g-star67

Hi all,

can someone please tell me if the ECU needs to be reset when the MAF is changed/replaced with a new unit?

If so, how is it done? Dealer or D.I.Y?

Any help/advice would be most appreciated

Thanks

Greg

Gigsy

It would be good to reset the ECU as it will have learned any inaccuracies of the old MAF so will take some time to unlearn them.

Can be done DIY but you need a copy of either RomRaider or Learning View (both free) and a USB OBDII cable (aka VAGCom cable off of eBay). They're pretty cheap and it's a useful thing to have anyway IMHO.

Bob Rawle

What car Greg ?

there is actually no real need to reset it as its only the fuel learning thats affected by a maf change directly, and the reset levels could be as bad as the learnt levels iyswim so it would still have to learn to optimum. Off boost only btw.

cheers

bob

g-star67

Hi Bob, it's a 03 Blobeye ! Thanks

Bob Rawle

Hi, no need to reset the ecu will sort it out quickly, its rare for a new age maf to need changing though unless its become heavily contaminated due to poor filtration.

best regards

bob

Gigsy

As I understood it, hesitation is often attributed to MAF issues with newage cars and is not uncommon?

(Least, it's seems to be a default dealer response to change the MAF on cars suffering from hesitation)

g-star67

The reason for the change is purely a "rule things out" option !

Then next will be change out the Idle Control Valve then if that doesn't help, its heatshield off the turbo to check model -buy a replacement & the downpipe and if that doesn't work ! set the bloody thing on fire lol

Gigsy

Check out the latest copy of True Grip... there's an article on cleaning the ICV.

g-star67

Thanks mate, i've read a similar article in the latest edition of "total impreza" mag !

Im no mechanic, and i really wouldn't have the patience to do it tbh !

May also try change the "boost solenoid" to see if that resolves the issue?

Having just read some other posts on here, it could be my downpipe cat has collapsed internally and changing it out to a decat or sports cat could solve it??? The only problem then is the cost of a remap as i believe that has to be done if changed?

Thanks

Greg

Gigsy

Yes, that's right... Total Impreza, not True Grip )

What are the actual symptoms your trying to fix?

g-star67

lol ! I should have put that to start with (sorry mate)

She has inconsistent boost ! Mostly only boosting to 0.5/0.6 bar then suddenly out of the blue will boost to 1.0/1.1

The car used to pull like a train, now most cars will pass by with ease ! Not that i drive around on the ragged edge ! Its just really frustrating knowing/feeling like the car just doesn't go well anymore !

I only use V Power, oil & filter changed every 6k, fully serviced with genuine subaru or upgrade fluids & parts,plus i've done the following mods: cotten green panel filter,boost gauge, Afterburner resonated centre section with a Ninja back box.

Next on the list will be a walbro 255lph fuel pump & maybe a decat downpipe !

Cheers

Greg

Gigsy

I assume it's been mapped for the mods? Does the Afterburner section mean you've removed any of the cats already?

Have you checked all the turbo plumbing? Is your BCS functioning? When did you fit the boost gauge? Idle control valve and MAF wouldn't be the obvious things to look at IMHO from the symptoms you describe.

Do you have access to a laptop and OBDII cable to be able to data log what's going on?

Gigsy

...just had a thought, check the Y pipe between the turbo and the IC especially - on Foresters at least, these have been known to go a bit brittle and crack.

However, if the boost gauge is a new addition, I'd start there.

Oh, and check you have a restrictor in the pipe from the turbo that goes to the T pipe which then goes to the wastegate actuator and BCS.

g-star67

Hello mate,

thanks again for all the info !

Hasn't been re-mapped yet as i didnt think it needed it with the little i've done to her.

The problem stated months before fitting the boost gauge, i only put it on to see the boost levels for info.

One of the guys from slowboy had a very quick run out in her and thought it might be a crack in the turbo housing or the actuator?

Ive just oredered a OBD2 cable and downloaded RomRaider to see if that can give me any ideas. I guess datalogging out on a run will show up something - just don't know how to analyse the info it collects !!!

Cheers

Greg

Slowboy Racing

Not going to be a cracked waste gate housing, may have suggested a waste gate issue. Sounds like the boost control solenoid valve if boost is erratic from .7 - 1.0 Bar, rather then spending loads on parts, if you need to borrow one to test and confirm, or need local advice let me know.

FWIW i see a fair amount of failed or failing newage Maf's usually around the 10 year mark, my choice would be to test these every six years as part of a scheduled service.

Gigsy

If you're seeing 1bar boost then you're getting overboost. IIRC, stock boost on an MY03 WRX is 07/0.8 bar.

When you do your logging, check IAM (Ignition Advance Multiplier - should be 16 or 1 depending on which ECU you have) as a general health check. As for actual data to log, Manifold pressure, throttle position, rpms, load and wastegate duty cycle would be the main ones I'd suggest. The pro mappers on here may be able to suggest other/alternative things they'd look at.

Also, download Learning View (also from the Rom Raider forum) as this will read the ECUs learning tables and see what the ECU has learn to correct for (MAF & timing).

The overboost is most likely coming from increased VE from the exhaust mods / panel filter (though less likely if you still have all your cats), the BCS sticking open or a leak in your boost pipe work. The wastegate could also be sticking, though less likely IMHO.

Personally, I'd look at the pipe work first and inspect every inch of it before spending any money replacing parts.

You can also test your BCS by connecting the two green connectors under the dash. This should start the fans turning on and off and the BCS should start clicking. Assuming it's clicking, you can also check whether the wastegate is opening correctly by blocking the outlet from the BCS back to the inlet manifold. This will limit you to wastegate actuator boost level only (c0.4bar). Any more and it's possible that the wastegate is sticking.

g-star67

Hi guys,

once again, thank you for all the advice etc...

