Tuning help needed!!

[smoked240]

I had my car dyno'd with a stock turbo at 10 psi and switched things around and now have a precision 6266 and worried I could damage my engine. I added a bit of fuel but I'm not good with engine tuning and won't risk trial and error with this.
I'm tuning an rb25 with AEM series 2 on e85. If any experienced tuner could help me out I would greatly appreciate it!

I would rather tune on 91 since e85 is pretty much gone in my area. But if staying e85 for now helps, I can suffer, closes e85 station is about 25 miles from me.

I could send my map I have also.
Thank you!

[smoked240]

Is there no one to help? I just need more fuel for my map I just don't want to screw it up.

[KAT-PWR]

You're going to need to play with fuel and timing. Pay a legit tuner to tune the car.

[smoked240]

You're going to need to play with fuel and timing. Pay a legit tuner to tune the car.

I did pay a legit tuner to tune my car, just installed a larger turbo but I have to trailer it 4 hours one way, I'd like to break the engine in more before I go that far. (Don't want to go that far and have something break.)

My map is basically sound I mean I spent $800 on it so it better be, it's just set for 10psi stock turbo but it's boost comp. since I only added a new manifold and turbo I should be set adding fuel and adjusting timing but my concern is which way I should go on the aem

[Croustibat]

There is no way anyone can tell, you need a wideband AFR sensor and gauge to tune fueling. This is a MAF system so it will match fuel and timing with the air mass entering the engine; turbo or manifold won't impact that unless you send more max air or there is a significant difference in spool and turbo efficiency (cams will though).
As long as you don't floor it or go beyond 10psi you should be fine.

Beware though, modifying fueling also has an impact on required timing.

Anything further is going to need a remap, basically more air = less timing ( it burns faster ). E85 is more friendly to tuning as very less prone to DET than regular fuels, but you still can damage the engine.

If you switch back to unleaded, you are going to need different fueling, but more importantly you really need to back off timing. Basically you can achieve the perfect timing with e85, which is something you can't with unleaded as that perfect timing is in "DET zone".

There are numerous caveats, hence the reason it is a job.

My advice: revert your fueling changes, use the fuel the car was mapped for, break it in nicely without flooring it, don't go over 9-10 psi, you will be fine.

[Kingtal0n]

get your wideband saying 11.5:1 for anything after 12psi of boost. interpolate the values from 13.5:1 to 11.5:1 as you move from 0psi to 12psi, then hold 11.5:1 all the way till 18psi. When you cross 18psi you go a little richer, 11:1~ then by 25psi you want 10.8:1.

These are street tuning numbers for pre-dyno. When you goto the dyno you remove fuel as the engine requires for best power vs how the engine behaves. thats advanced topics I cant cover here.

For timing, at 0psi from 2800rpm to 5000rpm there needs to be between 18 and 24* btdc of advance, more as the rpm increases slightly, perhaps 28 by redline (0psi)
when you pass into boost, 1psi-5psi, pull around 1* per psi of boost, so by 5psi you have 13* of timing for example, until you get to 9*, stop there. Using 9* of timing is a generic number also for the street tune. You don't add timing back until you hit the dyno, again, by watching what the engine does. Once you pass 19psi again you want to pull a tiny bit more, around 7* of timing for 20-25psi.

This is all for 93 octane pump fuel. BY using E85 you will need more timing, and you need to make sure the wideband is reading stoich values i.e. when it says 14.7:1 it really knows that your E85 is NOT 14.7:1 (some other stoich value) but it still reads 14.7 for simplicity. In other words E85 has a different stoichiometric value but the wideband should still read 14.7:1 when it is at the value, I think most widebands will work this way. You could probably run as much as 13-15* of timing for 18psi of boost on E85. I wouldn't try 9* its probably not nearly enough.

[smoked240]

There is no way anyone can tell, you need a wideband AFR sensor and gauge to tune fueling. This is a MAF system so it will match fuel and timing with the air mass entering the engine; turbo or manifold won't impact that unless you send more max air or there is a significant difference in spool and turbo efficiency (cams will though).
As long as you don't floor it or go beyond 10psi you should be fine.

Beware though, modifying fueling also has an impact on required timing.

Anything further is going to need a remap, basically more air = less timing ( it burns faster ). E85 is more friendly to tuning as very less prone to DET than regular fuels, but you still can damage the engine.

If you switch back to unleaded, you are going to need different fueling, but more importantly you really need to back off timing. Basically you can achieve the perfect timing with e85, which is something you can't with unleaded as that perfect timing is in "DET zone".

There are numerous caveats, hence the reason it is a job.

