Arthur,

I rechecked the regulator. There certainly doesn't appear to be any gas coming out. I sniffed the hose and thought I detected a little gas, but it was pretty faint. How subtle might this be? (The regulator is the round device at the rear of the engine on the fuel rail with a vacuum hose on it, right?)

Now no codes (not even one flash) come from my reader on pin 19 or from the pushbutton module. All the other pins give readouts (which I have cleared) but not the one that I'm having trouble with! The LED comes on when I press the button, but no flashes. Of course, the Check Engine Light is still on.

Greg

__________________
Greg Stein
'94 E420
'86 420 SEL
'79 300 TD

If the reg was leaking, you would see gas in the vac line after a short run/idle. [ 2-3 min] It is possible not to have gas coming out of the reg port with the vac hose off and engine running , but still have a leak when the hose is on b/c with hose on , you have fuel pressure on one side of the Reg diaphragm plus engine vac sucking on the other side...meaning they are more likely to leak-by when they are hooked up then when the hose is off.
So, the best of the two test is to look for gas in the line after a 2-3 min ilde..that will be max condition for possible leak-by.
If NO, that is not your problem......but that does not eliminate a possible vac leak .
One causes rich adaptation and the other causes lean adaptations.
The first Possible Remedies list by Aldata for limit conditions are " Vac Leak/FP Regulator"..so, they should both be checked...what one is looking for is Unmetered air or fuel...which the ECU can not handle.

But then again, that ECU does not have a good lee-way..so, the question remains..How bad is adaptation requirements and why..
Benz made a change , so a change may be in order...just don't want to do that on assumption, that's all. Specially when FP reg and vac leaks are known common causes for that exact condition.

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A Dalton

OK. I'll check that again.

Is there a preferred method for checking intake manifold leaks, or a best place to hook up a vacuum tester? In the old days (I'll date myself now) we just sprayed carb cleaner around until we noticed a change in the idle speed.

Greg

__________________
Greg Stein
'94 E420
'86 420 SEL
'79 300 TD

Vac leaks are very hard to find on these systems b/c many can be Internal leaks that you will never see.

..the most common [ and I am only giving you these in probability rank b/c of known failure rates..I am not saying these are the problem] on these systems are Purge valve , egr valve , and Switch-over valves.

Purge is very common and an also mentioned on Alldata..they get crap in them from the canister and do not close/cycle well, thereby causing lean conditions.
Egr is same deal..they get dirty and do not snap shut...a hand vac test for this . The others can be check by pulling off every hose and checking for cracks or loose fitting.. I usually take a pair of sharp dykes and take every hose off, cut of and inch , and press them back on wit a little squirt of WD-40
On SOV's with plastic lines , I simply replace the plastic with rubber.

If you engine is running nicely, with good gas milage and nice power , you are probably fine and just need the extra % of adaptaion....but check these things anyway cuz they are free and should be part of general maint. anyway...........just like air filter and MAF cleaning.

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A Dalton

One last note on Fuel pressure.

You said you have checked it and it was Ok.. around 50, I think you said.

Well, a proper FP test involves 3 specs.
The first is with the REG vac hose ON, the next is w/vac OFF , and the 3rd is after 30 min for pressure retention test.
The first 2 are the important ones and have to be spec b/c if they are not , then the FP can be too high due to Reg control...if this is the case , you can have rich adaptation b/c the fuel duration is calculated by fuel rail pressure being spec.
So, those first two specs have to be checked @ idle and compared tp spec chart [ meaning, you are not just looking for FP, but rather , you ar looking for FP WITHIN spec, specially with Regulator vac hose ON] . FP with vac hose OFF is always higher than with vac hose on...and is too high for normal operation.

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A Dalton

You should get something - one flash or mulitiple, may not be holding it down long enough, or too long, should be 3-4 seconds.

Well, I know what I'll be doing tomorrow.

The FP with vacuum attached was ~50psi, and w/o about ~60 psi. Both within spec. 30 minutes later it was still about 50 psi.

I'll check out those valves tomorrow, recheck the codes, and let you know.

Thanks guys!

Greg

__________________
Greg Stein
'94 E420
'86 420 SEL
'79 300 TD

< >>

DM N/59 will not give any codes nor can it be Initiated after clearing until the systems has done all emmisions related self-test. That brings it back to mean. This requires drive cycles until ALL DM emmssions Self Test have been done.
N/59 module codes are Emmissions Related ONLY codes. This is the ONLY module that can not be reset until self-test are completed by design in order that one can not clear a CE lamp or erase impending emmissions codes when going for DOT Mandate testing.
All other modules can be cleared back to Single Flash/No Code status for diagnostics at will.

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A Dalton

Hey guys, just wanted to let you know that I'm still working on this. I've checked as many of the possible intake manifold leak culprits as I can think of, haven't found a smoking gun. Performed the fuel pressure test as described on Alldata, all within spec.

It's hard to test power, since I just got the car. It does seem a bit sluggish lately, but I blame ethanol. The shifting has always been a bit harder than I was used to on my old merc and at times it doesn't downshift like I feel it should. The mileage is lower than I would like, about 15-16 mpg. I'm not a lead foot, but my driving is 90% around town.

Are there any other suggestions?

I suppose that replacing that chip is a relatively inexpensive thing to try, though I would like to get to the bottom of all this. How do I go about getting one?

Thanks guys, I really appreciate all the input.

Greg

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Greg Stein
'94 E420
'86 420 SEL
'79 300 TD

What's the latest status on fault codes and CE light?

When you're ready, check out my main web page about halfway down. Send me email and we'll get one to you.

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Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Deanyel,

Check engine light still on, still getting code 19. You were right about the codes, I would get nothing until I drove for a while, then the codes would return.

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Greg Stein
'94 E420
'86 420 SEL
'79 300 TD

I think it was Arthur that said that, but I was thinking it, you've got to drive it a bit for the codes to come back. Sure looks like time for a chip.

Thanks for noticing that..I was ready to move on......

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A Dalton

You're at no risk of being underrated here.