antman89iroc

For EBL FLash system on my 89 IROC (converted from MAF), should I locate my intake air sensor in the manifold or the air filter?

I notice when tuning this system seems much more sensitive to IAT/MAT values than the MAF/165 setup. When the intake temps are low, VE learning wants to add fuel. Conversely, when temps are high, it wants to subtract fuel. All of this seems correct except when you factor in that my (stock) setup uses a sensor in the manifold (MAT) rather than the filter (IAT). The "heat soaking" of the MAT seems to lag too long behind changes. Also, the fact EBL it calls it "IAT" in the tables leads me to suspect I need to relocate.

Also, when making intake air temperature related changes, I presume I need to adjust the CT/IAT blend table. It appears the higher the IAT % of CT value would "pull down" the CT value and therefore enrichen the fuel. Does this sound correct?

Street Lethal

iTrader: (16)

It doesn't really matter. I re-installed the IAT sensor back underneath and into my TPI plenum, but I am running an IAT sensor with a birdcage from a V6. No difference from what I can see in terms of skewed ambient readings, but I credit the birdcage. The stock TPI IAT is simply a coolant temp sensor, so might want to consider getting one from a V6. Cold air is more dense, thus the reason why the VE learn is adding more fuel, in turn pulling fuel when the air gets warm, not to mention will also pull timing when too hot so you feel like your down on power even more. My advice, get a birdcage IAT and keep it in the plenum.

antman89iroc

Interesting. What year/motor v6? So the bird cage style seems to respond less to heat sink while still being located in the plenum?

Are you using EBL and, if so, what tables are you using to tune it? I suspect the AFR vs CT will come into play as well.

Street Lethal

iTrader: (16)

Yes, I run the EBL-P4. I started with a stock LB9 bin to get it up and running, but then changed everything because my engine is worked. Any Grand National IAT will work, as the CTS versions are much more prone to heat soak when constantly residing above the lower intake manifold like that. Coolant temps of course play a big factor too, so try to keep them no more than 190-200 degrees if possible, otherwise when/if they reach 220 degrees plus the whole engine bay will get extremely hot without any form of heat extractor...

antman89iroc

Thanks. My coolant temps are fairly steady and fall into the 185-195F range and occasionally peak up to ~200-205 in hot/heavy traffic conditions.

Have you changed/adjusted your IAT/CT blend table or OL AFR vs CT table any? I suspect one or both may need some tweeking to get the tune balance over the coolant/Intake temp ranges. Although it is intuitive to some degree I don't know how each exactly fits into the PW calculation so I am not sure where to begin.

Also, it may be worth pointing out that all my tuning is for open loop. I plan to get to closed loop eventually but hoped to get OL very close first. I have a fair understanding of how to make changes but am a bit unsure of my overall strategy. Maybe I'm paying too much attention to OL and should go ahead and go CL and see what happens. In the past (with MAF) I didn't have good results with CL but again that was basically a stock ECM with chip changes. This EBL system is very different and more capable. I may simply be trying to "tune" in OL for the minor differences CL automatically adjusts. Any thoughts regarding these points?

Street Lethal

iTrader: (16)

Switch to Closed Loop, don't worry so much about the blending as that is just for warmup. Send me a copy of your bin file so I can take a quick look at it, PM it to me if you can. Or, if you need my email, just say the word. This is my 305 with 23x/23x cam, running TPI with a T72 turbo, and this is in Closed Loop. Never dips below 900-RPM, and never goes above 190 degrees, and idles like a kitten with small cubes, enormous cam and stock throttle body...

antman89iroc

Very generous. I will have to do it tonight as my bins are not available now.

Street Lethal

iTrader: (16)

Anytime. It's no biggie, I honestly only look for key things, takes a few minutes...

antman89iroc

PM sent.

Dominic Sorresso

Although I don't run EBL on my LT-5 (come on RBob, please would ya), I spent quite a bit of time this summer working on the IAT table given that it is now in the air filter duct and not in the airhorn. The result was much more consistent
BLMs whether idling or cruising. Intake air clearly heats up when sitting at a light which resulted in a motor that began running a bit ratty until things cooled down. And I'm not chasing my tail adjusting VE because Intake Temps change even during a datalog session.

ownor

iTrader: (5)

Dom, is your IAT a birdcage style sensor and also is it near the radiator or close to anything with coolant?
I had a problem with the IAT mounted in the TPI Camaro style air ducts going over the radiator where it would always heavily heat soak with the vehicle parked after prior warm up.. Would run lean for some minutes after start up and then clear up again as IATs dropped to more actual values with airflow across the sensor.

