Limp Stillen Supercharger dtc p1239

Z4fun · 10-21-2019, 01:57 PM

Quote:

Originally Posted by cgr406

I checked w/ Aaron a while back & the replacement cables that he has are the same ones (Stillen Gen II) that came w/ the full SC kit that I bought from him. So, I'm wanting to try something different. I will also try wrapping / insulating the new cable.

Oh ok , makes sense. Plz post pics of ur fix , im sure all of us would like to see how it came out when ur done.

Z4fun · 11-01-2019, 07:36 AM

Hey guys , after some testing and research we concluded the cause is 100% heat. since the wire is being heated its increasing the resistance causing and interruption in the signal throwing the tb off and causing it to go into limp mode.

My mechanic said he tested the wire cold then warmed up the car and tested again and saw a dramatic rise of resistance in the cable. The two options we had is to insulate with a sleeve or try to reroute the wire. Since I am adding a vented hood, we decided to go with the sleeve. (attached pic)

In doing more research this is actually a well known fact in thermal electrical engineering here is the definition for Heat resistance.

Heat Resistance

Heating a metal conductor makes it more difficult for electricity to flow through it.

In metal conductors, electrical current flows due to the exchange of electrons between atoms. As electrons move through a metal conductor, some collide with atoms, other electrons or impurities. These collisions cause resistance and generate heat. Heating the metal conductor causes atoms to vibrate more, which in turn makes it more difficult for the electrons to flow, increasing resistance.

https://nationalmaglab.org/education...eat-resistance

WhiskeyHotel · 11-01-2019, 08:23 AM

Yes, the actual equation is R=Rref(1+a(T-Tref)) and the temp coef (a) of Cu is +0.000393 per degree centigrade. That means the effect is pretty small at the lengths and temps you would experience under your car's hood. (That Bunsen burner temp in your example link is ~1700 degrees C!)

Example: 100 feet of 20 gauge wire with resistance of 1.015 ohms at 20° C (room temp). If the temperature of the wire goes up 10°C, the resistance will change by 0.0399 ohms (10 degrees * 0.00393 per degree * 1.015 ohms = 0.0399 ohms).

The wire resistance will now be 1.015 ohms + 0.0399 ohms = 1.0549 ohms.

In my opinion, that wouldn't be enough change to account for the large increase in resistance your mechanic is seeing. (I think - I don't know what the increase was. I also don't know how the resistance was measured nor do I know which of the conductors he measured and there are grounds, power, and sensor signals going to the throttle body. You can see that I am shooting from the hip here.) My electrical engineering spider sense is tingling at this point. There could be something else going on - connector pins heating up and losing continuity - something. I hope the proposed solution works - but I am a bit skeptical at this point. Let us know how it goes.

Z4fun · 11-02-2019, 08:35 AM

Quote:

Originally Posted by WhiskeyHotel

Yes, the actual equation is R=Rref(1+a(T-Tref)) and the temp coef (a) of Cu is +0.000393 per degree centigrade. That means the effect is pretty small at the lengths and temps you would experience under your car's hood. (That Bunsen burner temp in your example link is ~1700 degrees C!)

Example: 100 feet of 20 gauge wire with resistance of 1.015 ohms at 20° C (room temp). If the temperature of the wire goes up 10°C, the resistance will change by 0.0399 ohms (10 degrees * 0.00393 per degree * 1.015 ohms = 0.0399 ohms).

The wire resistance will now be 1.015 ohms + 0.0399 ohms = 1.0549 ohms.

In my opinion, that wouldn't be enough change to account for the large increase in resistance your mechanic is seeing. (I think - I don't know what the increase was. I also don't know how the resistance was measured nor do I know which of the conductors he measured and there are grounds, power, and sensor signals going to the throttle body. You can see that I am shooting from the hip here.) My electrical engineering spider sense is tingling at this point. There could be something else going on - connector pins heating up and losing continuity - something. I hope the proposed solution works - but I am a bit skeptical at this point. Let us know how it goes.

