Short Turbo Temp Sensor?

[Bergerac]

Is there any drawback to deleting the turbo water pump entirely? Thats what I'm currently running and figured that since I never shut the car off immeidately after hard use, I'd most likely be fine. I just switched to running an NA tank.

Probably not, the idea of the pump really appealed to me after owning other 90s turbo cars where Ive pulled up in the garage after a hard run to see a red hot turbo through the hood vent. It would really simply things under the hood not having all those coolant hoses.

[Spencan]

markl951- Can you share how you modified the timer circuit, please?

TIA

[markl951]

markl951- Can you share how you modified the timer circuit, please?

TIA

No problem. It's your classic 555 Timer circuit. Remove R3 and replace it with a larger value resistor. Doubling the resistance makes the pump run appropriately twice as long. I taped my original resistor to the plastic relay cover so I'd know where it was if I wanted to put it back someday.

IMG_20191030_turbo timer.jpg (501.34 KiB) Viewed 611 times

[Spencan]

Thanks Mark! Where is this board located?

[markl951]

It's inside the relay. You just have to pop the plastic cover off in order to get at it. I forget which relay it is. Let me know if you can't find it but it's next to all the other relays like the DME relay...

[Spencan]

Got it, thanks again

[Spencan]

I have been having the “boiling coolant” at the turbo after spirited drives so I had a computer repair shop try to do this modification. I went
On another spirited drive and now it does not turn on at all once I turn off the car. The coolant boiled again until I grounded the wire to the intake. But when I removed the ground, the auxiliary water pump immediately stopped.

Do I have a bad resistor or a shoddy sautering job?

[Tom]

Hard to know just from pictures, but the circled spot looks suspect. Looks like one of the pcb pads pulled off the board, which can happen when you overheat it with a soldering iron, and they tried to bend the lead over to connect it. Resistors are almost never bad, so more likely they botched it up. I'm happy to look at it if you want. There's a fair chance I could fix it. PM if you want to drop it off sometime.

Also, have you checked the little thermostat at the water pump, just to make sure it's opening? I've never had boiling coolant at the turbo, and am curious how you even know that's happening on yours? (Either way, the aux pump should come on when you turn off the car, so just curious.)

[Tom]

By the way, if you are handy with a multimeter, you can run these tests on that relay. I'm guessing it's not working right...

[Tom]

@Spencan I was able to fix your relay with very little effort, once I found my magnifying glass anyway. I was in the right ballpark when I guessed that they tore up a solder pad by mistake, but it turns out that pin has no solder pad and is not supposed to be connected to anything. Your repair guy apparently decided it needed to be connected to something -- so folded it over and connected it to the end of the resistor he just replaced. I clipped that lead away from his solder blob, and successfully tested the relay. It now supplies power to the pump for almost exactly 60 seconds when the temp sensor grounds out, and when you turn off the car. Feel free to pick up any time. Here's a shot of a normal relay and what he did to yours....

aux-pump-relay-fix.jpg (474.54 KiB) Viewed 450 times

p.s., the original resistor in that spot is a 1/8th watt (or less) resistor, so I probably could put a pot in there so you can adjust how long the pump stays on, but I'm kind of thinking that's a solution in search of a problem....