2002 SG9 Forester Power Issue

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RSR 555
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2002 SG9 Forester Power Issue

Post by RSR 555 » Fri May 11, 2018 8:52 pm

Hi all,

Needing some ideas on what can be going on with my dad's foz. It's a late 02 2.5 NA model with auto trans and standard trim. The trouble we are having is the engine losses power under load and feels like there is a slight miss (like a fouled plug) when at idle. Below is a list of what we have tried and what come from that. Since we owned the car, the check engine light has come and gone without any change to performance or drivability. There is an error code U0030 which relates to HO2S sensor issue but we changed this out when we first saw this error code. We have owned the car for 3 years and the error code hasn't affected the car in any way and don't believe this would cause the issues we are having. So come forward 2 1/2 years later and now we are having this power loss issue. We did buy this car with blown head gaskets and replaced them and timing belt, all was good except oxygen sensor fault.

Here's a list of what we have tried...
1. Changed spark plugs for brand new ones (purchased iridium ones) and miss went away for 1 week.
2. Changed spark plugs leads for brand new ones and miss went away for 1 day.
3. Changed the coil park for known good used one and found no difference.
4. Changed the fuel filter for a new one and no difference.
5. Changed the fuel pump for a new one (pressure tester showed pump working at 75%) and found no difference.
6. Changed the spark plugs again with new copper plugs and car ran great for 2 weeks, then back to giving troubles.
7. Changed out the injectors for known good used ones and found car ran good for one day, then symptoms returned.
8. Cleaned out the throttle body and idle control solenoid without any change.
9. Replaced the ignition relay for the hella conversion setup and all good, even U0030 code disappeared but got code P0328, so replaced knock sensor and no codes have returned.

Car appeared to be fix, as dad drove the car for 100kms without any issue but then today it came back.

Any ideas or help would be very appreciative.

Cheers,
Paul
You know you are getting old when the candles on your birthday cake start to cost more than the cake itself.

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Gannon
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Post by Gannon » Fri May 11, 2018 9:34 pm

I have a mate who own a workshop and is having a very similar issue with a customers 02 Foz.
He has done everything much like you have and is now thinking it might be an ECU or imobiliser issue
Current rides: 2016 Mitsubishi Triton GLS & 2004 Forester X
Ongoing Project/Toy: 1987 RX Turbo EA82T, Speeduino ECU, Coil-pack ignition, 440cc Injectors, KONI adjustale front struts, Hybrid L Series/ Liberty AWD 5sp
Past rides: 92 L series turbo converted wagon, 83 Leone GL Sedan, 2004 Liberty GT Sedan & 2001 Outback
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RSR 555
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Post by RSR 555 » Sat May 12, 2018 12:33 am

Funny you mention this Gannon, I read something last week about someone having to replace their ECU because they couldn't fix their U0030 fault code. I would like to do this if it guaranteed to fix our issue because I cannot return an ECU if we use it and it doesn't fix the issue.

However you also mentioned the immobilizer, do you think this could cause the engine to miss? I would have thought it would just stop the engine altogether. There is one issue we seem to have with the car that does seem to relate to the immobilizer, and this is if we leave the ignition on (usually after communicating with the ECU for a few minutes) and then turn off the ignition, then try and start the engine, the engine trys to start but stalls immediately. So we have found that we need to turn the key off, then remove the key from the barrel for a sec, then start the car again. If we just unlock and start the car, all is good aside from the missing issue.
You know you are getting old when the candles on your birthday cake start to cost more than the cake itself.

RSR Performance
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Gannon
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Post by Gannon » Sat May 12, 2018 7:21 am

Yes I agree, I doubt the immobiliser would cause a miss but I wonder what would happen if you disconnected the imobiliser while the engine is running? Would it cut spark or fuel,... or does the ECU only look the immobiliser signal when starting?
Current rides: 2016 Mitsubishi Triton GLS & 2004 Forester X
Ongoing Project/Toy: 1987 RX Turbo EA82T, Speeduino ECU, Coil-pack ignition, 440cc Injectors, KONI adjustale front struts, Hybrid L Series/ Liberty AWD 5sp
Past rides: 92 L series turbo converted wagon, 83 Leone GL Sedan, 2004 Liberty GT Sedan & 2001 Outback
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RSR 555
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Post by RSR 555 » Sun May 13, 2018 12:31 am

I have never tried or heard anyone trying to disconnect the immobilizer whilst the engine is running but could be worth a try.

