dpmotorcycles

Hi Folks, my name is Paul and i’m new to your forum, we have had our Impreza 2L turbo (year 2000 UK) for about 4 years and it ran trouble free until this year. I work in a garage and have had the car looked at but we can’t fix the problem so i am here looking for some advise from you Subaru experts if you don’t mind.
Firstly the problem – the car wants/needs to cut out normally once some times twice before it will run right, just after it has cut out there is a lack of power for a short time until it get going. This problem gets worse the colder the weather is however it does it all year round regardless to the weather. When the weather is cold and we are sat on the drive warming the engine you have to hold it about 1500-2000rph to keep it ticking over, if you take your foot off the loud pedal it will just die, if you leave the drive straight after starting it will die at the 1st junction once you have dipped the clutch. Once the car has cut out it runs fine its just as if it need to cut out before it will run right??? So thats the problem, now this is what we have checked.
Fuel pressure 2.6 bar 3 bar with the vacuum off
All vacuum systems vacuum tested and ok
Throttle body cleaned and idle control valve
Map sensor changed
Car plugged in to a Bosch diagnostic system and everything check, no faults found
Lambda checked and working, also tried the car with it unplugged so it reverts to default
Earths checked
Temp sensor is doing the right thing according to Bosch diagnostic system started at 4 degrees from cold and rose to mid 70’s – 80’s made be higher i never made a note.
Turbo actuator working fine
All service items changed.
Please help i am stuck and don’t know where to turn next, thank you in advance Paul

alcazar

iTrader: (2)

For Map sensor, do you mean the MAF? Was it changed for a new one, or a second hand one?

Have you connected the two black connectors under the steering column and read any codes that are stored?

Have you checked the engine coolant temperature sensor? (Not the one for the gauge, the one for the ecu?)

On mine, fuel pressure sits at 3.3 bar, and never falls below 3.1 bar even under 1.5 bar of boost and WOT...could your fuel pump be tired? Mine has a Walbro pump.

First thing I'd do would be check the codes, then the coolant temp sender.

dpmotorcycles

Hi thanks for the reply, with regards to the MAP sensor, yes it was the MAP sensor because the diagnostic was giving up some silly minus figure which was incorrect so we changed the sensor like for like (used).

I have not bothered collecting the blip codes as the diagnositc equipment will gather the same information.

Engine temp sensor (ecu) was also tested on the diagnostic equipment and proved to be ok, however i tried checking the voltages on the pins in line with the information from autodata and the readings did drop but the start point was not the 2.4v as described and another reading was also incorrect so it was inconclusive i feel.

Thanks for your information on the fuel pressure, autodate says 2.5 to 3 bar so im ok with there figures but abit shy of yours.

Does have anyone else have any suggestions i can use along with the input from alcazar?

killbill

iTrader: (3)

fuel pressure should be 3bar at idle should it not.

have you checked the intake pipe where it joins the turbo ?? i have had 2/3 imprezas n the past with same issue and the intake was split,new pipe sorted it.

dpmotorcycles

thanks for the input, question back to you, if it was a split pipe why would it run ok after it had cut out and got warm? same goes for the fuel pressure i have read a few posts on the web about 3bar so i agree this is a good pressure to have but once again why should things change when it warmed up, after the initial stall things are fine

alcazar

iTrader: (2)

Any engine won't run stoich until it's warm. The mixture is rich until then.
If the temp sensor IS out, it could be cutting the fuel too early? Or too late?

Any split maybe tiny, and when warm, doesn't leak, or not as badly?

Or, worse still, makes it run weak at a rich mixture setting, so trying to run on normal fuel mix = stall, and then, worse still: runs weak on normal fuelling and could be detting

dpmotorcycles

cool i will get the smoke machine on the pipe work and see what it shows, i must admit i am thing of throwing another temp sensor at it, if it fixes it then great if not its something else eliminated.

RalphJarvis

I have a MY99 uk2000. 5 yrs ago it was doing similar things. I'm also a mechanic and we had checked everything with no joy.
Turned out to be a failing MAF.

As I know now the MAF sensor particularly on 99/00 is notorious.
Especially if you have a K&N or foam filter element that could get oil residue into it.

Get a NEW one from a reputable source. The newer ones have a green marking & I believe are date coded, and supposed to be more reliable.

I'm getting rid of mine by fitting a Simtec ECU that doesn't need a MAF

Hope you sort her out soon.

Search on here for more posts regarding the MAF sensor and it's annoying ways.