My advice: revert your fueling changes, use the fuel the car was mapped for, break it in nicely without flooring it, don't go over 9-10 psi, you will be fine.


I actually converted to MAP when I went AEM. Thanks for the info, this is what I've been doin when I take it out but due to the cold it's a bitch to get running on E85.
For simplicity I'll stick with E85 until I go to my tuner. I would stay E85 but it's starting to disappear in my area and the highest we have is 91 sadly.

I also have a aem wideband tied in but the gauge bounces all over until I'm holding steady boost about 5psi and higher.

[smoked240]

get your wideband saying 11.5:1 for anything after 12psi of boost. interpolate the values from 13.5:1 to 11.5:1 as you move from 0psi to 12psi, then hold 11.5:1 all the way till 18psi. When you cross 18psi you go a little richer, 11:1~ then by 25psi you want 10.8:1.

These are street tuning numbers for pre-dyno. When you goto the dyno you remove fuel as the engine requires for best power vs how the engine behaves. thats advanced topics I cant cover here.

For timing, at 0psi from 2800rpm to 5000rpm there needs to be between 18 and 24* btdc of advance, more as the rpm increases slightly, perhaps 28 by redline (0psi)
when you pass into boost, 1psi-5psi, pull around 1* per psi of boost, so by 5psi you have 13* of timing for example, until you get to 9*, stop there. Using 9* of timing is a generic number also for the street tune. You don't add timing back until you hit the dyno, again, by watching what the engine does. Once you pass 19psi again you want to pull a tiny bit more, around 7* of timing for 20-25psi.

This is all for 93 octane pump fuel. BY using E85 you will need more timing, and you need to make sure the wideband is reading stoich values i.e. when it says 14.7:1 it really knows that your E85 is NOT 14.7:1 (some other stoich value) but it still reads 14.7 for simplicity. In other words E85 has a different stoichiometric value but the wideband should still read 14.7:1 when it is at the value, I think most widebands will work this way. You could probably run as much as 13-15* of timing for 18psi of boost on E85. I wouldn't try 9* its probably not nearly enough.

Very helpful info!! I'll pull up my map tonight and do some adjusting. My timing on the aem shows 36* while boosting but I'm assuming you subtract the 15* the timing was synced at?

Thanks for the help!

[Kingtal0n]

Very helpful info!! I'll pull up my map tonight and do some adjusting. My timing on the aem shows 36* while boosting but I'm assuming you subtract the 15* the timing was synced at?

Thanks for the help!

no, no.

You set the timing in the ECU to match the crankshaft. I go over how to set sr20 timing in several threads. You need to verify the timing matches the crankshaft, or else nothing you do will matter and the engine will blow or give terrible performance/economy to say the least.

Once you can see (some number) at the crank, and it matches some reported number (at the ECU) then you check multiple rpm: does it match at idle? 2000rpm? 4000rpm? Make sure it always matches up.

Then you can make your changes. If you want 9* in boost you put 9* in the map. It runs where you tell it to. There are trims in the ECU "behind the scenes" such as TPS trims and coolant trims, AEM has more trims than I can count. So you have to go through the entire instruction manual looking for all the timing trims or at the very least be sure you are getting the timing you think you are getting.

It is very common for "tuners" to over time the sr20det engine. 36* is way too much timing. What does your knock sensor say about that? Further more the a/f should be consistent. It should not jump 10x units (from 13 to 14 for example) while holding steady throttle (steady vacuum signal) the only "jumping" it should do is from 14.5 to 14.8 during closed loop operation, such as cruise and idle, off the narrowband Oxygen sensor, if closed loop is enabled. A good fuel map has very gradual, smooth changes.

random example, notice how it smoothly goes from one value at the bottom to another at the top, there are no jagged areas, no dips or crevices "pot holes" in the map, the engine will transition smoothly and the a/f remains consistent when you hold a load value.

http://smg.photobucket.com/user/jonbar87/media/aemmap.png.html

[smoked240]

no, no.

You set the timing in the ECU to match the crankshaft. I go over how to set sr20 timing in several threads. You need to verify the timing matches the crankshaft, or else nothing you do will matter and the engine will blow or give terrible performance/economy to say the least.

Once you can see (some number) at the crank, and it matches some reported number (at the ECU) then you check multiple rpm: does it match at idle? 2000rpm? 4000rpm? Make sure it always matches up.

Then you can make your changes. If you want 9* in boost you put 9* in the map. It runs where you tell it to. There are trims in the ECU "behind the scenes" such as TPS trims and coolant trims, AEM has more trims than I can count. So you have to go through the entire instruction manual looking for all the timing trims or at the very least be sure you are getting the timing you think you are getting.

