Demon Jinx

Hi there guys I need help please!!!!! My 99 WRX STI has an misfire and splutters between 3500rpm and 4800rpm then it pulls again. I had MAS sensor problems but that is sorted now. Has anyone got a wiring diagram as it sounds like spark though. Can it be spark plugs? I am sure it can be coils but I swoped it around with another set and still it does that. I am not to sure if it can be fuel cause doesnt make sense that it comes right at 4800RPM. Any help please guys!!!!

Glowplug

iTrader: (8)

Welcome to SNet.

Plugs are always my first port of call when a miss is occurring.

Remove, check condition and gap. Re-new or re-gap as required.

0.65mm

Demon Jinx

Awsome bro thanks!!! Can it be anything else? Will get the plugs sorted then

Glowplug

iTrader: (8)

It's a Scoob==>(translation: could be a whole myriad of things)

To check the plugs condition and gap is free and easy to do. It is a good starting point where missing is an issue. From there you can work your way to the leads, coil pack and beyond. Personally i don't see the point of messing with anything until you have eliminated the sparks.

Have you done an ECU reset since sorting the MAF issues??

Demon Jinx

Yes I did the ECU reset! Will do plugs and check.!!! Just hope I can get Scoob sorted!

Glowplug

iTrader: (8)

And the reset finished with the 'all clear' flash, yes??

In which case you know it is not sensor related.

Demon Jinx

All clear no engine light and no fault codes....

Glowplug

iTrader: (8)

Spot on. Get those plugs out.

Demon Jinx

What is the correct spark plug???? Net says PFR6G and currently its running onIFR6T.
Please help!!!!!!!

Glowplug

iTrader: (8)

Demon Jinx

Thanks b13.... This thing is realy a pain in the **** now..... I gapped the plugs but still the same. Can it be that the plugs a f.....ing me around? I mean the fact that they are not the right plug in the first place.. and also can they induce a misfire between 3500rpm and 4800 rpm?

Glowplug

iTrader: (8)

Yes, i would always use the NGK PFR??'s at 0.65mm.

Demon Jinx

Ahhh shweet because the gap I got of the net is 0.8! Let me go and pick up plugs will post later again thanks again....

bolasti

iTrader: (6)

if not change ht leads (had this problem ages ago changed leads then was fine) it only misfired at certin revs like urz. good luck mate

Demon Jinx

Thanks Bolasti but this thing has got individual coil packs....... Any other suggestions?

Glowplug

iTrader: (8)

I thought the MY99 had the single coil pack on top of the manifold.

bolasti

iTrader: (6)

no worrys mate. theres a lot of info on this site only a matter of time b4 ya get her running sweet good luck

Demon Jinx

Nope This is WRX STI has got individual coil packs......

Demon Jinx

Thanks Bolasti..... Need all the help I can get!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Glowplug

iTrader: (8)

So you have these??

http://www.importcarparts.co.uk/part...en=&searchKey=

Demon Jinx

Exactly the same bro! Is it possible to covert to single coil pack?? If so wiring Diagram please guys!

Glowplug

iTrader: (8)

Bugga! Been on the wrong track.

On the end of each pack is a rubber, as carefully as you can, pull off the rubber and check very closely for cracks around the exposed tip. If you see any cracks the you need to replace the pack. I had 2 go the other week after the Mrs blew my I/C pipe off, i managed to get a good used set off here for £70.

Yes can be converted, here you go. Bill did it a couple of weeks ago.

https://www.scoobynet.com/scoobynet-...onversion.html

Demon Jinx

Next Question how will I find the one that is buggerd if I cant find any cracks in them? any ideas??

Glowplug

iTrader: (8)

If there are no visible cracks and they look in good condition, then they are usually considered to be good.

So back to the plugs.

Demon Jinx

B13bat installed brand new plugs!!!! Still the same cganged all the coil packs still the same!!!! Next question!! What is the symptoms of a lamda sensor failure?? How can I test lamda? What will happen if I unplug?? Could that be my fault?

Glowplug

iTrader: (8)

Lambda will give 'lumpy' idle/running and higher than normal fuel consumption. Not sure which Lambda you have, but if you find the loom plug where it connects, you will have 3 or 4 wires, the gold colored terminal is the signal wire, use a milti-meter with the engine at idle, it should read 0v-0.7v changing almost constantly. If it sits at a steady v then it is duff.

Again cost nothing to check.

edit: If you unplug whist running, then it should throw an error code/CEL

Demon Jinx

Ok checked it.... I get a steady 5.3V reading? If a start the car the RPM goes up and goes down a few times before leveling out.... Can this cause my problem?

Glowplug

iTrader: (8)

You get a steady 5.3v with the engine running and the Lambda connected?????




Are you starting the car with the Lambda connected??

Could be. The thing with the Impreza is, it only uses the Lambda when off boost (open loop). When on boost (closed loop) the ECU takes over the fueling. So if the problem is there when on boost you probably have more issues than the Lambda.
But with a steady 5.3v on the signal wire, i would say yes, and it should be throwing a code 32 via the CEL too.

Demon Jinx

No fault codes or anything!!! Doesnt realy make sense though!

Glowplug

iTrader: (8)

No it doesn't.

I know the fault system has pretty wide parameters but to be getting 5.3v from the Lamdba should surely be enough to throw a fault.

Where abouts are you?? It may well be worth a trip to a good RR to see if they can pick it up. Probably cheaper than a new Lambda.

I know Scoobyworld do a rolling road check for £50.

Edit: Same sort of problem, just in a different range. https://www.scoobynet.com/general-te...ew-member.html