Stuttering/hesitation at low revs?
 

As of this week I'm experiencing this rather annoying hesitation when initially pressing the acceleration pedal. This is especially noticeable when taking off slowly in a start-stop traffic jam.

If I give it a little extra than I normally would it seems just fine. What would be a likely cause of this? Note that I'm on about 156,000 klm's and had the 150K service done in December.

The only thing I can think of is that I did manage to drive the car to the emptiest level fuel I have ever done (took 62 litres to fill up).

Thanks,
Pete.

ECU maybe?
 

Kinda sounds like your ECU is giving you problems. What year is your SVX? I have a 93 and had the exact same symptoms around 120K miles. I had to crush the little metal bead in the ECU to correct the problem. Hope this helps.

~Ray

Thanks Ray - it's a 1994 (the chassis plate build date is Sep 1993).

Not sure what you mean by crushing? As in something was loose? Or you destroyed a part on purpose?

Thanks,
Pete.

It's a long story (and unspecific if you don't have a '92), but he did indeed mean 'crush' as in 'destroying a part on purpose'.

I'm sure this is going to raise some eyebrows amongst many 'newbies'............

-Mark

yep, i said crush :)
 

You take the ECU out and on our cars (yours too since you have a 94 before subaru "fixed" the problem) and there is this little wire that has a cylindrical metal bead on it. You crush it (WITHOUT breaking the wire) and wa la! your hesitation is fixed. That was kind of the "short explanation" as to how to fix it. There are actually a few people on here (ardubjay for one) that have a document on the exact procedures with pictures in it for what to do.

~Ray

Go here and check this document.

http://www.subaru-svx.net/photos/user.php?How-To|14270

Randy ii

Mine used to do that intermittently.....would have to apply more accelerator pressure and then it would tear off down the road.

Could never find a cause or cure....tried different fuels, cleaners etc and the cables were all loose and freemoving (no impediment there)

Since it came up every once in a while, I tried not to worry about it too much but it was definitely at very very low speeds

*mash foot onto throttle, hold on...problem gone*

:D

Well this is certainly interesting if not bizarre!

Thanks for that How-To link, only it doesn't explain what the crush is technically achieving?

Anyway, the warning about premium fuel being a possible cause for hesitations makes me think that in my case the problem may be related to how empty I drove the tank, and that perhaps the fuel I got was not up to standard (for you Aussie's it was from a Woolworth station).

Also, this problem has never ever surfaced before - if it was the ECU wouln't it have been there all along?

Finally, the word hesitation is probably not strong enough for what I'm experiencing. The car kinda "stutters" actually - like someone who can't drive taking of in 1st gear and not controlling the clutch very well if you know what I mean. I actually feel embarrassed in traffic at the moment, because that's probably what everyone around me thinks when they see me take off.

Any other suggestions? Can't wait to empty this tank and fill up again to see if it indeed is a fuel issue, buit that'll take another week probably.

Thanks again,
Pete.

Fuel
 

Fuel could be a possibility, I think that the almost empty tank is more likely, particularly since we've just had that hot stinking humid weather for the past couple of weeks.

I've used Woolworths Premium a couple of times with no noticable problems. Perhaps for your next tank you might want to try Shell Optimax. Don't know what they do to this fuel but the few times I've used it in the SVX and the Liberty it seemed to make the cars run smoother. (Might only be wishing on that score as I had to pay "Real Premium" prices for it)

Kenn:cool: :cool:

Hi Kenn,

So if having run to such an empty tank may have caused this, then what would fix it? Any ideas?

Thanks again,
Pete.

Hi Pete,

Don't really know if there is much of fix for the problem if its rubbish or water dragged up from the tank. It may have been a bad batch or one with ethonol in it, tho' Woolies said they don't use that. On the other side is that Woolies buy their fuel from Caltex here and Caltex were known to use ethonol. Shouldn't happen in Premium fuel tho'?

Some of the old bombs I used to drive would run from empty to empty and had problems with idle. OK when revved, then just about die when stopped. Periodically we would take off the fuel filter give it a good thump and back flush it. Car would run OK until next empty. Trouble thinking along those lines is that those old bombs had carbies so I don't know how injectors would handle this.

I tend to think that it may still be some moisture problem (not an expert on this) I would assume that your tank has been kept clean as you use PULP. Perhaps fuel filter if the next tank is the same. Sorry not much help....

Kenn
BTW Just got my work car back (ford Falcon BA) They had to rebuild the top of the engine (due to cylinder and vavles coming together (interference motor?)30,000 kms 9 months old) the silly thing keeps surging when in idle now. Work mechanic suspects that the ford dealer has put a one way only fuel filter on backwards, will have to wait and see.

No, the problem with the ECU comes up after you have had it for a while. See, here is what happens....subaru designed the SVX to be a touring luxury car. Therefore they didn't want it taking off like a bullet, but rather to have it gradually accelerate (one of peoples biggest gripes about the SVX ironically enough) so what they did to ensure the SVX would be gradual like they wanted was to design the chip to only let a certain amount of current pass though the ECU when you accelerate. Thats what that little metal bead is supposed to do, dissapate the current going through the wire. When that starts going bad then you when you try to accelerate from a dead stop (especially if you need to accelerate quickly) the car will lag and act almost like it is going to stall, then suddenly take off. At least thats what it did on mine. I think in this instance that the gas has absolutely nothing to do with your problem.

If i were you I would at least dig out the ECU and see if yours has the little bead on the wire. If your SVX is one that has that still i would go ahead and do the crush mod. Trust me, your SVX will me 10 times more responsive and will accelerate faster overall after getting rid of it.

Hope this helps.

~Ray

No, the problem with the ECU comes up after you have had it for a while. See, here is what happens....subaru designed the SVX to be a touring luxury car. Therefore they didn't want it taking off like a bullet, but rather to have it gradually accelerate (one of peoples biggest gripes about the SVX ironically enough) so what they did to ensure the SVX would be gradual like they wanted was to design the chip to only let a certain amount of current pass though the ECU when you accelerate. Thats what that little metal bead is supposed to do, dissapate the current going through the wire. When that starts going bad then you when you try to accelerate from a dead stop (especially if you need to accelerate quickly) the car will lag and act almost like it is going to stall, then suddenly take off. At least thats what it did on mine. I think in this instance that the gas has absolutely nothing to do with your problem.

If i were you I would at least dig out the ECU and see if yours has the little bead on the wire. If your SVX is one that has that still i would go ahead and do the crush mod. Trust me, your SVX will me 10 times more responsive and will accelerate faster overall after getting rid of it.

Hope this helps.

~Ray

If your SVX used to have fine accelleration and now it doesn't then I think your throttle body may be dirty. :) Cleaning it out worked for me. :)

Ray, are you absolutely certain about the reference to his '94 (built in '93) being a candidate for the crush mod? I went back into the Yahoo archives (my CD) and noted that the only references for the 'mod' were '92's and '93's (which were actually built in '92- if memory serves me right). As an example, I thought I had checked out my '94 (built in 3-94) at the time this controversy was 'raging' and it was not applicable.

I also found references that other model years might be harmed if modified.

I'm just looking to err on the side of caution and make sure the info we offer is accurate. The improvements are well documented and worth the effort if his SVX is 'appropriate' for the 'crush mod'.

-Mark