Baja seems to run better on 89 octane? (bucking issue continued)

[jseabolt]

This maybe apples to oranges but I've heard talk here at work about people having issues with their 2 cycle weed wackers and leaf blowers not running well on 87 E10 and they run better on 93. I always run non ethanol 87 in my Trabant, lawnmowers and anything 2 cycle with no problems.

 

I've always ran 87 in my Subaru because the owner's manual says to.

 

So yesterday I decided to top my '03 Baja (non turbo) off with 89 octane just for kicks. It's too early to tell but this morning while driving to work I did not notice any bucking at cruise and the car seems to run smoother. 

 

I realize higher octane fuel will NOT give you more power. High octane fuel is somewhat of a misconception. The higher the octane the more the fuel will resist detonation. Particularly in a high compression or turbocharged engines. I do run 93 in my turbocharged Fiat Spider and my turbocharged Yugo. Not sure if I really need it but typically 93 is usually mandatory in turbocharged engines.

 

However modern engines do have an engine management system. If the knock sensor detects a "ping" it will back the timing off. Despite the fact we had this Ford truck at work which never saw more than 30 miles per hour and it pinged like mad. Unless the knock sensor was bad or it had so much carbon buildup that was the best it could do.

 

But I wonder if the system will advance the timing further on higher octane fuel until a knock is detected. I'm sure it doesn't go crazy because the EPA has limits on things like this.

 

Any chance running 89 has allowed the computer to advance the timing a bit more causing it to run smoother?

 

By the way, another apples to oranges story, My Fiat Spider, if the engine does not have enough advance, it will exhibit basically the same symptoms. Back in the 1970s, the EPA said these cars had to run at TDC to pass emissions. But these engines are intended to run at 10 BTDC by the factory and even better at 15 BTDC.

 

However while tinkering with the timing on my Spider and Yugo during the tuning phases after installing my turbos, I found these cars will buck and carry on if the timing is set below 10 BTDC.

 

So I wonder if I am on to something.

 

I'm not experiencing any kind of knock with my Subaru. Just wondering if any of you guys had any experience running higher octane fuel in you Subarus.

 

I run 87 in my 1998 Chevy van with 142,000 miles on it with no problems. My Subaru shouldn't need higher octane fuel because it's only got 77,000 miles on it.

 

On a side note. My Subaru once needed new tires and just for kicks on a trip to the beach I decided to over inflate the tires to 45 PSI and run 93 octane. I'd top off before leaving the house and 300 miles later would top off again. I gained a whopping 3 extra MPG! 

 

Even if running that much tire pressure and high octane fuel did in fact improved the fuel economy, wearing out tires and the higher cost of fuel would not offset gaining 3 miles per gallon.

 

One more thing. Last two times I've driven this car, I've noticed it is getting 20 MPG around town. Seems like it used to get 23 mpg around town and 28 on the interstate. It may just be my driving habits but does 20 mpg around town sound normal or a bit low?

 

I got new plugs, plug wires and fuel filter.

Edited August 9, 2016 by jseabolt

[1 Lucky Texan]

many folks with older soobs had had to replace knock sensors. Suppose they 'lose sensitivity' or otherwise have intermediate modes of operation before complete failure? (cheap sensors from ebay seem to work well for people, clean the mount point with a wire brush, dress the cable in the same direction as the stock unit and don't overtorque it)

 

how did the old plugs look? presence of carbon buildup in combustion chambers could raise compression and yield better-running results from higher octane fuel.

Edited August 9, 2016 by 1 Lucky Texan

[montana tom]

I try to run non ethanol in my 2000 obw and here it is only sold as high octane premium . 20 mpg sounds way low .. mine is 23 towing a heavy load and 25-28 under normal conditions. Of course there is almost no city driving around here, so its 70 + unless we hit the interstate then its 80 +. I always run my tires at 40 psi all the time and I bump up the rears to 45 psi when towing.  As far as the fuel making that big a difference with your problem... I doubt it. I think something else is causing your bucking and low milage. Plugs wires and fuel filter are always a good starting point for this kind of problem. Time will tell , you will get this figured out.  As LT said try replacing your knock sensor , might not throw a code but could be part of the problem.

