Does E10 cause rough idle?

Messages
960
Location
Maryland, USA
I always refuel at the same Chevron gas station in Virginia on the way to work. Since last month the pumps have E10 labels on them. My 2003 Toyota Echo (47k miles on the engine) is equipped with a knock sensor, and the owner's manual states that the engine will run with E10. My experience is the engine does feel more responsive and stronger as I step on the gas padel. However, the engine idle is a bit unstable which goes back and forth between 7k and 8k RPM as the engine vibrates (not sure if this is called knocking). I always clean TB/IAC/MAF plus a bottle of Techron in the gas tank every 1500 miles. I wonder if this rough idle has to do with E10 or my automatic transmission is going bad. Does anyone using E10 have the similar experience with the engine performance? So far, I donot see any drop in gas mileage. I am getting 45-47 MPG on E10 with the same gas pump. Should I switch to another Chevron gas station in Maryland that sells straight gas?
 

sifan

Thread starter
Messages
960
Location
Maryland, USA
Since the check engine light is not on, will there be codes? I have a ScanGauge, and used it one time to clear the codes caused by mis-fire on cylinders when the check engine light was on.
 
Messages
4,844
Location
Saskatchewan
quote:
Originally posted by sifan: However, the engine idle is a bit unstable which goes back and forth between 7k and 8k RPM as the engine vibrates (not sure if this is called knocking).
Are you sure that's not 700 to 800 RPM? [Wink] That's not knocking. Knocking makes knock sounds that are similar to hitting the engine block with a hammer. Ethanol actually increases the octane rating. Regular E10 is 90 octane around here. I would try using regular gas to see if that fixes the idle.
 
Messages
7,409
Location
Austin, TX
Sorry I don't have time to look up your particular ECU/ECM but this info should give you some background: CEL or DTC Fault Levels Some ECUs have multiple levels of fault storage. These are called 'Active', 'Registered' and 'Stored'. Here's what they mean. Active Faults - These faults are detected while the car is running at idle or speed. They represent a component that may be or is currently failing. These codes cannot be erased. They are only meaningful with the ignition on and the engine running so DTCs found in this system with the "key-on-engine-off" usually have no meaning. Sometimes it shows a components not present on the car as failing so these codes do more to confuse than to serve as a diagnostic tool. But if the code persists, and the CEL lights, then it indicates a bad component but not necessarily the DTC that's stated!!! Thus the confustion. Registered Faults - These faults are recorded in the temporary memory of the of the car's ECUs. This temporary memory records the the fault indicating that it has occurred and is continuing to occur but it hasn't exceed the preset number of times to make it a Stored fault. When that certain number of failures has occurred, the fault is now moved to permanent (Stored) memory and the CEL lights. Some ECUs that have internal fault registers, the CEL may stay on after the Stored or Permanent fault has been erased if another occurrence of the fault has happened since the 'permanent' fault was stored. To extinguish the CEL, you should always erase both Stored and Registered faults after fixing the faults indicated. Stored Faults - These DTCs are sometimes called 'permanent' codes. When that preset number of failures has occurred, the fault is now moved to permanent (Stored) memory and the CEL lights. These faults are recorded in the ECU's permanent memory and are the main cause of CEL light. They have been generated because the fault exceeded the preset number of times set up for for that function. These DTCs can (and should) be erased after the fault is fixed.
 

JHZR2

Staff member
Messages
46,024
Location
New Jersey
quote:
Originally posted by eljefino: You clean your MAF every 1500 miles? Seems excessive to me.
and techron every 1500??? Maybe excessive maintenance is the culprit [Wink] JMH
 
Messages
4,478
Location
Southern California
I have a Hyundai Sonata with the 2.7L V6 equipped with a knock sensor transducer on each cylinder bank, so my observations will not necessarily carry over for your Toyota. Since January, 2003, Californians haven't had a choice regarding 10% ethanol content gasoline - it's mandated as the oxygenator content for the previously used, suspected carcinogen, MTBE adulterated gasoline in all grades of highway-use gasoline. I use no additives - my judgment is that brand name pump gasoline has all that's required. I've noticed no cold or hot starting or drivability issues, nor knocking, pinging, or idle problems. My highway mileage at 70 mph with A/C operating full-blast is consistently over 30 mpg using a hand calculator. In town, this engine's good for 23+ mpg.
 
Messages
102
Location
WI
If there's no CEL, I say run another bottle of Techron or BG44K in the next tank. Since you had always ran 100% gasoline before, I wonder if the ethanol loosened some gunk that may be now be affecting an injector.
 

sifan

Thread starter
Messages
960
Location
Maryland, USA
I just refueled with E10 yesterday, and got 47.06 MPG. The idle remains unstable, but not as bad as before. I will throw in another bottle of Techron and see.
 

sifan

Thread starter
Messages
960
Location
Maryland, USA
I have installed a Frantz TP oil bypass filter on my Echo with filtered oil returning thru the oil filler cap. Even though the PCV is at the opposite end, some oil is still sucked thru it. That is the reason why I cleaned the TP/IAC every 1k miles. Now with an AMW PCV catch can installed I clean them less often. I clean MAF, and use Techron every 1.5k miles to prevent engine pinging from resurfacing.
 
Messages
1,304
Location
Kankakee, IL
You know I have seen it show up more in 4 Cylinder cars than 6 or 8 cylinder cars. I have had cars that never did like that stuff. One got 42 MPG all the time and on gasohol it got39.5 never better. Ran a bit rougher. Get used to it the EPA loves that stuff.
 
Messages
102
Location
WI
ADM and the corn lobby loves the stuff. My car knows nothiing different and it does run rougher, with some tankfulls feeling rougher than others (I use mostly Mobil and BP Amoco).
 
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