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2006 XT 4EAT
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14 Posts
Discussion Starter #1 (Edited)
Random stalling problem

Hi all.

I'm hoping some of you may be able to help with this :)

I own a 1999 S Turbo with PPP installed and around 125k miles.

I've owned the car just over a year. Over the last few months the car has been randomly stalling. Upon stalling, it's generally the case that the car won't start again for an undetermined amount of time. At first I figured that the problem was the fuel pump connector as I found the connector was warm and upon cleaning up the corroded terminals, found that the car worked fine again. Everything seemed fine for a couple of months then the problems came back again. This time though, it would appear it's not the fuel pump connector. The last time, the connector could be moved a little and that would induce the stall. This time, any movement of the connector will not cause the car to stall. Due to the essentially dangerous nature of the car stalling randomly, I've just parked the car up. The last few times I've tried to start the car it just won't start.

I'm sure I've read that the 99 cars were known to have MAF problems. Should the car still start without a faulty MAF connected as I've tried that since it's not been able to start, but it made no difference?

Some other general points. The car has been well serviced to date. On warm days and normally when the tank is full, I sometimes get the smell of fuel in the car. I've discovered a couple of holes in the centre section of the exhaust which I'll replace or fix once I've sorted this problem. The only time I received a CHECK ENGINE light is when I disconnected the MAF to try to start it.

Through my research the possibilites seem to be:
Failing fuel pump
Fuel pump relay
MAF
Immobiliser part of alarm faulty
Fuel pump connector or wiring still at fault
Some other sensor telling the ECU to cut the fuel.
Have I missed anything?

Can anyone suggest what would be a good course of diagnosis?

Many thanks,

David
 

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Emeritus Forum Staff
2015 Triumph Tiger XCx 1 Down. 5 Up.
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5,242 Posts
Is the stalling totaly random or can it be made to stall under certain circumstances? I had an 205GTi that would stall if you de-clutched and braked too hard. Being able to reproduce the problem consistently should help to diagnose.

Subaru mafs can be a little delicate sometimes so it could be that as you suspect... if someone lives close by, it might be possible to swap theirs out and do a quick test.
 

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2006 XT 4EAT
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14 Posts
Discussion Starter #3
Yes totally random. Has been, when car is stationary at lights, cruising at 70, when driving at 30. Nightmare really. Doesn't matter if engine is cold or warm.

If MAF was causing the fault, shouldn't the engine start without the MAF connected up?
 

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99 UK S-turbo
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8,566 Posts
Sure sounds like a faulty MAF, although any air leak downstream of it to the engine could cause it as well.

I'm sure my car starts with the MAF disconnected, which reinfirces the diagnosis of a dodgy MAF I think as the learnt adaptions will need the dodgy signal to be correct, but with a big incorrect adaption it probably won't.

Simon
 

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2015 Triumph Tiger XCx 1 Down. 5 Up.
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If MAF was causing the fault, shouldn't the engine start without the MAF connected up?
No, engine will need MAF connected as it will need a reading from it (even if it's the wrong one).
 

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2015 Triumph Tiger XCx 1 Down. 5 Up.
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No, engine will need MAF connected as it will need a reading from it (even if it's the wrong one).
Happy to be corrected on this BTW as I've not tried it in a Forester but previous cars wouldn't start without the MAF connected.
 

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No, engine will need MAF connected as it will need a reading from it (even if it's the wrong one).
They will start with the maf disconnected, but not if the maf is connected but not in the air stream (such as if you have it plugged in but have the airbox off). Without the maf connected it goes into "limp" mode where it will run with the presets (open loop?). At least this is how it is with my 04.
 

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2006 XT 4EAT
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14 Posts
Discussion Starter #12
Thanks for the replies :) Replacement MAF has been ordered today so I'll let you know how it goes.
 

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2006 XT 4EAT
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Discussion Starter #14
I went for item 300422929465 on ebay. Sorry wouldn't let me post direct link due to my post count being less than 15.

Seems to be the same sensor part as the one I removed from the car.

Received it yesterday, and so far (touch wood) car has been starting and not stalling. Not driven much yet but I'm hoping it's sorted :)
 

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2006 XT 4EAT
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Discussion Starter #15
Sadly, it doesn't seem to have fully cured.

Car worked fine for a while but one day, went to the car and it wouldn't start. Engine just cranking but not firing.

Tried a few days later, started on second attempt. Used the car and it drove and ran fine for about 12 miles. Went through a car wash and it wouldn't start on the way out. Would just crank, fire slightly run very rough for a few seconds then die. Left it for about 10 mins, car then started up fine. Drove it back home and just parked it up.

Any thoughts what I should replace or test next?
 
A

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I would say your crank sensor is shot, it is located under the alternator.
It maybe worth removing it and seeing if needs cleaning, they are magnetic so can pick up crap..
 
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