SAI / 249 Bypass - guide

**h100vw** · 03-10-2013, 08:50 AM

Basically, no. It's all got to stay.

I have blanks for the side of the head and Phase 1 or Phase 2 software to take care of the incorrect flow code.

Gavin

**noone** · 03-10-2013, 12:47 PM

Seriously, a Polo GTI with stock ECU is such a different car, get the tune, all bypasses, etc for <$800 and 1/2 a days efforts. (Hoping my guestimates are ok Gav). If you want the best from it on a budget, the PD160 intake is overpriced for what it is, but really worth it.

No SAI that's prone to failiure, no Vac stuff on top of the engine, no 249 / 112 fiddling with your boost levels (max please).

You cant spend money in a better way on your Polo, best bang for buck, stupid gains in HP and torque. It will unfortunately have the side effect of encouraging you to get suspension work and sticky tyres.

**sambb** · 22-04-2014, 08:55 PM

read a few posts here about using 300 ohm 1 watt resistors for the n112 and n249 solenoids. Just wanted to check that that info is correct. I measured the solenoids at 30 ohms which would suggest nearly a 0.5A draw (more like 6+ watts)? Am I missing something??

thanks

**h100vw** · 22-04-2014, 09:05 PM

I think that's right Sam. In fact I thought it might even have been a touch bigger. 380 ohm. I had a look in my cupboard but must have used them all.

Gavin

**sambb** · 22-04-2014, 10:06 PM

anyone know why the resistor value has to be so high? Surely the solenoid would have to be almost purely resistive. Don't understand what the other 300+ ohms is needed for when it seems you only need 30 ohms to mimic the solenoid. I'll try to tong the n249 solenoid and see what its really drawing?

**h100vw** · 22-04-2014, 10:30 PM

VWVortex.com - Installing resistors after removing SAI pump and n249.

330ohm 10 watt. That's what I am using Sam, I am sure your theory would hold water but if the resistors are too small you get the code up. I ran 300 and then had to go bigger.
Gavin

**rgvlee** · 22-04-2014, 11:02 PM

Does the forge sai block off plate fit? The one they make for the mk4 golf gti?

**h100vw** · 22-04-2014, 11:11 PM

It would, I have some though. like the one in the cheapy thread.

Gavin

**sambb** · 22-04-2014, 11:51 PM

found this on another VAG site RE the resistors:

"I was contacted directly by ***** from ******. He assured me that the resistors he sells have been tested by many and work well and safely. The resistors used for the various solenoids are 330 Ohm and rated for 1 watt. The measured resistance of the actual solenoids is closer to 30 Ohms or so, but in ***** experience (and his customers), the 330 ohm value is sufficient to satisfy the ECU's circuit tests. The higher resistance also makes for lower current and heat in the resistor, which is good."

"The only application I cannot recommend for a resistor is the SAI pump itself. The pump circuit is relay-driven and as such, it is not metered by the ECU whatsoever. Putting a resistor in place of the pump will serve no purpose other than to waste electricity. The resistor would perform a function of keeping the harness connector clean and insulated, but a little bit of electrical tape would do that as well. "

So there you go. 30 ohm resistors would satisfy the ECU checks but would fry themselves and open circuit unless they were minimum 6w and even then would run very hot if soldered into a loom (as they would pull 0.5A). They use 330+ ohms so that the current/wattage/size of the resistor comes down. I thought the ECU would see such low current (40mA 'ish) as an open circuit, but apparently not.

If anyones 300+ ohm n112/n249 solenoid resistor didn't work, possibly it was because the wattage was too low (even 1 watt sounds borderline) and it couldn't dissipate heat when heat shrunk into a loom and then fried internally and open circuited.

"