Edited August 9, 2016 by montana tom

[jseabolt]

Although I do my own maintenance, I took it in to the dealership for a 60,000 mile checkup. I was actually suffering from an illness at the time so I had them replace the plugs and coolant while I had it up there.

 

Last time I checked the plugs they looked OK. But I guess it wouldn't hurt to replace them.

 

What prompted me to replace the plug wires in the the first place was I did not get one seated all the way onto the plug and 1000 miles later, my car developed a bad misfire and the check engine light came on. My code reader pointed to the cylinder. I replaced them with NGKs and the misfires went ahead. I guess the spark having to jump from the wire to the plug caused it to breakdown.

 

At one time I had to replace the bank one O2 sensor. That's what my code reader said.

 

On the other hand my father owned a '93 BMW 325 which called for 93 octane. When gas shot up, he started running 87 and the car started to run like crap. It developed a low RPM misfire but the check engine light would not kick on. He ended up taking it to German Motors and the guy said it was a bad O2 sensor. So could it be possibly one of the O2 sensors on my Subaru is bad but the computer is not throwing a code?

 

So I've got three possible bad components. The knock sensor O2 sensor and the TPS.

 

There is a local guy who works on Subarus people says is really good. Do these shops have a diagnostic machine they can plug into the OBD II port and run it through the motions and possibly pinpoint the problem without having to replace components until the problem goes away?

 

I mean, I can buy a TPS and a knock sensor cheaper and probably replace it myself cheaper than what the guy may charge to just hook it up a machine.

 

 

 

But thought I might just be spinning my wheels.

[jseabolt]

I try to run non ethanol in my 2000 obw and here it is only sold as high octane premium . 20 mpg sounds way low .. mine is 23 towing a heavy load and 25-28 under normal conditions. Of course there is almost no city driving around here, so its 70 + unless we hit the interstate then its 80 +. I always run my tires at 40 psi all the time and I bump up the rears to 45 psi when towing.  As far as the fuel making that big a difference with your problem... I doubt it. I think something else is causing your bucking and low milage. Plugs wires and fuel filter are always a good starting point for this kind of problem. Time will tell , you will get this figured out.  As LT said try replacing your knock sensor , might not throw a code but could be part of the problem.

 

I'm skeptical myself. This problem is very intermittent.  It seems when I try something (like driving around with the gas cap loose, running non ethanol fuel, etc), it seems to go away then may come back. but it doesn't do it all the time. Like this morning over an 8 mile course, it didn't do it at all.

 

I knew a guy with a Nissan Stanza that would die for no apparent reason. but if the car sat for 30 minutes it would restart and maybe OK for a week or two. 

 

The dealership could not find anything wrong with it. They told him he would have to wait until whatever was wrong with it, burned out before they could pinpoint the bad component.

 

But one mechanic did offer a suggestion. He said when the car did die, to unplug the ECU for 30 seconds and plug it back up. Then the car would restart.

 

He finally got feed up with it and unloaded it on a trade-in.

 

Sort of like what I did with my 94 Wrangler. It had an intermittent starting issue. I might have to hit the starter three times before the engine would fire. A mechanic said the crank sensor was bad and replaced it. 6 months later it started doing it again so I unloaded it and bought my Baja!

[1 Lucky Texan]

well, it can get complicated knowing exactly what to do, but here are some points to consider;

 

there are options, depending on what you already own and your level of 'need'/commitment as for reading 2-3 'levels' of information from the car's ECU.

 

If you have a laptop, there are cables and software you can use to do quite a lot of examination of the ECU's settings and parameters - $$ to $$$ and moderate to heavy in difficulty/learning curve, but close to a dealership in utility.

 

There are handheld code readers with various levels of utility, $$ (mostly replaced by the below...)

 

There are wireless adapters paired to smartphones. $ to $$ , these will be the best 'value' IF you already own the smartphone. Torque is the most popular app. The adapters are often called ' elm327 ' blue tooth adapters.

