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Old 02-11-2001, 09:35 PM   #1
Pipercub
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Join Date: Aug 2000
Location: Remington VA`
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2004 Impreza STI
82 BRAT with 12 in. lift

Post Got a 99RS with turbo? I need your HELP!!!

I have: 99 2.5 RS w/ MAF, SAFC, Vortech 4:1 RRFPR, EGT guage, J&S safeguard, high flow fuel pump, and boost guage.

core issues, idle when cold is low and at times violent on the verge of dying. The EGTs are good through acceleration and cruising saying that my mixture is good but decelling or shifting, say at a redlight, produces some black smoke and a slight backfire saying it is sloppy rich. It also has poor transition from idle to 2k. Other than that it has good EGTs in the 1300's as you cruise or accelerate. So in short, as long as you are above 2 k and accelerating or maintaining then it runs great. Decel, idle cold or transition from idle to 2k and it is crap.

What strikes me as odd is to get a good idle I have about 3% + on my 1k point on the SAFC (low throttle). I would expect to have the opposite as the fuel pump should be overdriving the stock FPR. Yet here I am adding fuel at idle. And it idles fine when warm but has to be reved above 2k until warm or it goes into convulsions and dies. Now to get it to cruise and accelerate properly the 2k point (low) on the SAFC is set to 25% LEAN and the 3k is 35% lean and about 35% over the rest of the low curve. This gives me EGTs in the 1300s or slightly lower at lower RPM cruise, and not going over 1400. The car doesn't stumble other than ccasionaly in transition from low to high throttle where I currently have it set at 0 accros the board. I am not too worried about that as it is just a matter of fine tuning that band. What seems odd here is the transition from 3% + at 1k to 25% - at 2k. Now the warm idle isn't bad but the cold idle is terrible. The real driveability problem is the off idle to 2k ish range. I have to rev it higher than normal to make a smooth start from a stop. I am sure it is partnered with the 3+ to 25- thing going on in that range but it needs those settings to idle and cruise respectivley. And of course the paradox of it being soooo rich at decel that it has a slight pop and whisp of black smoke.

The Decel air function on the SAFC is perhaps part of the problem. There is no real documentation in the manual other than a dexcription of what it is for. Currently the throttle is set for 4% and NE1 is 2.2% and Ne2 is 1%. This keeps the engine from stalling when you come to a stop (when warm). But to be honest I really don't know what the heck this function is doing or what these points mean. I know that NE1,2 are 1k and 2k rpm, but what is 2.2% in relation to ne1? What is the function here and how do throttle, ne1,2 interact?
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Old 02-12-2001, 06:27 AM   #2
Pipercub
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82 BRAT with 12 in. lift

Post

Ok 99 w/ turbo anyone?
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Old 02-12-2001, 06:42 AM   #3
adam99rs
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Post

It's early here, so I'll be bri:

for your idle problem, definately sounds like a vacuum problem. On my car, I couldn't/didn't use the decel. feature...I would set it back to "neutral", or "O", then start checking for vaccum leaks. A leak could also very well cause your sputtering up to 2k. Also, what is the actual fuel pressure at idle? Do you have a guage on the rrfpr?

As for the black smoke, could be a few things. Popping doesn't necessarily mean "rich"....boxers pop with freeflowing exhausts, so no real harm there I can see (mine pops like mad!) Black smoke...could be fuel, but there are a few other things. On my car (I was running around 18 psi day to day), it turned out to be valve stem seals going bad...slowly. No big deal really, but when they go, you will be doing some head work. Maybe have the motor checked by the dealer for CR, leakage, et.? How much boost again are you running?
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Old 02-12-2001, 10:52 AM   #4
markus
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I don't have a turbo, but something strikes me here to comment.

At idle (the proper one), you should be showing no boost right? This would mean that the RRFPR is not adding any addiitonal fuel, so in that case you should require zero enrichments at idle otherwise you will run rich. The black smoke likely indicates this is the case, but if not, you could always pull the spark plugs and see if they're telling you that you're running too rich.

If everything still shecks out, try the vacuum leak.

Just a thought based on no similar experience.
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Old 02-12-2001, 02:56 PM   #5
Pipercub
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Post

I have a Bosh BOV that is not adjustable. I have checked the orientation and it matches every picture I have seen of this valve in use.
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Old 02-12-2001, 03:16 PM   #6
stimpy
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I would try venting the BOV back into your intake tract if you haven't already. I know that MAP systems it doesn't matter as much, but the MAF is judging how much air is going into the engine and when you vent some of that air back out, your A/F mixture at idle is all messed up.
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Old 02-12-2001, 04:17 PM   #7
Pipercub
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That is the plan tomorrow after work. I am going to use the other inlet that is set up for the bov to vent back in. I am aware of the problems associated with venting the BOV to atmosphere with a MAF but I was hoping for the SAFC to correct for that. I know that by venting back into the inlet that I can at least eliminate a few variables such as the decel air function, and the air leaking at sub boost levels.
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Old 02-12-2001, 04:39 PM   #8
SYMS GT
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'91 SS Legacy EJ257
DOHC/18g/FMIC/V.8 6spd

