im trying to cure running problems with impreza turbo 2000 uk 97, i had a mobile diagnostic guy come yesterday and he got 0.0 volts from the lambda sensor and slightly low readings from the maf with 4 stored codes for maf. so now ive taken out the lambda sensor as got a new genuine replacement being delivered tomorrow but i heard you can run the engine without the lambda sensor but mine still runs really rough with it disconnected or is that normal...? also did the check where you unplug the maf with the engine running and the engine cuts off straight away.

 

Not very often the Lambda fails at 0v, and if it did it would definitely throw a CEL.
You will only have 1 code for a MAF, code 23.

See here to do your own diagnosticts.

The Lambda is only used during 'open loop' running (off boost). When you give it some boost (closed loop' running) the ECU takes over the fueling.
So yes it will run rough with out one.

Waste of time, it proves nothing. It will store you a nice code '23 MAF' though.

 

no im not getting any engine fault codes... i did have the maf code up when i 1st bought the car but i changed to a metal mesh induction kit and got maf cleaner and havent had the codes ever come back but on the diagnostic it showed no current fault codes but maf 23 STORED 4 times from before now i started it up without the lambda its got the engine check light on, so it is normal for it to run rough with no lambda connected so as the old one wasnt working its made no difference still running rough the same... will it run back to normal with new lambda connected?

 

Yeah, as the Lambda degrades the ECU 'learns' to trim the signals. But once the Lambda fails beyond the ECU's limits then you have running issues as the ECU can't cope.
The same can be said for most sensors on the Scoob.

 

ok i hope the new lambda cures the running problems because as it is its not really drivable, it idles so low it cuts out and when you try to give it some power higher up it doesnt like it and tries to cut out to, but you can keep it running with a slight bit of power but dont think i could drive it the way its running as not sure if it would be able to accelerate much without jumpung and cutting out. would the low reading on the maf plus old stored codes mean the mafs on the way out to...?

 

It may be the Lambda or could be the MAF. You will not know until the Lambda is fitted.

The stored codes could be from people doing the 'test', but if the MAF is failing then the i/k will not be helping, and could be the cause. Unless you have a FMIC or other reason, then i would refit an OE airbox with a KnN panel filter fitted.

 

ok not got a fmic ive got an sti v6 top mount. i know that paper type induction kits cause maf failure as they are coated in oil and that contaminates the maf sensor wire for example K&N thats why i got a blitz stainless steel mesh induction kit so shouldnt cause any maf problems also ive had the car 2 years with this set up and its not caused any problems or maf code. if the maf is failing what are the symptoms...?

 

Fair enough.

Similar to what you are experiencing. But as you have the new Lambda on way...

Ensure you do a full reset after fitting.

 

ok will do ill let you know how it goes tomorrow lunch time, hopefully its not the maf to as theyre nearly £300 new and not sure about a 2nd hand one, mines a purple label...

 

ok just put the new lambda sensor it disconnected the battery to reset the ecu also after reconnecting did the blacks and greens plugs together to do a system check and find and codes but nothing, anyway started it up and its made no difference its still the same... so it must be the maf! i cant believe i wasted £134 on a lambda sensor when it wasnt the problem. when its idling its very low to the point of stalling also when you do the accelerator it keeps trying to cut out low down revs 2000 then about 4000 but you can rev it hard past to high revs but you get poping from the exhaust do you think it could be the maf...?

 

OK. When you connect just the 2 blacks and turn on the ignition (not starting the engine), what does the CEL do??

 

just the ignition or try to start it up?

 

Just ignition.

 

codes 23 and 17...

 

MAF and No4 Injector.

 

Correct Matt

Goujon, now do a full ECU reset as per JGM's site.

Connect Error code Connectors and Test Mode Connectors :
2 black connectors under dash, connect black to black and 2 green connectors under dash, connect green to green, they are by your left knee when sat in the drivers seat and often taped back to the loom if they haven't been used before.

Turn ON ignition but don't start the engine

Engine Check lamp comes on

Press accelerator pedal to the floor

Then return it to the half-throttle position and hold it there for two seconds

Release foot off the pedal completely

Start the engine

Check engine light error code is indicated by Pulsing lamp

If an error is detected then Check the ECU Code

If no error is detected - drive the car sensible for a couple of minutes
i.e. until warm (do not use boost or high rpm!)

When the ECU has been reset the Check Engine Light will flash

An Error Code is indicated by a flashing check engine light
of varying length of flash,
a flash of around once a second is the okay code and indicates all is well.

If an error code is detected Check the ECU Code

Turn ignition OFF and Disconnect Connectors

If there is a fault Check the Appropriate Sensor

 

yeah just checked the codes and saw 17 means 4th injector i already new 23 was maf... anyway followed the instructions you said and its made no difference it still runs the same, idling very low trying to cut and very poor throttle with lots of juddering cutting hesitation. so the 4th injector is causing the problem... do i need to replace the injectors or just the 4th 1 being if its faulty or damaged or blocked or can it be cleaned?

 

Yep, fairly conclusive, you need a MAF and injector #4 needs investigating. It could be a simple wire/connector problem or it may be deeper and require the injector to be removed.

 

what are the likely causes or faults with a bad injector? also where abouts are the injectors located? is it an easy job to swap injectors, do i need a whole set of 4 or just replace 4th, are all injectors the same as seen yellow 440cc sti 1's on ebay quite reasonable price...

 

Check injector wires and plugs. The link below is your friend.

https://www.scoobynet.com/technical-...d-updated.html

 

ok i worked out where the 4 injectors are located they look accessible but not sure if its the actual injector or the plug what shall i do...? also need to know the correct type of injector if i do need to replace them is it a phase 1 round head?

 

It will be very hard to diagnose the injector whilst you have MAF issues due to the poor running. If you get lucky, you may hear a change in the engine if you have a play with the injector connectors/wires with it running. I wouldn't get too hung up on the injector until you have the new MAF.

 

ah ok so you think the maf is the main cause of the engine running rough? i cant even drive it anywhere i took it to the end of my street and it was just trying to cut out all the time and didnt like it when i tried to accelerate does that sound like a bad maf? know anybody selling a purple label maf or where i can get 1?

 

are all purple label maf's the same...?

 

Oh yesh, the MAF imo is the main cause, the injector will not be helping.
Have a look in the for sale section, there are always a few on ebay.

 

ok cheers yeah found 3 on ebay so see what happens as long as all purple maf's are the same then no worries, im sure they are as are used on some forresters and legacy's.

 

Yes, just check the part number on the same label. The long on at the top.

 

My fourth injector is rather noisy... i think this may mean an upgrade to 440's and an ESL

 

do you know anything about injector types? like which ones are for my97 is it phase1 round end type? also do yellow 440cc sti injectors work for turbo 2000 uk?

 

Your car is a Phase1, so will have 380's IIRC. They should be grey in colour.

440's would work, but you would need a remap etc...