 

Given that use of any of the above devices may very well point to a system that still needs the attention of a pro, spending much money and time on them might be better spent at the repair shop. But, once you learn what you're doing (and let's face it, in addition to folks here on this Forum, there are youtube videos and other Net resources) you could use the information to do more of your own repairs AND perhaps help family and friends with their cars.

 

 

So, if, for example, you discovered your timing was retarded to the max, or fuel trims were double digits - that info might lead you to certain sensors that need further testing or even replacement.

Edited August 9, 2016 by 1 Lucky Texan

[rocketman]

I switch to real gas a year ago, made a huge difference. I also have a elm 327 blue tooth I am going to see if I can pair it with my Walmart next book 8 with Bluetooth.

[jseabolt]

well, it can get complicated knowing exactly what to do, but here are some points to consider;

 

there are options, depending on what you already own and your level of 'need'/commitment as for reading 2-3 'levels' of information from the car's ECU.

 

If you have a laptop, there are cables and software you can use to do quite a lot of examination of the ECU's settings and parameters - $$ to $$$ and moderate to heavy in difficulty/learning curve, but close to a dealership in utility.

 

There are handheld code readers with various levels of utility, $$ (mostly replaced by the below...)

 

There are wireless adapters paired to smartphones. $ to $$ , these will be the best 'value' IF you already own the smartphone. Torque is the most popular app. The adapters are often called ' elm327 ' blue tooth adapters.

 

Given that use of any of the above devices may very well point to a system that still needs the attention of a pro, spending much money and time on them might be better spent at the repair shop. But, once you learn what you're doing (and let's face it, in addition to folks here on this Forum, there are youtube videos and other Net resources) you could use the information to do more of your own repairs AND perhaps help family and friends with their cars.

 

 

So, if, for example, you discovered your timing was retarded to the max, or fuel trims were double digits - that info might lead you to certain sensors that need further testing or even replacement.

 

I will give the ELM327 a shot. I found one for about $7.00 on Ebay. Once it arrives I will do a diagnostic and report back. Thanks.

[jseabolt]

OK got the OBD II module in the mail the other day. I downloaded a few apps. 

 

Elm327 does not work. Or I can't get it to communicate with the module.

OBD car Doctor (free) works

Piston works

Torque seems to work but I have no idea how to use it.

 

OBD car Doctor seems to be the easiest so far.

 

OK so what data do I need to look for that might indicate the problem? Or point me in the general direction.

 

One odd thing. When running the system, it said the air intake temperature was 111F yet it was only 71F that morning. Where is the additional heat coming from?

 

Although I got rid of the original corrugated intake system and replaced it with a pipe and two elbows, it still pulls in cold air from the outside through the duct.

 

 

I might have to run this 89 out of the tank first and go back to 87 to see if the bucking comes back.

 

I didn't get a chance to pull the EGR valve while I was off. I did stop by Advance to get a gasket and they are showing two different types. One with a screen over one port and one without and apparently I have to pull the EGR valve first to see which one my car has. But I may not even need a new gasket anyway. I thought it would be a good idea since I had the valve off.

 

Then Tuesday was driving my 98 Chevy van and heard this scraping sound when I hit the brakes. For some reason the squealers on the pads did not make contact with the rotor before the friction material was almost gone and it was metal to metal on the inside pad. But luckily caught it in time before it did any damage to the rotor.

 

So I put brake pads on the van Wednesday before having minor knee surgery on Thursday so I am banished to driving my automatic van for awhile. Can't drive any of my stick shifts until my bummed up left knee heels!

Edited August 20, 2016 by jseabolt

[rocketman]

I have not tryed it yet,but I think coolant temp readings and fuel trem..

[Bobaru71]

One of the reasons that your Baja runs better (that many people forget ) on 89 is the added detergency which of course cleans the intake valves and some of the piston tops resulting in the smoother operation. I run 93 octane Shell v-power in my 99 SF consistently merely for the detergency and no perceived power increases. This way I forego any recommended fuel additive cleaning every 5k and the detergents keep my entire fuel system clean on a constant basis. I get ~27-29mpg with a/c on during my commutes using 93. 

