SueBRoo

HELP WANTED.


WE ARE HAVING BIG PROBLEMS WITH OUR RALLY CAR. ON SATURDAY WE SHOULD BE RALLYING AT LEYLAND TEST TRACK NEAR PRESTON BUT UNLESS WE GET THE PROBLEM SORTED WE WILL HAVE TO PULL OUT. WE HAVE TILL 8pm TOMORROW EVENING TO SORT THE PROBLEM.

I HAVE PASTED THE ABOVE FROM THE BRITISH RALLYING FORUM. ( I AM MEARLY THE CO DRIVER AND FEMALE !!






Anyone got any sugestions or experience of the following.

Impreza clubman car.

We have an intermittent 'misfire' which virtually stalls the engine. When driving along on a light throttle pressing the accelerator causes the engine to suddenly stall/stutter/pop/bang/fart, you get the idea

Lifting off for a few seconds and then accelerating seems to clear the problem. Unfortunately its a random but frequent problem though it does seem to only occur after several miles, i.e when everything is hot.

The car has just been fitted with GEMS but the problem was there on the original ecu. My feeling was the throttle position sensor pot as this is really the only thing directly affected by the throttle pedal action.

Perhaps It could be the coil randomly breaking down or a fuelling problem?

Anyone ever come across a similar problem

Cheers










I know that the coils are fairly problematic, and the air mass meters can screw up if they get contaminated with oil from an airfilter.











if its got GEMS on shouldn't be any issues with air mass sensor as its redundant!! coils, fuel filter.....or plugs would be first port of call (NGK PFR7b's gapped to around 0.7mm work best!!)












Thanks guys,
we are still investigating but the car has gone to Belgium this morning.

Its a weird one though, I would normally expect coils, leads to break down at high RPM not from low down!

Steve









the only other thing that spring to mind are has it got a std tank?? could it be suffering fuel surge...more common under hard cornering but can be found with low fuel levels!!
what age / model is it??











Its an Sti red top engine and Its got a Baffled alloy job in the boot. It hard to tell if its an electrical misfire or a fuel problem which is why I suspect the throttle pot. It could be confusing the Ecu Into dumping tons of fuel in at low speed. Steve Simpson of Gems will be coming back next week so perhaps we will get to the bottom of It then















I had similar probs with my old toyota supra, not quite as bad but the poor thing used to really suffer from intermittant power loss once warm.

Having replaced, fuel filter, air filter and plugs it was still not better, even went through 3 tanks worth of STP injector cleaner without a result.

One night when she was running really bad I opened the bonnet to take a better listen and caught the sight of blue discharge sparks inside the coil.

Got a second hand coil but still had a problem, again in almost complete darkness I spotted a spark earthing from the coil to dizzy lead.

A new HT kit had everything back to normal.


My legacy gets a bit of a missfire when petrol level is low, i think this may be due to a bit of crap in the tank or maybe a blocked breather causing a vacum.

As for a gems system, my car has an early "implant" and the hot wirw unit is still fitted, maybe it uses the air mass sensor for air temp measurement..or may just be there to keep a scruiteneer happy.












Stop messing about with it and take it straight to townend garage,what ever the problem is they will be able to sort it Steve Simpson works from there most of the time so kill two birds with one stone,TEG have any of the bits that might need replacing or it might "just " want remapping by simpson either way you will end up with the problem fixed by the experts











Steve Simpson mapped it in the first place.

We had the problem in Belgium all weekend.

Tried changing the coil and ignition pack tonight but the problem is still there.









Problem persists, I don't think its a fuel problem as the fuel pressure in the fuel rails is constant, even when it cuts out. Also it backfires like anti-lag when it comes back, igniting unburnt fuel in the exhaust.

Last night I replaced the ignition coil and amplifier to no avail....today I will swap the crank & cam sensors. It's definately heat related, yesterday it took 13.4 miles for the fault to start! I have already changed the Manifold pressure sensor. Aparrently the throttle pot is not used other than for starting, it is mapped from the pressure sensor. I still might try replacing it though. Steve Simpson is away all week so I'm on my own! (No software to look at the ECU signals).






