Problem starting when engine "medium warm"!

P

pgodoe

Member
Sometimes I have problems starting when the engine is "medium warm"... funny thing. ( I know the starter motor need a change, and at the audi service, they found some strange readings from the MAP-sensor) However, in my mind that does not explain why I have had trouble starting only when the engine is "medium warm".

Lets take a scenario: I'm out driving for about an hour. make a stop for about 20 min and then try to start it again. The starter motor kicks in and turn the crankshaft, but failure. I have to give it some throttle as I turn the key to get ignition. Strange.

When the engine is cold I have never had problems (only owned the car for 2 weeks though) When the engine is warm, ( start, stop, start, stop ) no problems.

Any ideas:) ?

Cheers

-P-
 
Hi -P-
It's possible that one of the engine temp sensors (air, fuel or water) is faulty as this could affect the fuelling under certain conditions. A diagnostic scan may pinpoint the fault but if not, I've read that VagCom can be used to graph the sensor output signals starting from cold and this can highlight the type of 'mid range' fault you are seeings.

Cheers Spike
 
spike said:
Hi -P-
It's possible that one of the engine temp sensors (air, fuel or water) is faulty as this could affect the fuelling under certain conditions. A diagnostic scan may pinpoint the fault but if not, I've read that VagCom can be used to graph the sensor output signals starting from cold and this can highlight the type of 'mid range' fault you are seeings.

Cheers Spike
Click to expand...

Thanks, Im am fairly certain that the problem only happen after a stop for about 30 minutes. I'll just wait and see.

cheers,

-P-
 
spike said:
Hi -P-
It's possible that one of the engine temp sensors (air, fuel or water) is faulty as this could affect the fuelling under certain conditions. A diagnostic scan may pinpoint the fault but if not, I've read that VagCom can be used to graph the sensor output signals starting from cold and this can highlight the type of 'mid range' fault you are seeings.

Cheers Spike
Click to expand...

One more thing: What kind of VAGcom do i need? does the 409.1 stand up for the challenge?

cheers,

-P-
 
same problem

engine turns over but fails to catch - always after a stop following a longer journey
then a 10 minute wait or so after engine failure for a better chance of starting
r
 
From the repair manual, it looks like the map-sensor my be the problem. Apart from measuring the manifold pressure, it also has a air temp sensor attached. I will try different things and let you know how it works out.

-P-
 
pgodoe said:
One more thing: What kind of VAGcom do i need? does the 409.1 stand up for the challenge?

cheers,

-P-
Click to expand...
Sorry I missed this earlier question. Maybe you already have the answer but I used VagCom software version 409.1 for a couple of years (with a genuine lead) and it worked fine for checking fault codes and monitoring sensor output.
Let us know how you get on

Cheers Spike
 
I just had a chat with my audi; it says

17559/P1151/004433 - Long Term Fuel Trim Additive Air; Bank 1; Range 1: System too Lean

From Ross-tech:

Possible Symptoms
Malfunction Indicator Lamp (MIL) active
Possible Causes
Intake System faulty/leaking
Fuel Pressure, Fuel Pressure Regulator and Fuel Pump faulty
Fuel Injectors faulty/leaking
Exhaust System faulty/leaking
Activated-Charcoal Filter/System faulty/leaking
Secondary Air Injection System faulty/leaking
Lambda/Oxygen Sensor(s) before Catalytic Converter faulty
Lambda/Oxygen Sensor(s) after Catalytic Converter faulty

Possible Solutions
Check Intake System for Leaks
Check Fuel Pressure, Fuel Pressure Regulator and Fuel Pump
Check Fuel Injectors
Check Exhaust System for Leaks
Check Activated-Charcoal Filter/System
Check Secondary Air Injection System
Check Lambda/Oxygen Sensor(s) before Catalytic Converter
Check Lambda/Oxygen Sensor(s) after Catalytic Converter

Any ideas? considering the starting problems when "medium warm".
 
brilliant - yes that was the problem. Got them to replace temp sensor and no problems at all since. many thanks - saved me time + money!
 
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