D-Jet Running Issues
- Thread starter Sam Lever
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Sam Lever
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Update alert........
Further early-morning investigations revealed a couple of injectors that had wiring that had definitely seen better days. I would say by the look at a couple of the terminals that they were not making reliably all the time. This is not exactly a smoking gun, but not good either. I've re-terminated and put new plugs and boots on all 6.
The newer TPS sounded a lot more like it should when connected up to the loom and opened than the older one that I had on the car, so I fitted the newer one again and set it up. I also re-terminated the 4-pin connector for that, seeing as I'd bought the bits anyway.
The car now drives near faultlessly. There is no faltering at a constant 50mph (the symptom that made me experiment with the other TPS in the first place) and none of the stuttering and buggering about that it has been inflicting on me recently at low speeds.
So, I conclude the older of my two TPS's is as good as junk. I am unsure right now whether the 50mph original problem was down to inconsistent connection and drive to two of my injectors (4 and 5, so not necessarily next to each other on the firing order, but the injecting order is different to the firing order in any case) or the 28psi fuel pressure that we ran before.
I shall, in due course experiment by lowering the pressure to 30psi as a half-way house and see whether it still drives as well. If it does then I think lower is probably better, so that we avoid any danger of over-fuelling, but mainly I am just relieved now that I have run the problem to earth and the car is back to its old self again.
Thanks for the hints and tips, and for reflecting my own thinking back at me too. This is very helpful in having the nerve and persistence to follow your hunches to their logical conclusions.
On a side note, I did see a listing on ebay for a genuine Bosch D-Jet TPS printed circuit board. The photo showed this as just the board that the contacts sweep and that is riveted to the main carcass of the TPS. I didn't buy it, as it's printing was very slightly different to mine and the part number etched onto it different to mine. However, it does occur to me that it must therefore be possible to get an electronic component manufacturer to make these PCB's up in future, as we are all going to need them and they are the only real wear & tear part of the TPS anyway, but when they go, the cars run like Sh1t!
Happy weekend to one and all! I'm off to the Silverstone Classic
Further early-morning investigations revealed a couple of injectors that had wiring that had definitely seen better days. I would say by the look at a couple of the terminals that they were not making reliably all the time. This is not exactly a smoking gun, but not good either. I've re-terminated and put new plugs and boots on all 6.
The newer TPS sounded a lot more like it should when connected up to the loom and opened than the older one that I had on the car, so I fitted the newer one again and set it up. I also re-terminated the 4-pin connector for that, seeing as I'd bought the bits anyway.
The car now drives near faultlessly. There is no faltering at a constant 50mph (the symptom that made me experiment with the other TPS in the first place) and none of the stuttering and buggering about that it has been inflicting on me recently at low speeds.
So, I conclude the older of my two TPS's is as good as junk. I am unsure right now whether the 50mph original problem was down to inconsistent connection and drive to two of my injectors (4 and 5, so not necessarily next to each other on the firing order, but the injecting order is different to the firing order in any case) or the 28psi fuel pressure that we ran before.
I shall, in due course experiment by lowering the pressure to 30psi as a half-way house and see whether it still drives as well. If it does then I think lower is probably better, so that we avoid any danger of over-fuelling, but mainly I am just relieved now that I have run the problem to earth and the car is back to its old self again.
Thanks for the hints and tips, and for reflecting my own thinking back at me too. This is very helpful in having the nerve and persistence to follow your hunches to their logical conclusions.
On a side note, I did see a listing on ebay for a genuine Bosch D-Jet TPS printed circuit board. The photo showed this as just the board that the contacts sweep and that is riveted to the main carcass of the TPS. I didn't buy it, as it's printing was very slightly different to mine and the part number etched onto it different to mine. However, it does occur to me that it must therefore be possible to get an electronic component manufacturer to make these PCB's up in future, as we are all going to need them and they are the only real wear & tear part of the TPS anyway, but when they go, the cars run like Sh1t!
Happy weekend to one and all! I'm off to the Silverstone Classic
I went through all that as well. Turned out my issue was a bad MAP sensor. Had it rebuilt and the car is simply amazing now.
My first move would be to get the fuel pressure gauge hooked up. Don't put it in the cabin just in case, strap it to the wiper. Do your high-demand test and look for a hiccup in pressure when you jump off and on the throttle.
Suspect fuel pressure regulator if test needle is jumping around. Quick, cheap test.
Suspect fuel pressure regulator if test needle is jumping around. Quick, cheap test.