Has anyone ever heard of the rin reading as low as 88 or the lin going as high as 185? What could cause such a thing. My rbl and lbl readings never went above 160 though. I'm having this problem but no SES light?
Sometimes the car will idle with the rin & lin staying around 127-135 just very erratic and will soar one way or the other for no apparent reason. Could it be possible something in my computer is causing this? Please help,
Fred

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1994 Z28, A4,
BEST 1/4 12.413@109.55
BEST 1/4 MPH 110.49
BEST 60' 1.668
BEST 1/8 7.884@86.35
BEST 1/8 mph 86.77
Race Weight 3600lbs
No new times with P&P heads Flow 239.4 INT 182.1 @525 lift, or
24lb SVO inj's...

 

Fred, what are RIN and LIN, I dont have that program so I can only guess, are those short term or long term learns?

Exaust leak, flaky O2 sensors, if it were a bad PCM then probably other things would go wrong as well, I think PCM failure is pretty rare. You could try unplugging the PCM batt for a few seconds to see if the learns continue to flake out on you...

 

Rin and Lin are short term memory readings at any given time that show up on a scan master. According to Fred the Injuneer, his scan master paper work on his site, the readings should never go lower than 108 and not higher than 160. My o2 sensors are brand new from Napa-(Ecklunds). Why or how come I'm not seeing a SES light?
Fred

 

Well, the long term learns are 108-160 that much is correct (its a setting which can be changed if programmed differently), as for the short terms I do believe they can go higher, not sure about lower. I remember putting the car in closed loop and locking my BLMs at 128 and seeing short terms go pretty high and staying there (this was with modded car).

How is your MPG?

How are your long terms? If they are 122-135ish or so and your MPG is decent then I don't think I'd worry. Do you have an actual data logger instead of just Scanmaster? That would be better for trying to correlate data like engine load vs your BLMs/INTs etc, instead of trying to do that stuff in your head.

Are you running a hotcam or something along with your heads? If you've got a cam has it been reprogrammed, mail order? Dynoed?

Just trying to get an A-Z feel on the situation... Probably most important is to check the long terms, short terms are somewhat expected to bounce around, thats what the stock O2s do, supposedly the constant switching between rich/lean/rich/lean/rich/lean is what makes the CAT work at its best, not a dead even 14.7:1 all day long, slightly varying between the two.

 

UPDATE; I had been noticeing that after a good warm up period my right o2 sensor while driving would only fluctuate between 300 to 425 mv's. The left o2 sensor would be bouncing back and forth between 100-900 mv's. Even though I just replaced both o2's I dropped my y-pipe last night and swapped out the right o2 sensor. Afterwards I took it for a ride and noticed both o2's fluctuating between 100-900 mv's.
The car still isn't perfect though because now the left RBL will read around 130, but the LBL will still go to 160. The rin and Lin stay fairly equal though when at any speed, usually 115-134.
Something else too at idle the left o2 will read 150-250. The right o2 will stay between 850-950. I noticed the Lin at idle would drop off slowly to 160-165, then slowly come back to 128-135. The Rin would drop to 107-110, then slowly come back to 122-129.
ARE THE o2's SUPPOSED to fluctuate between 100-900 at idle???
Right now I'm wondering if the left o2 needs changing too, or do I just need to mess with the throttle stop?? I will be bringing a laptop home tonight and installing my new program for the 24lb svo injectors.
I currently run a LT4 hot cam kit, slp 1 3/4 headers, ported-polished 1.57-2.00 LT1 heads, no cat, borla cat back, stock tb-intake, slp cold air, tuner cat programming. MSD coil, LT4 KM. That's about it for the engine. I also notice at idle the knock retard is like .3... Hope this info helps you to help me. BTW before the 24lb svo inj's and heads I dynoed 324 RWHP-310 RWTQ. Should be around 350 RWHP now.
Fred
Fred

[This message has been edited by Fred94LT1 (edited August 13, 2002).]

 

I'd fix that knock first, although it sure sounds like your lean at idle, but why would the computer not compensate for that...

How is your timing work, has it always showed .3 knock at idle? I ran a plenty larger cam and never saw idle knock, was running about 11.4:1 compression on 91 octane MTBE gas.

From your post your running pretty lean at idle so much so (160) that the PCM can't compensate, since you show lean supposedly and knock, I'd richen it up slowly and see where those BLMs move. The BLM split is likely related to the cam overlap plus possibly need for more timing work, I dont recall mine being off by that much even with the larger cam, HOTCAM should be fine in closed loop operation...

 

Since the O2s are new, basically I'd trust them and just work on those BLMs, see if the situation improves, then go from there. I date my FLASH files 0811a, 0811b etc and use notes, so you can go back just incase it doesn't end up working out.