marvgomez

is 30 Ohms acceptable for the intake air sensor ?

gmbchef

i think so. Supposed to be 13 to 33 ohms.

marvgomez

Had the 4k cutout a while back and a very knowledgable local Ur owner suggested checking the connections at the air temp sensor. I did, they were bad, resoldered, bingo!

Got the cutout AGAIN, connections look fine, measure the resistance in the harness and I see ~30 Ohms. 8-( Now what ?

racingiron

<ul><li><a href="http://www.intendedacceleration.com/tip_2.html">Courtesy of Ned @ IA</a></li></ul>

gmbchef

Where did you perform the test? Try checking the resistance at the ECU connection.

marvgomez

I poked a couple of pins into the wires just before they go into the loom.

marvgomez

thanks for the pointer. I guess I should go check values at the ecu.

urq20vt

pins 18 &amp; 19. The intake air temp sensor circuit is not a great design, so any contact resistance has a big affect on the readings of the sensor. The later Audi turbos use a sensor with a higher resistance range, so they are not very sensitive to variations contact resistance to the sensor. IME, the intake air temp sensors themselves rarely if ever fail, but the contacts do. This accounts for 90%+ of the 4k RPM cutouts. If you are reading 30 ohms of resistance with the engine off and cool, it won't take much additional heat and/or resistance in the lines to cause the 4k RPM cutout.

Personally, I prefer to crimp the contacts at the sensor for a good mechanical and electrical connection, then solder them and cover with heatshrink so that they are more immune to vibration and corrosion. If there are splices in the wires, try to get rid of them. Any place where you join wires you introduce more resistance, so you want to minimize the connections as much as possible.

I would also consider adding a contact cleaner and enhancer to the ECU connections.