First off I forgot to address your previous timing question. Idle ign advance was averaging +12.8* in the log I posted although +10* seems to be the norm. This was without any management.

I'm pretty sure that the ECU adds a small percentage of inj pulse duration when the AC is on and that translates to too much added fuel when larger inj's are installed. The bigger the inj's the more fuel is added and the more potential for problems. I also don't believe that the ECU stores separate LTFTs for AC on and AC off (nice if it did!). I think I understand now what you're doing by skewing the AFR sensor. You're compromising between AFR and FT to avoid excessive trims when the AC is switched on and off. That makes sense although I still dislike the idea of altering AFR feedback at idle and low load conditions. I pretty much rely on accurate AFR feedback to compensate for a lean idle condition I have when IATs get really hot. I'm still not sure what causes this although I have some half-baked theories on it...

Your idea of using dual maps with a AC-triggered switch is brilliant, IMO. Luckily my little 440's don't cause such issues. As always, it's a pleasure to discuss these matters with you.

 

Hey Crush, back to my lean idle with high IATs. First a little setup info: My air filter is located near the firewall, tucked into the fender where it relies on cool outside air coming up from a vent in the front fascia. It's basically a CAI when moving but a SRI (HAI) when stationary.

I had a theory that as my underhood air temp became heat soaked and IAT measured by my draw-thru MAS/IATs grew (often 120F+), the ECU was adding the correct amount of fuel for that air density but the actual (presumably cooler) post-IC air density entering the engine was higher, resulting in a lean AFR. But the problem with this theory is where does the extra oxygen come from? If x volume of air passes the MAS, x volume of air should enter the engine regardless of changes in air temp and density.

Any ideas why my AFR gets very lean and fuel trims change dramatically when IAT goes above 100F? I'm stumped... TIA.

 

that would do it if the air passing through the maf dropped considerably in temp as it passes the intercooler. which is a stretch without co2 or n2o spraying the IC. Then again how lean are we talking here?

btw its always a pleasure to talk to you aswell Fred!

 

Yeah, it seems unlikely to me too that the IAT is being cooled that much but the only other ideas I have are longer dead time for the 440s vs oem compounded by lower idle voltage due to my undersize crank pulley. Idle voltage now is ~13.4V and IIRC it was more like 13.8-14.0V with the oem pulley. In any case it's never been an actual problem so much as bothersome when I'm viewing OBD data when it happens. The AFR never gets leaner than 16:1 and corrects to 14.7 pretty quickly. I'd just love to know why it does this for the sake of knowing.

Here's a recent data log. Note how the max LTFT has dropped from -25 two years ago to -19.4 and how small the STFTs are. The exception being those areas in red (circled in black) where the Split Second Enricher has activated and skewed the AFR sensor to read lean. I also highlighted the lean idle cells by circling them in yellow.

 

how consistant is that lean spot? Iv noticed very similar issues just after decel to idle when the ecu goes back to closed loop (normal driving).

 

It's pretty consistent. My LTFT is always significantly closer to zero at idle and STFTs tend to be higher. When stopped after a long drive I can see my STFT climb as I idle and IATs increase. I'd suspect a vacuum leak except that I can't find one and idle vacuum remains high at 20-22 in-hg.

 

perhaps a leak around the maf, maybe as the pipes expand its allowing a leak around the maf flange. not likely but in anycase its worth a go. check the o-ring while your at it.

 

It's not leaking at the MAS but a leak somewhere would explain it. I guess I'll have to do a boost leak test to be sure. Thanks.

 

its not very likely but then again i didnt think id pinch the o-ring on my maf sensor, it happend though.

 

Anything is possible but I already checked the MAS and o-ring.

BTW, I double-checked my ELM327 scan tool and it does work with ScanXL at 115,200 bps so there's no point in getting a faster one. According to GLM software a ELM327 v1.3 can read 49 PIDs per second and OBDPros tool reads 55. It appears that OBD2 logging can't acheive anywhere near the sample rates that Paul was talking about. I assume he meant the X1 or standalone.

