LauraS

While checking the diagnostic panel terminal 14 this error code was detected "TN/TD signal (RPM) interrupted". Does anyone know what this is referring to and what it means in relation to the operating system of the engine.

dolucasi

I checked the circuit schematic and I stand corrected. The TD signal appears to be powered up by my fuel pump relay ('89) which means with your MAS unit.
So it is powered up by MAS, goes to the EZL, ECU, X11 ports.

So if there is an interruption to this signal it is likely that the ECU will throw a code.
Not sure if this code might be generated because of a stall by mistake (because in a stall everything is fine except the engine dies and the ECU might be tricked into the TD signal being lost because the FPR turned off the pumps and most likely the TD signal)

So I would erase this code and see if it comes back in absence of a stall. Unfortunately if there is a stall, one then could not determine if this is a cause or an effect.

LauraS

Thank you. I cleared the code and it has not returned. I guess maybe fooling around wih checking connections and as you say the occasional satll might have been the trigger. The car started this morning frst try, engine went to 1000rpm then slowly descended dw to abaout 500 before recovering back up so about the same as before. Possiby the accumulator is weak and the fuel pressure takes a moment to build? Anyway the G.S. now has the car. It was the best gramma could do.

dolucasi

Good to hear Laura. Grandma to the rescue.

We know that your fuel system does not hold pressure and goes down to near zero overnight.
When this happens, there is a chance that the morning start might be a little more difficult I suppose because there could be some air in the system and it may take a second start.

BTW, remember we compared fuel pressures with you after engine shut-off. Also recall mine holds pressure ~2.8bar immediately after shut-off but holds pretty steady for hours.
Spec is over 3 bars.

Long story short I just changed my fuel filter (overdue, it had been 55K miles) and in the process I checked out the accumulator. It was original with the mercedes insignia only.
I had a spare one from a junk yard that actually is a different part number and with both Bosch and Mercedes insignia. It was larger in volume by a good 40% as well.
I tested both, and both would hold 50psi with no major leaks but my original drips a few drops of fuel. Also both when the air compressor is stopped will hold some pressure just like they should. So I swapped in the JY find just to see if there is a difference.

Just tested the car and still will stall on the first warm strike if I do not assist with a little gas pedal. I'm pretty confident this behavior (warm stall) in my case is not related to the accumulator. Not sure what it is but it is not the accumulator. I have decent pressure in the system after one hour.

Now back to your GS's problem. When I replaced the fuel filter, of course there is air in the system and even though the pressure builds up in one second the air has to clear before the car will start and keep running well. And my car took a little longer to start after the filter replacement and it stalled once or twice till all the air was cleared out of the system.

I think this might be happening to your GS's car since the fuel pressure is zero, maybe some air bubbles develop by the morning and it has a harder time to start and stalls once.

LauraS

When I was testing the fuel pressures I did leave the gauge attched to see how long the pressure would hold. It started out at 4.0 and in 5 hours hd dropped to 3.5 but then I didn't check until the next morning and the pressure was 0. The car was starting warm first try when I returned it. Fuel filter has only about 3Km on it but accumulator is original.

dolucasi

Checking the accumulator is easy but a bit messy.

Use most of the tank till the gauge light comes on
Jack up car
remove plastic cover
have a bucket and a 3/8 inch drill bit ready
loosen the clamp on the rubber hose aide of the accumulator, this is the gas tank side.
pull out the hose and let it drain a quart or so in to the bucket, you will surprised to see some water and gunk in there if it was never flushed.
plug the hole with the 3/8 inch drill bit round end.
You can turn on the key to ignition on, engine off a couple of times to develop the 5 bar pressure (you could start the car too but I do not like starting cars on jack stands)
See if anything drips at all. It should be bone dry. Yours especially is a very minor drip

I would have your GS do this. He is the teenager after all.

- Cheers!

LauraS

Thanks, I will get the gS to do that someday when I see him. I got the car running pretty well. It starts cold and hot without a lo of cranking and it has good performance. One thing though is that 17 error code keeps coming on. I tried to check the duty cycle with a variety f multimeters and evn my old Snap-on dwell gauge. Nothng seems to work to give me a a reading o the X11 diagnostic.
My new multimeter when set at duty cycle % shows something like 99 -100% whereas the old one reads the opposite at around 00.0%, when set to volts I get 0.1V and when I tried the dwell meter it showed about 26degrees. The car however runs so well I can't believe there is much wrong. If this were your car where would you start? Should I get a new EHA, rebuild the FD, try another O2 sensor? The car is gone for at least a week but I have my doubts that it will last much longer.

dolucasi

Code 17 is still a problem. I think you were supposed to measure your fuel pressures with the EHA disconnected after the car warms up.
I would actually also connect your EHA current meter while doing this and leave one lead unconnected (which disconnects the EHA).
After the pressure readings, connect the meter and report on the reading.

