barchud

Hi all,

First post here, so bear with me please - I'm no engineer!

I'm having a problem with a slight misfire on my 2003 2.0GT Legacy. I'm told it's an STi EJ20 engine, so hopefully familiar to many of you. When cold, its fairly pronounced spluttering at 1800 - 2000 revs. When she's warmed up, the low end is fine, but I get the occasional blipping in power all the way through the boost, which seems to top out at 5000rpm. It's so slight, its only really noticable on smooth road surfaces however.

Some specialists have checked the log, which has no error codes and the ECU is standard. They say it's the MAF sensor but another fella who knows his way around these things says its more likely a coil pack. I've had new RG7(?) plugs fitted and the coil packs examined for obvious probs - nothing.

Before I have to sell one of the kids to get a new MAF sensor (I thought Subaru were talking Yen when they gave me the price) - should I be checking anything else first please????

scoobian

if you could get yer car on a Crypton Tune, it would tell you if theres a plug/lead/ignitor problem



aaaaaah those were the days <sigh>

Glowplug

iTrader: (8)

Did it do it before the new plugs? Are they gapped correctly 0.7mm? Ngk pfr7 or 6 are recommended. Hth

barchud

Yes, plug change was first attempt to fix problem, so it can't be them.

Incidentally, I dug out the invoice to check, the plugs are indeed PFR7s - you know your stuff!

barchud

The garage did a full diagnostic on the car, so shouldn't that have picked up anything a Crypton Tuner could?

Some one suggested disconnecting the MAF sensor and seeing how it runs then. If it's still misfiring, it's the sensor - if it gets worse, it probably isn't.?

Glowplug

iTrader: (8)

Yeah that works but i wager if you pull the plug it will stall could try a ECU reset and see if its any better after that, then see if i kicks up any fault codes, if it is the MAF then you should get a code
.
JollyGreenMonster.co.uk
Btw I dont know much about your model, is it the standard engine or has it had the EJ20 fitted later, and if so is the ECU standard to the new engine or to the original

barchud

It's a Japanese import - so it was built with EJ20.

I'm pretty sure the garage said they'd reset the ECU also.

Just tried starting it with MAF disconnected, which it did no probs. I ran it cold round the block, and it seemed to run about the same as it usually does. (I didn't fancy burning it up the main road with no MAF sensor, so left it at that).

Funnily enough, it stalled when I reconnected the sensor - so it suggests it must be producing some kind of signal, either that or it was working and I've just blown it up! Do you know if these sensors fade out and then stop working or do they just work or not work?

Help appreciated BTW.

Glowplug

iTrader: (8)

Yep, sounds like youv'e just blown it Doh, Just kiddin Have read that the early Mafs are rouhgty toughty but the later ones are a bit more feeble. The ECU can 'learn' to run a slowly degrading MAF but when they are gone they are gone!! I would still go for a ECU reset, its free and dont take long to do

barchud

Sounds sensible - I'll give it a go. Thanks