My experience with Subaru factory immobilizer units is that if they aren't connected, the ECU will not allow the injectors to pulse and if you have the wrong coded key, then the security key light stays lite and engine won't crank.

I now have a similar car that starts and runs perfectly but unable to be driven for a long drive to test out any issues but we are thinking of trying bits like ECU, immobilizer and key out of it.

Hopefully we have an answer soon
You know you are getting old when the candles on your birthday cake start to cost more than the cake itself.

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Suby Spanner
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Post by Suby Spanner » Sun May 13, 2018 9:56 pm

Does the car have an air flow meter? I've done a few on Suby's. Given the cars 15 years old, even just cleaning it may work: But make sure you only use air flow meter cleaner.

As for the O2 sensor fault, does it have 2 sensors? One after the Catalytic converter? Some times the cat's get oiled up, so removing the front sensor, and filling the cat with a can of the intake/upper cylinder cleaner, cleans the cat enough to keep the code at bay for quite a while.

My old boss's daughter had a 2000 wrx which had a random miss fire/stall, and of all things it turned out to be a crank sensor.

What brand of spark plugs and leads are you using? I will only use NGK. Been fooled by too many other brands, too many times.

Can you read the fuel trim data, especially at idle, and under load? That may be a good clue.

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RSR 555
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Post by RSR 555 » Sun May 13, 2018 10:06 pm

After more research on toonga's favorite website.. google.. I found someone had similar issues and even mentioned that all their troubles started after they had blown head gaskets. They found that after they repaired their head gaskets, the air/fuel sensor was damaged (they suspect water damage) and they replaced it. This fixed their troubles, so we headed out today with great hopes of solving this damn misfire issue. First thing was to remove the 2 catalytic converter sensors from the donor vehicle and fit them in dad's foz but unfortunately no change. Really starting to get to me at this point !!!

So, what else can we try off the donor car that we haven't already tried??? We decided to remove the cam and crank angle sensors and fit them, no difference. Well lets try and swap the ECU... guess what !!! Nada.. not a god damn thing. Seeing that we aren't getting any codes, we had to think back to the days of carburetors and distributors.. well if we had this issue on a MY Series, what would we do? We decided to assume we hadn't changed anything and start from scratch.

1. Pull out spark plugs and check.. all looks good, so clean and refit.

2. Next check the HT leads. Removed donor cars leads and check resistance against the new ones we have in the car. At this point I would like to bring to your attention that our new leads are pretty blue NGK ones from the auto parts store, which a couple of weeks ago, we went back to the store and doubled checked the resistance of another set (they were the same as our set). So with the donor car's used OEM set, we could not get a very good check, so lets just try them. Well, well, well (not 3 holes in the ground but) it looks like we may have success. Early days but from the test drive, the car has been fitted with a turbo charger. Car runs perfectly and no hesitation at all. We are going to buy a new set of OEM ones tomorrow and let you know how it goes. At this stage, I'm not trusting the aftermarket brand leads.
You know you are getting old when the candles on your birthday cake start to cost more than the cake itself.

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RSR 555
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Post by RSR 555 » Sun May 13, 2018 10:23 pm

Sorry, was writing my last post before I read your post but will reply to your suggestions.
Suby Spanner wrote:Does the car have an air flow meter? I've done a few on Suby's. Given the cars 15 years old, even just cleaning it may work: But make sure you only use air flow meter cleaner.
No AFM on this model but we did clean out all the manifold sensors like MAP, IACV and Air Temp in the air box.
Suby Spanner wrote:As for the O2 sensor fault, does it have 2 sensors? One after the Catalytic converter? Some times the cat's get oiled up, so removing the front sensor, and filling the cat with a can of the intake/upper cylinder cleaner, cleans the cat enough to keep the code at bay for quite a while.
It does have the 2 and yes, we just changed them out with know good ones but didn't help. We shall give the cleaner a go in the cat. Cheers
Suby Spanner wrote:My old boss's daughter had a 2000 wrx which had a random miss fire/stall, and of all things it turned out to be a crank sensor.
Yeah, changed both today without any change.
Suby Spanner wrote:What brand of spark plugs and leads are you using? I will only use NGK. Been fooled by too many other brands, too many times
Funny you mention this.. today we fitted the used OEM ones off the donor car and problem seems to have gone but early days.
Suby Spanner wrote:Can you read the fuel trim data, especially at idle, and under load? That may be a good clue.
We did a few weeks ago and everything was matched to how the car was going but nothing showed a reason for the miss but this doesn't show mechanical issues but electronic issues. Should have gone back to basics earlier.

