Solving Engine Performance Issues (Part 2) - EricTheCarGuy

See Part 1

Vacuum leaks

Voltage leaks

Power Balance

Compression testing

Leak down testing

Here we are with part 2 of the Subaru Performance Series and as you can see we still haven't found the issue but to me I feel that I've eliminated a lot of possibilities and I feel I've narrowed it down to a problem in the driveline in fact the next part of this 'series' will be changing the transmission fluid and filter as well as the fluid in both the front and rear differentials, I'll post links to those after they are uploaded. The point of the series however is to avoid throwing parts at a problem like this, don't get caught up in replacing sensors that you don't have evidence are bad it gets expensive and is hardly ever effective. If you have a performance problem start with any check engine light codes and repair those first, if you don't have any replace basic maintenance parts like plugs, wires, air and fuel filters and THEN start looking for other causes, I feel you'll be more effective with that approach instead of putting a new sensor on because it fixed your friends car.

If you have automotive questions the fastest way to get a response is to head over to my website and forum as I no longer answer YouTube comments and it takes me a while to get through email these days, here's a link.

---

Click below and Stay Dirty

Visit EricTheCarGuy Forum

Visit my Facebook Page:

---

Stay dirty

ETCG

Due to factors beyond the control of EricTheCarGuy, it cannot guarantee against unauthorized modifications of this information, or improper use of this information.  EricTheCarGuy assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. EricTheCarGuy recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video.  Due to factors beyond the control of EricTheCarGuy, no information contained in this video shall create any express or implied warranty or guarantee of any particular result.  Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not EricTheCarGuy.

[VehicularDIY]

Hi Eric, if you want to lock the center diff to rule it out try installed a 35A fuse in a vacant slot labeled FWD in the engine compartment fuse panel.

This is only for emergency situations but you'll be able to drive it and it may cure that problem. I had the same issue on an Impreza and doing that made it drivable for 2 years. It felt like a binding/skipping especially when doing a U-Turn. Puttting that fuse in made it drive perfectly normal.

[dochollliday]

Dude you don't need to apologize for the lengthy video or dragging it out. unless everyone else can afford 110 per hour mechanic fees like here in Tucson it's dam good to have someone concise and patient to use reasonable deduction with process of elimination to point a lot of these things out.I was ASE certified back when Datsuns and small foreign cars were coming to America and all the 1/4 spaghetti lines that used to run all over the motor.you for sure have tipped me on some things that fixed cars for me and sometimes it helps to have a second opinion of things so yes thank you Eric.

[GeneralCheezyPrductionz]

It's transmission bro. Trust me. As soon as you threw parts after the fuel filter I noticed. My car had the same problem. I serviced it so much it ended up being just that. Dropped 1k on it plus smaller msc stuff like the tune up stuff. And its always a sure sign if the transmission struggles to accelerate in the beginning. Good practices and informative video . Good Luck

[CommaCam]

Big thank you for this video. Eric's discussion of "pirate air" just clued me in to solving a really annoying issue that developed right after I had my car in for a major service. For several weeks now it's been idling rough and giving me a power lag right at the beginning of throttle opening in every gear (manual trans).... I looked around the air cleaner assembly and found one of my valve cover breather tubes had come completely disconnected from its air duct input! Either it worked its way loose over time or, more likely, the techs just didn't reconnect it after service. Literally an instant fix.... No more rough idle and perfect throttle response. Everything downstream of the MAF needs to be tight or crazy shit happens apparently.

[fatwalletboy]

Eric is quite possibly the best guy on you tube for explaining car issues.
Easy guy to listen to. Great vids.

[mustie]

I find that googling the problem helps too, as alot of times the same problem happens on many of the same car, and you can see what others have done to fix it,

[Flakey]

This kind of thing is SO frustrating! I feel for you Eric. Had this for years, YEARS with my Mustang. Turned out to be a cracked exhaust manifold gasket that just didn't have a big enough exhaust leak to be easily heard over the cat-backs. Was so happy when I finally figured it out. 

