Running very rich...
 

Hey all,

A little advice please. http://www.hampshiresubaru.co.uk/php...on_biggrin.gif

I have a UK MY99 turbo wagon which is running seriously rich. It honks of un-burnt fuel form the exhaust and even pops and bangs when changing gear below 3k! I have run a check using the plugs underneath the dash and it reports that the O2 sensor and knock sensor have had it.

I've replaced the O2 sensor with a second hand item with no change. I've yet to change the knock sensor. Will I need to perform an ECU reset in order to clear the fault and hope that the second hand O2 sensor is working 100%? The mpg is also a lot more shocking than usual.

The exhaust is a 3" system which is daft as the car is basically standard apart from PPP. I'll be changing that soon though.

Any help would be grand. :thumb:

Ben

Is it a full decat exhaust?

Ben

You can do a ECU reset.

does the error codes stay on permanently? ive found the o2 sensor (error 32) will show when water gets onto the wiring plug for it - can drip down from underpan on bonnet

also, the knock sensor error (22) can be thrown damp/wet connections on the MAF on 99/00 cars - most people say its a failing MAF but i found that once i cleaned up the connectors (also cleaned earthing points) and made a type of shield for the wiring connector for the MAF it went away. the maf sits conviently below the bonnet vent where water & damp can easily get in to it. the shield was simply a plastic bottle with bottom cut out of it that is then mated up to intake pipe

Yeah classic Lambda failure symptoms. I would replace both sensors with 'new' items. Don't be tempted by the cheap universal Lambdas on ebay, they last about 100 miles (got that t-shirt). And make sure you get the correct KS for your MY.;)

Here for the Lambda.

And here for the knock sensor.

You should do a full ECU reset to ensure the sensor is good after fitting and to clear any stored codes.:)


Easier to leave/put the bonnet vent blanking plates in place. They serve no real purpose, except to let water into places you don't need it.

Cheers for the replies.

Yes it is a full de-cat. I have had three classic turbos previous to this one and never had a problem running a full de-cat exhaust.

Cheers Gambit, I'll give those suggestions a go.

Ben

Cheers! :thumb:

ive a perfectly good knock sensor here if you need it. went down that road before :(

also, if its stuttering/hesitating when trying to accelerate again its MAF symptoms. knock sensor i was told will not cause car to run bad it just removes the ecu capability to wind in timing if knock is detected.

Splitpin on here was my fountain of knowledge for issues like this, he knows the 99/00's inside out.

Cheers pal.

ECU located and bought. :thumb: I'll let you know when it turns up.

How is an ECU re-set done?

good stuff re: replacement ECU :)

ECU reset here
http://www.scoobypedia.co.uk/index.p...ledge/ECUReset

or you can disconnect battery and leave it sitting over night that'll also clear it

Cheers guys!

Both pages bookmarked!!

.....

never realised it done a final check. i usally just hit the "reset ecu command" on my PS3!

Update.

I've replaced the o2 sensor and cleared the fault. The knock sensor fault (22) is still showing.

The car does not seem to want to boost much. When on wot the car stutters and hesitates.

Any more ideas?

Ben

Have you carried out an ecu reset after replacing the sensor?
If you have then it could well be that knock sensor :(

Tony:)

I have also changed the exhaust to a 2.5" system, fully de-catted ans changed the ecu for a standard one.

When I removed the old exhaust there was a spark plug in the tail pipe, presumably for a flammer. Would this affect the running?

Cheers

I have. I wouldn't have thought the knock sensor would case rich and lumpy running though?

Hmmm a bit more back pressure could mean your now overboosting, does it do it in 3rd, 4th and 5th?
You could try being in 4th gear and putting your foot down from say 2k rpm, if by 4k your feeling those pulses then a good chance its overboosting in the cold weather.
Remap time :D or a manual boost controller (though the remap would be better tbh)

Tony:)

Cheers.

It doesn't feel like overboosting, more like it's holding back or hesistating slightly. It does it in all gears. The car also doesn't like to be driven in low gears, say 30-35mph in fourth gear.

I have an mbc on order. :-)

If the KS is fcuk'd then it is possible that it is sending info that knock is being detected and therefore the ECU is pulling the timing accordingly.

Not really an ideal time to fit a MBC. You will need to know that the engine is running tip top A1 before fitting it. And after that, if raising the boost you will need, at the very least, your AFRs checking to avoid any det occurring.

Cheers fella.

I've got a spare ks that I can try tomorrow. Would this account for the hesitancy too?

Cheers! ;-)

Right then, the saga continues....

I have changed the Knock sensor and O2 sensor for genuine items. The maf has been checked and is fine. The ecu has been re-set and there are no faults found.

But....... The car still runs very rich. It almost smells like a two stroke on start up from the exhaust. It still pops and bangs when driving under normal conditions and sometimes when on constant throttle it pops constantly. MPG is still down too.

The car is booked in with Subaru 4 U on the 10th but does anyone have any more ideas?

Cheers

Ben

do you have any means of checking your fuel pressure ?

No, I don't.

Could it be that the fuel pump is faulty?

fuel pump would usually cause it to go lean, i was thinking about the regulator or possibly a leaky injector