I am taking my car into Subaru tomorrow for a diagnostic test

I am extremely worried that somehow they will fake the results of the test to make more work for themselves and making me pay for work that does not need to be done

Can this be done?

I am a girl and have been conned before by garages and I do not want this to happen again

 

Unless your car is going in for warranty work I'd avoid going to dealers....find a specialist, nearly always cheaper and more than likely do a better job

 

warning - shark attack on its way

 

if its a CEL thats on, its just as cheap to buy a code reader yourself and see whats wrong , rather than let a garage do it.
Once you know the code you can find the problem and work from there

 

The problem is that my car has been coming up with different codes.

My car is stalling at very low revs done a blink test came up as 22 which is the knock sensor and was told that this would not cause car to stall.

Reset ECU and came up with code 24 which is IACV and not 22 so I am completly confused and dont know what else to do except go to a garage who have the proper machine do the test unless anyone knows where I can get a cheap machine so I can perform the test myself

 

Where about's are you located?

 

I am in Croydon

 

Your not far away from Rich @FB Tuning,very good and well trusted by many on here

 

Not all dealers as sharks, we certainly arnt that's a fact, were quite away from yourself though being in the not so sunny cumbria lol

they should just do the test as asked and nothing more, if you explain you've done a test and its showing those codes then I think you'll be fine. they may advise what you need to do to rectify the fault.

 

when u have a knock sensore code ideally u need to replace it.. i had the same problem aswell as the iacv all i did was removed it cleaned it up free of carbon but a new gasket on an reset ecu an i have never had a problem

 

The first thing I would do is clean the sensors with brake cleaner.
a few months back I had the dccd flashing and checked the codes it was 20 something cant remember now, cleaned all the sensors and good as new.

I then had the ecu read for free when it went in for a service and there were no problems.

 

ok just got back from garage and this is report:-

Engine light on and poss code 24 in system half hour check

Carried out checks to car loss of power and engine light on, code 24 in system, idle control valve fault, possible idle control valve fault, may require removing and cleaning, also possible fault with MAF, fault with this will also cause fault code 23 & 24 this will also cause lack power. Customer aware

Well I am no further forward!!!

Now on way home stuck open at 4000 revs and will not drop

 

To re-iterate, find a good independent and use them, they have all the diagnostic stuff that dealers have + better stuff like the ECUTEK Delta Dash and a rolling road etc. They don't tend to rip you off either, cetainly if you want repeat business.

My experience of Subaru dealers (and BMW ) is that they are a bit of a joke though I'm sure there must be one of two good ones around.

 

You havent even told us what car it is , has it been moddified ??

If its a 99 mafs are a common fault . but if the revs are stuck at 4k sounds very much like a idle issue , iac valves second hand will prob cost to 10.00 .

Cleaning you could do yourself just dont damage the seal .

Rich

 

Car is subaru impreza turbo 1999

Prodrive pack on it, aftermarket K&N induction kit

Blizt dump vale

Boost control but running at normal boost

245 bhp

 

K.n induction kit will kill those maf's , could be either maf or iac or even the dump valve sticking ..

 

Any suggestions on what I should replace first

what type of air filter should I chnage it to?

Should I put the original dump value back on

 

I would get a maf sensor clean up the iacv... And I Beleave using The standerd Recirculating Valve is better than after market...Also get a panel filter

 

If you have the std dump valve try it thats no cost ,

Personally would just use a panal filter , Try a iac valve but still could be your maff.

Sorry carnt be more help , if you had been local would of happly tried both from my car for you .

 

My old JDM classic had an HKS 'mushroom' green air filter on it when i bought it back in 2003, and it went through MAFs like you wouldn't believe, to the point where I'd carry a spare in the boot. I didn't realise that it was the filter that was killing them until I read it online.

I bought a standard airbox from a breaker and put a decent panel filter in. No more CELs and no more spending out on MAFs.

 

IMO that all makes sense to me; A important thing that must be understood with "plug in" diagnostics is that you cannot fix a car by reading off fault codes....the codes are there to AID the investigation of a problem, it is not the end-all/do-all of vehicle fault diagnosis.

A failing MAF may not throw up a MAF code, but can cause idle instability/stalling which the idle control valve will struggle to manage with (especially if clogged with carbon/soot which is common....hence the advice to clean it).

The only thing missed on that report is mention of an air leak. This can also cause this issue. And that needs to be tested via other means (smoke generator is the best for this).

Finally, and this is IMPORTANT...it maybe there is more than one thing at fault with the car. As mentioned you have a cone filter - these are well known to cause problem with MAF sensor. YOu also have a open vented dump valve...again these cause idling issues.

You say the car is now stuck at 4000rpm, now the obvious port of call here is the idle control valve. As mentioned remove it and clean it, I advise to clean it with carburettor cleaner (which the garage rightly advised as well). Reset the ECU after replacing the valve to clear any fault or limp-home strategy. If no effect and still idling high temporarily blank off the idle valve (make sure nothing gets sucked in) ...it shoudln't idle at all (or start). If thats the case you've found at least one of your faults...be it wiring to the valve or the valve itself (I can't stress enough that wiring faults on such old cars should never be ruled out).

If it still idles high with valve blocked off, you have a big air leak somewhere. Manifold gaskets, sticking throttle body or linkage, brake servo leak, split hoses, dump valve seals (on the manifold vacuum side) failed. etc.

 

Which panel filter is best

 

Green cotton, STi or if you have deeper pockets, Cosworth/RCM

Do you still have the housing?

 

The standard one.

 

OK just called RAC out

Guy cleaned teh idle control valve & throttle body where excerlerted link is and it seems to be running fine should I still buy a idle control valve

 

Just take it off an clean it with brake cleaner

 

dont buy it yet because you might not need it. Wait a bit and make sure it is infact 100% or else you will end up buying one uneccesarily.

 

Funny you mention this as my ex had the same problem on her catalunya.

Cleaned out the idle control valve and the butterfly in the throttle body. Car ran perfect for 3 months and then the AFM went faulty. Replaced that aswell as taking off the induction kit(forgotten the make) and replacing that with standard airbox. Can ran fine for years after till we sold it.

As an AA man I would recommend going to an independent specialist rather than a dealer

 

Don't worry about the dealer v specialist banter, I know dealers who are far better than speciallists and vice versa, there is no "x is better than y" here, just go to a good recommended garage, be it a dealer or speciallist.

Tony

 

In terms of cost a specialist will always be cheaper than a dealer when it comes to classic imprezas. If it was something like a 2009 onwards model then even I would be wanting to visit a dealer.