How to keep your car in "cold start"

[Billf6531]

Now this is becoming an interesting thread.

Russ, I see that you dropped the closed loop enable temp to 30*C from 51*, but with that cam, and in cold start open loop (he starts at 20* ambient), wouldn't the open loop EQ table be commanding in the 11.5 afr range? I get the sense from the description that the car is choking on fuel.

[bulletLS1]

WOHAAAAA!!!! Now I have a change in the IMPROVEMENT side!!!

REALLY REALLY THANKS!!

My start up in cold is much more improved, althoug like it stills misfires a little (but only if provoked), cold response is terrific to say the least, NOW really scares yoursef, upon warming the maners became less voilent more subdued... when fully warmed, still have the problem of "say going downhill (shallow) with TP 0% for at least 30-50 sec, and accelerate (to keep with the trafic) I think 5-10%TP one (or more) Cyls die, If kept TP same opening for about 30 sec that same cyls "turn on" inmediatelly functioning crisp and normal... If TP is slowly and deliberate accelerated (constant rate of accel/press) around 80-90% TP they "turn on" inmediatelly with the anoying snappy roar.... curiosly if steady TP 10% "unknown cyls off" I cycle the IGN key quickly again all cyls function...." with this Im really lost because is not a fuction of plug fowling or chamber (a single one) starvation.

That as far as one night testing, and the LapPC died of lowbat during very first cold start

THANKS AGAIN FOR YOU ALL
MY FIRST INTERESTING THREAD WHOA!

[bulletLS1]

Also I have a lightened flywheel & clutch cover, LTheaders, Z06 block, oem corvette coated pistons, all arp (that does not count) "regular" intake, P&P MAF (yes, I kept using it), P&P TB., BIG catback, if that info works

[Russ K]

Now this is becoming an interesting thread.

Russ, I see that you dropped the closed loop enable temp to 30*C from 51*, but with that cam, and in cold start open loop (he starts at 20* ambient), wouldn't the open loop EQ table be commanding in the 11.5 afr range? I get the sense from the description that the car is choking on fuel.

Bill,

I didn't touch his open loop table. And yes, at 20*C ECT @60 map kpa, the commanded open loop AFR would be ~11.5. There needs to be changes made to this table for sure.

Russ Kemp

[bulletLS1]

enclosed are scans.
one of them was in dead cold morningfrom start, other was noon and the car was used in the morning, last is a very uniform driving while in trafic, is a very shallow uphill.

note: One of the o2sens shows way different from the other, shoult the Mv readings shound be fairly close when cold and "overnight fresh". later in the second start I revved the car to see if heating might do something.... (at the end they where more or less the same)

[Russ K]

Use the Idle-Airflow config file for the cold start idle scan to operating temp. Use the 1998-Camaro config file for the driving scan.

Russ Kemp

[bulletLS1]

last keek I got rotavirus, and was "fulminated" in bed....
Ill post soon the scans, Thanks

[Russ K]

sorry to thread hijack
Do you v8 guys with OL tables stay at a perfect 14.7 stoich on the WB during DD?
When I've just started the car, I've noticed my AFR will stay perfect at 14.7 until it goes into CL and starts jumping all around (probably because of NBs)?
thanks

No, the commanded AFR at operating temp will stay at 14.7. The actual AFR will vary, depending on how close your tune is.

Russ Kemp

[slow6]

In OL (just started the car) my Real AFR is perfect 14.7!
but once I get in CL the NBs make my Real AFR jump around (normal)
Thanks guys

[bulletLS1]

actually my car seems to work more predictable in this few first seconds, I supose in OL, hence my need to:
BACK TO BEGINING OF THREAD.

then I will manage remaining parameter to mimick the better driving characteristics, althoug It may NOT be the optimum last bit power wise but it drives so much confortable, (I already have my sushi-scooter type R for race!)

[bulletLS1]

Esteemed russ:
in the iddle-to-temp test, should I let the car iddle and not touch the gas until warm, (it may take a while!)?

[Russ K]

Esteemed russ:
in the iddle-to-temp test, should I let the car iddle and not touch the gas until warm, (it may take a while!)?

Yes, just let the car idle till operating temp. Don't touch the gas pedal or drive the car when scanning the idle.

Russ Kemp

[bulletLS1]

Ok russ, I have your scan:
enclosed is also a .htp for bone stock oem, and last modification, (the one you sent + some mods in regard w/rpmlimits, & iddles) this is to compare from what I started.
Relevant Info:
car is a M-6, with stage II heads, 218-227 lunati cam, all p&polish (TB & maf) long tube headders (not covered in termotech) w/the o2 sens very far away (9" from the collector). no cats. (cat syms), oem injectors, oem nonZ06 intake, lightened flywheel. starting temp arround 20deg ambient. 5000' omsl.
hope this info will help
Thanks

[Russ K]

The STIT & LTIT look very close. Why do you have your idle speed lower than stock?

Russ Kemp

[bulletLS1]

I like the rumble-rumble of the v-8 sound furthermore with a "hotter cam"; although in my city heavy, HEAVY trafic I always wished for a lower iddle, instead of the buzzing like OEM, (kinda my taste).
Im just going to raise the rev limiter because in the of-ramps I´m getting the partypooper too soon and in an anoying portion, maybe 300rpm more should suffice.

[bulletLS1]

Esteemed russ, Why you wanted the iddle test?
STIT: short term IT?
LTIT: long term IT?
I remember fuel trim, but IT?

question:
supose I want to lean out the iddle section, IN the VE table I have to LOWER the efficiency values in the table right, but the VE tables are only accesed when (I think) maf failure. what else I can modify?
this is in carburetor (I know, how primitive!) talk, to tweak the air screw out.
also I know for this "change" to be apreciated I have to kep the iac step count constant. right?

[Russ K]

STIT = short term idle trim, LTIT = long term idle trim. This is for the idle speed control, not fuel trim. The Maf is used unless the Maf fails, then the VE table is used. If you want the cold start AFR leaner, then you need to reduce the open loop table, just don't go lower than 1.00.

Russ Kemp

[bulletLS1]

I know there are a million combinations to arrive at a desired afr, soooooo:
if I alter the "closed loop table" and I eithed enrich or lean it, would be the same as to alter the PE afr?
I know the PE is only in heavy acceleration, but the CL table if modified in higher map it will futher enrichen or leann it on top of the comanded pe value?

[Russ K]

The open loop table is for the none PE commanded AFR, the PE EQ vs. Rpm table is for the commanded AFR when in PE. I'm not sure what you question is.

Russ Kemp

[bulletLS1]

sorry, Im getting lapsus stupidus!.
please explain:
PE enable TPS
why two tables if "hot select" will never be reached.

please explain, If there are switching between R/L, and independent for both banks, I can modify AF independently for each bank, i.e. if STFT in one bank is way positive, and the other bank is way neg. (have scan to prove)