Good reading here. The search function worked quite well for me this time.

I have an 09 tC 5 speed and I want very little boost, on the order of 5 PSI. My car is a daily driver and I drive quite a few miles each day, 95% highway.

I think you guys(in this and other posts) have answered most of my questions. I have quite a bit of experience with GM's, I have been a super mod on several sites and I'm an A&P mechanic and have always performed my own mods and maintenance. From what I've read, the stubborness of the tC ecu is probably second only to the SAAB Trionic 8 for which at least they have handheld tuners that work.

I'm looking for a little confirmation on the fuel control method for a turbo tC.

I plan on buying a basic kit from either Dezod or Turbo Toyotas(because theyre local) and run 440 injectors with an AEM F/IC. I just want the ability to tune the whole powerband in open and closed loop. I'm hoping for power output of around 200-220 whp with a good idle.

Can you guys tell me yay or nay, or offer any suggestions?

Thanks

 

Not sure what you're asking exactly, but 200-220WHP is very low for 5PSI on a 5-Speed. For 5 PSI, you should expect to be in the 220-240WHP range.

 

lol aim low + hit high= VERY HAPPY so he can expect the low hp but hell be a very happy guy when he makes more haha

 

Yeah thats exactly right, I would rather be happy if I gained more HP. No one likes being promised the world and then have the promises not met after paying out for the kit.

I basically want to slightly exceed the power output of the stock 04+ SAAB 9-3 2.0T Aero, which is the car I wanted but didnt get due to very poor resale value. I figured 5 PSI would give me at least 200-220 at the wheels which is nearly what the BSR stage 1 gives the Aero, and the tC weighs less which always helps.

So my plan to use the AEM F/IC should work out pretty well?

Thanks.

 

Yes, this does work very well. Add an O2 signal modifier for closed loop AFR enrichment and it works even better. I'm running a T3/T4E 50 trim with a 6psi WG spring, 440cc, 2.5" exhaust and am 100% CEL and 'hiccup' free. My car drives like it came from the factory like this.

BTW, there is a lot of misunderstanding in this thread about how the stock ECU determines correct fuel delivery. The ECU does not rely on a static table of values based on rpm and TPS or load. Regardless of when engine airflow increases or by how much, the ECU uses the MAS to measure MAF and add the correct amount of fuel. It further fine-tunes this mixture using AFR feedback from the primary O2 sensor while in closed loop. In open loop the ECU ignores the AFR feedback and adds additional fuel to acheive a richer AFR. The key to getting a good OL AFR is the new injector size. In my experience 440cc results in OL AFR of ~11.5:1 which is close to ideal for this kind of setup.

* The most important factor to make this work is maintaining accurate MAF measurement with the turbo setup. The turbo intake/MAS tube must read MAF very close to the oem intake or you'll have issues that you can't tune around as you can with add-on engine management.

 

I'm not sure if anyone said this already, but you have to remember the load that the TRD reflash accounts for that will no longer be there. It'll run rich and rough without having to turn the supercharger.

You'll also have a problem with getting full boost somehwere in the 3k rpm range versus the supercharger at 6.5k. It'll run lean for most of the rpm range. That's what that drawn graph someone was indicating basically shows.

I thought about keeping the reflash to tune off of when i go turbo, but from what I've heard, it's not a good idea for some reason?

 

I'd like to know which piggyback engine management would do both closed loop and open loop as well!

 

No offense meant but you really should learn more about how recent Toyota engine management systems work before making incorrect assumptions like these. If the EMS relied solely upon static table lookup based on various sensor inputs, you might be correct. However the EMS is dynamic and self-learning, based on wide-band O2 (AFR) sensor input. As such, it does a remarkable job of maintaining a stoich (14.7:1) AFR within a ~25% variance range of the static table data, when in closed loop.

As far as running a turbo with the TRD flash, the biggest complaints I've heard were that it pulls too much ignition timing advance and is harder to tune with a piggyback. I can't say first-hand because I haven't needed or tested the TRD flash to run 440cc injectors, 6psi and 260BHP on my 08 XB. The oem ECU is working flawlessly after learning the new fuel trims for the 20% larger injectors.

The most popular piggy with OL and CL AFR control seems to be the AEM FIC. The OL AFR control (O2 sensor signal modifiier) and MAF table (MAS signal modifier) both work very well. I wish I could say the same for it's other functions. Specifically the crk and cam sensor intercept and signal delay used for ignition timing retardation. Adding 2.2K parallel resistors to the FIC inputs seems to help a lot of TC owners get rid of some or even all of the FIC caused misfires.

 

-Durr

Don't think you understood what I wrote. I know the stock ems corrects for fuel adjustments to try and keep the car running stoich under no boost and boost conditions(TRD Reflash).

I meant that the adjusting trims (or at least I don't think) won't make up for that full boost at 3k something rpms with a turbo installed on a tC with 6-7 psi with TRD reflash only. Seen this myself. It'll run lean then go near 11.3 or so at redline I guess bc the TRD reflash accounts for gradual rise in pressure. Don't know that much about the stock EMS or AEM, but no offense taken. This was I believe an 06 tC custom turbo setup with TRD reflash at a local shop. This tC later blew up, so I won't mention any names.

My TRD reflashed runs 15.1 AFRs at idle mostly, but its probably bc the ECM O2 sensor is tied to only one exhaust port lol, while the AFR gauge is to all 4 collection point.

