Hola F-Buds,

Just as the title reads. I receive a blue (rich) smoke thru the exhaust every other time I startup my Z, I scroll thru my Scanmaster and the reading for CEL is at 01. I let it warm up completely and the number is still 01. I'll take it for a cruise, stop at a light, check it again, and it will read 01-09 but never any higher.

Why won't it read 16 like it's suppose to at idle?

Stock PCM was swapped back in, PCM was reset at fusebox as well as disconnected negative battery terminal to ensure no electricity shock when R&R'ing.


Oxygen sensors only thing I haven't replaced yet... possible remedy?

Thanks in advance.

Ruben F.

 

The current fuel cell is dependent on three things...

MAP reading... RPM... and EVAP purge status.

I believe the only time cells 16, 17 and 18 are used is when EVAP purge is below 5 or 6% or something.

So I suppose that it's possible your car is attempting to purge even at idle?

Check the fuel cell at WOT, it should read 15 if the EVAP is above 5 or 6%, and 18 if it's below.

As for the blue smoke, I thought blue was oil, black was fuel and white was coolant?

I'm not 100% on this fuel cell stuff, but I think I'm right.

 

15 16 17 are open loop cells, cells are dependant on map and rpm only. at wide open throtle if your cell is 15 that means your adding fuel during wot, because your blms were above 128 the instant you went into wot.

now for the question. ive seen 00 on my scaner before, but your car my be likemy buddys is stays in openloop for about 10 sec. no matter what the conditions. but if its acctually using 01 as soon as you crank your, well thats a new one on me.

 

Based on the BLM boundries in LT1 Edit for my car, Cell 15 is for times whem MAP is above 80 kpa and RPMs are above 2000. That certainly doesn't seem like an open loop time, as I've had it go to cell 15 with 40% throttle at 35 MPH before.

I've drawn out the map before, although it was already done on Christian Millard's site in one of his Excel files showing fuel cell hits, and found that cell 0 is the lowest cell, and 15 is the highest cell used for normal driving. Cell 16 is idle with EVAP below 5%, 17 is for deceleration with EVAP below 5% and 18 is for acceleration with EVAP below 5%.

I have NEVER, EVER seen my car go into fuel cell 18 at WOT, not even when the PCM was pulling fuel at WOT.

From what I've seen, the PCM doesn't have a "WOT" fuel cell. It uses the same fuel cell it would under normal circumstances (based on MAP and RPM) then uses the PE vs RPM (%change vs RPM) and PE vs TEMP (%change vs TEMP) tables to add the additional fuel called for in power enrichment mode.

 

if your car show a blm higher than 128 when you go to pe mode or wot whatever you want to call it. it will use cell 15, and if your car is showing cell 15 for wot that means your car is adding the correction factor to the pe mode programmed fuel ratio. it will add however much it was adding in cell 15 to the pe mode and show cell 15 at wot on the scanner. and if it shows cell 15 at wot that means your not acctually getting the correct a/f ratio you have programed for in pe mode, this is the reason for the blm blocker, it makes the pcm use cell 18 like it supose to (no added fuel). this also why people tune the normal driving blms to the 122 so when they go wot it uses cell 18. and also if the car is useing cell15 you will notice on the scanner that the blms are not at 128 they are showing the blms of cell 15. but when the car uses cell 18 it show a blm of 128 (no correction.)

it is not a wot fuel cell. the pcm ignores the o2s no matter what cell it uses. wot open throttle is not open loop but it might as well be, the o2s are ignored. but what countsis what blm are showing while your in pe mode, this tells whether its added fuel (cell15) or not (cell 18)

 

When I locked the BLMs to 128 for WOT, it still showed cell 15...

I remember reading on the LT1 Edit mailing list archives that cell choice had to do with EVAP purge... I guess whoever wrote it could have been wrong though.

 

I've got most of this info in my online ScanMaster writeup. I've never heard of EEC purge as being a determining factor. I've helped people by analyzing 100's of DataMatster, FreeScan and AutoTap logs, and I've seen numerous cases of the PCM defaulting to Cell 18 at WOT. And if you look at the BLM's its because the PCM was cutting fuel. Pretty much follows the logic Cell 15 if it was adding fuel, Cell 18 if it was cutting fuel. There are subsets of Cell 15 useage though, where it uses either the previous value of the Cell 15 BLM, or defaults to Cell 15 with locked BLM's at 128. Have not detected the logic for that one.

Never saw a case of the engine cold starting in Cell 01. Never saw a case of a PCM going to closed loop within 10 seconds of startup - normally in the range of 200-220 seconds.

 

I didn't mean to be difficult, and I thank both of you for helping to clear up my confusion. I also apologize for "stealing" the thread, but maybe the information will help the original poster.

I found those messages in the LT1 Edit archive... If either of you would like to read them, please let me know and I'll forward them to you. They were from Scot Sealander and Christian Millard.

 

I've done lots of MAF tuning to get my Ltrims in line for the dyno this past weekend, and my car still hasn't gone to cell 18 for WOT. It only goes to cell 15... The car is pulling fuel everywhere except in cell 15 where it's dead-on at 0% for both banks.

With the MAF table set the way it was, and the PE vs RPM table set to stock, a dyno pull showed a 12.7 AFR to begin the pull and ending at 12.2. Adjusting the PE vs RPM table showed a final AFR or 12.8-13.0 (can't remember which right off), but still the car only uses cell 15 for WOT...

I'm just glad that I've gotten it nailed down and nothing is wrong.