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I had been getting the P 1163 code for a fault (open or positive) in the ECU reading the fuel temp sensor on my 01 TDI New Beetle, the thermistor inside the injection pump. I replaced the FTS following instructions on the forum ( carefully open the fuel pump top quantity adjuster compartment cover, used security triple-square socket, replace cover gasket). This did not work and examining the wiring from the fuel pump connector socket I noticed several bare, worn wires. I was able to make the CEL go away for a year by using a liquid electrical tape on the socket, both sides. Admittedly this is a rather irreversible step and is probably not advisable.

Anyway the fault came back after a long trip and no amount of fooling with wiring insulation resolved the problem. In fact the CEL could not be cleared by vagcom.

Looking at the resistance between pins 4 and 7 on the injector pump side connector, I found an open circuit, and concluded that there was a break somewhere in the pigtail on the pump itself.

Since I'm not inclined to do a tear down on the fuel pump, I used for him guidance to bypass the fuel temperature sensor in the following way:

Since the FTS itself was open circuit I did not replace it. For what it's worth the resistance of the year-old FTS was correct at ambient ( I determined this by opening up the pumpin placing probes on the contacts to the thermistor itself).

I used a wire tap to connect wires 4 and 7 on the fuel pump pigtail side, closing the circuit going to the FTS. Are then placed a 2200 ohm (red, red, red, gold) 0.5% resistor in line on the wire 4 pin 7 of the wiring harness connector to the fuel pump. This allowed me to clear the CEL which did not return. As explained elsewhere, this has the effect of making the ECU think the fuel is always at 72 degrees. I am dubious about any performance benefits as argued for elsewhere, and plan to replace this resistor with a new FTS mounted on the outside case of the fuel pump itself with thermal adhesive of the sort used for heat sinks when my time permits.

The interesting observation I would like to make is that my persistent smoke on heavy acceleration problems went away completely after this repair. The engine is otherwise exquisitely tuned (Malone stage 1, modest upgraded injectors). I am of the opinion that even though I repaired the bare wires and replaced the FTS before, clearing a check engine light, the resistance was still wrong in the fuel temperature was not realistic. I should have had the good sense to check the fuel temperature with the vagcom when I made this repair.

My point is that don't assume that just because you clear the CEL for the FTS, your fuel temperature sensor is working optimally. Check its output. Apologies if this is obvious to you more seasoned mechanics out there.
 

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Discussion Starter #2
That should say "2200 ohm resistor inline on the wire for pin 7 on the harness side fuel pump connector".
 

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Interesting info on the tdi mod/repairs; we don't seem to hear much around here about working on tdi's as sites like tdiclub are dedicated to it and most tdi folks, congregate there. .

I guess the next question would be; what year, engine and trans do you have; what hardware mods have you done to it and how do you like the results along with your Malone tune? Thanks! :)
 
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