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  #16  
Old 11-01-2011, 07:55 AM
Tapani Tapani is offline
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Re: hesitation when pressing gas pedal

Check that the ECU connectors are fully pressed in. If that's not the problem, thoroughly check you wiring harness.

A bad MAF can do weird things.

Again, a diagnostic tool is your window to see what's really going on.

Tapani
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  #17  
Old 11-02-2011, 06:42 AM
THE NEW GUY THE NEW GUY is offline
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Re: hesitation when pressing gas pedal

Looks like you was right again: When I install the MAF from my outback in the SVX , the SVX becomes furious again!
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  #18  
Old 11-02-2011, 08:08 AM
Tapani Tapani is offline
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Re: hesitation when pressing gas pedal

There's link in this thread to "how to resolder the MAF".....

http://www.subaru-svx.net/forum/show...756#post686756

Cured all my driveability problems..... and is an interesting exercise - and it's completely free !

If you swap a MAF from another vehicle be sure it is exactly the same type.

Tapani
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  #19  
Old 11-02-2011, 08:12 AM
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icingdeath88 icingdeath88 is offline
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Re: hesitation when pressing gas pedal

Quote:
Originally Posted by THE NEW GUY View Post
Looks like you was right again: When I install the MAF from my outback in the SVX , the SVX becomes furious again!
The outback MAF will function, meaning it will make the car driveable again, but you will lose a significant amount of power at higher RPMS, due to the MAF maxing out. You should try soldering the MAF, and if that doesn't work get another SVX MAF.
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  #20  
Old 11-02-2011, 08:20 AM
Tapani Tapani is offline
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Re: hesitation when pressing gas pedal

If the MAF maxes out at a lower mass air flow (than expected) it will also make the car run pig rich - except maybe while in closed loop .... if the fuel trim can compensate. Right?

The ECU will see a higher than actual air flow under all conditions and will look for fuelling data at all wrong places .

Get the right one or repair the one you have.

Tapani
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  #21  
Old 11-02-2011, 08:24 AM
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Re: hesitation when pressing gas pedal

I think it will run lean at higher RPMs because it's getting more air than it's able to read?? I think it reads correctly, but it just can't read above a certain flow rate of air. But I'm not sure.

Closed loop might be alright.
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'94 Laguna Blue LSi ~159k.......JDM ultra short-geared 3.900 STi Version 7 6-speed w/ Cobb shortshifter, ECUtune 244,8.1mm/256,9.1mm i/e cams, group N motor mounts, '97 grille, JDM clear corners, Momo JDM Legacy GT steering wheel, apkarian's LED tails, silver STi BBS wheels, PWR radiator, redstuff pads f/r, drilled/slotted rotors, bontragerworks rsb #18, Koni/GC 450f/375r coilovers, Megan Racing adjustable lateral links, KMac c/c plates, Stebro exhaust, ECUtune 1v5, Optima battery in the trunk where it belongs. Turbo project

'97 Ebony LSi ~137k #036.......Power mode mod, JDM clear corners, BBS wheels. AUX/pocket mod

Now a mod "over there" ............Photo album
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  #22  
Old 11-02-2011, 08:32 AM
Tapani Tapani is offline
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Re: hesitation when pressing gas pedal

When I saturated mine (stock sensor) @ 5000 rpm I hit the fuel cut off.

If a non-original sensor saturates let's say at 4000 rpm, it will read 5V .... the ECU will think you're gulping air worth 250 hp and will fuel accordingly, eh ? I'd say rich.

Tapani
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  #23  
Old 11-02-2011, 09:31 AM
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Re: hesitation when pressing gas pedal

Quote:
Originally Posted by Tapani View Post
When I saturated mine (stock sensor) @ 5000 rpm I hit the fuel cut off.

If a non-original sensor saturates let's say at 4000 rpm, it will read 5V .... the ECU will think you're gulping air worth 250 hp and will fuel accordingly, eh ? I'd say rich.

Tapani
Hmm, makes sense. I was thinking it wouldn't be able to make it read 5V, only like 4V for example, even if there's more air than that. Lean.

