Let's see if this works...

[SSpdDmon]

My idea to combat heat soak in the LS1 has been to securely and remotely suspend the IAT at some point in front of the lid in the path of the air it draws from (i.e. behind the washer fluid resiv...resi...that plastic container thingy that holds the washer fluid - sorry no spell check :lol:).

If shipping goes well, I plan to MacGyver my idea this weekend with some fishing string and this:

https://www.casperselectronics.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=109019&Category_Code=camaro1996upv8

Yeah, maybe I'm a little crazy for blowing $$$ on something I could splice in an extension on for free. But, this way I don't have to hack up the wiring. My plan...

http://www.installuniversity.com/install_university/installu_graphics/freshman_year/whisper_lid/airbox_clamp_locator.jpg

...will be to suspend the IAT sensor just behind/below the hood latch with some fishing string so that it is securely exposed in free air - the same free air the lid pulls from. Without an immediate source for heatsoak, I anticipate good things (i.e. more accurate IAT readings) from this simple relocation. I just hope 3 feet is enough and I'll have to find something to plug the hole in the lid.

I will post results next week, assuming I get the order this weekend.

[5.7ute]

I am suffering from the same IAT swings from heatsoak on my self made aluminium OTRCAI. Since my intake is directly in line with the grille on the front of my car I was thinking about doing something similar but with the added security of a small filter before the sensor to protect it from bug damage etc. Hopefully it will let me have one base tune for IAT's without having to change the A0014 table to keep up with the ever changing ambients here.

[ViolatorTA]

Taking it out of the stream into turbulant air and moving it further away from the intake. Somehow I think you'll still get problems, just different ones.
Hope it works out the other way though.

[SSpdDmon]

To update, the parts came and I have relocated the IAT to just above/behind the washer fluid reservoir. IAT readings are much more accurate to the real temperature of the air entering the lid. NO MORE HEAT SOAK! :D I sat in a drive through line wating for my burger for just about 5 minutes and never broke 100*F (outside temp was 70*F). 3 blocks down the road, I was back down to the high 80's, and fell into the high 70's once I hopped onto the highway. Before the relocation, I was seeing another 20*F or more on my IAT readings in low airflow scenarios.

I'm going to keep an eye on things over the next week to see whether or not this has a true effect on anything.

[mr.prick]

the air box gets hot sitting over the radiator.
i have been reduced to doing all my logging at sun set or later.
i have found that heat soak generally makes IAT temp
10* above the out side air temp. and at a light or at low speeds even higher.
congrats on your invention.

[Bruce Melton]

Is this in hopes of curing the hot restart stumble?
I have been wondering how to beat that-

[mr.prick]

if you look when you IAT is high the car will lean out screwing up logged data.

[SSpdDmon]

Is this in hopes of curing the hot restart stumble?
I have been wondering how to beat that-
This is to combat inconsistent fueling. If you're having hot start problems, I'd try increasing your Startup Friction Airflow Correctoin table for the temps where you're noticing problems.

Pics:

[joecar]

Jeff, in post #4 you meant "windshield washer reservoir" rather than "coolant reservoir"... :cheers:

[SSpdDmon]

Jeff, in post #4 you meant "windshield washer reservoir" rather than "coolant reservoir"... :cheers:
Good eye...

Quick update - I went to a complete MAF tune (MAF threshold set to 400rpm). This combined with the IAT relocation has my AFR's within ~0.5 points on my WBO2. :D Transitions are now on the rich side instead of the lean side. Other than that, no real side effects noticed yet. Thinking about keeping it this way after a little fine tuning. More to come later...

[Bruce Melton]

This is to combat inconsistent fueling. If you're having hot start problems, I'd try increasing your Startup Friction Airflow Correctoin table for the temps where you're noticing problems.

Pics:

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..
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.

[SSpdDmon]

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..
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.
What do you mean induce it?

[dfe1]

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.

[Bruce Melton]

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.

"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?

[SSpdDmon]

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. :D

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.

[redhardsupra]

have you looked at temp blending?

[SSpdDmon]

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.

[mr.prick]

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?


1798

[SSpdDmon]

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?


1798
It's not always a constant variance though. I've seen 5~30 degrees of variance depending on the situation.

[mr.prick]

aaaaaaaahhhhhhhhhh

[ViolatorTA]

I believe the SLP IAT sensor module is just a resistor in a pretty case. Same as putting a resistor in the IAT plug that makes the PCM thinks it's a constant 40deg with no variance. This wouldn't be a probable way to tune since you'll be taking in warmer air than the PCM is actually seeing.

[ViolatorTA]

I though of the same thing just about using the MAF, setting blending at 1.0 and a stock VE. I posted about it a few days ago. I havn't had a chance to run OLMAF yet though but CLMAF was working ok. Did you set up with O2's on or off? I'm going to log on the way to work today with mine off and see what I get.

[SSpdDmon]

I though of the same thing just about using the MAF, setting blending at 1.0 and a stock VE. I posted about it a few days ago. I havn't had a chance to run OLMAF yet though but CLMAF was working ok. Did you set up with O2's on or off? I'm going to log on the way to work today with mine off and see what I get.
I don't have any NBO2's. :lol: I've been thinking about buying some. But, only if I can get the fueling close enough...

[SSpdDmon]

Update here: http://forum.efilive.com/showthread.php?p=49817#post49817

Now working from stock MAF curve and adjusting IFR (VE still ignored with B0120 set to 400rpm).

[ViolatorTA]

Good stuff. Keep it comming and I'll keep looking for more info.

[SSpdDmon]

The latest....

Here's a log from yesterday (6:30~7:30) on my drive back to Lansing. Transitions and cells less than 5 have been filtered out. This tune is still IFR, 100% MAF, and the IAT/ECT blending vs. grams/second has been disabled (100% IAT biased). AFR is 14.63 commanded and 12.6 when PE is active. IAT registered between 73~77 degrees the whole time (~1 hour).

The good: Well, look at the picture.

The bad: In between idle and about 1500rpms, fueling richens up between 0.5~1.0 AFR points below commanded AFR. If I were going back to closed loop soon (may be), I'd think this is well within the realm of control. Aside from that, no other noticeable side effects.

Total time invested in tune: ~10 hours

[ViolatorTA]

Seems the MAF/IFR tuning seems to be working well. I've been going the other way as in back to VE SD but with a different approach than the standard. The VE table is looking great where I was making adjustments not to get to 1.0 but to even out what was the majority cell numbers. On the rich side but started getting real nice until tonight. Got home from work, loaded up the changes I made last night now heading toward the 1.0 mark after getting pretty even and realized my WBO2 took a dump. I have a spare sensor but this will be on hold until tomarrow now.

[SSpdDmon]

That sux. I keep hoping my sensor doesn't go out on me. Try to recalibrate it every month or so.