Kind regards,
Ralph

killbill

iTrader: (3)

the exact problems you have on your car , i had on mine twice.

both times it was the intake split at the turbo.

worth checking mate

dpmotorcycles

thanks for your feedback so far, if we have time tomorrow at the garage ill run the smoke machine on it to check for split pipes, i think the gaffer did a check on the MAF but ill check tomorrow with him, i will feed back what we finf out.

alcazar

iTrader: (2)

You haven't said, (or I've missed it) whether the MAF you put in was new?

dpmotorcycles

Hi, i think you must of missed it, i replied saying it was not the MAF sensor it was a MAP sensor we replaced and it was used. Iv just checked with the gaffer regarding the testing of the MAF sensor and it was tested and is giving 1.5v from wire 1@ idle so that is working fine.

dpmotorcycles

After you guys mentioning the possibility of a leak from the inlet pipe this has triggered a thought, i feel that the brakes are hard to press and it feels like there servo pressure is down, could this have anything to do with it? the brake servo was tested to see if it holds vacuum and it did from what i remember.

something i though was another issue but might be related, after the car has stalled and i try to restart it the cranking is very slow it sounds like the engine is almost seizing or the battery is going flat, the battery is new and we are running top grade oil in the motor. This slow cranking only happens after that stall it never happens at and other time of starting?

Sorry to throw some other issues in there but at first i never thought they could be related

alcazar

iTrader: (2)

I'm not sure you can test a MAF like that. It varies so much as the airflow varies, and it's that you need.

Ask one of the experienced tuners on here, David at API, Allan Jeffery, Mark at Lateral.

APIDavid

iTrader: (4)

I'd change the MAF as a start, followed by Neutral start switch. the intake pipe leak would be a nuisance but is unlikley to feature just when cold.

David APi

dpmotorcycles

Hi David, is the Neutral start switch same as the Neutral position switch? and why would this only cause a problem when cold or in the early part of the journy or until it has out once. when the car has warmed up there is never an issue? thanks for your input so far.

dpmotorcycles

Today we did the smoke test and there was no leaks in the inlet pipes.
We also did further tests on the temp sensor it sould read 2.4v at 20 degrees and .9 v at 80 degrees. My temp was 40 degrees and the voltage was 1.8v and as the temp rose the voltage dropped as it should and read .9v at 80 degrees which is correct but the lower voltage is about 20 degrees out. We are thinking this could be enough to through the mixture setting out, does anyone agree?
We also ran the car with the MAF sensor unplugged and the thinking is it ran smoother low down the revs, but does the ECU revert the car to a kind of limp mode after detecting the MAF was unplugged because it did not like to rise above 3000revs?
We are agreeing with the comments that the MAF may need changing but don't want to spend the money and find out its not the fault, once again any advise would be great

Hos Hosslehoff

I've just had the same issue with it cutting out on start up but running fine when warm. Turned out to be corrupt data on the ecu. Mine has an Apexi ecu. If yours is standard then I'm not so sure :-(

ukpaisley

iTrader: (4)

Cam sensor , change this , a pal of mine has a similar issue, would only start ok when warm and run, when cold missed and just managed to start.

It is most def a sensor, these fail, shuch as MAF and crank ect. Also the cold start (Temp Sensor ) plays alot to how a car responds during warm up.

dpmotorcycles

hi mate, it starts fine first time and runs great after it has cut out once so its not the cam sensor, the MAF is also ok so i think we are going to go with the temp sensor soon as we can get one. ill you all informed.

dpmotorcycles

changed the temp sensor today for a new genuine one and made no difference, look like the MAF next

dpmotorcycles

Hi Guys, new MAF arrived today and now fitted and made no difference, has anyone any other suggestions please?

madscoob

iTrader: (3)

symptom of unmeatered air, runs rich as firk until warm, then just runs rich, i would be checking you intake pipe after the maf and before turbo

dpmotorcycles

i have done a smoke test on all pipes, no leaks

Jolly Green Monster

iTrader: (4)

Is it a brand new maf from subaru?

Compression test?

TonyBurns

iTrader: (3)

Have you checked the air filter?

dpmotorcycles

Thanks for the reply, Yes genuine MAF and new air filter, not done a compression check as it runs fine once it's been thought process of stalling, the restarting seems to be getting worse at the moment, needs a lot of cranking before it fires up after stalling, however the first startup of the day and when it's warm it fires up straight away, extended cranking is only after the stall.

dpmotorcycles

I followd a post of your with a guy who had a issue if the car slimiest stalling and you told him to wire the pump direct showing it was a relay problem, could this be similar?

dpmotorcycles

Evening Folks, i have good news i managed to fix the car this week with help from my mate and Gaffer Will. We went back to basics and checked the valves and found the Valves were kept open(no gap between the cam and buckets. We took the shims out and had them machined to allow the vales to close. The car was rebuilt along with a set of Gaskets and the jobs a good one, the car is running great.

Thanks for all the advise, i hope someone findes the information here of use, i found so many posts with no conclusion so i thought it best to post this update.

Thanks again

merlin24

iTrader: (1)

Glad you got it sorted in the end although a Compression test would have confirmed the 'internal health' of the engine before looking at possible external problems.
At least you can go out and enjoy the car now

Mick