Engine Problem

Hi Volker,

Since our last correspondence I have tried to clean the oxidation on the top electronic board of my ECU as much as I could.
Due to your advice I did not go further. Any how there is no change in the behaviour of the engine. There are sweet spots - certain revolutions (engine rpm) and throttle level when the rpm drops and I have to decelerate or accelerate to regulate the engine. As I mentioned before these are around 1300-1800 rpm and 2700-3100 rpm. There is a higher level but I do not want to rev up the engine to such a high level.
Other than this I have checked my fuel tank to see If there is dirt inside. There are rust spots but not much dirt was found. Furthermore I have been able to find five new injectors which I have installed to see If there is a change.
Also the rpm limiter Adi mentioned was replaced nothing has changed. When the cold engine is started the choke brings up the engine rev to 1600 rpm and it goes down gradually to 800-900 rpm as the engine warms up. Hitting the cold start valve does not change the rpm.
In general there is vibration of the engine during driving and also at idle after warm up at every rpm level.
You cannot feel the problem in the newly warmed up engine only after couple of hours of starting shutting off and restarting the problem is felt.
You have previously suggested that I should get a new ECU. This option is always there. If you do not mind I would like to send my existing ECU to you for inspection. You do not have to send it back to Turkey by mail. I will give you a local address in Germany for you to deliver it. I will have it delivered to me later. I want to make sure that my problem is with the ECU and/or the ECU is faulty and it has to be replaced. Due to my business I am involved in board repairs constantly. If you do not want to deal with this unit because of its condition can you please provide the outlines on how to perform the tests I can have it done. I am ready to pay for this service, too. This is not a problem. It took me a long time to bring this car to this condition and driving it only to the mechanics and back makes me sad.
Enjoy the IAA show
regards
juan

Ignition coil?

Hi Ismos,

If by ignition coil you mean 'die Zündspule' it is 0 221 122 001 Bosch. I also have an old version which I may install but do not have the number in hand.
Die Vorwiederstaende: 0 227 901 012 and 013 are also there.
Apart from those MPS (Saugrohrdruckfühler) was serviced by part bob from Bosch. I was told it is working fine.
Five out of eight injectors were replaced by new ones last week. I am still looking for three brand new ones. I am open to any suggestion where I can buy the rest.
TPS(Drosselklappenschalter) gold plated board was replaced with a new one. I bought it in Holland (NL)
Zusatzluftschieber will go through 'maintenace' next week.
The Impuılsauslöser was replaced with a new one from MB (original Bosch) couple of months back. since then the car was driven only couple of 100 km.s
Zündschaltgaeret 0 231 402 001 (TFUDX
Unterdruckvertseller 1 237 121 373
Kabelsatz was replaced with a new one. Mechanic said when the engine was attached to the Bosch test geraet it was ok. with the old cables the oscilloscope images were not good.
Fuel pump(original Bosch), Dämpfer and Filter (Bosch) fuel line pressure is 2,0 constant during idle and at higher revolutions.
Air filter brand new
Air filter sensor brand new
I did not check the Thermozeitschalter.

Hi Juan,

when I read that u have replaced trigger cams: Make sure that the plate and cams are properly fixed. I have seen strange effects with loose cams before. Additionally close the fuel line to cold start valve. With that u exclude any effects from cold start valve and thermo time switch.