 

The ECU doesn't care about boost (MAP), only MAF and O2 feedback. However you raise an excellent point about MAF exceeding the allowable fuel trim at 3k rpm. My setup accounts for this by using 20% larger fuel injectors to extend that trim range. I can see how the TRD flash with 410cc or even 440cc injectors might not have enough fuel trim left. Also, 410cc is only good for ~225bhp. If that TC you mentioned was running more than 6 psi boost from a small turbo, no wonder it blew up.

Bascially what I've done is to increase FI size enough to handle 6 psi (~250bhp) while still remaining within the trim range at idle and off-boost cruising. The same approach should work with the TRD flash within certain limits, of course. If you ran 500cc injectors you would extend the trim range by +20% to account for the extra boost induced MAF from ~3k to redline while remaining within the trim range at idle. 550cc might also work well but may be too big for the ECU. IME, the ECU handles +/- 20% fuel trims very well given a few hundred miles to learn them. Beyond that is speculation.

FWIW, my car idles and runs like stock, AFR is a constant 14.7 until boost hits (1 psi) when it goes to 12.3 (SS Enricher) and then drops to 11.3 in open loop.

Why isn't your ECM O2 located in the down pipe? I consider it much more important than the AFR gauge. Not to mention that if it's pre-turbo it might not handle the high EGTs.

 

Good stuff ScionFred.

Yeah, I told them they'd blow that motor, but he jumped the gun at his own cost lol.

It's because the stock O2 wire won't reach far down enough, so its just before the collector on cylinder 4 I think, maybe 1? Well, it's been running this way for about 28k miles without any problems, so I think it'll be ok. (Will put on a Precision SC61 in the next few months or so and will fix that) Think that's how I'm slighlty leaner at idle though. I'm at sea level and mostly humid here, though that shouldn't matter with Toyota's ECM.

For your first line.....the ecu can't care......the trd people put at this rpm and load, we want this load out (target afr right) which means it should be in boost or not (not good with terms). Man, i think neither of us are wrong lol. At least your keeping me on my toes

 

Thanks and good catch pointing out why the TRD flash might not be able to cope with the very different boost dynamics of a turbo vs a SC with the TRD 410cc injectors. I hadn't considered that before. There is a barometric pressure sensor but it doesn't measure MAP, just atmosphere. Enough to allow for altitude compensatiosn.

I think I understand what you're saying. There must be a programmed zero point for the fuel trims based on load, rpm and maybe tps, etc. It's best to stay as close to zero trims as possible which requires a piggyback and a good tune. My no-piggy method requires letting the ECM re-learn new fuel trims but works quite well within it's limits.

Good luck with the new build.

 

You're welcome. I think the barometer is another reason why the MAF can't be placed under boost pressure and everything work oem-like without some piggy-back and good tweaking like the blow through from Ptuning.

Thanks, I hope it all goes without major problems:?. May start out my base tune with my own tweaks with oem tune or ride out to a Scion tC experienced tuner right away. The fine tune of course will be done by a seasoned tuner, but I'd like to see what I can do with this new set up.

 

I'm running a draw-thru MAS and this setup works a lot better than the FIC or APR X1 did on my car. The only noticeable difference between stock and turbo'd is the extra power. Maybe it shouldn't work this well in theory but it does.

If you're going with the FIC the software can create a base tune that will get you in the ballpark or you could get a base tune from another SL member. Good luck with everything.

 

That's interesting, but cool lol. Thanks, I hope it goes well too.

 

I've left out a lot of details about my 1 year boost adventure for the sake of brevity but I've been running 6 psi boost with stock ECU management for over 20k miles and one dyno session now. This setup does work well and I hope yours works equally well.

Out of curiosity, what's your proposed turbo setup consist of? Inj size, boost psi, piggy, etc.?

 

I havent been on here in fooooreeeever. But i did this on a blow thru set up. It actually worked pretty well. AFR's at boos were in the 10's and it idled right at 13.7ish. Drove like stock. The biggest difference, i believe, is the fact that it was blow thru. The ecu read everything really easily. I drove it pretty conservatively at first to let the ecu learn, then went ***** out. I had the dezod precision turbo that comes with the automatic and then upgraded to a T70 .63A/R exhaust and .70A/R compressor.....it was an ebay turbo that i got rebuild with garrett internals.

I've since moved on and have a Subaru...to the OP, good luck!! If you have any questions let me know!!

 

Sorry, not always on SL like I could be.....

My setup as of now is just a Precision SC61 turbo. I'm planning on going with Descendant's exhaust manifold and downpipe and their complete intake system, but with an hks ssqv flange with return. I believe I have some 550s laying around somewhere and an fic all from a friends turbo Honda. The 550 cc's might not work bc I think they're Honda only from RC. Need to post this in my own thread. It'll be a while before I get my turbo setup to be honest. Taking the supercharger off tonight actually lol.

 

sorry to revive this thread but i've been pondering this question for quite some time now and i have an answer.

one of the new members of my local scion club is running 10 psi on 550cc injectors.....with the TRD reflash. he using the dezod s1 kit. on paper it should run like crap and bog but it runs pretty stable and its wicked fast.

his afr's in boost is between 10.0 and 10.5 and around 14 ish in cruising. i'd be happy to provide proof at a latter date.