Help!!

Up until now my STI version IV has performed beautifully but in the last 2 days it has developed a strange fault. Once warmed up, if I give it a bit of stick (not that much either but say up into the 6000 RPM mark), it then runs like a dog on light throttle load between 1800 and approx. 3000 RPM where it is like someone has turned on a 'run nicely' switch and all is well until I slow down again and then it runs like a dog again.

After the problem started, I deliberately ran the fuel tank down low so that I could fill up with a nice tank of fresh SUL 97 (Esso) in the hopes that it may have been a duff load of fuel but it has made no difference.

I suspect (hope?) that I may have a split pipe from the inlet manifold to the MAP sensor - as this would explain the symptoms perhaps?

Two questions:-

1. is this a reasonable explanation?

2. WHERE IS THE MAP SENSOR AND IT'S RUBBER PIPE?

Many thanks for any assistance?

Steve

 

MAP sensor on MY00 UK spec is just in front of the right suspension tower cover between the bonnet stay and the airbox. It has a three pin connector and is labelled Denso. On the inside of the wing next to it is the wastegate control solenoid valve, and going the other way towards the intercooler is the pressure source switching solenoid valve. May be different on STi. Don't know if a split would explain your symptoms. Do you have a boost gauge? - may shed some light.

Could also search earlier posts on how to use underdash black and green connectors to see if there is a fault code which you can read by the sequence of flashes when you reset the ECU - see recent post on ECU reset - few weeks ago in Drivetrain for Link to MRT site on how to do this.

 

John,

Thanks for your reply. Your description seems to make sense and I believe that I have found the device and the pipe that feeds it from the manifold. There is also another pipe that comes out of it's side that goes to wastegate control solenoid if I am not mistaken? Sadly (happily?) all the pipework is in excellent condition and no splits are apparent. Maybe my original diagnosis was wrong (it would not be the first time).

I do not have a boost gauge unfortunately

Steve

 

I must get a boost gauge myself - just working on whether an electronic homemade one is feasible at the moment. But knowing that there are no ECU fault codes stored and knowing what the boost is doing will at least give you a starting point before you start getting expensive.

 

John,

I have considered running the diagnostics switch with the green connectors but as there is no 'Check Engine' warning indicator, I am assuming that the ECU is not currently aware of a problem so the diagnostics will not display a fault code?

The fault code would be 45 according to some info. I have here.

After the month I am having, please let it not be expensive!

Steve

 

Richard/Matt,

Thanks for the replies. I shall research the solenoid issue as you have suggested by searching further here.

Regards,


Steve

 

The well documented 'hesitation' issue is similar in that it is also most apparrent (sp?) on a light throttle...but between 2.5k and 3k rpm.

I much improved a particularly bad case of this by cleaning the solenoid and pipework plus relubricating the dump valve.

I suspected the dump valve at the time...it was *very* sticky. It's only a 5 minute job to remove and try pushing it open. Be careful of the i/c fins though, lol!

Regards
Richard

 

Hi,
I also have a similar, although not so severe problem. It seems to have started after I fitted a SS midsection (also have SS backbox)

The problem is on a light throttle the response seems too jerky between 2000 and 2750 ish rpm - most noticable in 3/4/5th.
This sounds like your problem Dowser..
How do I get at/clean the D.V/solenoid/pipework?

thanks for any advice
Matt
(97WRX)

 

Hi Matt

Do a search on 'boost solenoid' &/or 'hesitation' - there's a *few* posts on the subject.

As for the dump valve - on my99/00 it's attached to the intercooler, but maybe the 97's is separate? I cleaned it will wd-40 and then washed this away with electrical cleaner.

Richard

 

Thanks Richard I'll have a search around.
Matt.

 

AFAIK, you only know there is no error if you get an even on-off check engine light flash. If you are not getting this, then you are not getting any info. Check again, but when I reset, I warm up, turn off, connect the two sets of plugs, turn on to position II, floor the accelerator for a few seconds, release, start the engine, then start driving, then the check engine light flashes its stuff. I think there is a way to do it when stationary too, but I've not looked into it. I think you need to get the even on-off pulses rather than nothing at all to know that there is no error code. You best look into it in a bit more detail rather than rely on my dodgy memory.

 

Hi all,

Steve, I was reading the Scoobynet board and found your message about he problems you are having.

I also have a STi IV (Type R) and I'm experiencing the same problems.