Hi Volker,

If you mean the the adjustment of the distance b/w pertinaxnocken and the amboss. I checked the original that arrived from MB with the device of Norbert and made the adjustment before installation. Also I asked my mechanic to check the cams of the Zundverteiler whether it was loose or not. He gave me the ok to use the original that came with the car. I have a spare one as well. Both were used to test if exchanging the ZV made any difference. Unfortunately the result was the same. after new amboss was installed ignition timing adjustment was made with the stroboscope lamp.
You had suggested to check the ignition timing at idle,1500 and 3000 rpm. This I would like to test this week If possible.
After new injectors were placed we have checked for any leakage as well. There was none.
The problem occurs at multiples of a certain rpm ie 1350, 2700 probably at 4050-4100 level. So it seems to me that the problem is cyclical. Does this ring a bell? You had mentioned in one of the articles that the ECU is a primitive pc but instead of software control it has the electronic blocs. Which area of the ecu ( If there is any) receives/ processes rpm data?
Rgds juan

I forgot to mention that I have also had the compression of each cylinder measured.the lowest was 150. It varies b/w 150-165. Only one was 180. I think in this one the injector was faulty. We first noticed that spark plug was wet and then checked the injector. Decided to replace it.
Are these ok? Where can I find the data for the compression values?

Hi Juan,

well cams can be loose if the rep kit's screws are not tight etc. I have seen that.happen.

I have no guess what should cause a problem at multiples of 1350 rpm. Remember it is an analogue ECU.

Ignition coil or rotor. ?

Electronic ignition unit checked?

Hi,

there is nothing neither in ignition or in injection system that makes special operations a certain multiples of 1350 rpm.

rsadut schrieb: Kabelsatz was replaced with a new one.

Do you mean the wiring loom? May I ask where you sourced it?

Hi Ismoz,

I had the original wiring loom. I have obtained all the sockets from a Bosch dealer in Sweden.
Than took it to a local manufacturer to do the wiring. If you need addresses I can provide the details.

rgds
juan

Hi Volker,

Based on your advice I looked for a former Bosch specialist who is now a MB specialist. He is working on the car now. He has the electrical wiring diagram. He found the following faults with the engine. Firstly he claims that the DKS wiring was done wrong. He has changed it. Secondly he also told me that one of the injector connection (5 and 6) was wrong. He corrected it. He also mentioned that the ECU was causing problems at the connection port. I have had this problem when I took it out for cleaning. Anyhow he has also cleaned the bottom board but he is not sure about the re-soldering he has done. Is it possible to have the wiring diagram for the exterior resistors to check the correct wiring.

brgds
juan

Hi Juan,

those connectons are printed on the PCB.

Hi Volker,

I got my ECU back from the Bosch service. Please see the picture attached. The picture shows the exterior resistor panel. Out of the 12 white cells four of them are black and white. there is no continuity on the b&w cells. the rest show continuity. when I measure all show 1.0 on 200M(ohm). What do you make out of these pictures and the info.

rgds
juan

Hi Juan,

why would a Bosch service remove all power resistors and not put them back???

There are 6 and 30 Ohm resistors. Measure with proper range setting on multimeter. When I come to Istanbul next time I will want to see that Bosch Service.

Hi Volker,

thank you for the assistance. I checked all the resistors.

Starting from socket connection to the other and each four cell lower left+ lower right+ upper right+upper left I measured the following:

6,0+6,4+6,0+6,2; 6,4+5,9+6,2+6,2; 30,7+29,3+31,0+30,5. Are these within tolerance limits?

brgds
juan

Hi Juan,

not knowing your measurement equipments accuracy I should say yes.

Hi

Just checked the specs on the net for my device. the tolerance is for reistance it is +/-(% 0,8+2).

Hi,

regarding your PM on vacuum level. If you ask it here again, I will reply as I always do.

Hi Volker,

I do not remember asking any questions about PM on vacuum level. Could this be an answer to Nother question.

As mentioned before I will mount back the resistors as they seem ok and close the box. Are there any basic measurements you can recommend to check the ecu and its components.

The reason the MB service (former Bosch service) claims he wanted to check the bottom board was failure to start the engine. That means : after he made repairs in the injector line and cabling of the DKS he could not start the engine. When he tried with another ecu from a 450 it worked. He claims he thought there was a problem with the ecu. I have had this problem as well when I started to write to you about the ecu. When you shake the socket area after several trials it works.


Rgds
Juan