verbs

While dynoing a while back, I had my car dialed in perfectly for maximum hp. My a/f ratio was 13.2-13.4, and I put down an extra 8rwhp or so throughout the powerband over a mid-hi 12 a/f ratio.

Unfortunately it was 75 degrees back then, and now it is 105 every day, and my car seems to be detonating on the track using the settings that got me my maximum horsepower.

I had my MAFT set at +2/-4 (or +10% base -8% WOT), and things were dandy.

Now I need to set it at +2/-1 (or +10% base -2% WOT) just to keep from detonating.

I compared my o2's on autotap between the dyno run at 75 degrees (at +10%/-8%) and driving in 105 degree temps now (at +10/-2%). Even though I've completely richened up my MAFT to adjust for the heat, my o2's are nearly identical!!!! Wierd.

Anyone else having this same dilemma???

Is there a standard rule that as temperatures go up X degrees, then a/f ratio adjusts by Y???

Y2K1 SS 5.0 THIS

TTT

TrentSS

Verbs...I'm "somewhat" in the same boat as you! Quick story here, back in late February I had my car perfectly dialed in. My L-trims at idle were a perfect Zero(0)and my O2's were great. No matter what gear I stabbed the throttle my car never saw KR. Fast forward to NOW. My L-trims are still zero and my O2's continually range from .890 to .896; however, I'm getting up to 3.2 degrees of Knock Retard!! Even though I haven't gone back and readjusted my MAFT, I'm showing identical averages for O2's!! Like you, I'm going to try to readjust my MAFT and if that doesn't work I'll be finding some Union 76 unleaded 100 octane to see if I'm seeing false knock. I have no banging going on anywhere. I love these cars but having to fine tune to compensate for seasonal changes can be cumbersome. Let me know if you find anything!

red ws6 99

Well since the MAFT settings will affect your timing also you probably have to much timing the summer temperature and octane. Thats one of the major problems with a MAFT.

Gary

Mr Cowl Hood

I have two questions.

1. I am wondering how you have knock now that you didn't have before at 75* temps. If you have a 160 Tstat and your fans are keeping the coolant ~175-180* then all else should be the same. It apparently wasn't dialed in right earlier.

2. How exactly does altering the MAFT affect timing. I know it can affect AFR's temporarily, but never timing. Please explain.

red ws6 99

The MAFT works by lieing to the compter telling it you have less air coming into the engine that it actually is. Since the computer calculates load based of the maf signal (among other things) it adds more timing. Also with the MAFT whenever, you have a temperature change it will have to be readjusted.

Gary

verbs

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Mr Cowl Hood:
<strong>I have two questions.

1. I am wondering how you have knock now that you didn't have before at 75* temps. If you have a 160 Tstat and your fans are keeping the coolant ~175-180* then all else should be the same. It apparently wasn't dialed in right earlier.

</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">It was dialed in just right before.

The other problem I have is that even w/ a Tstat, my coolant temps are well above 180 degrees. I go from about 195-200 on the highway to as bad as 215 if I'm in bumper to bumper traffic.

BLUEBYU

iTrader: (1)

SLP fan switch!!!!! Best mod I have done..and I have done a few <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

verbs

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BLUEBYU:
<strong>SLP fan switch!!!!! Best mod I have done..and I have done a few <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">How much can a fan switch help if I've already told my HPP3 programmer to turn the fans on earlier????....as well as my having a 160 stat???

BADSS

iTrader: (7)

Verbs- you should not be running that hot- even in 105 degree temperatures. With the 160 thermostat, lower temp fan settings, and FTRA (which raises temps since it blocks airflow to the radiator) I hardly ever see coolant temps over 190- even when it hits 100 degrees here. Check to make sure your thermostat is opening when it should, and that both fans are coming on when they should. Could be a faulty thermostat or a malfunctioning fan. BTW, try adding some Redline Water Wetter to your coolant. I run 2 bottles- it will bring the coolant temps down a few degrees. My coolant temps stay between 180-190 almost all the time.

Superman

With a 160 stat and water wetter I run 180* during cool weather...BUT as soon as the temps go above 75* the temps go up to 215* even on the highway.
<img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

BADSS

iTrader: (7)

Dan99Hawk- Do you have your fans set to come on early? You guys really should not be running that hot with a 160 thermostat if your fans are set to come on early- particularly on the highway where there should be lots of airflow through the radiator to cool the motor. These motors have two cooling fans- make sure they are both working properly. If I run the car hard, I see 195 degrees, tops. It usually fluctuates between 180-190.

verbs

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BADSS:
<strong>Dan99Hawk- Do you have your fans set to come on early? You guys really should not be running that hot with a 160 thermostat if your fans are set to come on early- particularly on the highway where there should be lots of airflow through the radiator to cool the motor. These motors have two cooling fans- make sure they are both working properly. If I run the car hard, I see 195 degrees, tops. It usually fluctuates between 180-190.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yeah, on the freeway I don't get much above 195...maybe 200 tops, but day to day slow rush hour driving is what drives the temps up to 215.

I do use redline as well. I'm thinking about upgrading to a bigger radiator as well.

Superman

My fans do come on early.. if I remmember right 180 for the low speed amd at 190* both fans at high speed kick in... still gets up there just sittin in traffic and cools very slowly on the higway.
I`m thinking maybe the 24,000gw trans cooler is creating some heat or blocking the radiator a little.

Vettepartz

Don't forget that almost all gasoline companies go to a more oxygenated fuel in the winter months for better emissions. A ratio of 14.2 to one works better in the winter and 14.7 to one in the summer. Just another possibility.

02blackbirdws6

I bet it's a temperature sensitivity in the MAF. As temp rises, resistance increases in wires and resistors. I bet you were right on the detonation line and the heat pushed you over. Your MAFT may amplify the problem through translation, also. You'll probably just have to keep tuning to the weather.

The Dragon

iTrader: (6)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 02blackbirdws6:
<strong>I bet it's a temperature sensitivity in the MAF. As temp rises, resistance increases in wires and resistors. I bet you were right on the detonation line and the heat pushed you over. Your MAFT may amplify the problem through translation, also. You'll probably just have to keep tuning to the weather.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Ditto that.

BigBake

As temperature increases resistance goes down, not up in resistors. So your MAF voltage would increase.

<small>[ June 13, 2002, 03:43 PM: Message edited by: BigBake ]</small>

Mekkadon

iTrader: (3)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">The other problem I have is that even w/ a Tstat, my coolant temps are well above 180 degrees. I go from about 195-200 on the highway to as bad as 215 if I'm in bumper to bumper traffic.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Good lord man it must be hot over there. I have a manual fan switch and set to "low", cruising on the highway it doesn't even break 195. In stop and go traffic, I turn it on "high" and it still doesn't reach past 195. I live in Tennessee. My friend has a 1999 Z28 M6 and he goes past 215 with the A/C on in stop and go traffic!!!

Torqued

Mekkadon, do you have the FTRA?

In 90 degree weather with AC on, I run around 195 with the FTRA and the thermostat mod. Does that seem like a normal running temperature? Would I run any lower with a 160 stat?

Thanks.