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running lean?

B

Brennan7

New member
hey guys, I have a 1997 grand prix GT. I recently top swapped it. I got an air/fuel gauge hooked up yesterday and it says it's running lean. It drives perfect until its at idle. The RPM's drop down to like 400 and then jump back up to a normal idle. I have an alternator voltage booster so im running at like 15 volts, and when this happens the volts drop down with the RPM's to like 12 volts, and then slowly go back up to 15. This only happens when the car is warmed up.. please help!
 


You did a bad thing.

Your transmission is going to hate you and nuke :)

is the AFR gauge a wideband? If not, then its useless.

what IS a normal idle speed for your car?
 
Your alternator cutoff is set to approximately 600rpm, therefore anytime rpm is below that number your alternator is commanded off.

You hooked up a gauge and it says you are running lean. Please elaborate on where and what is lean. Your gauge during idle and normal driving should bounce up and down. The faster the better. At WOT it should peg rich and when you let off the throttle expect it to be lean.
 
lol I know matt, my trans already nuked on me. I just got it rebuilt and got it back 2 days ago lol..no it isn't wideband.

and Bill, it actually always stays lean, it never goes rich or in the optimal zone...ive gone WOT, normal driving, and idle. it barely ever moves, it does a little bit but still stays lean.

do you think it could just be my alternator voltage booster?
 
No, I'm kinda thinking the problem is located between the seat and steering wheel. :th_laugh-lol3:

Check the connections/wiring on the gauge. If the car was running lean all the time, you'd throw a code or two about it. Which leads to the diagnosis of it being hooked up wonky. :th_thumbsup-wink:
 


Lol ok bill you must be a comedian haha...I had a shop install them but ok..

and bio r u sure its the 1st o2 sensor?
 
yes, 100% sure. the rear o2 sensor barely reads anything and is only there to show catalyst efficiency to the pcm.
 


........ if the guys at the shop wired an af gauge after the cat dont EVER let them touch your car again....

just get rid of that damn thing... even when its installed on the proper sensor its still not going to be accurate.....
 


Wow, I figured a mechanic wouldn't have made that mistake and thought you said you installed it.

I like to laugh though... :th_thumbsup-wink:
 
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