Post

FWIW...
On my GT I'm using both Dec-Air setting and venting my BOV into the intake. Best of both worlds on this one.
Settings being used;
Dec-Air
.3 thr %
2.6 ne1
2.5 ne2
Low Throttle Setting
0% at ne1
2% at ne2
Throttle Point
Lo 9%
Hi 37%
Also I'm running my Ne-points from ne1 at 1500rp and ne8 at 6500rpm; gradual curve between points.
These are the settings that are working on a MY98 GT at 3200 ft/elev., ~7psi, and with HP pump, AFC, and Vortech 4:1 rrfpr. Hope these points might work for you.
-Matt

[This message has been edited by SYMS GT (edited February 12, 2001).]
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Old 02-12-2001, 07:46 PM   #9
JDM5LugHatch
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I am not sure if this will help but here it goes. There is a place in Maryland I think Altered Atmosphere but anyways they have an all wheel dyno. The best thing to do with any turbo application is to get it tuned and tuned professionally. Now I hear they know there stuff and that they know the Super AFC's like the back of there hands. I am also sure that they will help to fix and diagnose your problems. This is just a suggestion. I have no clue how much they charge but you can be sure it is not cheap as dyno time and tuners are not. I have seen so many people mess up their cars because they were not tuned properly. To me it is clearly worth the money to get the car tuned right by a professional. The way I look at it is $200-$300 is a small investment when you consider the price of a turbo and the price of an engine or at least the cost to rebuild one. It sounds like you know what you are doing and that you may be able to get it all worked out if you know what the problem is. So I am not in any way shape or form saying that you are not capable of fixing the problem. Also the benefits that can be gained from dyno tuning your car can be incredible.

Just my 2 cents.

Chris www.hometown.aol.com/awdimprezars

[This message has been edited by AWDiMPREZARS (edited February 12, 2001).]
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Old 02-13-2001, 01:40 AM   #10
Pipercub
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Post

Well some more investigation has yielded more evidence and suspects but no new answers.

I looked everywhere for a vaccume leak and found nothing yet and I don;t believe there is one. I used ties on all the little connections (which were super tight to begin with) and hose clamps on the larger.

But I have suspicions about the BOV. At idle this thing was venting a good bit of air. When I placed my hand over the outlet and blocked that air the idle changed big time. It idles OK when warm and when I blocked off the outlet it starts to rais and lower.

Furthermore, as I drive down the road there is a zone before boost builds where I can hear the BOV whooshing steadily. It seems as if the boost shuts it and it is silent until you back off the throtle where it gives off a good burst of air as it should. But all that air blowing out has got to be changing the mixture.

I have an intlet where the BOV vents back in behind the MAF and I didn't want to use it in an attempt to minimize turbulence behind the MAF. But with all that air being lost/gained after the MAF that has to be a factor in the stability of the tune. So it looks like I am faced with the less desirable option of using the inlet that vents the BOV back in behind the MAF and eliminating the decel air feature and all that whoosh before boost closes the BOV.

To answer some of the above questions:

I have the BOV venting to the atmosphere so I have to use the decel air function on the SAFC.

I know the boxer burble rumble sound and this aint it, there is a pow sound, one distinct pop after releasing the throttle.
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Old 02-13-2001, 01:50 AM   #11
RS'ted
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Post

Pipercub,

What brand is the blow-off valve ? Is it adjustable ? It should not be leaking at idle. I had this problem when I first installed my IHI with a factory Legacy Nippondenso valve. With nothing to go on I assumed the arrow molded on the valve would indicate airflow direction out of the valve. But it needed to be reversed in order to function properly. Now I'm using a adjustable HKS valve.

Ken M
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Old 02-13-2001, 05:13 PM   #12
Pipercub
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82 BRAT with 12 in. lift

Post

Problem solved 99%!!!!!!!!!!!

There was no vaccum leak! I changed the inlet config to have the BOV vent into the inlet and although it was not my first choice ALL driveability problems have been solved. THe only remaining problems are caused by the settings that had been made to correct for all that missing air. I have cleaned up almost all of those in about 30 min of driving. Now the car runs as stabile as it did NA. I guess I should buy a spare MAF and keep it in the glove box! Well what can I say, no more bucking and heaving and lurching!

Thank all of you for your input and your contributions, I thank you, my tranny thanks you, and the neighbors who listened to my 3in open reving at 3k RPM at 5:00 AM thank you.
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Old 02-14-2001, 02:01 PM   #13
stimpy
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Thumbs up

/me bows j/k
Glad to hear you have it taken care of. How is the car treating you? I am hoping to have all the parts for my legacy turbo install on my MY00 in the next month or two...can't wait to be blown!

-Jon
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Old 02-14-2001, 02:13 PM   #14
Pipercub
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82 BRAT with 12 in. lift

Post

The tuning is almost 100% perfect driveability. Now the tuning for power phase is in the works.
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