I was just wondering if you had found a solution to it as it's driving me nuts at the moment.

The local Subaru garage were I get my car serviced haven't found any error codes. I've changed the HT leads to performance ones and the spark plugs to NGK Platinums aswell but it still hasn't sorted it.

The problem did seem to start after a big 30k service. I tried cleaning the boost solenoid yesterday and it did seem to fix the problem for a short time. I drove the car straight after I had done it and it was going like a rocket and running really smoothly, as it used to do. When I drove it today, on a long journey it ran like sh*t all the way. The power is still there but the engine just feels rough and was hesitating/misfiring at the low end of the rev range and under hardly any accelation. The problem doesn't seem to be there all the time either, very weird.

I'm going to check the oil level again to see if it is higher than it should be. I've read that this can contaminate the boost solenoid..

I'm considering taking the car to a rolling road to get it checked out...

If you could pass along any info you find etc that would be much appreciated.. I'll do the same.

Best regards,

Mark

 

Hi Mark,

<<I was just wondering if you had found a solution to it as it's driving me
nuts at the moment.>>

Yes an No! In the end, I took my car to Lockyear Cars where I bought it
earlier this year and got them to run a diagnostics check on it. No problems
reported (I suspected this would be the case!). There was memory 'event'
regarding the oxygen sensor but this had occurred only once was not
considered relevant. They could not reproduce the problem - the &%$")!?@
thing is intermittent unfortunately although a pattern does emerge in my
mind:-

If I accelerate hard and then drive hard for a short while and then slow
down, the fault often manifests itself.

I drove away after the 'select monitor' diagnostic session onto the M25
where I made use of the car's potential, then turned onto an 'A' road and
the fault had re-appeared so I took the car back and left it with them. They
felt sure that it was oil in the 'vacuum valve' and they cleaned it out for
me.

The car appeared to be OK in that I could not immediately get it to
mis-behave but the symptoms returned in a small way on my last drive out
which is infuriating.

However, ....... there is a second pattern developing and this may hold the
key. When I took delivery of the car in January, they had given it an 'oil
service' and I noticed that after a run, as I reversed down my drive there
was a smell of hot oil. Research on the Internet pointed to perhaps a
leaking front CV joint (a well known fault!). I had also started to acquaint
myself with the engine bay and had incorrectly checked my oil level and
noted it was too low ( had found the gearbox dip stick in error making me
the major dip stick!). I took the car to Lockyears and asked them to check
the CV' which proved to be absolutely fine (I had the opportunity to look
underneath the car whilst on the ramp and boy did I like what I saw!). I
mentioned the oil and it turned out that there was too much. They put in a
pre-selected amount from a dispenser (4.75 litres exactly with the new oil
filter full) but clearly the level was too high. They drained the lot and
re-filled it. Over a long period of time the smell went away and the car
performed perfectly.

I had a six month service at the end of August and the oil smell re-appeared
followed shortly afterwards by the 'hesitation'. I note that you too have
just had a service. I know that this engine is very sensitive to oil level -
mine is a fraction high but having spoken to Lockyears this morning, it is
OK as it is - on my dip stick, starting from the bottom, there is a small
twist, a hole, a second hole, a notch and then a large twist. The correct
level is between the two holes - NEVER above the top hole - and no more than
1/2 litre is required from the centre of the two holes to the top hole.

I suggest you do check the oil level.

<<I tried cleaning the
> boost solenoid yesterday and it did seem to fix the problem for a short
> time. I drove the car straight after I had done it and it was going like a
> rocket and running really smoothly, as it used to do. >>

Please tell exactly what you did and confirm how you identified the unit.

Following receipt of your instructions on the above, I will let you know how
I get on. Please let me know your findings and perhaps between us we can
crack this annoying glitch!

Regards,

Steve Richards

 

Steve,

I had this problem for ages....like about a year!
it drove me nuts - car ran fine when thrashing, but as soon as it got hot (i.e. just after a nice blast) it hesitated like hell on light throttle between ~2000 and 3500 rpm.
I tried loads of things - cleaned the MAF sensor twice - first time it seemed to cure it, but I think it was a red herring, as the problem came back again after a few weeks.

Eventually I tested the lambda sensor, which turned out to be duff. I replaced it about 6 weeks ago.....and it hasn't happened since.

Here's a link to a site where they tell you how to check the lambda sensor...dead easy, but it's essential to use a digital voltmeter.

