Further R107 D-Jet frustration

Hi Volker,

I have (probably) located a "warranted" good MAP sensor from fuelinjectionproducts.com however, I am reluctant to spend the expected $450USD (more for me - I'm spending $CAD!!) unless I know this is the issue.

I am skeptical - this afternoon again I tested my current MAP sensor: both resistances are correct (90 and 350) and the unit holds vacuum.

I tried a little experiment: With the ECT sensor disconnected (the car will NOT run if it is connected, without exception) I disconnected the vacuum line to the MAP sensor and installed my hand-pump vacuum tester. I applied around 0.5 bar of vacuum and started the car. It ran as usual. I gently increased the vacuum to around 0.7 bar and the revolutions increased a little. At 0.7 bar it held its vacuum for a long time. Plugging the ECT sensor back in this condition of course caused the car to die.

At the ECT sensor plug one terminal goes to ground and the other does not. Am I to assume the wiring here is OK?

I realise this is all a bit confusing but I am really at a loss at what to do without throwing $100s++ at components just to see if they help!

J.

Hi J??? ,

if you search on this website you will find reports where this company was not praised for its performance on MAP sensor tuning and repair. Just recently a BMW case.

I really recommend you find someone with a 450 SL/C or W108 280 SE 4.5 or 450 SE / SEL around you and swap it. I have a whole pile of 0 280 100 100 MAP sensors lying here that were "raped". I recently had a case where such a MAP sensor had a strange black cap, rivets were removed and replaced by M5 screws and when I tried to adjust it I had to give up as inner components were also swapped resulting in a completely wrong curve. I will most probably see another such case next weekend during our grease monkey come together.

It is a nightmare to see what Americans do to those MAP sensors.

Just an example of a "tested" MAP sensor on ebay . God help us!

Hi Volker,

Here in Canada (not to be confused with the USA…) we have a significant deficit of D-Jet cars available for me to borrow parts so, in the name of science, I continue to try and diagnose rather than buy parts “just in case” they work. Like you, I’m looking at MAP sensors on EBay USA and have very little confidence!

So, a quick question. At the ECU connector I find a resistance value (c. 2.5kOhm) between pin 23 (ECT) and pin 1 (air temp). In my head there should be no connectivity between the two at all. This resistance is about the same as between 23 and 11. Could this possibly be the source of an electrical short? Any ideas?

Thanks for your help so far,

Jeff

Hi Jeff,

as both are connected to ground (11), you measure both in series.

Hi Volker,

I'm not sure that answers my question.

Indeed I can measure Pin 1 against Pin 11, and Pin 23 against Pin 11, but in my quest to find the fault in my system I decided to try Pin 23 against all the other pins in an attempt to find a possible short/wiring fault. I measured a resistance value between (of course) Pin 11 and then again at Pin 1.

As Pins 3,4,5,6, 16 and 24 also measure measure against Pin 11 would, by your logic, I not expect to see a resistance value when testing Pin 23 against 3,4,5,6,16 and 24 also?

I try to ask as few questions as possible, and have followed very closely all troubleshooting methods detailed on this excellent site, however with all components testing within the correct range I am really struggling to get this otherwise immaculate 450SL running with the ECT sensor connected.

The MAP sensor coils both show correct resistance and the diaphragm holds vacuum with no loss. By all accounts it is OK. Is there anything else I can test for?

Thanks

Jeff

Hi Jeff,

correct pins 3-6 should also show engine temp resistor when measured to pin 23. Injectors only have 2.4 ohms.