[nkthars]

Eric, that subaru uses a friction clutch to transfer power between front and rear. A friend of mine with a 2005 impreza was experiencing similar issues, along with clunking during tight turns, very similar to bad CV shafts. The fix was to simply change out the transmission fluid. Subaru's fluid works twice as hard as it needs to operate the transmission as well as the front/rear differential clutch.

[srarcade]

I've never heard the term "pirate air" before to describe the intake leaks but I love it! "Harr harr mateys I'm the Pirate Air here to plunder ye horsepower!"

[adejong]

He is totally and spark plugs matter SO MUCH.
Good advice..exactly what I did some time ago.

[Lykos]

Is it worth cleaning a MAP sensor in the same way that you'd clean a MAF sensor? My understanding is that they have similar functions.

[rammer]

Cleaning the mass air sensor definately helps alot for lean tip in and lean problems when its dirty but one thing where Eric messed up is you clean the mass air sensor from the air cleaner side where the air passes over the sensor cuz thats where the buildup is.

[leolee]

Hi Eric,

I know it has been 2 years since you posted the video and the problem should have been solved by now.

But it was mentioned that if there are any engine performance issues; always check the basic stuff.

One item often neglected are the battery terminals. Oxidation, corrosion, expansion movement due to variance of temperature in the engine-bay will deteriorate the contact surfaces at the terminal posts.

I find that the elbow grease that accompanies sanding down battery terminals and their clamps; well-worth the effort.

There are literally hundreds of electrical connectors in any modern engine and it would require a very dedicated motor-head to remove & clean up all of them. So a good 12 to 14 volts from a pair of clean battery terminals is a MUST to drive electrical current pass all those hundreds of connectors.

I've started cars that would not start, resolve poor idling engines, etc, all with a simple 1st step of a light sanding to the battery terminals.

Note : always follow your car's recommendations before removing the terminal clamps. Generally, always remove the negative clamp first.   

 

[jimidee]

Whenever I am troubleshooting a problem like this I go thru the same things you do but one thing extra I do is clean electrical connectors while I have then apart like on the MAF. I use a premium contact cleaner DeOxit. In my opinion the best stuff there is. I fixed up a 96 Rodeo for my daughter and all kinds of problem were taken care of by pulling the connectors on the computer and replacing them. I think the guy that sold it to me thought he was ripping me off but this has turned into a sweet little car mostly by going through all the electrical connections. Even the headlights were brighter.

[michaelovitch]

even closer.
same principle.
the metallic wiring is there to calm down the flow and avoid bad turbulences.

if all the sensors or accessories are too close the ones to the others they create turbulences bad for measurement.

[SirDeanosity]

Lawn mowers are the same "No we don't need a new lawn mower" I told my son. New plug, air filter, and fresh gas w/Sea Foam the first new things to try. That engine started like a firecracker! And used half the fuel for the same lawn.

[whorayful]

Eric you're spot on about the Subaru transmission, I used to own a 2005 model, drove me mad, if you want to highlight your problem take the car onto some loose gravel and try again. The Subaru is basically a front wheel drive car which in auto trans models normally puts about 10% power to the rear through a multiplate wet clutch.  When the trans detects speed difference between the front and rear shafts, wheel spin,   it increases the rear axle clutch pressure to take the drive to 50 - 50. Only problem, once the clutch is fully applied there is no difference in speed between front and rear, so after a few yards of travel it releases, seeing the problem? I used to have trouble with mine on steep gravel roads, snow would present similar issues. Cheers.

[Streamliner]

That's true, I changed my spark plugs recently and I noticed the idle is very smooth

[ravi]

Thanks for this useful video Eric.

Couple of weeks ago i did the exact same thing for the performance issue. Engine hesitation in lower speeds and stop and go traffic to be exact.

I cleaned the MAF and Air temp sensor. Cleaned the PcV system and suction pump. On my Audi A4 2001.

The performance is better than before but not really to the full level.

I now see the engine hesitation in day time when the temp is 100+ here in Arizona. However the car seems to run fine in the evenings and night.

[NathanGrant]

There are simple tests for all sensors before you would replace them. Also....make sure you let the MAF sensor dry before you hook it back up. Love the info in these videos. Eric rules!!!!