Another_User

I have done searches...it looks like Bink is resident FTC expert...but anybody have any ideas? I am dropping in and out of open loop at what seems like random intervals. Can anybody help make any sense of it? I am attaching a link to my latest log...
http://users.adelphia.net/~someoneelse/25AUG04_01.zip

Another_User

Ok...I think I have narrowed why this has happened down to the low-temp (160) thermostat. It only appears to happen when my coolant temperature sneaks to about 80 degrees C or below. So if that is it, what do I change?

Another_User

Well, ironically that is where the Open Loop FA vs Coolant Temp vs MAP changes. Is this where I should be looking to make some changes?

jimmyblue

iTrader: (11)

Only difference I've heard of, between Cell 22 and
the other high-MAP FTCs (12:15) is the EVAP system
purging or not.

Any time you show a Fuel Air Multiplier <> 1.000 you
are not in closed loop. The narrowband O2s can't
be used to close non-stoich operation (or not
very far from it anyway) so they don't try except
at 1.000.

What's the beef?

I don't see much WOT in that log but where you
do open it up, you have 900mV O2s so you are
obviously getting your power enrichment. You
might want to see whether that KR is event
triggered or just burst knock from too fast a MAP
rise, by playing with the burst knock threshold
(higher) and the maximum burst knock retard
(lower, like 1.234 so it stands out if that's the
cause).

Other than that bit of KR I don't see a problem
here.

Another_User

It looks to me like it goes into cell 22 and gets stupid or something. It seems like it might be getting a little lean to me, but I am not sure. And it gets knock retard just about every time it goes into cell 22. Also, 20 and other open loop cells keep coming up. If I am not mistaken, don't the LTFTs lock in open loop? And why would my EVAP not purge all of a sudden?

Unfortunately I cannot adjust my burst knock....98. It sucks.

And that knock retard is with some timing removed from my stock table...here and there.

jimmyblue

iTrader: (11)

LTFTs will zero if negative and lock if positive, is
the way I understand it. Also, LTFT learning will
not go on at FAM <> 1.000.

You can minimize the KR by decreasing attack rate
and increasing decay rate. Suppress the jump-up
and speed the go-away.

Also try bumping up your VE table in regions that
are pointed to by the cells 1 and 2 ticks prior to
KR onset. Fast throttle transients expose the SD
tune. If you see "lean holes", dips in O2 voltage
when you mash the throttle fast, try that. You'd
rather shoot some extra gas and not knock as it's
just a temporary thing until the MAF swings back
into line.

If indexing between lines in your OLFA table makes
a difference then I guess it must be "straddling" the
PE value you're shooting for (but also there are PE ECT,
IAT adders and these might also be stepping though
my car has the normal ECT range all zeros).

Didn't know the '98s had no burst knock access. Is it
that there is no burst knock function, or just the
HPTuners doesn't touch it? Might ask them about this
and see if they'll add it, if it's active in the PCM.

P Mack

iTrader: (6)

That is a weird log file. Just looked at an old log file and the only time I see cell 22 is in open loop, either off-idle when the engine is cold or during PE at wide open throttle. Maybe the 98's have different software or something. I've heard about the trucks only using cell 22 for evap, but it's different for f-bodies (at least for the year 2000).

deezel

You could check your closed-loop enable temps. Also PE Delay vs. temp.

Log file looks ok to me (except the 4*KR). After about 10 minutes of warm up, the only time you see cell 22 is under acceleration (~50%tps+), which is normal.

wait4me

iTrader: (10)

anotheruser, the o2 sensors have to be at a certain temp to work properly, so if they need heated up, the car will use there heating element, and also put the car in cell 22 to richen up the mixture to make the eghaust burn hotter to get the 02s back up to temp.. sometimes the o2s need replaced because they are just getting worn out. or the o2s might be too far down the line in the pipe making them not heat up properly, that fixes that problem.

P Mack

iTrader: (6)

I don't think it looks normal. On line 1435 he goes from closed loop (cell 6) to cell 22 at 4% throttle. My stock closed loop enable temp is like 34 celsius. Since he's not in PE, and the car's already warm enough to go into closed loop and shouldn't go back, there's something else going on.

Oh yeah, and a rich mixture makes the exhaust cooler not hotter.

deezel

His log is the first ten minutes or so after a cold start. There are other things going on besides closed loop vs. ECT (such as rev limiter delay, PE delay). After ten minutes into the log there is no more of this funny behaviour observed. I have seen similar behaviour on my truck numerous times (popping back into OL cell 22 from CL after a cold start). Once it warms up, all is good.

Jes (wait4me) makes a good point. It may also be related to the O2 sensors heating up or being old. With a colder t-stat it might take a little longer for the O2s to fully heat up.

Another_user:
Does this trim cell behaviour go away after the car warms up? Or can you drive around in stop-and-go traffic for an hour and it still happens.

P Mack

iTrader: (6)

Good point, with headers moving the sensors farther back i could see the o2 sensors getting too cold and forcing it back into open loop. I don't think it has anything to do with coolant temp though, cause he is way above the closed loop ECT threshold.

HumpinSS

iTrader: (1)

If you are gonna buy new o2 sensors try the corvette rear senors. The wires are long enough to reach alternate locations and they are supposed to be a higher wattage o2 with better heating elements. Bosch sensor 13111

Another_User

I don't know... I was still getting cell 22 well into the trip. That was a pretty long trip. I traveled from my house, to the bank, left the car running while I hit the ATM, went to Chic-Fil-A, sat in the drivethru for a minute, waited for my food and drove right home. Cell 22 was coming up pretty randomly throughout the trip...along with nasty knock retard. I was think it might be because of some fueling issue. I made a 55 mile run on the highway today in the heat, I am going to see what happened there. I still think it has something to do with that silly thermostat...

Another_User

ttttt

Another_User

Ok. I have found out a few additional things from some new logs:
1) coolant temp has no impact on this occurence
2) my fuel/air multiplier is 1
3) there may be some lean tip-in

I would think an SES light would have lit if the PCM had detected a problem with the EVAP system. So what does that leave me left with as the possible problem? Wouldn't I see if my O2s were not switching properly? The signals look fine to me...

wait4me

iTrader: (10)

did you replace the o2s yet? .............

HumpinSS

iTrader: (1)

The therm shouldnt have any bearong on what you are seeing. Swap it back and see if it continues

Another_User

No...but it was fine before the swap...why would they both "fail" at the same time?

Another_User

I looked through my old logs, and it looks like this did occur, just not as frequently. That rules out all of my mods, including HPTuning, headers, thermostat, etc. What a bunch of crap. O2s or Evap? Any other thoughts on what it could be?

Gas cap leak? From time to time I have gotten a loud hissing from the rear of the car, particularly on long trips...maybe some venting issue?