tried resetting ECUbut now car wont' start...help please?

[Kreukishot]

I've got a 97 240sx...

Installed a different Air intake...everything was working fine...however for the past month i've gotten shitty gas mileage (15-17 MPG) so i decided to reset my ecu to see if it'd help....did it the old fashion way....dc'ed battery for awhile and hooked it back up (2 weeks after i installed AI)...however this still gave me shit mileage...2 weeks after.... i read on 240sx.org in their faq about resetting the ECU a different way...and followed these instructions:

1. Find the computer(Behind the plastic piece by the passenger foot
2. Pull it out
3. Turn your key to the on position
4. You will see a flathead screw looking bolt on 1 side of the computer. Turn this fully clockwise
5. Wait at least 2 seconds
6. Turn it back to fully counterclockwise
7. This will then show the trouble code - (The check engine light will blink to show this, for instance, blink..blink..blink......blink..blink, will be 32)
8. After you read the code, you can start the engine
9. Turn the bolt back to the clockwise position for at least 2 seconds(While running)
10. Turn it back to the counterclockwise position
11. Now shut the car and then start it again, this should of removed the code


In step 7...i got codes 125 and 34....which is the "Line Pressure S/V" and "Knock Sensor" ....now not sure wtf this is...i continued to step 8....now this is where there's trouble....my car doesn't start now....
Here's where i got my information:
http://www.240sx.org/faq/articles/ecm_reset.htm
http://www.240sx.org/faq/articles/ecm_codes_doch.htm

hmmm.....so as of now my car can't start......any ideas?

Thanks in advance for your input,
Chris

[Kreukishot]

update.....ive resetted the ECU (i believe)....it gives me code 55 now...however i still can't start it wen i change back to mode 2....=\

[projectRDM]

Code 125 is the dropping resistor, is your car an automatic? If so, plug the 2pin plug on the driverside shock tower back in. You're only shortening your transmisison's life.
Code 34, knock sensor, quit buying cheap gas.

There should be no reason the car won't start, you've done something else wrong.

I just reread your post, you do not go into diagnostics with the car running, only with the key on.

[Kreukishot]

car is auto.....(friend suggested to unplug this....i unplugged the 2 pin just to see how tranny will respond...didn't like it..and i know it'd screw up my tranny so i plugged it back in)....i've been buying 89/91 octane ever since i got the car....

charged my battery as well...

my car wasn't able to start at all...it's not giving me any error codes..juss the 55 normal operation crap...however even after i return the screw back all the way counter clockwise...it doesn't wanna start....i can hear the starter tho..but it juss gives the *clunk*...

EDIT: The only 'experiment' was that i unplugged the 2 pin plug...but after less than a mile of driving i plugged it back in...other than this i didn't do anything else....

[ledzeppelin240]

Are the battery cables tighned down to the battery post.

Go to this link.
http://www.paristexaslibrary.com/links.html

Scroll to the bottom where Mitchell1 OnDemand5 is. There is the user name and password there so you can access Mitchell1 OnDemand5.

Once in go to Engine performance, then Testing and Diagnostics, then Test W/Codes. Then Article Beginning. That explains how to check for codes and to erase them. Try what it says there incase something was missed in the FAQ you are going from.

[Kreukishot]

alright..thx for the help guys...i think it was part battery tie down and partially that i didn't charge the battery enough...got it started after i tightened the cables to the battery and after 2 hours of charging...

thx for the link led...looks like i got a crapload to read...

[idlafie]

I've got a 97 240sx...

Installed a different Air intake...everything was working fine...however for the past month i've gotten shitty gas mileage (15-17 MPG) so i decided to reset my ecu to see if it'd help.......however this still gave me shit mileage..
Thanks in advance for your input,
Chris

From an old post...

You might want to check these threads....
http://www.zilvia.net/f/showthread.php?t=63587
http://www.zilvia.net/f/showthread.php?t=54065

If your going thru gasoline like there is no tomorrow then you might want to check your ECU first before you attempt any repairs. Put your ECU into Diagnostic Mode...see www.240sx.org FAQ page for instructions. Once you put your ECU into Diagnostic Mode, then check to see what type of Diagnostic Trouble Codes your car is kicking out.

Once you pull the Diagnostic Trouble Codes, then pop the hood of your car & try to figure out what may be causing your problem. Areas to check are.
1). Fuel Regulator....sufficient / not enough / too much vacuum going to the Fuel Regulator??
2). Fuel Injectors...is one or more leaking??
3). Engine Cooltant Temperature Sensor - a faulty ECTS or bad wire leading to your ECTS may have your ECU thinking your engine is still cold & causing the extra fuel to be dumped in your intake manifold.
4). Idle & Timing...check your Idle & Timing - make sure they are set properly
5). Oxygen sensor - test it thru the ECU..The Check Engine Light .should flash 5 times or more in a 10 second period when the ECU/O2 Sensors are placed into Diagnostic mode.
Check these items out & let us know what your results are..
Anyhow, hope this helps..
ID

[ledzeppelin240]

Yeah some very useful information. It is usually just corroded battery terminals or that they are not tight enough. I have seen that a lot and also had problems with them not being tight enough. They might look tight but there is a lot of current draw on the battery on startup.