My 98 gt isnt giving me joy at the moment :(

Jono88

Forum Member
Joined
Aug 17, 2017
Messages
18
Location
gympie
Car Year
1998
Car Model
Forester GT
Transmission
Auto
Hey all. I have a 98 gt forester auto.
Currently have a massive flat spot between 2000rpm and 3000rpm but from around 3k and up it rockets.
Also economy... getting 200kms to a tank around town and about 350km highway. Also getting smoke from enhine baw when hot and smoke from exhaust but only when parked boot downhill.

I have done:
Afm clean
Spark plugs
Vacc leak check
"Cleaned" o2 sensor
Reset ecu
Upper cylinder clean
Checked all fluids
Injector clean x2
98 octane fuel only
Valve cover gaskets

Still no improvement and no idication of whats going on. Only code i have gotten is o2 sensor heater circuit

Any help would be greatly appreciated
 
Ill correct that i had 3 codes first scan

23 AIR FLOW SENSOR SYSTEM PAST
22 KNOCK SENSOR SYSTEM PAST
32 O2 SENSOR SYSTEM PAST

all being "past" codes not pending or current
 
:welcome: to the ORS forum, Jono.

Have you checked something really simple? The accelerator cable/linkages?
 
Thanks for your reply. The cable in all appearances is fine. It isnt loose or floppy. And when it get over 3krpm its drives absolutely fine... till it changes gear then it starts all over lol
 
Also thanks for the welcome Ratbag :D
 
Welcome aboard!

Are you still getting the O2 sensor code?
 
Thanks kevin.

I havent had a chance to rescan yet... but havent had any CEL. First svan had the 3 codes. And ive scanned twice since then with the o2 coming up as a past code each time. Also at one stage i had a fault come up in the transmission for an o2 fault ??? Weird
 
What colour is the smoke from the exhaust? A crook O2 sensor will certainly cause rich running and the exhaust tip will be black.

Can I assume you did the spark plug tube seals when you replaced the valve cover gaskets?
 
Yes i did the tube seals. The smoke is loke a gray color im thinking possible turbo seals as it only leaks when the turbo is tilted over the exhaust. Can smell how rich it runs when idling. Could overfuling cause the hesitation?
 
Hmmm, unfortunately I'm a complete novice when it comes to turbos so perhaps someone with more experience can chime in to help. Also, see if you can get some diagnostic help over at OzFoz.com as they are heavily into turbo Foresters.
 
I have posted on ozfoz also but no replies as yet :( your input is muchly appreciated
 
Firstly - identify the source(s) of smoke.

Engine bay sounds like oil dripping on exhaust manifold. That's not turbo seals, its rocker covers, oil feed or drain to turbo etc. Seals won't typically leak external to the turbo - they'll leak into the intake or exhaust.

Pull off your intercooler and see how much oil is in it. There will be some from blowby, but shouldn't be too much. Lots of oil here points to turbo seal, as does smoke out the exhaust.

Oil in either will stuff up either the timing & boost (ECU protecting the engine from detonation when it detects knock from the crappy fuel/oil/air mix), or O2 sensor being confused by the oil being burnt. Both would lead to bad fuel consumption.
 
Thanks for that duncanm. I'll pull it all apart this weekend. Hopefully it will start telling me a story haha. Being unfamiliar with turbos... Are the seals something a mechanically minded person can tackle?
 
Jono,

I note you said it smelt like over-fuelling.

Smell of the smoke is definitely a good pointer -- oil burning smells quite different from extra fuel or ATF.

Also worth asking over at subyclub -- usually very helpful and knowledgeable.
 
Cheers guys will investigate further with this knowledge ��
 
Does your foz have the idle butterfly in the intake manifold?

If so this will be causing the hesitation and poor fuel economy - they won't be opening up, creating a massive restriction in the intake.

I'm not 100% sure what the fix is. I think it might be "as simple" as removing your intake and removing the butterfly discs/plates then putting it all back together. ECU will be non the wiser.

I'll talk to a mate who had a similar issue and see what he said he did ;)

Cheers

Bennie
 
Cancel the above. He did that and it wasn't the issue.

He's said to unplug the MAF, start and go for a drive. If it drives better it's the MAF that needs inspecting and a clean - his had a very fine fibre wrapped around the sensor wire. Some MAF clear and a cable tie as a pick/scraper had it removed in a delicate operation.

Went like a rocket after that.

Cheap fix after spending hundreds on parts and many hours chasing the issue.

Let us know how you go ;)

Cheers

Bennie
 
So i have checked over the car and installed a new AFM. Things have improved but still have bad fuel economy running rich and down on power
 
Update....
Yesterday the car stalled at a stop light. First time it has stalled on me. Srarted straight back up but then idled very low when pulling up at home. Today it was acting like it was going to stall going up hill till i backed off the gass a bit and crawled up the hill.*

I pulled intercooler off and checked inside. Very minimal oil. Its all still silver and clean. TB looks good and clean. Bit of corrosion on the IACV plug which i cleaned. Also cleaned the boost solinoid.*

Intake pipe at turbo appears to be slightly kinked... but due to all my tools being at work i could not get at it to see whats going on. Had a look as light was fading to find tank access but gave up due to low visability and mozzies. Reset ecu and will see how things are in the morning.
 
In future, read the codes before you reset the ECU. Resetting the ECU clears the codes ...
 
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