 

Hey there great post. Now that I have all this done I'm looking for a base map. Im running around 8 lbs of boost and My fic has my fuel supper high. Does anyone have a good base map for the 06 tc with turbo?

 

I was referring to the X1. AEM EMS is capable of 250 shots/sec on the internal logger.

 

I leave zeros in the cruise values of the map on the O2 side. It works very well for small changes and such.

The one thing you must remember with the FIC is that your main fuel map, maf map and o2 map ALL must coincide with one another and take trims in account. If one is off, it's like a 3 dog sled team with one hooked up backwards, it makes no sense.

Air temp correction kicks in. Air molecules are expanded in hot temps which means less air actually arrives in the plenum per gulp on the throttle body. This is the opposite of air molecules on a colder day, which is why she leans out some during temp changes. There are more air molecules being gulped per throttle opening when colder out.

Also, if your turbo is not efficient at idle and the intercooler is a cheapy, this can add to IATs up to 20-30+ over ambient at idle.

On a pull through, if the MAF measures a certain amount of air flow, it then pulls it into the turbo, through the IC pipes (some gets lost in bends), enters the IC (some gets lost there too), then comes out and heads to the TB (some gets lost there), passing by the BOV (leak open at idle) then you have say 3 g/s^2 of air flow metered in, but only 2 might reach the plenum.....Food for thought.

 

base map screen shots posted on page one post one

 

base maps for download

http://scionlife.org/Scion_Docs/AEM_FI_base_files/

 

I'm glad to hear I'm not the only one who thinks it best to let the ECU handle small AFR corrections in closed loop. Good point about the importance of matching all 3 FIC maps. I'd also add that when tuning the FIC, less is more.


I agree with everything you said but my case is the opposite problem. I have more air (or denser air) at the manifold than measured by the MAS. Being a pull-thru setup, if the actual IAT in the manifold were higher (less dense) or any air was lost between the MAS and manifold, I should have a rich idle condition, not lean. The only logical causes I can think of are that either the manifold IAT is lower at idle or I have a vacuum leak allowing extra air to enter post-MAS. I can't find any leaks and idle vacuum is where it should be (22-24 in hg).

If MAS measured IAT (just after filter) is ~125F due to underhood heatsoak at idle but the SMIC is in a location where the temp is only 95F, could that possibly result in a cooler manifold IAT despite the air passing through the turbo? One thing that is very consistent is that the longer the car sits still and idles, IAT climbs and as it does, the AFR gets leaner. As soon as I start moving again, IAT drops and the AFR normalizes (trims actually).

 

I am not sure if it is best to keep going with this thread or expand to another.

I am helping a friend out by looking at his FIC for him and I have been doing a lot of reading, including this thread. He is runnig the dezod 57 trim kit with 550s. I had a few questions that I may have missed.

1. MAF tuning- Aside from the limits of the sensor itself, which we can clamp at that limit, is it a bad thing to allow the factory ECU control as much fuel as it can, and using the FIC to add/removing whatever percentage fuel that is needed?

2. Crush- We installed the base map that you created for the this specifc setup. I had to modify it quite a bit to get high load a/f in check(a/f were in 13.5 range). Is this normal?

 

it all depends on the sensors and their condition. the maps i posted are from my personal car and the sensors may not be in the best condition. as always those that i posted are base maps and should be tuned for your car.

ps..also to note that its possible i may have had a boost leak when those were tuned...I find em every so often from t-bolt clamps loosening up, couplings shifting, ect.

 

also its not the same turbo...I tuned those maps using a t3t4b not a t3t4e...cause of the larger comp housing on the t3t4e its going to have a broader effeciancy "island" (in other words its more effeciant than what I have). so im not surprised tuning was needed.

 

Okay, currently im short on money because I just had to replace my trannybut and a base tune will work fine. Running without the aem fic actually makes the car run better in my eyes.. But the base tune aem offers sucks. My car shutters and wont drive when I want it to go. It hesitates pretty bad and will only do it sometimes. Other than that it will idle.

Dezod Turbo Kit.
Garret 57 Trim turbo.
ptunning full exhaust
etc etc

Anyone that could help it would be great.