets immediately and needs a few cycles before it pops up again.

Jeremy5848 · #7 02-02-2017, 07:27 AM

The shut-off is electrical, not vacuum.

Diseasel300 · #8 02-02-2017, 10:04 AM

Are you sure the solenoid isn't gummy and otherwise hanging up? If it isn't fully closing, you can bet the car will take longer to stall.

jay_bob · #9 02-02-2017, 10:06 AM

When you clear codes you also clear the "I/M Readiness" flag. That flag takes several drive cycles to reset back to normal. You cannot pass smog unless you are clear of all codes, and your I/M Ready flag is true. This prevents you from pulling the trick of clearing codes right before entering the test.

The other thing in the fuel flow chain are the fuel filters. Have you replaced the o-ring that seals the top of the pre-filter (on the top side of the main filter stand, a hose plugs into the top of it). That o-ring can be a source of trouble.

VW1300 · #10 02-02-2017, 11:35 PM

Quote:

Originally Posted by jay_bob

When you clear codes you also clear the "I/M Readiness" flag. That flag takes several drive cycles to reset back to normal. You cannot pass smog unless you are clear of all codes, and your I/M Ready flag is true. This prevents you from pulling the trick of clearing codes right before entering the test.

The other thing in the fuel flow chain are the fuel filters. Have you replaced the o-ring that seals the top of the pre-filter (on the top side of the main filter stand, a hose plugs into the top of it). That o-ring can be a source of trouble.

Thanks Jay_Bob, I've always figured there must be something like that but didn't really know.