Dominic Sorresso

Ownor,

IAT is a bird cage style found on the LT-5. I have it positioned in the downstream of the radiator. The air intake on the Vette sits over the radiator stack and then transitions to an air bridge into the airhorn. My IAT is in that transitional area. So it sits downstream from the radiator stack but would be measuring air that has been warmed by the rad. With the A/C control system, I get a reading of the intake air from the outside air A/C temp sensor. So while datalogging I can watch that and view the BLMs. After logging, I will look at IAT reading and see what happens to the BLMs while the motor sits there. That's how I played w the IAT v Coolant table.

antman89iroc

Hey all- do you know if Bob "tuned" the EBL flash bins to work with the intake air sensor mounted in the air duct or in the manifold? I presume it's supposed to be in the air duct since it is referred to as "IAT". Mine is currently mounted in the back of my HSR plenum (stock location) but is a bird cage type sensor. Should I move it?

RBob

iTrader: (1)

It can be tuned for either, although it is better to use it as an actual IAT. The problem with a MAT is that it heat soaks, which can cause surging on a restart. This will show up in a data log as an excessively high IAT/MAT temperature for a short period of time.

I've also seen this issue with the over the radiator intake ducts that the 2.8l Camaro's used. As Owner above posted the IAT in these sit right over the radiator. And of course even with a bird cage style IAT they heat soak.

RBob.

antman89iroc

Thank you for the info, Bob.

I used your provided bin EBL_F_3006 5.7 TPI 6-speed Alum heads (port mod) as my starter bin. Do you know where the IAT would have been located in this application and possibly the type of sensor? I hope to emulate your setup as closely as possible so it is at least in the ball park.

With this in mind, how do you suggest I configure my IAT? Currently, it is a bird cage-type sensor in the back of the HSR plenum. I have the "stock for IROC" filters in front of the radiator with the Y-duct over the radiator, straight to the TB. Currently, my MAF is still in place but I plan to replace it with a pipe of some sort. I can locate the sensor in the Y-duct or possibly put it in the pipe replacing the MAF. Or should I put it up in front of the rad? Suggestions please?

RBob

iTrader: (1)

Place the IAT sensor (bird cage style) where it accurately (as best as can) reports the incoming air temperature.

With the Y-duct intake can place the sensor nearby in intake area of it.

RBob.

ownor

iTrader: (5)

had a similar setup on the camaro that wrote about. it used the air box design that you mentioned for the v6, over the radiator. at first the IAT setup was with a CTS-style IAT in the HSR plenum, then changed it over to a bird cage style IAT sensor and put it in the plastic collector at the filler plate/radiator. both not a good setup imho.
in a TPI-style (Miniram, HSR, etc) manifold setup, where would you best put the IAT and what style sensor?

RBob

iTrader: (1)

The bird cage style in the air-cleaner Y duct works OK. The only issue is heat soak when the engine is turned off. At restart it can/will go lean and surge for a short while. Once the sensor cools off it all works again.

As posted right above, place a bid cage style IAT in a location that best reports the incoming air temperature.

RBob.

Dominic Sorresso

RBob,

Is IAT input used during O/L operation? I'm thinking that at re-start, you will be in O/L for a short time.

ownor

iTrader: (5)

That's exactly what I'm getting, due to the IAT located directly over the radiator.. No fix to that calibration-wise? For "best reporting incoming air temperature", where would you best put it on a TPI/HSR engine?
And yes pretty sure OL it will use IAT as an input. Imho the only thing that changes with CL is the P (PI?) control loop for O2 feedback and BLM/INT to reach the designated target/reference AFR.

antman89iroc

Ok, here's an update. I took the bird cage sensor and mounted it in front of the TB. I replaced my MAF sensor with a piece of 3" pipe. I mounted my IAT sensor (with nitrous nozzle down stream) in the new pipe. I insulated the pipe and sensor with some header wrap. Now the IAT readings are MUCH lower than when mounted in the plenum. I still have some retuning to do but the BLM's are more in line than before. The header wrap seems to keep the heat soak to a minimum as well.

ownor

iTrader: (5)

thanks for the feedback on your approach. might be the best place to put an IAT on a TPI-style setup i guess.

antman89iroc

Working well so far. The temperature here had dipped pretty low for the south. 9' this morning. I notice it becomes much richer so I dialed the air/ct blend back some to be more biased to the coolant temp at cruising air flow. I suppose I will have to wait until spring/summer to get it all balanced right. At least the adjustment seems to be working as it should. I'm also planning to make a heat shield for the Y duct to insulate it from the radiator. A piece off aluminum with some hood insulation on top, sandwiched between the radiator cover and Y duct should do the trick. I will probably make it Y shaped to extend back under the inlet pipe and hose too. Not just for the sensor readings but also to Keep from heating up the intake air in summer. Keep you posted.

