That is interesting!

I have had hesitation problems with 2 2.5's...I presume it is the same problem, almost as if the speed control is kicking in whilst cruising and trying to slow the car down.

I finally sold the first one without fixing it, and now I have a Forester doing the same thing to me, but only when the Check Engine Light is on...which it is at the moment, thanks to a minute pinprick of a hole in the exhaust system.

 

I see your first attempt was to clean all electrical connections ... did you clean all the chassis ground points ?

I saw something about this when I first bought mine, some of the points where screwed right over painted metal [should ground through the screw but ... ] so I sanded to metal and used anti corrosive battery terminal grease to avoid rust. I havn't had any of the associated issues so, not sure if that helped or not.

 

@ETC...... hey, yep I cleaned and sanded all the grounds and then gave them a healthy coating of dielectric grease( before trying this), this had absolutley no effect. I can definetly see the logic in the ground wiring kit, but to be honest I wasnt expecting the results to be so astounding. I have a feeling that newer models probably wouldnt benefit very much from something like this???

 

Cool, glad that worked out for you

Can't argue with results considering you did that one thing and got a marked improvement.

I wonder if the stock grounding is prone to internal corrosion on the wires or something ? . My tailgate cables [completely different thing I know] on my truck did exactly that, they were rubber coated and looked fine but after I got a recall letter and picked up a new set, I decided to test them by bouncing on the tailgate ... sure enough they started to give.

Something to suggest to others with a rough idle issue.

 

jc54bv:

I am having the exact same hesitation issues, and have replaced everything you have too! For the price of the cables, terminals, and heatshrink, it's worth a shot!

Would it be possible for you to post some pictures of your wiring job? I have a basic idea of the locations you grounded, but am not quite sure.

I look forward to hearing back from you! Congratulations on solving your problem! I hope it'll fix mine too!

Thanks,

Steven

 

Well.....unfortunately I don't have the pictorial I did anymore. My previous computer had a tendency to self mutilate every so often until it finally gave up on life and lost the file along with lots of other stuff. Here is a link to someone elses Subaru Legacy International • View topic - Grounding mod question .There are pics further down on the page. It is not quite how I did it but it gives you a pretty good idea. I just went to either side of the intake manifold, and to the two strut towers. All the cables should all link back to battery negative at some point, whether directly or from one cable to another. I can't guarantee that you have the exact same problem, but like you said, its worth a shot for the price.
I hope it works out for you.....if not you have a well grounded system as a by product.

 

Thanks for the link!

This may sound like a really retarded question, but what is the purpose behind adding extra grounding points?

 

I gotta be honest and say I'm not entirely sure. My opinion is that, in newer cars the engines rely heavily on electrical components readings to run properly, if at all. I'm assuming that it creates more clarity for signals to the ECU?

 

Considering that some of the sensors probably have signals in the millivolt range, that seems to make a lot of sense. I think I see a grounding kit in my future...

Thanks,
Wally

 

Another satisfied customer!! For almost the entire time I was running on my original engine I had this problem, then for months and thousands of miles on the replacement rebuilt engine, not a single issue.

Then the other day the hesitation, stumbling issue returned, and just as bad as ever, out of the blue. I came across this thread and went right out and cleaned up all of the original grounds in the engine bay, and ran a new one directly from the battery to the intake manifold (only had a little bit of wire lying around) and gave it a shot.

What do you know? It runs great again! Soo glad it was something simple and cheap

 

Is it possible for you to take a picture and highlight/circle the ground points that you cleaned and added? That would be super helpful, and I am hoping this might work!

Thanks in advanced!

Steven Wilcox

 

I have something similar to this problem but suspect that it has something to do with the transmition. I will have to take a look at what help this will have! When i go to drive my car every now and then it feels as if the ebrake is left on when it isnt. I went to back into a parking spot this afternoon and the car started going backwards only to stop halfway into the spot, and I was ona downslop....any idea?

 

I am now getting this hesitation at around 3k-4k. I found a thread over at NASIOC and will be performing the grounding mod in a bit. Here is the thread: Normally Aspirated 2.5l Hesitation Fix (grounding mod)

 

Follow up:
My hesitation was due to my plug wire on #3 breaking apart after the last spark plug change (I pulled on the proper location of the wires to take the wires off). I changed them in the parking lot of the local Subaru dealership (when I was out of town!). Fixed. Power everywhere. Seems stronger. Maybe the Grounding Mod helped a little bit?

