When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I regret to advise that you have gone in so many directions at once that I haven't got the FFI where you are or where you want to go and what is the real problem.
I just want to make sure that the technical comments are appropriate for those in the future that may say----Oh I have a simular problem!!
Hm, not really. I just tested three things, I don't call it going in so many directions.
I have tested what was easily accessible and related to the fuel regulation (and most possibly broken according to other people experience): O2 sensor, air temperature sensor (just because it was right there) and airflow sensor.
I saw that the reader for the diagnostic was easy and I got confirmation of the airflow error... so I was just asking if what I got from the sensor was clearly a sign that it was broken. Nothing more.
I can't answer that question because I have not gone into WIS to determine what the actual value parameters are for a good sensor----you said you have access to WIS you can make that determination by researching your car and systems.
Older cars such as yours can't be diagnosed with the current factory diagnostic tools. The process is very detailed and you have to read\know\understand the factory actual values then do the tests such as you are doing then compare the data with what the factory determines to be the correct parameters----that takes much time--that I do not have!!
I have been checking on the link you provided me, but I cannot find anything useful, surely my fault. Besides that it is not possible to search for keywords, the bulletins about the airflow sensor are not really helping. The only one I found says that the error code 4 (mine) in the diagnostic is recorded when the controller detects a shorted or a open sensor and to check the cables before shipping back the sensor in warranty.
When I did the test of the sensor (the first time, not in the video) I briefly got >100kOhm of resistance, which could be interpreted as a open circuit (at least, if I expect
Last edited by gpaolo79; 07-14-2015 at 05:26 PM.
Reason: forum just erased 70% of my message...!
What I wrote is that it is exactly because I'm trying to read, know and understand that I'm asking so many things.
I have checked the O2 and air temperature sensors, compared the values with the charts and saw that they were ok.
Now I have checked the air intake sensor, but I wasn't able to follow exactly the indications because I had no plug to connect the multimeter without removing the connector and checking the voltage with the ignition on, so I checked the resistance and I saw a very erratic reading.
Since I'm not asking if I should read 7kOhm or 7.1kOhm, but if this strange behavior is symptom of a broken potentiometer, I would guess that it is not necessary to go through the entire encyclopedia of the car sensors if someone has some experience in this.
If it were a normal potentiometer in a normal electronic equipment, I would not need to read the label to tell someone that it is broken, because I have been designing, building and repairing electronics equipment for almost the last 20 years. In this case, it is something new, so I was asking for double checking.
If it matters, I have been reading and watching video of people who had this same problem with the sensor and they test the resistance of the new one and it changes smoothly when they move the air plate, so I'm pretty sure that mine is not working correctly, but again, I was just asking for confirmation.
If you can't tell, that is fine, really. If you don't have time to go through the entire database of Mercedes, I completely understand that and I would not even expect it. But if I have been checking three things listed in the first three pages of the injection system troubleshooting before beginning to unplug valves and disconnecting pipes without knowing that I was doing, please don't say that I'm jumping here and there and that it is not even clear what the problem is when it is described in the first post.
gpaolo 79 now come on dont give up , there are members trhat want to help . But work step by step .Get one problem sorted first ,then we can try and help on another .The problem i find is that, you car is very rare, in it being a 200e .But some one will help you .
Hi optimusprime, thanks, I'm doing my best. I just fear to touch something and to more damage. Anyway, I have ordered the replacement and as soon as I come back from vacations I will change the potentiometer and see what happens.
It seems that my car is rare indeed. In Italy, it was extremely common, as the 190E. Here in Spain where I live now, I haven't seen a single Mercedes of that age below the 300D. I guess that every country had its segment of the market.
Anyway, I think there will be no more news until august. The part needs a few day to arrive from Germany and I will leave next week until the beginning of August.
Thank you for your assistance and I will let you know how it goes...
gpaolo i hope you right about the potentiometer i have never had problems with mine, or know of any one that as . But i will do some checking the part out and see if i can come up with the problems that go with it. See you later .
Hello people, I'm back from holidays and I have just finished installing the new potentiometer.
You can see in this picture as the old one had the contacts completely worn out:
After resetting the Jtronic and calibrating (as best as possible, it is not really as straightforward as it seems in the instructions), I've got the voltage at idle in range:
What I have observed is that the economy indicator was back at left side of the range as it should be, but since the car was already warm from previous tests I'm not 100% sure that the issue is fixed. I will have to try it tomorrow to see how it starts.
Anyway, the diagnostic does not indicate any more failure and this was for sure something to get fixed.
I will let you know how it goes...
Tonight I tested the car, in what was one of the worst conditions (few hours after a drive). It took a while to start, so the problem is not really solved, but now the econometer stays on the left side, about at 1/5 of the scale during the first phase of the idle, then it goes down quite fast.
Despite it is not the solution, this has been a great improvement. Since in a couple of months I have to go through the yearly check of the car I want to ask a recalibration of the idle while they are checking for the exhausts, to be sure that the new airflow sensor is correctly seen by the controller.
In the meanwhile I will keep investigating, checking also the other things that you have mentioned in this thread (now that I have seen how to remove the air filter...). Today I have also seen that the gasoline circuit seems to hold pressure well also after some time that the car has been stopped, so there should be no issue there.
gpaolo have you cleaned out the air control valve see picsin my early post . .Its just remove it from the engine and let it soa over night ,or you could spray inside it with carb cleaner.,at the same time check the hoses for crap and splits.
I have checked the idle air valve and it seems working fine. Resistance is correct and it moves quickly when it is powered.
While I was there, I have also checked the OVP relay and it is fine too.
If there isn't any other idea, I think I will take the car to the mechanic to get the mixture adjusted, after changing the air flow sensor it may be worthy to have it tuned.
Hi all, yesterday I took the car to a new mechanic (Bosh specialist) to have the air/gas mixture tuned. He seemed quite confident of the nature of the problem, and this was the first time in years. He told me that it is a matter to adjust the air plate to get the right amount of air and that it is a quite long task to get it exactly adjusted.
In these days I have seen that, after the sensor replacement, the situation has stabilized. Now when the car is cold it always takes some seconds to start (5-6 seconds), but the econometer gets on the left side quickly enough.
I will see if this time is the good one. I will keep you informed!
Bye
Hi, I went yesterday to collect the car.
After the adjustment, it starts better but it still needs a couple of seconds to start running. The mechanic told me that the injector are not in perfect shape, so he suggests to change them (40€/each).
I will put it in my to-do list for this month maintenance...
Anyway, the car now seems to be running a lot better also in normal drive, for sure the mixture adjustment was a good thing to do.
Resuming, for other people with the same problem...
The original situation was random extremely difficult start up, especially when the car was parked in the sun and when parked for a period of time between a few hours and 3-4 days. Econometer indicating a high gas consumption during the first minutes running at idle after a difficult start. Hot start was fine.
All sensors have been tested fine except for the intake airflow potentiometer, which was completely worn out. Also the test port was indicating a potentiometer failure. Idle air valve was tested fine too.
After changing the sensor, the situation stabilized. The gas consumption wes greatly reduced at idle and the car was taking always a few seconds to start up, in every conditions.
After the mixture calibration, the car is starting up in a couple of seconds and it seems that the injectors (25 years old...) need to be changed. In general, it runs better and it is more responsive.
So it seems to have been a combination of different issues.
I guess that for me this thread has reached its purpose. I will update it when I will change the injectors, in the meanwhile thank you for your collaboration!
07-14-2015, 03:49 PM
