need some help,
99, auto, only K&N.

in second and 3rd around 4100 rpm the throttle feels sluggish, like the timing is off of being retarded my the ECU. i recently... 1500m changed oil and plugs... car ran AWESOME! now, it is doing this again... gas? i am using 87oct.

what can i do???
what is causing this???

http://www.i-club.com/ubb-files/smilies/confused.gif

-Brian-
http://www.i-club.com/ubb-files/smilies/monkey.gif

Retarded as in like "BORN ON THE 4TH OF JULY" or like "RAINMAN" or like Italian from the word Ritardando?
adamsrs www.unnatural.org (http://www.unnatural.org)

Bad News: http://www.i-club.com/ubb-files/smilies/frown.gif

I think that is a common 99RS issue that I have no been able to figure out yet. No one has given a good answer on that topic. If anyone does let us know, except if you say, "put in a programmable ECU!"

I have a 99RS Manual, at about 3500 RPMS till 4100 RPMS the car is sluggish and then kicks in like a Turbo. I notice it especially in 2nd and 3rd gears. Of course it happens in the fun gears. Anyway if you drive it a long distance at a constant speed the hesitation will dissappear for a while. Once back in traffic though it will reappear, DOH!

I just recently changed spark plugs and that helped for about 3 days but it is back again. I think the real problem is the ECU. It learns and it doesn't learn well. I am thinking a programmable ECU will be the only solution. So that is my next step, otherwise I think you are out of luck...

By the way piggybacks don't help much either. I have a S-AFC and S-ITC and they don't help that problem.

As for the gas. I am not sure about that one. Maybe you could try some dry gas and see if that helps. There could be water in the tank and that might get rid of the problem, but I doubt it. I really think it is the ECU.

By the way I am running 89 octane.

Sorry,
skywalker

[This message has been edited by skywalker (edited March 29, 2001).]

Skywalker said it well. My MY99 is totally random in terms of suffering, and then not sufferning, from this problem.

I think it's a combination of the ECU rethinking things and gas changes.

rj

Does it in my MY00 also...my A/F ratio guage also goes to nothing (super duper lean) when it happens...the it jumps back to normal and the car shoots off...

from what I read...it seems to be our knock sensor going off....

So what happens if we replace the knock sensor, or MOVE it?

I notice a programmable ECU seems to help this issue. Do they use a different knock sensor or the same one?

this discussion about the "hesitation" is so large I can't remember most of it...

from what i remember...

insulating the knock sensor (wrapping it in a thin layer of rubber) works a bit...but the rubber can wear off

"Gary's Fix" seems to work the best for a DIY fix...its splicing the wire for the knock sensor and putting resistors in to filter out some of the noise

and I believe programable ECUs have new sensors...I'm not sure though...

I'm still confused as heck on the issue...so don't read into what I said too much...i think the only way to un-confuse myself is to actually try some of these fixes to see if it helps...http://www.i-club.com/ubb-files/smilies/tongue.gif

is there a FAQ on "gary's fix"?

i remember reading about it but never assocaited the two in my head.

Search for it in the archives...there are threads explaining it...as for a webpage with info...I couldn't find one...all the old links are dead...

AutoBri: S-ITC (http://www.apexi-usa.com/electronics_superitc.asp) -> You got it!

Those don't have an effect because the ECU is still learning. The piggy backs just adjust on a constant setting, they don't adjust to the ECU "retardness." http://www.i-club.com/ubb-files/smilies/biggrin.gif

Anyway I will have to see what I can find for filtering the Knock Sensor then. Maybe get a new one. Maybe insulate it better?

STiShawn: I don't think the muffler and intake will fix the problem but maybe the fuel fitler, maybe? Hmmmm

Maybe is SHIV could enlighten us mortals into this issue. He has a 99RS, but of course he has a programmable ECU.

Saw Jai: Where do you splice the wire? At the ECU or at the Knock Sensor? I would make sense to do it at the ECU to get rid of the noise that can occur before it reaches the ECU, but I could be totally wrong.

duct tape cures all
http://www.i-club.com/ubb-files/smilies/biggrin.gif http://www.i-club.com/ubb-files/smilies/monkey.gif http://www.i-club.com/ubb-files/smilies/biggrin.gif

just ocurred to me... on my last tank of gas i ran REAL low for a bit... maybe i should try the fuel filter... how much do these run?

don't you have to pull the back seat to get at it?

The Fuel Pump is under the back seat. I am not sure where the fuel fitler but maybe it is time for a change. That should be under warranty just to let you know. I think i will have them replace that at my 30K tune up in two weeks.

I have a stock 1999 RS and have had none of the problems that have been described here (fingers are crossed). I run 89 octane fuel and every 5-6k miles I run some injector cleaner through the gas tank. Did any of you put aftermarket intakes on your 99's? If so it may be the notorious MAF sensor. All the articles I've read suggest the cut out happens at over 5500 RPM (Sport Compact Car) using aftermarket intakes that don't keep the large plastic box in the back of the engine. The air flow gets all screwed up with out this box causing the motor to run way too lean and cause the knock sensor to retard the timing and kill a ton of power. That has been a huge reason I've been reluctant to tamper with a cold air intake. I am planning to try and adapt the stock intake as told elsewhere on this forum in another posting. Just a little info I picked up. Hope it helps!!!

You know you might be right. I never had any problems until I just put in a K&N air filter in the stock box and removed the second filter all together. Ever since then I have had problems. Stupid MAF. http://www.i-club.com/ubb-files/smilies/frown.gif Need a better ECU and a MAP.

Oh well we'll see what happenes.

Have you changed your fuel filter?
My RS has no more lag, it used to, but an intake and exhaust will fix it real good.

Shawn,
exhaust will have no bearing on knock sensor.

i have read more troubles with the knock sensor and throttle retarding with an aftermarket intake than with the stock setup.

i mean look at the above post... skywalker is using a S-AFC and it doesn't help.

(BTW what is a S-ITC)ignition controller?

brian

FWIW - On a loosely related subject, I recently heard that 87 and 89 octane rated gas are the same fuel - the price difference is a marketing ploy. Common perception was that there was some mixing going on, but I understand nobody does that these days. They come from the same tank.

Really, the gas is the same. Because I have more than definitely seen a difference in performance between the two, 89 is much smoother and gives a little more power. As for 92 and 89 though I have seen no difference.

Just thought I would mention that during break-in my RS's ECU basically "learned" that I was going to shift 3500-4000rpms.
The hesitation at 4k became apparent when I went to an auto-x after break in was complete. I'd get lag then a surge exactly as you describe. My guess is that the ECU learned to cut fuel delivery near 4k which was my former shift point.
I'm debating an ECU reset to see if the lag will go away. Then again I'll most likely shift near 4k anyway while daily driving so the ECU will probably just relearn the same maps. http://www.i-club.com/ubb-files/smilies/tongue.gif
Also I should probably note that I have an 01 so it doesn't seem this is a 99 only issue.

[This message has been edited by Xio (edited March 31, 2001).]

I'm almost positive the fuel filter is on the driver's side in front of the master cylinder (pretty sure, I'll have to look). If this is true, Subaru hasn't changed much since at least 1981 (I own an 81 GLF coupe also).