[1 Lucky Texan]

first, try taking a temp reading after a cold start - confirm the reading is near the ambient temeprature - if not the engine temp sensor may be bad.

 

If you're concerned about the piping causing high intake temps, consider insulating it with something. A wrapping or split some kind of foam tubing to place around it. etc.

[ccrinc]

Jseabolt: what is your altitude?  Something I've discovered many people don't take into account is how "high" they are, although the local gasoline companies do. (Like in Colorado, "regular" is 85, while mid-grade is 87, premium is 89 or 91.)

 

What Subaru recommends as preferred octane is based on the car being at sea level.  Higher altitude requires lower octane. 

In your case, it seems that you're experiencing the reverse however.  But, it made me curious about it.

Just a thought, but you may be on to something.

 

Emily

[jseabolt]

first, try taking a temp reading after a cold start - confirm the reading is near the ambient temeprature - if not the engine temp sensor may be bad.

 

If you're concerned about the piping causing high intake temps, consider insulating it with something. A wrapping or split some kind of foam tubing to place around it. etc.

 

I actually ran the test after leaving the dentist so the car had been warmed up. It may have just been from sitting. However after I drove the car on the highway for about 2-3 miles, I would have imagined the air flowing through the intake pipe would have cooled everything down by then. Well it did drop a bit but was still 110F after a few miles.

 

Just curious if the range between the air temperature sensor and the actual ambient temperature should be that much.

[jseabolt]

Jseabolt: what is your altitude?  Something I've discovered many people don't take into account is how "high" they are, although the local gasoline companies do. (Like in Colorado, "regular" is 85, while mid-grade is 87, premium is 89 or 91.)

 

What Subaru recommends as preferred octane is based on the car being at sea level.  Higher altitude requires lower octane. 

In your case, it seems that you're experiencing the reverse however.  But, it made me curious about it.

Just a thought, but you may be on to something.

 

Emily

 

I live at 1200 feet above sea level. I've heard of 85 in Colorado. I read an article which says if you fuel up in Colorado then enter a lower altitude state while still running on 85 then top off with 87 , to unplug a relay or the battery cable for 30 minutes to let the computer reset. Otherwise the computer has a memory and the car won't run right. I don't know how true this is.

 

That's another thing I did the other day. There are three 30 or 50 amp relays in the fuse box. Mine are all red. I can't remember which one you are supposed to pull but I pulled all three and let the car sit overnight. It won't erase the presets or time from the radio.

 

Around here they sell 87, 89 and 93. For some reason Knoxville which is 100 miles south at 600 feet above sea level only sells 91 or 92 as the highest octane (best that I can recall) which seems contradictory. Lower altitude but lower octane for premium but still 87 and 89.

 

I don't know why. Large metropolitan area perhaps?

[ccrinc]

I live at 1200 feet above sea level. I've heard of 85 in Colorado. I read an article which says if you fuel up in Colorado then enter a lower altitude state while still running on 85 then top off with 87 , to unplug a relay or the battery cable for 30 minutes to let the computer reset. Otherwise the computer has a memory and the car won't run right. I don't know how true this is.

 

That's another thing I did the other day. There are three 30 or 50 amp relays in the fuse box. Mine are all red. I can't remember which one you are supposed to pull but I pulled all three and let the car sit overnight. It won't erase the presets or time from the radio.

 

Around here they sell 87, 89 and 93. For some reason Knoxville which is 100 miles south at 600 feet above sea level only sells 91 or 92 as the highest octane (best that I can recall) which seems contradictory. Lower altitude but lower octane for premium but still 87 and 89.

 

I don't know why. Large metropolitan area perhaps?

 

It's true about a car running poorly when leaving Denver for a lower altitude. About a 1500; drop and you can really feel it. 

 

As for Knoxville, I'm thinking it's the mix of the fuel itself.  Probably less (or more) ethanol.