 

Nick,

Thanks for that, well worth a try. I wonder if the tester circuit they describe can be used for any other purpose (for example an air/fuel ratio meter?).

I'll keep you posted on my findings.

Steve

 

Hi,

Just thought I'd mention that I stated in my original post that I had just fitted a SS midsection as thought this might be relevant but more importantly.......I had a service (inc. oil change) about a month or so before I first got the problem....mmmm.
Currently my oil level is about 2 mm below
the top hole, so pretty close...and I guess it must've used a bit so originally it was prob 100% full and maybe this has caused the problem.
Will try the lambda sensor test...

will let you know.
cheers,
Matt.

 

Hi Matt,

Just wondering if you tried the test on the Labda sensor & how you got on. Are the readings from the link above related to a subaru or what readings would come from a subaru?

Reckon I'm going to have to check mine as well this weekend as I had the odd idling & the low speed hesitation. Cleaned the MAF sensor, which was a good bit grimy. That seemed to cure the idling but the hesitation & more importantly the misfire is still there unfortunately.

Any info appreciated.

Cheers

Johny

 

Hi
didnt get round to testing the lamba sensor as it happens..problem
has seemed to cure itself so maybe it was duff batch of fuel. now running optimax and all seems well. was running fine again on normal SUL so optimax isnt the cure.
this hesitation problem certainly has been covered a lot! but there
seems to be no definite cure and different people seem to have cured/party cured it in different ways.
Maybe if it happens after people have changed exhaust etc then as the way the engines is breathing and getting rid of its gases is changed then the hesitation/poor running could be something to do with the valve overlap at certain rpm having more of an effect???!
I dunno!

cheers,
Matt.

 

Matt,

It does leave a divide & conquer only solution - trying to eliminate things 1 by 1.

Johny.

 

I've read the threads and you all seem to have the problem I've got now. I've had my terzo 5 wks now, its been runing fine i've had to use NUL cos every garage i've gone has had the SUL shut down
anyway I filled it with SUL the other day & since then its run like a dog. From cold its very noisy in the engine area now, from cold the revs are up and down, can feel the car shaking through the seat at times when its warmed up and yes ive also got hesitation at low speed.

Also when slowing down I can hear - well its like a load of the gases in the exhaust are not getting out all the time, it makes a backfiring type of noise, it dont sound good.

It drives like my old fiesta turbo now, basically im pi55ed off.
Can you give me a list of things to try please.

I know its not my thread but I had to type it somewhere before I forgot it all. SORRY

PLEASE HELP ME THOUGH

SCOBY

 

Scoby,

What exhaust system is on your car? Are you sure it didnt use to
pop/bang etc before you put SUL in? A bit of popping etc from the
exhaust is nothing to worry about. With the scoobysport backbox and centre I have it does it all the time...part of the attraction! If the exhaust you have is standard then I wouldn't expect it to be doing that...well mine never did before I changed it (MY97WRX).
Maybe the best plan is to take it to your nearest specialist and tell them the problem..they may be able to help.
YOu could try an ECU reset to see if this may sort it. If you search for 'ECU reset@ you should find tons of threads.
Basically it involves finding a couple of wires under the dash, connecting them for a bit and hey presto.....

cheers,
Matt

 

From what most posts say as regards misfiring is that it could be due to the cause of the plugs or coil packs.

Mine was misfiring loudly & badly over the past few days - really embarrassing when pulling away slowly between 1.5K & 2K revs. It'd misfire when I even touched the throttle. So....

Last night I took out the plugs (NGK PFR6B's) - two were quite darker than the other two. Checked the coil packs & the rubber is okay around the packs (some threads mentioned that is was deteriorating) - checked the inside & two were more burnt & scored than the other two. Now I THINK the two darked plugs came from the two coil packs that are burnt & scored more - stupidly didn't take note.

SO gapped the plugs from 0.8mm to 0.7mm & cleaned the coil packs by scraping the inside with a screwdriver & then cleaned them out with q-tips cotton buds.

Refitted the lot & most noticably (so far ony driven it 3 times) it doesn't misfire as often - you really have to let of the throttle & then blip the throttle to get it to misfire. It doesn't even sound as LOUD as before.

Other threads mentioned the precise position of the coil packs being important - I think I may try & fiddle with these over the weekend.

If 2 of the coil packs were scored & burnt more - causing the plugs to be a lot darker can anyone shed light on whether they'd be in fine working order. Plugs went in about 3K ago.

Johny.