CORV3TT3

Yeah, I know this is kind of an old thread- but Dominic... that's EXACTLY what I've been doing. I feel as though I am chasing my tail with VE as it adjusts for temperature. Not so much during PE modes- but more at lower KPAs and mid range rpms. Like around 1500rpms and in the 25-35 KPA areas... not uncommon to see a 12% VE swing.

I have a gotten a hold of a birdcage IAT and have closed off the tiny snorkel, removed the heat riser tube, and blocked off the vacuum to it. I am also going to try using a 3' extension so that I can put it up by the fresh air chamber plenum. On the '82, that chamber runs up to the front of the car by the radiator. The top of the air filter box has a diamond shaped opening that mates to the hood and it's around 4"x4"- so I should be able to pull a decent amount of air in. I've also removed the flip door and solenoid so the chamber is always drafting air.

I had a stock air box base that I trimmed to allow more air around it as I was looking to get the last couple of KPAs out of it, but I think pulling in hot air was reducing the density of the air charge in the end.

At least the intake I'm using doesn't have that hot water passage running front to back. That can only help.

So what do you think- would moving the IAT and using the fresh air chamber will help get to a more stable VE table?

ULTM8Z

Agreed.

Don't try to "cheat" and put it far down the intake tract and then expect to get more power unless the IAT tables reflect where the sensor actually is.

On my 7730 setup, I put the IAT sensor (a LT1 p/n) into the air duct right in front of the throttle body. It pretty much copies the LT1 location. I then grabbed the Inv MAT look up table from a 94 A4 Trans Am and put the values in and suffice it to say, the engine is VERY happy with it.

I left the MAT compensation counts table as factory ANHT values. For some reason, that seems to be the only LT1 table that doesn't transfer over well to $8D. Everything else transfers over beautifully... AE parameters, throttle follower settings, decel enlean, CCP, etc... pretty much turning my 7730 into a LT1 computer little by little.

ULTM8Z

Edit... I didn't realize you were running a MAF car...

Dominic Sorresso

Yeah but as someone else wrote, the IAT table now needs to reflect values that approximate what the sensor is actually seeing in the new location.

antman89iroc

Latest update. I moved my bird cage IAT sensor again. This time I put it right up front. I have stock Camaro filters but no boxes, the bottom of the filters are getting air from the grill/air dam openings. I made a bracket and put the sensor under the filter where it reports actual intake air temp. I do notice a small amount of heat sink at stop lights and during shut down but not as much as before and it goes away very quickly. Now the reported temps are much lower than before.

ownor

iTrader: (5)

Thanks for the update. As you reported, with a bird-cage sensor exposed to actual frontal air flow that much, I would also expect it to be quite robust against heatsoak or at least it will dissipate it quite quickly. Seems this would be the best spot to put it. However, the correct adjustment of the IAT/CTS Blend is still a big factor.. care to post your table here?

antman89iroc

I don't have access to it now but it is a lot flatter than before. On the low end it is ~40% down to ~10% up top. More bias to the air temp than engine temp.

antman89iroc

I noticed this morning when it was cooler, the ecm is pulling fuel which indicates that I may need to raise the coolant percentage on the low end so it does not add as much when cooler (and therefore the ecm won't need to pull fuel) It takes some time and varying conditions to get the slope and %'s right. Since it was about right when the ambient temp was higher, and I change the percentage to lean it out at cooler temps, I will likely need to add some back in via the VE table. Make sense?

ownor

iTrader: (5)

I find this quite hard to tune in. Since the CTS will likely also be cooler on such a morning, you could also attribute the richness to the OL AFR vs CTS table, no?
Other than that, yes what you're stating about adding VE in when removing some IAT bias is probably right, assuming CTS > IAT and the ratio in the Blend Filter also being more biased to IAT to start with.