Today replaced:

Crank Sensor,
Cam phase sensor,
Spark plugs

Still no joy, problem exactly the same. MTF = 13 miles!
Am now looking for a failing 12v/5v supply on ignition, ecu sensors, etc etc but not looking promising!










might be a bit basic......but could it be a faulty FIA switch?? stranger things.........








Have you considred it may be an intake leak somewhere? I assume you have checked the lead resistance out too. Maybe a dodgy earth, the scooby earths are known to be poor as std.

I know i'm probably stating the obvious...but sometimes you forget the basic. I allways do a viual inspection, then test supplys,earths and signals in that order.

Last year i spent several hours helping to trace a fault which was caused by a missing diode in a rev counter wiring that snet a back emf to the coil!













Have checked plug leads, 11K, Have checked out earths, all seem OK, tried a permenant 12v feed to the coil from the alternator over the weekend in Belgium, which I noticed also backfed the ecu and everything else and that made no difference either.

Now started to trace out sensors to ECU plugs to look at signals but the problem is that the fault only appears when the engine gets hot after about 13 miles from cold.

Have eliminated throttle pot, fault remains when it's disconnected.

As far as an inlet leak, I'm not really sure how to test for that. Could that be heat related?










I had a power-loss problem on throttle once, it was eventually traced to a collapsed air pipe for one of the sensors....

dunno whether that's any help but I'm just trying to fire some ideas your way

SueBRoo

Well it looks like it has been sorted. Driven 50 miles this morning and as smooth as galaxy chocolate. (well as smooth as a scooby rally car can be)

Fingers crossed for tomorrow. Need to put the Mitis in their place

Pete Croney

So what was it?

SueBRoo

Earth Wire we think

TonyBurns

iTrader: (3)

Well i dunno if you take your car anywhere for rebuilds etc but i can recommend Pro-Sport in stockport
Pete deals with Subaru Rally cars and Road cars, both for servicing and repairs, an excellent place to take your car (as mine is in there now being serviced )
The number is 0161 432 9999.

Tony

Gridlock Mikey

Facinating stuff

It's easy to forget that there are "other" folk out there that know thier scoobies well enough to be able to try thier own fault finding.

Mikey

SueBRoo

Driven the car from Ashton in Makerfield to Preston tonight for scruiteneering. No problems !!! Fingers crossed for the rally tomorrow. We need a good result.

ustolemyname??stevieturbo

iTrader: (1)

Which earth wire?? Was it cut, chafed, bad connection, corroded?? Just in case its something to watch out for.

KLR16V

iTrader: (2)

Had identical prob on 93 wrx . I ran a seperate earth feed from the negative side of battery direct to ECU and this cured the very anoying problem . Must have been getting interference down standard earth or it was breaking down .

Mark

SueBRoo

Problem reoccured.

Did two stages, lying 4th overall, then half way round the third stage the misfire came back.

Back to the drawing board if anyone has any ideas.

whatever

Just a thought and apologies for knowing nothing about Subarus (running a Sierra Cosworth for rallying) but on a Cosworth engine there is a coolant sensor which if at all faulty will cause the symptoms you describe.....

Hope you get it sorted soon.

Nick

colin c

Ah someone else with the same problem as mine. The same syptoms as my on going fault. Mine started off occassionaly playing up about a year ago and it has gradually got worse to the point I now have a second car because I don't enjoy driveing my Scooby anymore

Last weekend coming back from Japfest it ran so bad I struggled to overtake a 1.2 Nova even though it has been rolling roaded twice recently at 300 bhp and also 319 bhp with 320 lbs/ft

I have been out 4 times today in the Scooby, first 3 times drove fine, tonight I dropped the girlfriend off in town and as I pulled away from a set of traffic lights quite rapidly it died in 2nd resulting in back fireing like anti lag which only cleared when I backed off again. All the rest of the journey home it did not play up.

Every time it plays up there is black smoke out of the exhaust.

If you find the fault could you please let me know.

Cheers Colin.



[Edited by colin c - 5/25/2003 8:57:09 AM]

sir clip

Colin your black smoke is exactly the same symptom as this car shows when its at fault... it also backfires and shoots out 'huge' flames from the exhaust.

The earth wire which was replaced was the one to the ECU. The ECU has been moved from its original location to behind the dash glovebox. It has made no difference.

Today we have been playing with the fuel side of things ....

Remember the car runs fine when cold - only when things get hot does the problem occur.

