I have a new ECT sensor on order,should arrive Wednesday or so. Going to NYC this week so I'll put it in Saturday.

 

It really would be helpful to see the fuel pressure while cranking, to be sure your FPR is working properly and you don't have a line restriction that limits pressure under flow.

Have you cleaned or replaced the MAF? At one point mine was a little out of spec and the car drove fine, but a new one made starting 100% better. Worth a look at least.

 

I had cleaned the MAF (with MAF spray cleaner) early on when this started made no difference.

Agree I need to look at actual pressure under cranking and running conditions but need to find a "T" fitting to get the gauge attached to the fuel rail instead of just screwing it to the fuel line from the pump. If the new ECT doesn't fix it Saturday, thats the next step this weekend.

 

A 15 dollar temperature sensor, and the car fired right up. Hadn't tried to start it in over a week and it took about 1 second of cranking. Unbeleivable that the ECM doesn't post a failure code of implausible signal code for a miss reading signal to the ecm. After all the car does know the outside temperature should be able to figure out a cold engine temp is somewhere near the outside temp. I put a meter on the old sender (forgot to do the new one before it went in) and one set of wires read about 750 ohms at an outside temperature of 75 degrees, the other pair of wires read about 195 ohms. The 750 reading changed pretty quickly as I held it in my hand, going down as it got warmer, the 195 side barely changed at all.

Oh, well now th car has new plugs and wires, and a new fuel pump and it starts easily which is the most important part. Probably could have thgrow a few other parts at it and never thought about the temperature sender since the dash gauge worked perfectly. Thanks for getting my son out of our other car and back into his.

 

I tend to agree. Should at least be implausable signal. That sensor causes more starting problems and thows now codes.

Glad you got it fixed. How many times did you drop that dumbass little plastic retainer clip?

 

I have an 02 A6, 2.7 that I have just replaced the therm, water pump, temp sensor, the whole nine yards and it started just fine at first now it sounds a lot like what Mark C is experiencing. I found two temp sensors, one is aft of the right head which I believe is the main one but there is another temp sensor in the lower radiator hose. Will either one affect starting or is the one in the lower hose just for the fan?

 

The one in the lower radiator hose controls the fan. The one behind the pass side head is the one that matters for starting. That's the coolant temp sensor, and it's been known to make starting probs without throwing a code. It's cheap, and easy to swap...if you wait till the coolant is cold.

 

Bought another one today, I had replaced it when I did all the other work but maybe I got water in the connector and shorted it. Does anyone know if there is a dedicated fuse or circuit breaker for the temp sensor?