Am away for a few days now, but will you give you a call and pop up to you when i'm back & see if it is the BCS or not?

Its great to know there are some really helpful people out there in just these sort of situations !

It is much appreciated

Thanks again

Greg

Bob Rawle

Std targeted boost is 0.95 bar to 5700 rpm then it reduces. So if a boost gauge is reading 1 bar there is nothing wrong as that minor difference could simply be down to atmospherics.

Check that the pipe exiting at the left front of the inlet manifold and is connected to the black plastic emissions valve is not loose or dislodged as that will cause problems. Also check the pipe from the left end of the inlet manifold to the fuel pressure reg is secure and fully on. Both of these are prone to coming loose and dislodged.

You won't hear the bcs clicking as described above, the ecu provides a single pulse to it during this test, you need to actually hold the valve to feel it as you will be unlikely to hear it. Its the earlier Jecs ecu's that pulsed the solenoid in the way described above not the later Hitachi.

Guys if you are going to post then you will be misleading people if you are not careful and considered in your input and whilst self mapping is a fun topic its not funny when it goes wrong.

For example given the model year and model of the car is stated surely that "should" tell a person what the AM max will be since that defines which rom file type is in use. This is not a CAN ecu so the AM max is 16.

just some input

cheers

bob

Gigsy

I think you've misconstrued my "should" re IAM... as I wasn't sure when the ECUs swapped to 32 bit (presuming now this was at the Hawkeye shape?) I didn't want to mislead the OP by saying "your IAM should be 16" if it wasn't and hopefully, unless there's something very wrong, once the OP had done some logging, the type of ECU he had would have been obvious to him at that point

Thank you for correcting me with regard to boost, as stated, I was under the impression that stock boost was a little lower.

From what you've suggested as things to check, it does seem that a leak is the most likely cause of the OP's problem so hopefully he'll be able to get to the bottom of things and save a few £'s by not simply going out and replacing parts adhoc as was his original intent.

dynamix

iTrader: (3)

For the amount of things that have been suggested to change it will be a lot cheaper to actually get the car mapped which may be all that is needed. At the very least get an expert to look at it, the cost of getting someone like slowboy or one of us mappers to datalog it may save a lot of money and potential breakages in persisting to drive it if it is being dropped into limp boost levels.

babber

Bob,

I have a rb5 that Dr Banks mapped on the standard ecu, with a Tek2. I am wanting a bit more, how much could you remap mine for please?

Thanks Phill

g-star67

Hi Duncan,

PM sent

Thanks

Greg

Bob Rawle

Babber email me on rbr@brdevelopments.com.

Gigsy my comment was not a dig but answering this sort of question carries a degree of responsibility so my "concern" is that the recipient does the right things to the right car iyswim and an either this or that sort of answer relating to ecu type was a concern (to me).

A lot or people simply skip the tedious bits (like logging) and blast straight into the "try this or that" mode which is when things can go wrong.

Hopefully the fact that I am taking the trouble to post in this section shows that I have no axe to grind, its great that people take an interest in self mapping ... always here to pick up the pieces or help of course. But as I said people need to post definitive and competent information mapping is not a game. I am lucky in that my hobby and passion is also my job. Not all my comments are commercially orientated !!

cheers

bob

Seanharvey1983

Hi bob . can you get in touch please as i have just purchased a p1 today and already have some issues. had a flat spot at around 90 going up cain hill and had to over for a car who wen past me as mine died then picked back up. also my clutch is ok ish round town bit juddery but when going fast it stays between changing up only for a sec when revs down can then change up again. ?? never had no issue like this with my sti. car has cost me a bit and guy wont refund me. brakes also not gread at speeds goes left and right slightly. can any1 help plz

Seanharvey1983

My p1 . today i have managed to get lights and indicators going after discovering they were either unplugged or disconnected . still no gauges on defis woeking or alarm. sure earthing problem somehwere hence these were unplugged. dunno how to plug gauges in as unsure which wires or where tpu them and same for alarm. any auto technicians able to help asap please. private message me.

As for the flat spot all seemed ok . have put shell v power in so hopefully that helps ; ) . clutch was still slow on release at high speeds changing gear and a bit juddery rouind the town. any help info gratefully received. thanks bob rawle for the call today to get me sarted.

dynamix

iTrader: (3)

Poss missing a return spring on the clutch arm

g-star67

Well guys,

"here is the news" lol

Met up with Duncan today at Hayes Engineering and he did some datalogging,diagnostics and had a good general look over/in the engine bay.

After some road testing he found the problem to be the cat below the Turbo !

So releived it wasn't something terminal !!!

So to that end i have to say - a HUGE THANK YOU to all of you who responded with ideas,hints & tips etc...

And a MASSIVE THANK YOU to Duncan for the work he did today.

Looking forward to getting the car fixed, then onto the Rolling Road,re-map etc... with the next wave of mods.

All the best guys & thank you all again

Greg

Gigsy

Glad you managed to get it sorted without recourse to buying parts on a trial or error basis. Sometimes, there's no substitute for an experienced diagnosis with these things.

Just out of interest, which cat do you mean when you say "below the turbo"... up-pipe (ie before the turbo) or downpipe (ie after)? Both could be construed as being "below" in a way.

g-star67

Hello mate,

its the up pipe cat !

Just got to source a replacement now !!!

Thanks

Greg

Gigsy

Decat... check the part number with Subaru but to the best of my knowledge, the up-pipe on a hawkeye WRX is the same as a newage STI and the Classic turbo - none of which have cats and all of which can be had from breakers for around £30 :biggrin: