stuartjw

As title I have MY00 impreza turbo - Standard UK model. I have read that ECU's cause this but I cant believe it.

When I get up in the morning it is fine - No problem. After I have been at work all day now and it is a bit warmer I get in the car and it starts OK except for a ticketing sound - Not sure if it has any relation. Then I will accelarate to about 2000RPM and now doing between 30-40MPH. Keeping my foot completely still on the throttle causes it to pull a bit then back off and again and again.

It seems that once it has warmed up it goes away. Not sure if it is still really faintly there. Is this the ECU bug? Could it be anything else MAF?

I read that if you remove the MAF cable while it is running the engine will keep going as it was if the MAF is broke - Is this correct?

Anyway any help would be appreciated - Its started to drive me mad!!!!

pslewis

The MY00 have ALWAYS hesitated - mine is pretty smooth now, I have learned to only put SUL petrol in .... it makes a lot of difference!

Pop a bottle of injection cleaner through the tank, use the best petrol you can and see if it helps.

Some will condemn the MAF ............ its up to you, you could replace for £70

Some have changed the ECU for a MY98 ECU and its cured the hesitation

Pete

stuartjw

It has always been run on Optimax (Since I had it anyway). It was not too long ago I put injector cleaner in it either. Is it a straight swap for an older ECU? From what I have read it seemed that the surging was under accelaration though - Is this different?

Also does yours only do it when cold as described?

Thanks

FB Tuning

iTrader: (30)

My car hesitates and surges a bit on light throttle too -It's a MY00

It even does it since it had an tek3 remap.

WRT changing ecus, the one fitted to your car is an AE802

It is a straight swap to change this to an AE800 or AE801 from a MY99, which may cure the problem you are experiencing.

You cannot put a MY98 ECU in, as the connectors are incompatible

pslewis

Thanks for that correction fiestaboy!

Mine does it when cold, on certain days, on light throttle ..... not much trouble when warm

I use Sainsburys SUL and its excellent

Pete

Dark Blue Mark

May well need a new lambda if its off boost. Could equally be MAF but its normall one of these 2. Some cars just seem to do it

Hows your fuel consumption?

MB

rgv_stu

mine does this too on optimax and its a MY98
any ideas ??

dij

IIRC,this problem is more likely to be a lambda sensor as this part that controls the mixture at under 4k revs (closed loop?)

However,the MAF is more likely to go wrong on my99-00 cars,and could contribute to the problem.

£77 for maf from subaru
£35? for lambda sensor from Halfords(£120 ish from subaru).

Dark Blue Mark

MY98 MAF sensors are a lot better and rarely fail... Again O2 sensor is quite likely,,

MB

Dark Blue Mark

Dij, not necessarily below 4k rpm to be closed loop. Its generally above 0.5 bar boost or on WOT the MAF takes over from lambda. MAF still has an input off boost though...

MB

rgv_stu

ok then O2 sensor sounds probable, best place to buy ?? MY98

Dark Blue Mark

http://www.cats-direct.com/

3 wire zirconia.

MB

stuartjw

Fuel consumption has been the same since I got it so quite shocking!!!!! Are the Lambda sensors easy to replace - i.e. where is it located? Also would this not produce a CEL if it was faulty?

Dark Blue Mark

Dont always give a CEL, quite rare IMO. Lives in the downpipe just after the turbo. MAy not be that as its always difficult to diagnose over the net! They have a varaible life of anywhere between 10 and 40k miles

Worth changing every few years anyway IMHO. Mr Lewis may disagree If it fails, it will fail such that the ECU richens the mixture and you do use more fuel. If your sensor costs £40 it will pay for itself quite quickly... esp if it gradually gets worse over time.

MB

stuartjw

The car has 38000 miles on the clock and I doubt it has ever been replaced. Do you need a special tool to do it and does the ECU require a reset?

grahamfrary

Is the MOT a reliable test of the lambda sensor? That is if the car passes the emissions test with a spot-on lambda reading, does that mean the lambda is definitely OK?

XNWRX

Would say more likely to be due to the O2 sensor, or better to say a grounding issue which causes inconsistent O2 sensor reading.
Solution : add huge grounding cables running from the battery minus pole to different engine and body points.

Dark Blue Mark

Never known grounding to be an issue - very much doubt its that or it would always have been a problem.

MOT is a good test, if the sensor has failed they really struggle on the emissions. Same with MAF on idle.

Best to do a reset, as th ECU may have done some "learing" but will pick up on it in a short time anyway....

MB

MrDBM

same car, same problem - pretty much cured by replacement 02 sensor - code 32 IIRC

stuartjw

Ah - I posted a thread last week or something with the MOT emissions on it - Not sure how I would find it on search as I tried searching for my nick name.

The thing was as far as I can remember the idle % was 0.00 and the fast idle was 0.39% (i.e. 0.01% off failing its emissions - If someone could find the post it would be better.

Would this make sense that the O2 sesnsor is at fault?

thanks for all the help.

Dark Blue Mark

If it failed emissions it will either be MAF or Lambda (o2)

Unplug the MAF and see if the car stalls. TBH I would replace both at that age - many will disagree, but given the fragile nature of these and proven failure rate... Will cost you about £100 and an hour to fit. Easy stuff. Do a search and you will find out how to change them. You will need Torx drivers for the MAF - can get from Halfords.

MB

pslewis

I thought the Fast Idle fail was 0.3% and above?

CO2 Lambda only lasting 10k - 40k ..... what utter rubbish! I have cars on original Lambda Sensors at 56k, 65k, 97k, 47k ..... my old cars have never needed one replacing either! Complete TOSH!

Pete

stuartjw

Sorry yes - Just found the results:

I have the MOT print off and the figures are:

Fast Idle Test: Max 0.2% actual 0.00%
Natural Idle test: Max 0.3% actual 0.29%

Would these suggest a particular sensor?

Thanks

Welloilbeefhooked

iTrader: (3)

Stuart, I thought that this was covered in your previous thread?


http://bbs.scoobynet.co.uk/showthread.php?t=420751

stuartjw

I could not find my other thread to see if there were any updates - I know where to look no though. The surging seemed to get worse so I wanted to try again - Sorry.

I disconnected the MAF sensor and the engine stalled instantly - Does this mean it is more likely to be the Lambda sensor - Think I will get one from halfords on my way home tomorrow to try it out.

It only seems to happen on slow accelaration or constant slow speed - i.e. 2000RPM or so.

stuartjw

Is it safe to run the car with the lambda disconnected? I have just read a thread that to test it you disconnect it and drive round for a bit!!!!


Also is the MAF problem on cars registered on 21st December 2000? Did they change in september?

pslewis

The MAF problem happens if you mess about with the Induction System .... don't scare yourself about it.

It could be the MAF, of course, but don't believe that these sensors go wrong on cars that are lovingly maintained and not foooooked about with!

Pete

Mike P

Had a MAF fail on my non-mucked about with, lovingly maintained scoob.

When I had it replaced at Power Engineering they said see so many MAF failures they keep ten or so sensors in stock for 99-00 cars.

Mind you, having said that this doesn't sound like the classic MAF failures symptoms - it's cutting out when the sensor's disconnected, which is as it should be.

powerman1

My MY00 used to do it from cold and had only done 12k when I bought it.It had been in for a few subaru services and 1 MOT when I sold it at 32k and no faults found, just put it down to the nature of the beast.i dont think it anything to worry about although a little bit annoying I agree

powerman

Dark Blue Mark

Pete, please dont be rude, ive always given you the same courtesy in the past.

Ive had a couple of MY99's and never fiddled with the airbox, and still had MAF failures, and 02 come to think of it. Just because you haven't had issue, doesn't make yours the benchmark for all cars. I am purely talking Subaru here, not your previous cars. They do go wrong. In fact, many believe its the reason for the later AE802 ECU map being so conservative, because Subaru had a number of MY99 engine failures which they put down to lean mapping... missing the MAF problem. Id love to know how many they have sold

Safe to run in the very short term with 02 disconnected.

MAF problem is prevelant on any MY99/00 car. Bugeye's seem ok, and pre MY99 also rare to get a problem.

MB