The C5 >01 and mine, have the later MAF mounted temp sensor which is in a pretty good spot fwd of the bottom feeder radiator..Originally Posted by SSpdDmon
Occasionally if I stop for about 10 min it restarts ok, but won't idle for a min or two till it figures itself out.. I think it might be going lean due to hot temp sensor or hot air. Need to induce it when I am hooked up.
2000 C5 Coupe, 6M, Callies/Mahle stroked LS7 (441), Blackwing, Halltech, LS3 intake, 90mm Shaner TB, ported L92 heads, FAST 50# inj, not too much cam, Kooks 1 7/8" headers , 3" catless mid pipes, Z TIs, track suspension, , 3:90 rear, EFI V2, LM-2, etc.
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What do you mean induce it?
If you have a C5 and are experiencing IAT heat soak problems, consider a ram air system. I installed a VaraRam and IAT readings are now within 1 or 2 degrees of ambient. There is still a bit of heat soak after the engine is turned off, so IATs after a restart are somewhat higher, but they quickly drop once air starts flowing again. This is with the temp sensor located in the mass air sensor. When I eliminate the MAF and get the temp sensor out of a metal enclosure, I'd expect a noticeable reduction in the effect of heat soak. I don't know if there are any viable ram air options for F-bodies, so relocation of the IAT sensor may be the best approach.
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"What do you mean induce it?" SSpdDmon
Get it to go bad when I am EFILive so I can see what is happening.
Seems if the heat soak is real, and surely is, that the temp sensor is reporting the air temp the TB feels untill the flow cools it to nearer ambient. Cooling takes place within seconds after the air starts flowing.
Apparently GM wants the PCM to do something odd when high intake temps are sensed.
Regardless of what intake is used (at least on a C5 I am using Blackwing with fresh air intakes in fog light housings) the running air temp is within a degree or two of ambient because both the ambient sensor and MAF are forward of the heat source and getting lots of "fresh" air.
What is the PCM doing to react to the high sensed air temp? Is there a way to max out the temp sensor at say 90F - Or, is that >100*F air just not as combustible?
2000 C5 Coupe, 6M, Callies/Mahle stroked LS7 (441), Blackwing, Halltech, LS3 intake, 90mm Shaner TB, ported L92 heads, FAST 50# inj, not too much cam, Kooks 1 7/8" headers , 3" catless mid pipes, Z TIs, track suspension, , 3:90 rear, EFI V2, LM-2, etc.
PowrMax Performance
100 mm PowrMAF
LM-2 EFILIve package with TAQ -sLM2 V-2 serial cable> Package deals
Bruce, I think this is where the PCM code readers will need to check in. I get the feeling there's some 'behind the scenes' stuff happening. Either that or it's happening right in front of me and I'm too oblivious to see it. :lol:
When trying to think this out logically, I believe it's a proven fact that warmer air is less dense and therefore requires less fuel because of the lower oxygen content. This would mean we should typically see two scenarios:
1 - IAT delta (actual vs. observed) is small and readings are relatively accurate.
2 - IAT delta is beyond an acceptable range and readings are higher than actual intake temps (heatsoak).
Assuming the other variables in the fueling equations are correct, scenario 1 should prove to have more accurate BEN's because I believe the IAT effects AFR calculations. If this is true, any delta in IAT (scenario 2) is going to produce a 'chasing your tail' problem while tuning and result in larger swings in post-tune AFR's.
That's about the extent of my tech savy on this topic. The only other thing I can rely on is application, which leads me to my latest update:
Today is day three of watching the IAT relocated setup. As mentioned before, I'm trying this running on a pure MAF tune right now (B0120=400rpm and the VE is stock). I've been tweaking the MAF curve (roughly ~5 rinse and repeats) and the results of my drive in to work this morning are posted below. To me, this is nothing more than a MAF translator (on steroids) way of tuning. The only difference is, B0120 has eliminated the VE's influence. Again, if things keep going this way, I may never tune another VE again.
Note - Transitions, DFCO, and cells with less than 5 hits have been filtered out. Commanded AFR is 14.63 at cruise and 12.5~12.8 at WOT. LMK if you have any questions.
Last edited by SSpdDmon; June 18th, 2007 at 05:39 AM.
have you looked at temp blending?
Yeah, I played with that a little too. I started looking at the stock table vs. the stock table from a '99 f-body (which is lower) and kinda did a custom blend table. It now ranges from a .30 or 30% factor at 0 grams/second and levels off to a .05 or 5% factor at 80 grams/second and above. I also set the filter to 1.00 across the board so that it updates as fast as possible while temperatures change. With these settings, I see close to a .2 or 20% factor at idle (~7 grams/second), which increases my charge temp ~20*F at the cylinder.
maybe the slp IAT module would help get a more accurate temp reading.
the IAT tend to show 10* higher than out side temps actually are.
i know it`s not best to trick the PCM but if you are tricking it to read what it should be , wouldn`t that be best?
It's not always a constant variance though. I've seen 5~30 degrees of variance depending on the situation.maybe the slp IAT module would help get a more accurate temp reading.
the IAT tend to show 10* higher than out side temps actually are.
i know it`s not best to trick the PCM but if you are tricking it to read what it should be , wouldn`t that be best?
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