I'm not sure why you are not getting the duty cycle reading, hopefully it is not railed to 0% on your meter, which is fully enriched. We'll find out.

I would not replace any parts, just take measurements for now.

LauraS

I will do that when I get the car next. Grandson has it now and it runs well so he may not want to bring it to me.It isn't running rich or has gas smell and accelerats well with no hesitation or smoke at tailpipe. My new multimeter may be defective or not the kind to read duty cycle on these cars. The old one shows 70% with KOENR and 50% when in cold open loop (correct) and occasionaly shows around 47-48% when closed loop but then wanders all ove the scale. The new one just goes to the 98-98% and sticks there. I may not know how to run it.
but the new one shows something like 90% KOENR so definitely crazy. I am at a loss. I think maybe the o2 sensor needs testing again also. I will do the test you asked ASAP. I am getting so tired of this but would like to solve the problem just for my personal satisfaction.

dolucasi

You can always trust the average voltage method if all else fails when the car is back.

LauraS

o of my multimeterss showed a voltage of 0.1V? Not much math to do with a reading that low.

dolucasi

Your EHA is railed full tilt to maximum enrichment. Not a good thing Laura. I think this was also verified with your EHA current at +13mA/14mA.
It seems all systems are having to make the ECU enrich to the max and are working since the car is running OK.
Let's us know how the Fuel pressure readings go next weekend. Now your GS has to visit you for sure.
See, this is working all according to plan. If you had given him a honda-civic, you would see him once a quarter.....

LauraS

I have been thinking that maybe the best course of action is to order a new EHA and see if that solves the problem. At it's present mileage of about 130km it will probably be due for a new one anyway. I reccorded a FP differential of 0.4Bar with EHA disconnected but higher when connected. Would adjusting the EHA screw to a leaner setting help or even worth a try? The car runs great once under way but warm starts seem to be the worse issue plus a small uneveness in the idle speed. The cost is about the same here as you US with dollar exchange difference. I am not one t buy parts unless sure but in this case the likley culprit seems to be the EHA. The temperature gauge seems to be working fine so I guess the 4 pin temp. sensor shouldn't be a problem. The EHA seems to be the most likely component to have failed. A Civic would be no good as I would likely only see the gandson at Christmas.

dolucasi

The EHA's tend to leak before they malfuncion (by a lot). Which is why one hardly reads about failures in functional failure (as opposed to leaks). The are $250 US as you know.
Now, I believe yours was a Ebay find correct so probably used, so that changes the equation a bit.
A refurbished FD (good as new) is $400 US, so in the same scale at least.

Since one or the other is messed up anyway you can probably try to adjust yours to see if you can get away with it. Most likely, there is some blockage/leakage inside the FD that is causing this so EHA adjustment maybe futile but it may make things a bit better until you get the FD rebuilt.

Recall, just recently Nate tried the EHA adjustment and was chasing ghosts until he sent out the FD to flowtech.

I'm not a betting man but if I were, I would put my money on FD. I do not know if there are further tests you can do to pinpoint between the two but remember, the car is supposed to run OK (not perfect) with the EHA disconnected when warm. And if you can not do that with adjusting the EHA I think all arrows are pointing in one direction.

I thought you had a spare EHA no?

If you do not, I still have an open suggestion to you. I can send you a functional EHA that leaks a bit. Was in my car for about 70K miles. Perfectly OK to just see cause and effect but not to keep in the car outside an experiment.

