o2's not cycling between 0-3k RPM, Running WAY WAY RICH!!!

M

MrBoost

· Registered

Joined Jun 12, 2001

·

216 Posts

Discussion starter · #1 · Jul 18, 2003

Only show this user

Ok guys, need some help here.....

What would be a cause for o2's not cycling between 0 - 3k rpm?? Voltage is just stuck way LOW (yes, low not high), but I am running WAY WAY WAY rich from 0-3k RPM....(smell fuel, backfire, which I assume as unburnt fuel in the exhaust, etc.) Once above that RPM range, 02's cycle normally, and car seems to run fine....but the car's idle will bounce between 800 - 1800RPM and do everything it can just to maintain idle. I heard before that if o2's do not cycle at normal it's because fuel trims are way out of whack....any ideas??

 

F

flubyux2

· Registered

Joined Jan 14, 2002

·

1,300 Posts

#2 · Jul 18, 2003

Only show this user

my 91 had a similar problem when the 02 sensor got whacked out... it wouldnt cycle at all, and ran al ittle funky.

 

M

Michael

· Registered

Joined Sep 6, 2001

·

1,912 Posts

#3 · Jul 18, 2003

Only show this user

I'd bet a couple bucks on a vacuum leak.

 

F

flubyux2

· Registered

Joined Jan 14, 2002

·

1,300 Posts

#4 · Jul 20, 2003

Only show this user

W3rd, i second that emotion

whats your vaccum reading?

 

9

95stktrbo:(

· Registered

Joined Jul 11, 2001

·

4,075 Posts

#5 · Jul 20, 2003

Only show this user

mine was doing that at idle becasue I didnt have the AFC set right.

I figured since I had 650cc I should lean out about 15-20%. I was wrong. I have my 1k NE point set at -9% and then the O2's will cycle.

 

F

flubyux2

· Registered

Joined Jan 14, 2002

·

1,300 Posts

#6 · Jul 20, 2003

Only show this user

True, i forgot about that... if your fuel delivery is too rich or too lean for your ECU to correct, it wont go into closed loop. Like he said, if you are at idle and you remove so much fuel... your O2 volts will drop down and they wont come back up simply because your ECU has hit the limit in its range of adjustment; same goes for if you add too much fuel.

 

M

MrBoost

· Registered

Joined Jun 12, 2001

·

216 Posts

Discussion starter · #7 · Jul 22, 2003

Only show this user

thanks for the help guys.....I had a death in the family and am out of town probably till the weekend. All of my AFPR parts came in before I left....hopefully I can get that setup correct and check vacuum as well....