If your engine only goes up 10 degree from ambient that would be awesome, unfortunately for the rest of us with a cable sitting directly on an engine with an oil temp of 115+- C your resistance formula would make a large difference if you wanna recalculate it.

The point of my response was common sense with alittle info in heat and resistance for some ppl that don't need a degree to understand it. That's why I didn't have to pull formulas and stuff. The cause was heat and the failure is the wire or connector under the heat stress over a "PERIOD OF TIME" not a one time thing. materials can heat and cool multiple times before getting to the breaking point.

we appreciate your criticism, but would rather appreciate a solution to the problem at hand.

cgr406 · 11-02-2019, 07:09 PM

So I installed the Michigan Motorsports TB cable about a week ago & wrapped it in teva tape, just cause it can't hurt. No codes / limp mode so far, but it's only been a week. Tonight i wrapped it in thermal insulation from Summit. So, we'll see how it goes, although now that it's November in PA, not sure how much more I'll be able to drive the car for a while.

Optimiser · 05-19-2020, 09:36 PM

Quote:

Originally Posted by cgr406

So I installed the Michigan Motorsports TB cable about a week ago & wrapped it in teva tape, just cause it can't hurt. No codes / limp mode so far, but it's only been a week. Tonight i wrapped it in thermal insulation from Summit. So, we'll see how it goes, although now that it's November in PA, not sure how much more I'll be able to drive the car for a while.

It's been a year so how is it now? More reliable?

cgr406 · 05-20-2020, 03:57 PM

Yep, so far so good. Although I've only put about 1,600 mi on it. The original stillen cable was OK for a while too, so I'm not sure this is enough of a test to be conclusive. I probably had about 3.5k mi on the Stillen cable before it started crapping out. Fingers crossed.

11-01-2019, 08:23 AM	#3 (permalink)
WhiskeyHotel Track Member Join Date: Nov 2009 Location: Oklahoma Posts: 530 Drives: 2015 GT-R PW Premium Rep Power: 17	Yes, the actual equation is R=Rref(1+a(T-Tref)) and the temp coef (a) of Cu is +0.000393 per degree centigrade. That means the effect is pretty small at the lengths and temps you would experience under your car's hood. (That Bunsen burner temp in your example link is ~1700 degrees C!) Example: 100 feet of 20 gauge wire with resistance of 1.015 ohms at 20° C (room temp). If the temperature of the wire goes up 10°C, the resistance will change by 0.0399 ohms (10 degrees * 0.00393 per degree * 1.015 ohms = 0.0399 ohms). The wire resistance will now be 1.015 ohms + 0.0399 ohms = 1.0549 ohms. In my opinion, that wouldn't be enough change to account for the large increase in resistance your mechanic is seeing. (I think - I don't know what the increase was. I also don't know how the resistance was measured nor do I know which of the conductors he measured and there are grounds, power, and sensor signals going to the throttle body. You can see that I am shooting from the hip here.) My electrical engineering spider sense is tingling at this point. There could be something else going on - connector pins heating up and losing continuity - something. I hope the proposed solution works - but I am a bit skeptical at this point. Let us know how it goes. Last edited by WhiskeyHotel; 11-01-2019 at 08:28 AM.

05-20-2020, 03:57 PM	#7 (permalink)
cgr406 Base Member Join Date: Sep 2013 Location: pittsburgh Posts: 106 Drives: '14 Z Sport Tour 6M Rep Power: 3367	Yep, so far so good. Although I've only put about 1,600 mi on it. The original stillen cable was OK for a while too, so I'm not sure this is enough of a test to be conclusive. I probably had about 3.5k mi on the Stillen cable before it started crapping out. Fingers crossed. Optimiser likes this. __________________ TopGunZ Rotrex SC / CJM RFS / 1300 / Ecutek / Dynosty / F.I. TP & CBE / Z1 / Swift / SPL / Whiteline / Hotchkis / Michelin SP4

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