1989 1.9 Gti Starting And Running Issues

[birdie205 0]

Did a road rally last month and on the way to the event noticed the tick over was a bit high, during the event did notice a few backfires from the exhaust.

 

At halfway switched off to fill with petrol and would not start again.

 

Checked ignition and spark at plugs all seemed ok , disconnected fuel line and fuel is being pumped.

 

Have replace maf, tachy, ecu and engine temp sensor and still the same.

 

If connection to maf is removed car will start but runs very rich( I believe this sends ecu into get you home mode), if maf connection is the replaced engine runs smoothly for a few seconds and and stops, this is repeatable.

 

I was convinced this was an engine temp sensor issue but now not so sure , voltage out of pin 10 on ecu to engine temp sensor is 9.9v on cranking not sure if this is correct.

 

Have tested resistance of both engine temp sensors at different temperatures , and they seem in line with config data and are the same values.

 

Engine will start from cold with engine temp sensor plug removed,but runs extremely rich, but as soon as engine temp sensor plug is connected engine stops

 

Have looked at the sad but believe this would not cause a starting issue.

 

Spent about 15 hours on this so far any help very much appreciated.

 

Thanks

 

Jon

[jackherer 543]

Engine will start from cold with engine temp sensor plug removed,but runs extremely rich,

 

That's normal behaviour.

 

but as soon as engine temp sensor plug is connected engine stops

 

That suggests the ECU temp sensor is faulty.

[birdie205 0]

Fitted new sensor, still the same , at a loss what to do now

 

jon

[philfingers 5]

i'm still baffled Jon, I think it's connectivity somewhere. As mentioned above my thoughts were ECT Sensor.

Anyone any other ideas?

You've changed the MAF, is it a known good one, based on your comments it will run when disconnected?

[205_sunderland 4]

sensors etc usually work or dont if new so try putting the old maf back on (if you replaced it with used one) and see if its the same or if systoms change at all, mine is running pretty crappy at the minute and im about to change the same things. As mine runs ok from start with idle too high then once running for a few minutes it goes through a phase of cutting out on idle until it warm where it starts to idle right. It also smells mighty rich and coughs under load at low rpms so ill keep you posted how mine gets on aswell.

Edited September 6, 2011 by 205_sunderland

[Weser 30]

Im no expert but it sounds like something to do with either the maf and the ecu. Beacuse it runs smoothly when you reconnect until the ecu gets a reading. Thats my thoughts.

I take it that with everything connected it wont start cold or hot? (obviously now you cant really get it hot)

It does have symtoms of tempature sensor however it seems to be working correctly.

This maybe my stupidity but I just want to make sure maf = air flow meter? If so what about prying the lid off and giving it some different airflow readings by moving the arm inside to give a different resistance and seeing if it will start/run then.

 

Just a thought when you are cranking the engine to start does it smell rich or not? will give you an indication to which way you need to go.

[birdie205 0]

had another go last night checked every wire connection we could etc, it will run by moving the arm on the afm manually but stops immediately you touch the throttle, although by moving the arm I think i am just counteracting the erroneous messages getting to the ecu.

[Paul_13 212 1 Cars]

Throttle position sensor dead?

[birdie205 0]

good idea, i'll try that , only thing I have yet to replace

 

thanks

[Taylor_kid 1 1 Cars]

Would it be wrong to assume that as there has been no further responses since the suggestion of replacing the Throttle position sensor, that this was the problem?

[birdie205 0]

Final update this is now fixed, thanks to all at AB MOTORSPORT turned out to be faulty fuel pump delivering insufficient pressure.