 

Just an adder and another testament to how much of a difference this makes. In the past, with the hesitation I was able to manage an absolute MAXIMUM of 27 MPG on the highway, taking it very easy. Now, even on a recent highway trip in which I had to deal with a 45 min traffic jam (stop, move a couple feet, stop) I was able to rope in 29 MPG, and I'm totally confident that it could do much better.

So aside from a couple of other things that need to be taken care of, (wheel bearing, suspension, noisy tranny(my fault)) I'm more happy with my car then ever. :29:

 

does it work?

I am a 3 weeks new owner of a 08 legacy limited with the 2.5. I love it so far except the hesitation. I just installed an audio amp (only 225w) and a high CCA battery, but noticed today at highway speeds trying to keep foot steady and on cruise it slows by 3mph or so and then picks back up. When at a stop ight it seems to want to stall but does'nt ( this exsisted before the install). Could this be the same problems everyone else seems to have?
I have been reading all the posts and links related to this thread and wow I must say I hope it fixes my problem.
My question is will the ground mod work on an 2008. I did not see any posts or replys on newer models like an 08. Thanks in advance.

 

Solved for me too!!

1999 legacy wagon 2.5-same exact problem everyone else is having, saw this thread and thought yes! Work in an all make shop and have seen tons of weird problems caused by bad grounds. Gotta start with the basics, which we often forget!
Cleaned 5 ground points under the hood -all were painted, added a ground to and empty bolt hole next to the knock sensor and added a drivers side strut tower ground right to the neg post. The difference was amazing-great power all the way through,no hesitation! Thanx so much!

 

Seems that after 100K or so for these machines that grounding can be a challenge. It is not surprising since these magnificent machines run a lot on electronics. Being a former IBM Field Engineer, we had seen a lot of old printer hardware brought back to life by simple cleaning of grounding areas. So this string does not surprise me and I will start this on my own 2008 Forester that is throwing a host of strange errors that my service shop cannot narrow down, which is exactly what I would expect from bad grounding. Thanks for this post!

 

Hey all,
I have a 1998 legacy outback which I bought around 4 months ago. I'm certain this will be familiar problem to many, but ever since I got it it has had flat spots right through the rev range and serious hesitation around 3000 to 3500 rpm. After months of agonising, sleepless nights and bleeding knuckles and no CEL I have finally found my solution :29:.

First let me explain what I have done up till today( again this wiil sound familiar to lots out there)

Cleaned almost every electrical connection and valve ( PCV and EGR included)
New knock sensor( CEL when I bought it, which has long since dissapeared)
New plug leads (NGK)
New plugs(NGK laser platinum)
New fuel filter
New air filter
Three or four bottles of injector cleaner
Checked all vacumn hoses, replaced a few too!
New upstream O2 sensor ( again no CEL but had heard that they play up sometimes without CEL)
Cleaned throttle body
Checked and adjusted TPS and has smooth increase in resistance, no spikes.
Had codes read a few times, but nothing was there, which was good I suppose, but got me no closer to solving my problem
And loads of other things too

None of these things got rid of the hesitation, except for a few minor improvements in performance here and there. I was getting close to actually taking it to a dealer to diagnose the problem :gasp:.

Then last night I was reading about Ground wiring kits, some home made and some store bought, I thought it can't hurt to try it.
SOOOO today I went out and bought a set of 16 ft jumpleads ( 6 gauge) which I would split in two so you actually get more for your money than buying some fancy single core, got a load of copper ring terminals and borrowed a crimper form work ( around $300 for one of these apparently)
and some heatshrink for the ends. I made up the lengths and took a ground from battery to Intake manifold drivers side (with a cut back to strut tower) then to passenger side manifold and onto the other strut tower, with a final one from battery negative to fire wall.

Took it out for a spin and guess what????? it only worked didnt it :29::29::29::29::29::29: It was a whole new car, power feels way up along with throttle response, and finally no hesitation what so ever.

Hope this helps out someone else, I was in a position where I could see no end to the problem. Oh and by the way I also got a haynes manual. The problem is listed in the trouble shooting guide but the solutions were vague at best.

Peace. I will sleep a happy man tonight, I now have a whole new love for my baby.

