Playing with ocscilloscope still a lot to learn. This is No1 injector firing
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| Solid State DME relay https://forums.tipec.net/viewtopic.php?f=25&t=24561 |
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| Author: | Endoman [ Wed Sep 30, 2020 3:02 pm ] |
| Post subject: | Solid State DME relay |
I bought a couple of the for both cars with pump prime from Focus 9 (the 944 did start quicker). Last night car wouldn't start, it was still warm. After a couple of tries it fired up and ran fine. This morning no start I pulled the DME relay and put the old one back in (always in the glove box). Car fired up as normal and did the Tesco run no problem. So be warned they are not infallible and I'm annoyed because they are not cheap. We always carry a spare, don't we? I'm tempted to send it back not had a year. Got the oscilloscope working at last (bloody software drivers) and it works a treat. Hantek 1008C, an absolute bargain compared to Picoscope. |
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| Author: | Wh1t3Kn1ght [ Wed Sep 30, 2020 7:25 pm ] |
| Post subject: | Re: Solid State DME relay |
Interesting - I've never in recent memory had to replace a DME relay, did 90k miles in the Turbo as well... Has the oscilloscope work then? Do you have some sort of interface for the probes that connects to USB / Serial? |
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| Author: | sgl1966 [ Wed Sep 30, 2020 7:57 pm ] |
| Post subject: | Re: Solid State DME relay |
I also had a problem with the solid state , all good to begin with but after a short while fuel pump running continually with engine turned off . Old relay back in , all good . |
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| Author: | Endoman [ Wed Sep 30, 2020 8:11 pm ] |
| Post subject: | Re: Solid State DME relay |
Oscilloscope connects to laptop and has 8 channels. You can select a baseline check display which will run above your test. Probes are simple crocodile clips so a bit of ingenuity required to get the right contacts. They do supply an induction probe for ht leads and I bought a probe to check high currents also by induction it will do low currents if terminals are inaccesible. I've used it on the coil. HT leads and MAF. There is a steep learning curve, some good youtube vids (some rubbish) and a good book Automotive Oscilloscopes: Waveform Analysis Book by Graham Stoakes. As my 944 does not have OBD (for what it's worth) I can now test crank sensor, hall sensor, wheel sensors (though I have the Porsche tool). MAF was quite revealing. Seems daft but you can check cylinder compressions by watching how the current flows in the starter circuit. You can't have too many tools or gadgets. I'm the same at work first dentist in the NW to buy a microscope and digital xrays. You've got to have something to occupy yourself in these times. |
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| Author: | Endoman [ Sat Oct 03, 2020 6:12 pm ] | ||
| Post subject: | Re: Solid State DME relay | ||
Playing with ocscilloscope still a lot to learn. This is No1 injector firing
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| Author: | Endoman [ Thu Oct 08, 2020 8:10 pm ] |
| Post subject: | Re: Solid State DME relay |
Had to drop a part off at Wayne Schofield's place in Rossendale this morning and guess what the mechanical DME relay failed right in the middle of town holding up 2 lines of traffic. Jumped put swapped the 3rd relay and off I went. When I got back dismantled the errant relay and the signs of overheating are obvious, 3 joints on the pump relay are cracked. Works now when it's cool but warm it up and it starts to fail. I thought the solid state would have solved the problem but obviously not. |
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| Author: | Waylander [ Thu Oct 08, 2020 9:51 pm ] |
| Post subject: | Re: Solid State DME relay |
Just makes me think there is to much load on the relay, mine is original as far as I can tell, I have a spare but never used it in 7 years I would be taking a look at the draw from the fuel pump, to see if the issue is being forced by another problem |
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| Author: | tr7v8 [ Thu Oct 08, 2020 9:54 pm ] |
| Post subject: | Re: Solid State DME relay |
Pump starting to fail & using more current, maybe? |
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| Author: | Endoman [ Thu Oct 08, 2020 11:46 pm ] |
| Post subject: | Re: Solid State DME relay |
Fuel pump drain sounds logical, trouble is it's not that old. I'll check the current flow and connections including earth. Thanks for your insight. |
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| Author: | Waylander [ Fri Oct 09, 2020 2:51 pm ] |
| Post subject: | Re: Solid State DME relay |
so the fuel pump is on a 15amp fuse or should be, I think the pump should therefore be less than 10A |
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| Author: | Endoman [ Fri Oct 09, 2020 7:44 pm ] | ||
| Post subject: | Re: Solid State DME relay | ||
Ran the current draw test with the scope and it's very erratic. Average around 4 amps but it looks like there are a couple of dead spots on the commutator followed by a spike of around 10 amps. new one ordered. This Bosch pump is less than 4 yrs old previous one was 25. It's one of those tests where when you look at it everything is fine then next day it starts missfiring. Quantum fuel pump?
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| Author: | Waylander [ Fri Oct 09, 2020 7:50 pm ] |
| Post subject: | Re: Solid State DME relay |
Interesting stuff |
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| Author: | Endoman [ Sun Oct 25, 2020 10:48 am ] |
| Post subject: | Re: Solid State DME relay |
Pump and filter changed, old relay resoldered. No improvement. Cleaned bulkhead and engine ground points and it runs perfectly, for now. |
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| Author: | tr7v8 [ Sun Oct 25, 2020 2:13 pm ] |
| Post subject: | Re: Solid State DME relay |
I'm told there are a lot of dodgy copies of Bosch pumps. Not saying yours is but worth being aware of. |
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| Author: | pauly [ Sun Oct 25, 2020 5:33 pm ] |
| Post subject: | Re: Solid State DME relay |
tr7v8 wrote: I'm told there are a lot of dodgy copies of Bosch pumps. Not saying yours is but worth being aware of. There's plenty of cheap Chinese copies, pumps, injectors etc. Official dealers are the only way to be sure. |
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