Fuel question.. did I do something BAD??

FOB_ocity

Learner
May 26, 2008
9
0
0
Houston, TX
My 7M-GE has a rebuilt engine with approximately 80,000 miles on it, new head gasket and so far, she'd been running on 91 octane up until the last few weeks. Rising gas prices and financial evaluations made me pinch pennies at the pump by switching to 87 octane...

Now my car isn't running and I've checked ignition system. Replaced an old distributor cap and rotor, cleaned plugs.

Did a check on my AFM as per the Factory Service Manual. Open and closed resistance of the measuring plate and terminal resistances read fine except the E2-THA, which read about 1400 ohms, but I didn't know if that was due to the temperature being 87 degrees F at the time of the check.

Checked my fuel system. I have pressure, hear the return, replaced my inline filter (which was spitting out rust dust), so I pulled my injectors and rail and they look spic and span. I've drained and am about to drop the tank to clean and check the pump itself and I'm getting pretty desperate for advice.

Did my sudden switch to regular gas have any effect on my car? I didn't hear any knocking before she gave out, but I am looking at a .pdf version of the owner's manual and it states:

OCTANE NUMBER
7M-GTE engine:
For optimum engine performance. Toyota recommends using premium type gasoline with an
octane number of 95 or higher (Research Octane Number).
However, if such premium type cannot be obtained, you may use gasoline with an octane number as
low as 91.
7M-GE engine:
Select the octane number of 97 or higher (Research Octane Number).
Use of fuel with an octane number lower than stated will cause persistent heavy knocking. If severe, this
will lead to engine damage.

If this is true, what should I do? And if this is not true, based upon what I've given, what else should I check? I would appreciate any advice from you all.
 
Last edited:

AJ'S 88NA

New Member
Jul 26, 2007
2,419
0
0
Florida
Changing to the 87 grade would not have caused it to stop running. CRE runs 85 octane in his with no problems.
Are you getting any codes? Did it just quit, or was it a gradual thing?
 

Ma70.Ent

Supramania Contributor
Feb 26, 2006
1,871
1
0
NJ
I run 87 octane all the time...so I can't see the problem stemming from the fact that you switched to 87.
 

FOB_ocity

Learner
May 26, 2008
9
0
0
Houston, TX
AJ'S 88NA;1047892 said:
Changing to the 87 grade would not have caused it to stop running. CRE runs 85 octane in his with no problems.
Are you getting any codes? Did it just quit, or was it a gradual thing?

She doesn't pull any codes and she just quit. The ONLY thing I can think of that could've hinted at her bad health was having to tap the throttle to clear her throat the past two weeks after startup.
 

FOB_ocity

Learner
May 26, 2008
9
0
0
Houston, TX
Ma70.Ent;1047899 said:
I run 87 octane all the time...so I can't see the problem stemming from the fact that you switched to 87.

Thanks! That makes me feel a little better and a less guilty for the switch. I didn't know if the pdf owner's manual I had was from another country or so::shrug::
 

cuel

Supramania Contributor
Jan 8, 2007
1,536
0
0
Baytown, Texas
You jumpered Fp and B+ with the key on, and could hear fuel flowing in the rail? Any idea what fuel pressure is?
 

CRE

7M-GE + MAFT Pro + T = :D
Oct 24, 2005
3,485
0
0
Denver, CO
Oh c'mon.... it's not like everyone reads... well, it's not like anyone reads. Yeah... :nono:




Oh, I was going to say that it's not like everyone reads the sticker at the pump and decides:

Average American Public School Graduate said:
Hey, wow, might those letters mean something important? And why is it that many Europeans run such CRAZY high octane fuels... they must be making mad power.
:naughty:


For those of you who are now curious google Research Octane and Mechanical Octane.
 

FOB_ocity

Learner
May 26, 2008
9
0
0
Houston, TX
CRE;1048215 said:
Oh c'mon.... it's not like everyone reads... well, it's not like anyone reads. Yeah... :nono:




Oh, I was going to say that it's not like everyone reads the sticker at the pump and decides:

:naughty:


For those of you who are now curious google Research Octane and Mechanical Octane.

Thanks guys! I wikipedia-ed 'octane' and now I get it.

Besides the new info I just learned, this weekend I'll be cleaning the tank, testing the pump, replace it if necessary, then putting her back together with a new rail and new injectors. Wish me luck