Codes 19 and 20?
 

'94 E420 - Check engine light - checked analog codes and :

OK, I checked code 19, it says "Injector open or short circuit or emission control adaptation at limit"and code 20 is "Vehicle speed signal missing".

I reset the codes and then after two trips code 19 came back on. Anyone have any idea what this means, or what needs to be checked next?

Note: The car appears to run fine (though the accelerator has always been a bit touchy - I've owned the car for about three thousand miles, so I'm not sure how it should be).

Thanks -- Greg

If your speedometer is working no need to worry about #20 unless/until it comes back. #19 could be bad wiring harness if original. Next step would be to check codes on other pins to see what else you get.

Check my main web page (about half way down) for details on the #19 problem and a solution. :)

Code 19 is an adaptation limit excess code..it is also common on that chassis b/c the ECU had a small percentage +/- lee-way for limits before popping the code. That can be expanded to a larger % by changing the chip in the ECU [ do a search on code 19/JimF here]...

..but , before going that route, you want to check for BOTH vac leaks AND fuel pressure. A vac leak will cause ECU adaptation beyond limits to correct for the lean condition caused by the leak, and a bad FP regulator will cause a rich condition by leaking gas into the vac port of the reg or allowing too high of a FP. That rich condition will also try to correct , but if the system has to correct too much , same deal...pops the limit reached/exceded code.
So, I would check for both vac leaks everywhere and then I would check the FP regulator and pressure.
If the engine has many miles , then it is just in need of a higher adaptatation value than the ECU is capable of and the chip w/higher % limit can be done..but don't do that until you have checked the above first, as you may not even need higher adapations % limits.


EDIT *

Jim F and I were typing in the same time frame, so his Posting is the search notation I was referring to............he has those chips, if neeed.

I've got a spare wiring harness, so I'll go ahead and replace that as well as check for vacuum leaks and fuel pressure.

Is there a way to double check whether or not that chip is the problem?

Thanks! -- Greg

I certainly would make sure your vacuum lines are good. Don't forget the 'nipples'; they get small cracks and are hard to spot. Might just replace all of them.

The DTC#19 is not associated w/ a wiring harness . . . but if it NEVER been replaced, now is a good time. If it HAS been replaced, there's no need to do it again.

Not until you remove it from the fuel computer. I can assure you that's it's not the improved version.

If you find vac leaks or FP faults, just clear the code and run it ..if it was cured , the code will not come back up b/c you have solved the problem and the system has re-adapted within the limits.

However, as JF has stated , they found that as the engine wears , the adaptations limits of the original were found to be too close a limit for normal adaptations and by upping the +/_ percentage of his modofication, it gives the systsem more limitation % lee-way.
I have even seen a dirty a/filter bring on a code 19 with the OEM system..
But is your engine management system is in real "On The Money" running conndition, [ meaning no leak, wear, fuel mix, etc], then it will run within OEM limits just fine. There are many out there that do not bring on a code 19 and they have the OEM set-up.
A trick to do after you find any leaks or FP problems , is to get that code 19 cleared and then after you get a single Flash [ designating No Codes Stored], you then wait 2 secs, press button 6 sec , turn off key for 2 secs , on for 10 secs and start car...this will clear the adaptation memory back to mean [ zero] so the ECU does not have to readapt with drive cycles..you will then know you are starting with a zero base-line and if it hits adaptation limits after that memory clearing, then it has come from zero, not from the OLD adaptation memory that was set before the remedy...
Less chance of getting a false code while the system re-adapts that way..

OK,
Replaced the wiring harness, the old one wasn't all that bad off, but when I bought the car I was warned that the time was ripe (14 years) to replace it.
Checked the fuel pump pressure, just fine (~50 psi). Checked the intake manifold vacuum. seemed good (~15 Hg in, no wobbling), didn't spot any leaks, though the engine runs pretty much the same even when I've disconnected a hose.
I ran through the other diagnostics (thanks to the tested I built thanks to Dean's schematic). On pin 6 I got code 13, stop lamp. On pin 7 I got codes 5, 6 and 11. The only one that seems relevant is code 11 which says "Fuel safety shut-off to LH-SFI control module". Pin 19 yields code 19, back to "Injector open or short circuit or emission control adaptation at limit". Code 20 has not (as yet) returned. Pin 30 yielded codes 3 and 8, which I don't think are relevant to the problem at hand.
G. Johnson has suggested the air mass sensor, though I would hate to replace such an expensive item without further testing. Does anyone have any suggestions on what I could look at next?

JimF, what would cause the emission control system adaptation to go beyond the limit? I would rather get it back in limit (if that's reasonable) than to change that chip to accept a wider range (which is what I understand it would do).

Oh, I assume I'm doing no damage driving the car.

Many, many thanks. -- Greg

Did you check the FP reg port/line when checking the pressure.??

I used the test port that's on top of the engine pictured below. Is that the one you mean?

Greg

Yes, you could replace the MAF and that probably will add a few points (ie, raise it abit) to the S/A number and, while you're replacing, do the O2 sensor. Both 'fixes' are not cheap but the MAF is the expensive item.

The MB dealer fix for your problem is replace your fuel computer module, so if that's their solution, my is EXACTLY the same, except it's much cheaper but it does the same thing b/c it's the eprom that's in the new F/C module.

Leaving the way it is will do not damage but if you have to SMOG your car, it won't pass w/ DTC#19 present.

And all these codes came after you replaced the harness and cleared all the codes? Still runs OK? CE light on or not?

No..that is fuel rail pressure Test Port Fitting.

What we always check first when there is a fuel trim adaptation limit code
on EFI systems is the Fuel pressure REGULATOR vac port.

They are notorious for leaking by and that leak causes unmetered fuel to get sucked into the engine intake thru the vac hose , causing a rich condition that can be beyond ECU correction b/c it is raw gas that has by-passed all control systems [ un-metered fuel]
So, the test is to simply take the vac line off the REG. and look for eveidence of gas in that vac line..if ANY, replace the reg..it is leaking by...I also run the engine with the vac line OFF to see if any gas comes out the port..if YES , same deal..replace regulator..
That should have been done when you did the fuel pressure test b/c FP test is done with BOTH vac line ON and OFF. [ along with 30 min rest]
If no leak at reg , continue on with other possibles ..I mention this simple test only b/c of it fequency of failure rate on these and I have seen so many MAF and other sensors changed in vain b/c this FIRST test was not addressed.
Takes all of 15 secs., so I recommend getting it off the table ...
If it is bad , I also recommend my previous memorey Reset of ECU for Zero/Mean...after reg replacement.

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=2EI1B4MYE2ER0X76YW&year=1994&make=MB&model=E-420-001&category=C&part=Fuel+Pressure+Regulator

Arthur,

Yes, I disconnected the vacuum line from the regulator during the test. I didn't notice any fuel, but then I wasn't looking for any.

Deanyel,

I just reset the one code 19, not the others. I'll also try Arthur's suggestion of resetting the adaptation memory back to mean.

BTW, is there a simple method (eg disconnecting the battery for a minute) for resetting all of the codes?

Thanks -- Greg

Fault codes on the 38 pin connector are erased just as they are with the built-in pushbutton - by holding the button down for 8-10 seconds after reading the code.

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

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.

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

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.

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.

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

<<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.
>>

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.

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

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.

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.

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......

You're at no risk of being underrated here.