Just before 6pm this evening something must have been disturbed somewhere as the car was running faultlessly (whilst hot). But I don't think its been cured yet.

whatever - thanks for your imput, As I left this evening they were just starting to look at the coolant temp sensor - to trace its route back to the ECU. But its a pain to get at (living just behind the alternator on these jap things.)

Keep the info coming please....


[Edited by sir clip - 5/25/2003 7:25:22 PM]

ustolemyname??stevieturbo

iTrader: (1)

You say you have GEMS?? Does this have datalogging?? Does it show anything strange happening with any sensors, and fuelling?

Is the fuel pickup clean and unobstructed? Fuel pump sound? Fuel press reg functioning properly? Could the fuel pump be overheating? Dodgy injectors? fuel filter? fuel lines ?? are any squashed?

Are all pipes to map sensor etc sound?? no leaks?? possible dodgy map sensor?

Air filter/all induction pipes clear and in good order??

Can you hook an inductive pickup, or some other sort of test device to one of the leads, to see if you are getting a regular spark during the missfire?? Does the rev counter read as normal?
Checked cam/crank sensor air gaps?

Does the engine lose power to all 4 cylinders, or just 1 or 2 ? Is it a single coil car, or a 4 coil car?

rally colin

we had a similar problem on my Prodrive group N car a really bad miss fire between 4-5500 rpm it first showed only when the water spray was activated however it the happened again when the pump was disconected. I noticed that the rev counter would drop to zero and then pick up again. It would spit and bang to the extent I was nearly excluded for noise at longcross as they thought it was anti-lag
We changed the crank and cam sensors and it cured the problem. This only occurred when the engine was hot. We run a Prodrive ECU so the knock sensor is disconected and a few other sensors are used.

Interestingly when I put the sensors into a road car there was no sign of a miss fire even when hot. The only thing I did find was it was sometimes difficult to start and there was a very slight miss fire on idle.
I realise you have changed the crank and cam sensors but were they new ones or used? It maybe worth revisiting these sensors.
If you want to discuss further give me a bell 07771767874.


Colin

TonyBurns

iTrader: (3)

Ive already given a number for free info, as Pete and co support a rally car (Pro Sport) i would contact him to see if he has encountered this problem.

Tony

jim seaborg

OK, now I don't know anything about cars, but my '98 2.5l also 'misses' in all gears. But guess what, for me it only happens in the rain when there are big puddles on the road. It lasts for a about 2-3 minutes and then seems to just clear itself up and the car runs smooth again. But it is dangerous because I have to slow waaaaay down and pull over every time it happens. I know my oil pump leaks but this is probably not related. Also, I've noticed that it misses more with low gas and seems not to miss with fuel injector cleaner. A new fuel filter didn't make a difference though. I feel your pain!

colin c

Hi Stevie,

My Scooby is a 94 WRX and hear is a list of things I have tried to cure my fault.

Lateral Performance fuel pump.
Lateral Performance fuel pressure regulator.
New fuel filter.
K&N induction kit replaced with HKS induction kit.
Forge pump valve replaced with an Apexi blow off valve and now I'm not running a dump valve at all.
Disconnected my HKS EVC 3 boost controller.

I have got a set of Bosch coils on order to replace my coil packs which hopefully I should have in the next 2 weeks.
550cc injectors waiting to be fitted.

At my last rolling road day at G Force for Banzai Mag the operator reckoned I had an air leak which I can't find. I have checked all hoses, gaskets etc apart from the inlet manifold gaskets which I don't want to take off until I go for my turbo front entry conversion.

The problem seem to appear about the same time as I fitted my Apexi fmic, Apexi IHI roller bearing turbo and Scoobysport up pipe.

If I doing about 70mph on the motorway cruiseing and then go to accelerate to overtake this is when my fault mainly appears, it sounds like a hissing sound from the engine which is why I thought it was the boost pressure blowing the dump valves off their seats causing them to dump the boost under load. Now with the dump valve disconnected it sounds as though it's coming from the waste gate / turbo area even when running standard 0.8 bar boost pressure.

I am thinking about putting the engine back to standard and see if that cures the fault, then gradually refitting parts until the fault reappears. But it is going to be very time consuming and a lot of hassel.

Cheers Colin.