Sounds like you might be right though, that makes more sense.
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'94 Laguna Blue LSi ~159k.......JDM ultra short-geared 3.900 STi Version 7 6-speed w/ Cobb shortshifter, ECUtune 244,8.1mm/256,9.1mm i/e cams, group N motor mounts, '97 grille, JDM clear corners, Momo JDM Legacy GT steering wheel, apkarian's LED tails, silver STi BBS wheels, PWR radiator, redstuff pads f/r, drilled/slotted rotors, bontragerworks rsb #18, Koni/GC 450f/375r coilovers, Megan Racing adjustable lateral links, KMac c/c plates, Stebro exhaust, ECUtune 1v5, Optima battery in the trunk where it belongs. Turbo project

'97 Ebony LSi ~137k #036.......Power mode mod, JDM clear corners, BBS wheels. AUX/pocket mod

Now a mod "over there" ............Photo album
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  #24  
Old 11-02-2011, 10:20 AM
Tapani Tapani is offline
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Re: hesitation when pressing gas pedal

Well - dunno really, but I was able to see 4,8V with the ECUtuner just before the fuel cut off hit - and the serial link is not very fast.... thanks,

Tapani
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  #25  
Old 11-03-2011, 09:51 AM
THE NEW GUY THE NEW GUY is offline
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Re: hesitation when pressing gas pedal

I can still feel some hesitation but I think it's the original performace of this engine with stock ecu chip and 87 octanes gasoline.
You all are rigth about the MAF readings: The outback MAF have a diameter reducer on the plastic mold right before the sensor. It speeds up the air flow so it is reading more air than before; but I think the O2 sensors are doing their work by reducing injection duty time. At high rpms, performance is noticeable poorer than before. I've never reach fuel cut off point with my SVX, so I don't know how the reading are but I can try reading voltage and check what rpms correspond to 5v with this outback MAF.
I insist: even if I make the mix richer wit the outback MAF the O2 sensors will tell the ecu to reduce the duty of the injectors and will compensate to keep stechiometry, rigth? Is this correction fast enought?
I'll resolder the SVX MAF tonight. Let see if I can post some pics.
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  #26  
Old 11-03-2011, 10:54 AM
Tapani Tapani is offline
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Re: hesitation when pressing gas pedal

Fuelling is controlled by the O2 sensors while in closed loop, i.e. idle, cruise and low load acceleration. Stoichiometric AFR (14.7) is maintained to let the catalytic converters do their job, but are too lean under higher loads. This done by fixed maps and the O2 information is ignored.

Fix the MAF or get a correct replacement.

Tapani
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  #27  
Old 11-03-2011, 02:58 PM
THE NEW GUY THE NEW GUY is offline
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Re: hesitation when pressing gas pedal

Tell me one thing: when in desaceleration, above the 1200rpm the injection is cutted. Does it happen when the transmission is in power mode or manual mode? or when the gear is located on any other position different than D?
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  #28  
Old 11-03-2011, 08:59 PM
THE NEW GUY THE NEW GUY is offline
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Re: hesitation when pressing gas pedal

news on this case. on my way back home from work, in the middle of that rush hour trafic 5km/hr; hessitation came back very bad. Theres no stored codes on the ecu. Solder and clean the stock MAF, replace it and measure it: 1,204vdc at iddle and 4.943vdc maximum. Repeat the same with the outback MAF, install it on the SVX, repeat measures: exactly the same. I leave the original one on the SVX... Lets see tomorrow how it work at 24F in the morning.
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  #29  
Old 11-04-2011, 11:10 AM
THE NEW GUY THE NEW GUY is offline
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Re: hesitation when pressing gas pedal

The way to my work this morning was OK but I can still feel like the engine were choking when traveling around 10mph and press the gas suddentlly and slightly. This hesitation last only 1 or 2 secs, enougth to loose the change to pass another car on the rush hour trafic. Once this happen, the car is ok for a while. No stored codes, no CEL, but the auto climate on. Any ideas?
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  #30  
Old 11-07-2011, 12:35 PM
THE NEW GUY THE NEW GUY is offline
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Re: hesitation when pressing gas pedal

Ok fellows. I recently realize that this hesitations happens only when I'm stuck in traffic for more than 20 min. It was like if I were using the car in normal transmission mode, not in POWER. It was like if the transmission were taking too long to decide lower one gear. Then I remember that I never change the AT oil in this 6 months and I doubth that the girl before me where took that care to the car. So I decided to change the AT oil. I bought Mobil one syntetic ATF oil. I also prepared an "after cooler" for this oil and installed it between the water radiator and the AC condenser. (right were the power wheel coller is). The car is amazing now. I've never feel it like this. Very responsive and fast on the gear designation. No more hesitation.
So I think I had both, problems with the MAF (re-welding mod) and a very weared oil on the tranny.
I change the O2 sensors also in the process without any change. But you have to start somewhere!
I hope this experience wuold help someone.

Last edited by THE NEW GUY; 11-08-2011 at 01:06 PM.
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