Must say, thanks for your input and suggestions
You know you are getting old when the candles on your birthday cake start to cost more than the cake itself.

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Post by Suby Spanner » Sun May 13, 2018 11:13 pm

Damn.... What a nightmare.

I pull my hair out daily. 20 years ago, I never questioned aftermarket parts.
Now a days, I'm uber fussy on brands, and through trusted contacts in the auto game, I avoid most parts related problems...

On some vehicles the OEM parts are junk, and aftermarket are way better... and then there's a case like this now and again.

Keep us updated, hope that's got it sorted!

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Post by Venom » Mon May 14, 2018 5:30 pm

Ed from xtreme race tuning does do diagnostic work if you can record vehicle logs with that thing i forget the name of. He was out at dinner in a restaurant with his 9 month pregnant wife doing diagnostic work on my Outback with via his blackberry at the table. Service.

http://xtremeracingtuning.com/
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RSR 555
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Post by RSR 555 » Thu May 17, 2018 9:30 pm

Gannon wrote:I have a mate who own a workshop and is having a very similar issue with a customers 02 Foz.
He has done everything much like you have and is now thinking it might be an ECU or imobiliser issue
Hey Gannon, get him to try a set of genuine HT leads. We put the old OEM ones back on and the issues are all gone. We dismissed the leads so many times because we had purchased brand new ones and even went back to the parts place and checked the resistance against another new set and they were exactly the same. We tried to check the resistance of the factory ones (at this stage we are using the old ones because Subaru have to order the new ones from over east) and the old ones had very weird readings. Car hasn't missed a beat, so can't wait for the new ones to arrive.
Suby Spanner wrote:Damn.... What a nightmare.

I pull my hair out daily. 20 years ago, I never questioned aftermarket parts.
Now a days, I'm uber fussy on brands, and through trusted contacts in the auto game, I avoid most parts related problems...

On some vehicles the OEM parts are junk, and aftermarket are way better... and then there's a case like this now and again.

Keep us updated, hope that's got it sorted!
Yeah, we have found some aftermarket things to be good and normally without any issues but no good this time. I'll let you know how it goes once we get the new ones fitted.
Venom wrote:Ed from xtreme race tuning does do diagnostic work if you can record vehicle logs with that thing i forget the name of. He was out at dinner in a restaurant with his 9 month pregnant wife doing diagnostic work on my Outback with via his blackberry at the table. Service.

http://xtremeracingtuning.com/
That's pretty good service and I'll keep it in mind for next time. I'm wondering if I swapped the leads back and sent him the data, then see what he comes back with?
You know you are getting old when the candles on your birthday cake start to cost more than the cake itself.

RSR Performance
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RSR 555
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Post by RSR 555 » Fri May 25, 2018 8:33 pm

Suby Spanner wrote:Keep us updated, hope that's got it sorted!
Happy to report all is good and hasn't missed a beat.
You know you are getting old when the candles on your birthday cake start to cost more than the cake itself.

RSR Performance
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Post by Suby Spanner » Sun May 27, 2018 4:25 pm

:confused:

Not cool with regards to the aftermarket leads.

Good news for you though.

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RSR 555
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Post by RSR 555 » Mon May 28, 2018 8:26 pm

Yeah.. strange that they didn't perform like they should have but good that we were able to fix the car, as it was doing my head in. Hopefully this info can help others :cool:
You know you are getting old when the candles on your birthday cake start to cost more than the cake itself.

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Disclaimer: Not my website but hyperlink here to Subaru workshop manuals

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