Do you still have this vehicle would it be possible to get some pics of how you wired it in

 

jc54bv has not been here since 2014...... so, I doubt it. Sorry.

 

@Mike n

Grounding kits?? - ScoobyNet.com - Subaru Enthusiast Forum

Lighting and Other Electrical - Grounding kits?? - Has anyone fitted a grounding kit to their scooby? They are advertised in this months Total Impreza for £42 delivered. The theory sounds good but do they make any difference in the real world?

www.scoobynet.com

 

I clean all my electric ground wire and add new more two wires from the neg of the battery to a clean metal part of the engine and change my air filter clean mass air flow and the car just come back to life and fly like a jet no more hesitant. OMG what a change try that first before you change anything else in your subaru outback

 

Hey all,
I have a 1998 legacy outback which I bought around 4 months ago. I'm certain this will be familiar problem to many, but ever since I got it it has had flat spots right through the rev range and serious hesitation around 3000 to 3500 rpm. After months of agonising, sleepless nights and bleeding knuckles and no CEL I have finally found my solution :29:.

First let me explain what I have done up till today( again this wiil sound familiar to lots out there)

Cleaned almost every electrical connection and valve ( PCV and EGR included)
New knock sensor( CEL when I bought it, which has long since dissapeared)
New plug leads (NGK)
New plugs(NGK laser platinum)
New fuel filter
New air filter
Three or four bottles of injector cleaner
Checked all vacumn hoses, replaced a few too!
New upstream O2 sensor ( again no CEL but had heard that they play up sometimes without CEL)
Cleaned throttle body
Checked and adjusted TPS and has smooth increase in resistance, no spikes.
Had codes read a few times, but nothing was there, which was good I suppose, but got me no closer to solving my problem
And loads of other things too

None of these things got rid of the hesitation, except for a few minor improvements in performance here and there. I was getting close to actually taking it to a dealer to diagnose the problem :gasp:.

Then last night I was reading about Ground wiring kits, some home made and some store bought, I thought it can't hurt to try it.
SOOOO today I went out and bought a set of 16 ft jumpleads ( 6 gauge) which I would split in two so you actually get more for your money than buying some fancy single core, got a load of copper ring terminals and borrowed a crimper form work ( around $300 for one of these apparently)
and some heatshrink for the ends. I made up the lengths and took a ground from battery to Intake manifold drivers side (with a cut back to strut tower) then to passenger side manifold and onto the other strut tower, with a final one from battery negative to fire wall.

Took it out for a spin and guess what????? it only worked didnt it :29::29::29::29::29::29: It was a whole new car, power feels way up along with throttle response, and finally no hesitation what so ever.

Hope this helps out someone else, I was in a position where I could see no end to the problem. Oh and by the way I also got a haynes manual. The problem is listed in the trouble shooting guide but the solutions were vague at best.

Peace. I will sleep a happy man tonight, I now have a whole new love for my baby.

Just wondering if you have a video or pictures of the wiring you did Thanks

 

The simple way is to take a 2 or 4 gauge cable with a clamp on one end and an eyelet on the other about 28" long and run it to the intake manifold. Where ever you bolt the eyelet end, start another cable with eyelets at both ends and run it over to the other side of the intake in whatever route you choose. From the second eyelet bolt down spot, add another that will reach over to the body.

Another way to do it is to take one long length of cable and start at the battery post and everywhere you can bolt it down put in a splice joint with an eyelet to bolt it down. See pic where there's a splice in the middle. (This is a ford cable, but it's just to give you a jest.) Two on the intake and a large one over to the passenger body side. Also, have a cable running from the post to the body on the driver side.

If I remember, I'll take a pic of my grounding setup on the VDC when I get home. Sadly it's in the garage with the SC off due to a broken belt and the drive pulley, a Ford decoupler pulley, is not cooperating in coming off the input shaft.

You can also go to the link I posted in post 23 above.

 

The member you are addressing this to has not been here since 2014 - so best to start searching for "grounding issues" here in the Problems & DIY Maintenance section; I'm guessing something like this has been done.

 

Thank you sooo much for posting this it didn’t even think about that . I had boost problems at 2300 rpm’s I had my ground connected to the outside of intake heat shield which is not a good place and I swapped it around and it worked !!! I did the same tried everything and I saw this and I found it and it works!!!! I can’t thank you enough.