LauraS

Trying to source a rebuilt FD in Canada will be a challenge but I will try. Engine with EHA disconnected does run OK and you can easily see that it changes to the better when reconnected. For now apparently it does run fine once it has started and idles for a few seconds until it smooths out so not a big issue. If the FD had issues would the engine performance not be affected throughout the entire engine RPM range. Idle is fine once it recovers from probably over rich mixture at start up. I guess I am trying to convince myselt EHA is the problem. It is original to the car and has no leaks. Perhaps a 1/4 turn on the EHA screw will lean it out a bit? Don't know when car will show up ,maybe next week but I am going bird hunting a ways north for a few days so don't know when I will have a chance to see it in any event. I have a suspicion the grandson has been fiddling with the mixture screw since he was talking about trying to get more performance and of course knows how to find info on the net. Thanks for your kind offer on the sparee EHA and I might take you up on it but new ones are not that expensive. I do have my BMW money to play with !

dolucasi

I believe the way Flowtech works is they send you a refirbished FD, and you send them yours afterwards after you swap it in for core value.
I have never done this, maybe ask them and see if they ship to Canada. If for nothing just data collection.
I would not buy an EHA or an FD from a random ebayer though.

Tell your grandson not to mess with that screw if he has, and if he has, he needs to come clean now. Otherwise the diagnosis is impossible.
It is entirely possible it is messed up due to the fiddling.
Also tell him you can not make a car better or with more power than the spec 45% duty cycle. You know all this already so I'm preaching to the quire here.

If he has fiddled with the lambda screw, the first thing to do is to re-adjust it back, and not change the EHA at all, that could even make matters worse.

LauraS

Yes my worry is that the A/F screw was messed with since the car was running perfectly when I gave it to him. The problem is how do I get it back on track if the Duty Cycle is at 0 ? Is it too rich or too lean ? I will have to ggiv him a very stern talking to if he has caused me all of this added trouble.

dolucasi

At this point let's hope he messed with that screw. Because that is the easy fix. Duty cycle is actually near mercedes definition 100% (0.1V), so it is adjusted too "lean" and the ECU has to increase the EHA valve current to enrich it back closer to normal, if this in fact is what happened.

LauraS

I spoke with he grandson today and sure enough he admitted that he and a couple of friends decided to try and get more performance by giving the car a richer mixture and then when it wouldn't start he tried to reset the mixture screw but couldn't remember how far he had turned it but he did get it running again. So maybe not such a bad result afterall. Once he brings the car up this week I will adust the mixture and see if that's all thats amiss. Kids will be kids. I remember my brothers trying to hot rod their cars back in the 50's and 60's so no surprise what a teenager will do.

dolucasi

Very good news indeed! Hopefully he learned a lesson.

355190e26

Laura-what your grandson reminds me of what I tried to do years ago on my car. I wanted it to go faster, but didn't know how to properly adjust the screw. It was running so rich, I was getting about 14mpg!
Learned my lesson, now I don't mess w/ the adjustment unless I have my neighbor (retired mechanic who knows CIS) nearby.

LauraS

I have never touched that screw but will have to give it a try with the Duty Cycle meter hooked up.

dolucasi

I have only adjusted mine one time months after an EHA replacement and the FD was already tempered with. And that was to just push it from 35% to 45%.
And it took a tiny bit, like 1/8th to 1/6th turn CCW (its been a while so don't quote me on this). I believe you are supposed to go CW to lower the duty cycle from near mercedes 100% to lower. Honestly, I would measure voltage instead to bring it to a reasonable rough adjustment first and shoot for ~6V. Then switch to duty cycle to confirm. And run it around the block before the fine tuning.
Just remember to go slow, let the duty cycle settle after each tiny bit turn. And of course you should first warm the engine before any of this.

Good luck!

LauraS

Thank you. I will let you know how it all works out when I get to see the car. I appreciate all your help and in fact I don't know what I would have done without your help. It is greatly appreciated.

LauraS

Dolucasi, I can't thank you enough for your analysis of the grand son's 190E. I had him come up to visit yesterday since I postponed my hunting plans. I adjusted the 3mm mixture screw on the FD turning it about 1/8 a turn CW (rich?) and EUREKA !! I got a Duty Cycle reading from 0 to somewhere in the 30% range. With some very minor further adjustment I moved it to the 47-52% range and left it at that. The car now starts instantly cold or hot as reported by the GS.this morning. I also had him jack up the car and test the accumulator as per your instructions. He got a good spray of gas on his arm when he removed the hose from the tank. A 3/8" drill bit seemed too large and a smaller diameter one was needed to stem the flow. We watched for several minutes and no fuel leaked back from the accumulator so i guess it is OK. The fuel from the tank was clear with no water or particles either. The error codes 3 and 17 were cleared and did not return after running the car for aa test drive. All in all I am very pleased that the car is operating as it should thanks, once again, to you. My grandson learned a valuable lesson....not to play with something he doesn't understand.