It is very common for "tuners" to over time the sr20det engine. 36* is way too much timing. What does your knock sensor say about that? Further more the a/f should be consistent. It should not jump 10x units (from 13 to 14 for example) while holding steady throttle (steady vacuum signal) the only "jumping" it should do is from 14.5 to 14.8 during closed loop operation, such as cruise and idle, off the narrowband Oxygen sensor, if closed loop is enabled. A good fuel map has very gradual, smooth changes.

random example, notice how it smoothly goes from one value at the bottom to another at the top, there are no jagged areas, no dips or crevices "pot holes" in the map, the engine will transition smoothly and the a/f remains consistent.

http://smg.photobucket.com/user/jonbar87/media/aemmap.png.html


Ahh that makes much more sense! My tuner did all that and updated my software at the time but now that you mention it I'm pretty sure my map is all jagged. I'm not sure if I stated in the beginning I thought I did but it's an Rb25det. The tune he did ran beautifully and since than I added top mount manifold and large turbo. It is boost comp tuning.

Yeah the only time my afr stays solid is boosting.
So far I've been able to see 1 bar of boost but I cannot for the life of me remember what my afr was, I wanna say something like 10.4-11

[Croustibat]

I actually converted to MAP when I went AEM. Thanks for the info, this is what I've been doin when I take it out but due to the cold it's a bitch to get running on E85.
For simplicity I'll stick with E85 until I go to my tuner. I would stay E85 but it's starting to disappear in my area and the highest we have is 91 sadly.

I also have a aem wideband tied in but the gauge bounces all over until I'm holding steady boost about 5psi and higher.

e85 starts fine in winter, you need to adjust the additional cranking fuel table and the after start fuel table for that though. Most tuners dont because it is a pain to adjust (you need a cold engine for that ... ) If you have trouble starting, crank it just a little, stop for a couple seconds, then try again (and if needed, a 3rd time). It should do the trick.

Unless you run lean most of the time, fueling is not going to be a problem, the car may lose a bit of power and have bad mileage but i would not worry about it.

Your main problem is going to be timing, and that is going to either make holes in your pistons and/or make your turbo glow bright red, even at partial throttle, even with AFR set correctly. Using 91 with an engine mapped for e85 will make holes. Using e85 with an engine mapped for 91 will make a glowing turbo, basically. (and it will really run like crap, if it even starts). Both are very bad.

MAP as well as MAF compute the mass airflow and acts accordingly, it takes different sensors for that but the way it works is quite similar.

The AFR really should not be all over the place if it was not before considering your mods. You might have a leak at your exhaust (or you had when it was mapped and you don't anymore)

[smoked240]

e85 starts fine in winter, you need to adjust the additional cranking fuel table and the after start fuel table for that though. Most tuners dont because it is a pain to adjust (you need a cold engine for that ... ) If you have trouble starting, crank it just a little, stop for a couple seconds, then try again (and if needed, a 3rd time). It should do the trick.

Unless you run lean most of the time, fueling is not going to be a problem, the car may lose a bit of power and have bad mileage but i would not worry about it.

Your main problem is going to be timing, and that is going to either make holes in your pistons and/or make your turbo glow bright red, even at partial throttle, even with AFR set correctly. Using 91 with an engine mapped for e85 will make holes. Using e85 with an engine mapped for 91 will make a glowing turbo, basically. (and it will really run like crap, if it even starts). Both are very bad.

MAP as well as MAF compute the mass airflow and acts accordingly, it takes different sensors for that but the way it works is quite similar.

The AFR really should not be all over the place if it was not before considering your mods. You might have a leak at your exhaust (or you had when it was mapped and you don't anymore)

Yeah I was reading into E85 cold starts but I'm still new to tuning. I've programmed PLC's before so have the concept, just need to learn the aem along with tuning.

I ran all this by my tuner and he said to add 5% to my fuel map and go from there but since it's boost comp he would much rather have it dyno'd.

My gauge was fucky when he dyno'd it so he used his own, there's a loose wire in the clip that goes into the gauge itself. I watch my o2 on the AEMtuner and that's where I see 12ish while pulling around .8bar roughly.

I can still use E85 for the time being but I'm going to bring 91 with to the dyno and possibly 110 from our local airport if the funds are there.
I'll pull up aem tuner shortly and post some pictures.

Edit: I'm not going to throw out exhaust leak either, after I get it running I'll give it another check over to make sure all is well.
Thank you all for the help! Greatly appreciated.

[smoked240]

Yeah so my photobucket is junk so I need to make a new account and I'll post my map up. After looking at the fuel map it looks fucked?

Starts out level, dips a little further in the rpm than spikes up some to come back down than shoots up again way high. Starts to drop off after about 6500rpm.