Another stupid question, this time about DME relays
 

I understand that it is prudent to keep a spare DME relay in the car. No fuel pump, no go.:(

Have any of you tried these?

http://www.ftech9.com/new-products/?...tate+Relays%29

Are they worth the premium? Is the one that "primes" the fuel pump for 3 seconds the one to get? For cold start situations, I can see an advantage. For hot starts, not so much.

-Yogii
AKA 968 Virgin

You could also keep a jumper wire, invest the money or pay down debt with what the spare relay would have cost.
The F9tech products are interesting but:
1 - In 20 years I have had zero problems with the 993 part number DME relays from reputable manufacturers
2 - We do not know how the F9tech products will last, until they have lasted

Also I think the pump prime is not desirable and possibly dangerous as I have read they do not really affect cranking time (and maybe a few cranks is better to circulate oil before firing) and that they can decide to "prime" unexpectedly. You might find them "priming" after a crash and feeding a fire. Cost extra, maybe dangerous, and no benefit. This is my opinion based on reading the experiences of others. I'm all for improvements and have fitted some updated, newer, better technology parts to most of my cars but not if the old part works fine, costs less, lasts the same, etc.

I’m running both of the F9T Solid-State Relays in my 944 / 968.
My 944 is VEMSed, so the Pump-Prime Relay was not needed. In VEMS I set up Fuel Pump On after Powerup 3.0s, Pump Off after inactivity 0.52s. This works fine. Cold start after long sitting seems to have improved.
My 968 got the F9T, Pump-Prime Relay, because of the well tried and tested VEMS setting. No issues so far. 08-31-2018 --> https://rennlist.com/forums/924-931-...l#post15256966
And a further benefit, the huge difference in weight. ;-)

https://cimg6.ibsrv.net/gimg/rennlis...9aaec73bf9.jpg
Stock vs. F9T solid-state relay

I have used the F9 relay for a year and a half now, and these are my comments / conclusions:

1) No difference in starting, it fired up with one second of cranking both before and after the switch in relays.
2) I like the priming of the fuel pump for the auditory feedback that the pump is actually on ( the sound is too faint to hear during engine cranking or engine running, so before cranking is the only time I can here it ).
3) The first unit I got did not work, but was told that it was probably damaged by ESD, and it was promptly replaced with a working unit, which has worked flawlessly ever since.
4) Like others here, I keep the mechanical unit in the glove-box as a spare.
5) Overall happy with the purchase, but as others have stated, maybe wasted money to solve a problem I did not really have??

I have used the F9 relay with the prime feature for about 2 years now. My comments echo Nathan's pretty much point by point. I do think that a solid state relay should be more reliable over the long term compared to a mechanical one which will wear out, but who knows. The one I replaced, which did die right after my 968 arrived (literally after it arrived, I pulled it into the garage and it would not start the next time I tried) was from 1993 and had a 993 part number on it, so I can only suspect that it was original or close to original.

As with all reviews, YMMV.

FWIW - this relay seems to have just failed on my son's 924S. Seems to have failed in the pump priming state. Couple that with leaky injector, seems like it flooded the engine. Replaced with mechanical relay and have applied for warranty replacement as it was 3 years 8 months ago and they have a 4 year warranty.

WIll update this post if any other info presents itself.

Interesting, since the relay is solid state. I wonder what failed. I would be interested in knowing what component failed if you ever find out.

Lots of solid state stuff fails. I have 2 928S4 LH ECUs that need to be repaired, no moving parts inside. These are pretty vulnerable to stuff like jump starting or using an old buzz-box battery charger, or they can seemingly just die of old age. I also recently had a WiFi router fail, it was solid state and just sat there doing it's job for 5 years and then started doing weird stuff and needing to be rebooted a lot.

I like the idea of improving parts like the DME relay and I've thought about ways to adapt the relays in the 928 to condition the power to the LH and EZK (this might be a waste of time, the bad stuff might come in on the ground or through the inputs).

It'd be interesting to know if the 924S was jumpstarted or on a rude battery charger or what might have affected the DME relay. Those things are typical IMO and should not affect warranty. If it has a dripping injector it might have storage related electrical issues as well.

What trickle charger would you recommend that will not mess up the DME?
Next year I will have to put my car in "long-term" storage.

Thanks,

-Yogii
AKA 968 Novice

I bought the ftech9 DME relay with the fuel pump relay for my 968. Installed it and started the car, instant start after a 3 second delay. Then I tried a test drive, didn't notice it at first but it wouldn't shift, stuck in 2nd and "tiptronic" warning light was on. Back home switched back to the old relay, everything was good agin. Tried the Audi-VW #811 951 253 no problems, retried the tech solid state relay Tiptronic light on and no shift and no gear light (1 2 3 4).
Will try it in the 993 to see if it's a 968 only, (early Tiptronic compared to '96 Tiptronic S).
Guessing the second part of the relay is connected to the ECM and transmission,

811 951 253
 

Does the 811 951 253 VW relay have the pulse on start up

with the standard relay, my car fires the second revolution even if parked for a while.

its itching to go

Joe at ftech9 sent me a solid state relay without the pump prime circuit to try in my 968. Same issue, the Tiptronic warning light comes on and the 1234 indicator light is off. When in any "forward" position the transmission stays in 2nd gear, from 0 to 45, as fast as I wanted to go. Also when shifting from reverse to drive or back to reverse it slams into gear with a big lurch. Put the other two DME relays (811 951 253 and 993.615.227.01) all is normal, smooth shifting gear indicator light on.
Tried both of the ftech9 relays in the 993 and no issues, only difference is the early Tiptronic in the 968 and Tiptronic S in the 993. Running the ftech9 pump prime relay in the 993 and I think it starts quicker after sitting for a few days, but hard to tell.
It's a nice product and should eliminate DME failures, unless you have a "Tip" car.

No, it can't eliminate DME failures! And YES, it works in my 968 Tip, flawlessly. No issues at all.
👉 https://rennlist.com/forums/968-foru...l#post15582422
☝️klick posting #3