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ZUKIWORLD Discussion Forum => Suzuki 4x4 Forum => Topic started by: brawnyrebel on August 04, 2008, 03:29:48 PM

Title: mpg problem with a twist
Post by: brawnyrebel on August 04, 2008, 03:29:48 PM
 I recently switched back to 3.73's from 4.62's and i have actually been paying attention to the gas mileage now. It probably has not changed much from the axel swap  but i'm only getting around 12mpg. 31's and a 4-1 case. It has a 1.6 8v swap from an obd 1 tracker, header and big exhaust. The oxegen sensor is bent at the wire end from the engine leaning on it before it was put in. Also when i wired the generic style sensor to a stock plug i had two reds and a black on the plug and two whites and a black coming out of the sensor. Does it matter which red goes to which white?

(http://img.photobucket.com/albums/v293/brawnyrebel/DSC01214.jpg)
Title: Re: mpg problem with a twist
Post by: Jeremiah on August 04, 2008, 04:49:15 PM
How are you calculating your MPG? Have you re-calibrated your odometer for the larger tires? With 31" and t-case gears, I would think you should be getting much closer to 20MPG. Maybe a little more if it's fuel injected.
Title: Re: mpg problem with a twist
Post by: brawnyrebel on August 04, 2008, 06:13:22 PM
The speedo is dead on with the case and 31's. I found one of the little radar trailors the cops put out and cruised by it a few times to check.  I never calculated it with the 4.62's . I would be thrilled with 20 at the moment
Title: Re: mpg problem with a twist
Post by: captchee on August 04, 2008, 07:20:47 PM
 have you pulled the codes ?
Title: Re: mpg problem with a twist
Post by: Jeremiah on August 05, 2008, 07:07:27 AM
There's got to be something going on. I know the ECU will go into a "limp home" mode and run intentionally too rich (as it's less destructive than too lean) if it's throwing a code. Get that thing scanned.
Title: Re: mpg problem with a twist
Post by: captchee on August 05, 2008, 01:16:07 PM
 yep my bet is she is throwing a code  your MPG is just to low .
 my bet is that for some reason your ECM has went to limp home/ fail safe mode
Title: Re: mpg problem with a twist
Post by: brawnyrebel on August 05, 2008, 02:41:49 PM
 I agree that it is running in closed loop mode. It is obd1 so i flashed it and i only got the 12 code which is normal. I'm just curious if the sensor is bad but not showing a code. The egr system may not be working due to the hole inthe thorley header not lining up compleatly over the hole in the block  causing a little exhaust leak but i was told that it wouldn't cause a noticable difference. Thanks for the help so far fellas
Title: Re: mpg problem with a twist
Post by: captchee on August 05, 2008, 03:54:16 PM
 Buy  chance you have not taken the battery cables off  since you last  drove it for 30 minutes or so did you ?
 if so it cleared the ECM and all you will get is a code 12  tell more info is logged .
 you need a OBD scan.  take it to a dealer or local shop that can do that for you .
 if the ECM isnt shooting a code other then 12 then there is mostlike a problem with one or more of the sensors
Title: Re: mpg problem with a twist
Post by: Jeremiah on August 06, 2008, 12:49:29 PM
I wonder if the ECU could be bad? Not sure how to test for this.
Title: Re: mpg problem with a twist
Post by: brawnyrebel on August 06, 2008, 06:18:11 PM
 I have driven it a few thousand miles since the swap. When i start it the light stays on for a moment and then goes off like normal.
Title: Re: mpg problem with a twist
Post by: Jeremiah on August 06, 2008, 08:36:20 PM
The ECU doesn't always realize there's a problem & throw a code when it's broken. Just a thought.
Title: Re: mpg problem with a twist
Post by: captchee on August 07, 2008, 08:05:46 AM
The ECU doesn't always realize there's a problem & throw a code when it's broken. Just a thought.

yep very true exspecialy with older ECM's . if the sender completely dies . the ECM simply will not recourd information  and make adjustments  that the falty sender would be telling it to make .
 this is where running a OBD scan  comes in . you can eather go through and test each sendor  or have the test code run . this will tell you if a sender is not sending info to the ECM  IE its faulty or  it has a  wiring issue . there also is alot of  other issues past  bad or faulty sendors that will kick the ECM into fail safe mode . running an OBD  scan  will only give you information on the electronics . in wich case it will help you narrow down the possable problems


JT over on the suzuki forum has a good write up on this as well as how to  check the senders . he exsplains it much better then i can  and is much clearer .
 im not sure if  it acceptable to post such a link here  on this forum  though as some places frown on such things . so if you would like the link  i would send it to you in PM