 

Hey all,
I have a 1998 legacy outback which I bought around 4 months ago. I'm certain this will be familiar problem to many, but ever since I got it it has had flat spots right through the rev range and serious hesitation around 3000 to 3500 rpm. After months of agonising, sleepless nights and bleeding knuckles and no CEL I have finally found my solution :29:.

First let me explain what I have done up till today( again this wiil sound familiar to lots out there)

Cleaned almost every electrical connection and valve ( PCV and EGR included)
New knock sensor( CEL when I bought it, which has long since dissapeared)
New plug leads (NGK)
New plugs(NGK laser platinum)
New fuel filter
New air filter
Three or four bottles of injector cleaner
Checked all vacumn hoses, replaced a few too!
New upstream O2 sensor ( again no CEL but had heard that they play up sometimes without CEL)
Cleaned throttle body
Checked and adjusted TPS and has smooth increase in resistance, no spikes.
Had codes read a few times, but nothing was there, which was good I suppose, but got me no closer to solving my problem
And loads of other things too

None of these things got rid of the hesitation, except for a few minor improvements in performance here and there. I was getting close to actually taking it to a dealer to diagnose the problem :gasp:.

Then last night I was reading about Ground wiring kits, some home made and some store bought, I thought it can't hurt to try it.
SOOOO today I went out and bought a set of 16 ft jumpleads ( 6 gauge) which I would split in two so you actually get more for your money than buying some fancy single core, got a load of copper ring terminals and borrowed a crimper form work ( around $300 for one of these apparently)
and some heatshrink for the ends. I made up the lengths and took a ground from battery to Intake manifold drivers side (with a cut back to strut tower) then to passenger side manifold and onto the other strut tower, with a final one from battery negative to fire wall.

Took it out for a spin and guess what????? it only worked didnt it :29::29::29::29::29::29: It was a whole new car, power feels way up along with throttle response, and finally no hesitation what so ever.

Hope this helps out someone else, I was in a position where I could see no end to the problem. Oh and by the way I also got a haynes manual. The problem is listed in the trouble shooting guide but the solutions were vague at best.

Peace. I will sleep a happy man tonight, I now have a whole new love for my baby.

 

Breaking long silence of lurking by now -- Posting in 2023 that THIS WAS THE FIX for me as well -- For years the car had a really bothersome hang in any gear, not wanting to shift to the next and I would whip the stick over to the manny mode in frustration and shove it into the next gear. The MPG and gas gauge would go to empty once in a blue moon, would hiccup when you mash the gas from a stop, on & on. I too could make your head spin with the effort I've put into the thing to straighten out issues such as this. Well as of today, that one has been definitively solved!! All of those issues, G O N E with cleaning up the factory grounds & adding one 12ga wire from the battery NEG to the intake manifold. Purrs like a kitten, steps right into every gear now and turns a nice low rpm. I will now head to the new members section. Lol

Ours is a base model 2008, different than the 1998 from OP but still relevant I think, as all of these cars are getting older and rustier. Everyone check your grounds!! Can't wait to try on my Bugeye, which seems to hang in the 3-4k rpm range.

Peace. I will sleep a happy man tonight, I now have a whole new love for my baby.

This!! After years & years it now "runs great" !! Hang in there everybody, these machines just need some TLC.

 

My 1997 Outback had the hesitation stumble problem for a few years. I had seen this thread between various attempts to sort out the issue but like many others went down a troubleshooting checklist to no avail.

I made voltage measurements with a multimeter before and after making grounding improvements and want to contribute the results.
Before the changes I measured the DC voltage between the batteries negative terminal and the ground terminals on each strut tower. If the grounds are good there should be very little voltage between these points. With the engine running and all lights and accessories on, the initial voltage measurements fluctuated from approximately .3volts to slightly over .5volts. It varied erratically. Between the battery and the block it was much lower and fairly constant at approx .1 volts.
With guarded optimism and plenty of hope
I cleaned all the grounds and both battery terminals. Finally adding number 8 stranded wire directly between each strut tower ground and the negative terminal of the battery.
After the procedure the erratic voltage between the strut tower grounds and the negative terminal of the battery measured a much improved and steady .03 volts. The voltage to the block showed little change.

The test drive confirmed the fix! The improvement was both dramatic and immediate!