Starting Problem (Part 2)

[jfeb]

I posted a few weeks ago about problems I am having starting my S4. I have replaced the coolant temp senser and the battery and the car still takes 10+ turns of the starter motor to start and when it does start it coughs and splutters in to life, starting from very low revs.

Although the starter motor turns over freely I am starting to think that it must be the problem (or if not it must be a fueling problem).

Questions:
1) Would a starter motor problem show up on VAGCOM?
2) Does anyone live near Twickenham, have VAGCOM and be willing to plug it in to my S4 for a quick check? MRC gave it a cleath bill of health only a few weeks ago so I am expecting VAGCOM to be clear
3) Given that it isn't the coolant temp sensor and isn't the battery, what else might it be?

[s4-99]

Just a guess but could it be anything to do with the fueling ie fuel pump or something???

[jfeb]

I am wondering the same thing. If I can't find anyone local to check the error codes with VAGCOM I will probably have to take it to my local Audi dealer (God help me)

[UKS4APR1]

Just a thought, check for a leak in the pipework between MAF and Turbos which would cause a lean mixture.

[BaSen]

How about replacing your spark plugs? Just a quick thought..

[jfeb]

I haven't tried any of the suggestions above yet but I have noticed that if I depress the clutch when I start the engine it fires up OK. It hesitates slightly as the starter motor fires the engine to about 200-400 rpm but bursts into life fine.

Does this sound like a tired starter motor?

I notice in the owners manual it says to start the engine with the clutch depressed. Does everyone do this?

[DavidT]

You should start it with the clutch in really as the starter has to turn half the gearbox otherwise.

I reckon starter motor if the alternator is keeping the battery up OK.

[jfeb]

Quick update (seems the least I can do after asking for help):

I got my 3rd party VAGCOM interface cable from ebay yesterday plus the shareware software and found an error logged for the coolant temp sensor (as had been suggested by the forum). I have already replaced this and still have an intermittent problem with starting so will try some of the other suggestions.

So thanks for helping me find (and solve) problem number 1.

[richs4]

Does anyone have the part number for the coolant temp sensor? Think mine is on the way out as I've been having an intermittent starting problem and got a temp sensor error logged in vagcom.

cheers

Rich

[s4woody]

mite be fuel pressure..have u considered changing the fuel filter..mite be clogged..

[jfeb]

Woody - Is that a DIY job?

[Russ,greys4]

fuel filter isint hard, nxt 2 the tank. changed mine a while back, looked like it had never been changed. had the same problem as well

coolant temp sensor

changed it twice b4 it worked! theres only 2 that they make a green 1 and a blue 1, all VAG cars use thease. mine was blue 30 quid i think

[neckarsulm]

Are you sure your battery is OK?
It may appear OK in some situations but if you have a duff cell it can do all manner of things which you wouldn't immediately blame a battery for.
If it's older than 2 years or god forbid original it may be worth replacing it as it's that time of year

[s4woody]

it can be but a ramp really saves alot of scrabbling about on the floor..unless its jacked up enuf..

[richs4]

Since I got a fault code in VAGCOM for the Coolant temp sensor "reading implausible" I think I'm best replacing that first. So if I go to my dealer and ask for a "blue one" that will be sufficient info?

cheers

Rich