antman89iroc

Yes, but I am already in closed loop by this point. With the changes made it was better this morning and today so far. I also may need to add some fuel via the O2 tables since I tend to run a bit on the lean side of stoich.

ownor

iTrader: (5)

Sorry, didn't get that part.. you were saying, already CL at what point?
Little lean side of stoich only happens in CL? Have you tried 14.7 OL AFR tables for a cross-check?

antman89iroc

Sorry if I was unclear, when the blms dip in the cooler morning the engine is already in closed loop, so the OL/AFR table wouldn't be controlling fuel. And yes, it frequently runs a bit lean when in closed loop. That is why I may need to adjust the O2 threshold and upper/lower tables to target a little richer. One strange thing I have noticed about the EBL system is the O2 tables seem to be very high. I am running 600+ at certain points and close to that in the rest of the O2 R/L table. I presume that some of that is subtracted somewhere but I haven't figured out where yet. On my old MAF computer it subtracted .1 when the AIR system was "not diverted" (or maybe it was when diverted, I can't remember for sure) I'm sure the same thing is happening with EBL but it's not in the editor. Regardless, it is still pretty high at .500.

As far as cross checking in open loop, I haven't done that in a while but it would be a good idea. My OL/AFR table is ~14.7 at cruise map levels.

I appreciate your comments and help. This is one of those areas where a lot more is going on than "meets the eye" and I can get things screwed up if I don't pay attention. I have been "tuning" this new motor for almost a year now, probably 8-10 month with the EBL. It's runs great but has a few oddities here and there. It seems I get it pretty darn close then something like the season changes and it reveals some short cut I took and I have to tweek something and go back and forth a lot. Heck, I'm still playing with the spark timing and figuring out what makes this combination "happy". One of the "realities" of life is that most of the time the engine lives in the 1800-2500RPM range and the cam I chose doesn't like light throttle down low. But that's a whole other topic...

ACMX92

Has anyone seen increased heat soak with the V6 "birdcage" IAT sensor? It reads accurately when sitting for a while, but definitely sees heat soak after shutdown. I changed mine out as I was seeing really long crank times at relatively low CTS but high IAT temps.

I changed the sensor out and now see higher IATs and still deal with the long crank times. I have also noticed my IAT while driving is up about 20*F from before in similar weather.

I want to relocate the sensor but I figure I would wait to do that until I swap the TPI for a Miniram. Should I work on a blend table for now or try adding fuel during cranking?

ACMX92

I changed to a grommet mounted C5 style IAT sensor and installed it into a MAF delete tube. I still get heat soak and long crank times, but this sensor cools off much more quickly and shows more realistic air temps. On a 65*F day I was seeing 75* IAT temps while driving. I am going to try playing with the CTS/IAT blend tables some more and see if I can get this figured out.

drive it

iTrader: (1)

I've been following this thread-I get the VE tables closed loop on a cooler day nice 128+/-1 to 2 then on a hotter day or stuck in traffic and engine temps go up=higher coolant temp and IAT then it goes lean and back to surging at idle also. VE tables off by 8 to 10. I have the birdcage in the plenum of a super ram intake and it's supercharged. In the EBL P4 I see open loop AFR mult. vs CTS which would not effect closed loop. Then there is a CTS filter=one percentage input. And then IAT/CTS blend filter that is a scalar by airflow. In the IAT/CTS blend filter, which way would I need to go to enrichen when it's hotter? Or would the CTS filter work better for what I am seeing?

Here is a previous quote from Rbob that clears up the two tables.
"Yes, the CTS% is the amount of CTS out of 100%. So if the CTS% is 10%, then the IAT contributes 90% to the final value. Which is heavily biased to the incoming air.

The GmsSec value is the airflow through the engine. This is grams per second, and is calculated by the ECM. The airflow value is used in the intake manifold heating model to estimate the temperature of the air entering the cylinder.

Typically, the higher the air flow the less heat that is picked up. With the in-cylinder air being denser and requiring more fuel to obtain the same AFR."


With this in mind on a supercharged engine it makes for a unique situation. So in that case wouldn't it be better to increase the CTS %? Even with an intercooler the temps will not decrease near as much as on a non-supercharged and could even rise at higher airflow, so the heating model would be thrown off?


So I had some time to test-one bin with 0 on the CTS % and one at 50%, 80% and 100%. Watching the BLMs, Ints and wide band I could not see any changes as I flipped between the bins. So what am I missing? This is driving me crazy!

drive it

iTrader: (1)

Under scalars-what does CTS-filters effect?