Home / Toyota Supra Forums

Go Back   Toyota Supra Forums! Join the Supra forum! > Performance, Modification, and Maintenance Forums - for generation specific discussions > MKIII Supra

Reply
 
Thread Tools Display Modes
Old 02-06-2012, 03:02 PM   #1
Conga1991
3" Exhaust
 
Join Date: Jun 2009
Location: Avondale, AZ
Posts: 169
Conga1991 is on a distinguished road
Default O2 sensor bad= poor gas mileage

What I have is a 86.5 Supra with a rebuilt 7mgte, 57 trim, driftmotion ic set-up, 3inch exhuast all the way back (too loud for my taste) and a intake. Haven't changed the fuel pump yet, it's still the N/A pump but have a walbro fuel pump to drop in.

So, I've searched and came with nothing. I have replaced my O2 sensor a few times, it works great up until I hit boost (stock) and my cel comes on. once that does I get really shitty gas mileage, Im talking 220 miles to the tank at the most. When my O2 sensor didn't go out the needle on my gas gauge would just stick forever and not budge. Can anyone chime in on what could possibly be the problem? All help is definitely appreciated since I'm moving down to Arizona for school and don't want anymore poor mpg
Conga1991 is offline   Reply With Quote
Old 02-06-2012, 08:53 PM   #2
cre

Toyota
Racing
Development
 
cre's Avatar
 
Join Date: Apr 2007
Posts: 5,038
cre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond repute
Default

What you describe isn't consistent with a bad O2 sensor.... It's more consistent with a bad AFM, excessive engine knock, bad knock sensors or wiring, etc.

Have you bother pulling the diagnostic codes? If you don't know how look in the MKIII FAQ section for a thread on how to do it.
__________________
If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum.

If you're so inclined I'm always more than happy to accept tips via PayPal.
Tip Jar --->
cre is offline   Reply With Quote
Old 02-06-2012, 10:36 PM   #3
Conga1991
3" Exhaust
 
Join Date: Jun 2009
Location: Avondale, AZ
Posts: 169
Conga1991 is on a distinguished road
Default

Yes I have, I have a code 34 and 41. I just remembered I pulled the cps out and didnt jump the terminals for timing. Ill jump it, start it and see if there is any codes after that and let you know.
Conga1991 is offline   Reply With Quote
Old 02-06-2012, 11:38 PM   #4
cre

Toyota
Racing
Development
 
cre's Avatar
 
Join Date: Apr 2007
Posts: 5,038
cre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond repute
Default

34 is most likely the issue and timing isn't going to cause it.
__________________
If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum.

If you're so inclined I'm always more than happy to accept tips via PayPal.
Tip Jar --->
cre is offline   Reply With Quote
Old 02-10-2012, 11:29 PM   #5
Conga1991
3" Exhaust
 
Join Date: Jun 2009
Location: Avondale, AZ
Posts: 169
Conga1991 is on a distinguished road
Default

Okay, I'm using the stock 7mgte afm but with the Lexus electronic. Is testing the resistance on the Lexus the same as the stock 7mgte meter? Of course Im testing it now to make sure its in spec, if it is the same as the 7mgte's.

Im also running an upgraded ct-26 with a 57 trim.
Conga1991 is offline   Reply With Quote
Old 02-11-2012, 12:15 AM   #6
cre

Toyota
Racing
Development
 
cre's Avatar
 
Join Date: Apr 2007
Posts: 5,038
cre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond repute
Default

Yes, the actual sensor is the same... Same part number even. The method of testing in the TSRM isn't 100%... You'd need an oscilloscope and Toyota's advanced diagnostic publication to really test it. Has the air bypass screw been tampered with?
__________________
If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum.

If you're so inclined I'm always more than happy to accept tips via PayPal.
Tip Jar --->
cre is offline   Reply With Quote
Old 02-11-2012, 05:00 AM   #7
Conga1991
3" Exhaust
 
Join Date: Jun 2009
Location: Avondale, AZ
Posts: 169
Conga1991 is on a distinguished road
Default

I couldn't tell you... the screw is 3/4 of the way in looking into the chamber. Not sure if that helps or not.
Conga1991 is offline   Reply With Quote
Old 02-11-2012, 06:46 AM   #8
cre

Toyota
Racing
Development
 
cre's Avatar
 
Join Date: Apr 2007
Posts: 5,038
cre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond repute
Default

If you can see the screw, then the pressed in cover had to be drilled out and it's most like been screwed with (hehe.... pun)... See my thread in the FAQ on how to reset it to it's factory position. This isn't going to be the source of your error codes but may further contribute to fueling issues (especially if it's in further than spec).
__________________
If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum.

If you're so inclined I'm always more than happy to accept tips via PayPal.
Tip Jar --->
cre is offline   Reply With Quote
Old 02-12-2012, 02:56 AM   #9
Conga1991
3" Exhaust
 
Join Date: Jun 2009
Location: Avondale, AZ
Posts: 169
Conga1991 is on a distinguished road
Default

I'm sorry, I was referring to looking inside the chamber of the afm. the pressed in cover is still their, hasn't been tampered with.

Also I fixed the problem, didn't even think to check the wiring at the connector, it was bear with lots of PS fluid on it, cleaned it and now no more code 34 or 42. Drove around my neighborhood with the diagnostic jumpered and have a code 51. Must be because of no A/C.

Cre, Thank You! Without you I would be a lost cause not knowing what to look for. I know UTI will help me with that =)
Conga1991 is offline   Reply With Quote
Old 02-12-2012, 04:20 AM   #10
cre

Toyota
Racing
Development
 
cre's Avatar
 
Join Date: Apr 2007
Posts: 5,038
cre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond reputecre has a reputation beyond repute
Default

Fix the code 51 if it's genuine. You cannot set the ignition timing with any error codes present. The code 51 won't stay stored. If you press the throttle while in diagnostic mode you'll get a code 51 but if you take your foot back off the throttle and the A/C signal is correct (off) then the code will go away again after 30 seconds or a minute.

No sweat.
__________________
If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum.

If you're so inclined I'm always more than happy to accept tips via PayPal.
Tip Jar --->
cre is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
gas mileage on NA 87 supra jason7504 MKIII Supra 3 04-05-2010 01:20 AM
Toyota Supra Twin Turbo Auto Black Low Mileage 39000 One Owner (1993) Yagga Buy/Sell Cars 0 02-26-2010 05:15 PM
gas mileage? supfoo514 MKIII Supra 26 09-29-2007 08:16 PM
hesitation, high cold idle and poor gas mileage sd88supra MKIII Supra 14 02-06-2007 04:17 AM
Gas Mileage MacDrevi0us Non-Generation Specific Questions 1 06-09-2006 03:51 AM


All times are GMT. The time now is 08:46 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

1986



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87