Tunning question

[Gravy]

Something i gotta admit I'm not a pro at, last year i got my A/F ratio right and drove the car, didn't worry about power but just to be safe. Now I'm not looking to put down anything great, just get the car running as best it can, and today toying with the data logger, i came by something odd.

I took it out on the first drive of the year, didn't go faster than 60, and never went above 6188 rpm. However, on that pull in second gear i hit an injector IDC of 78.9. But with upgraded injectors, is the logger seeing the expected OEM 360cc injectors or the 450's i have in there now?

Also can't seem to find the info on what i'm looking for, i know under hard driving 11-12 is a good AFR, but what does everyone shoot for while cruising at say, 55 down the highway?

I have other questions, but i gotta google them before i post up in here.

Gravy

[Shane@DBPerformance]

IDC is IDC regardless of what injectors are in the car.

The factory ECU will use the stock O2 sensor to shoot for 14.7:1 A/F during idle and cruise. If you lean it our or richen it up, the ECU will just override it and try to go back to 14.7:1, if everything is working correctly. Normally you try to get the fuel trims as close to 0 or 100(depending on how your logger reads) as possible, so that the ECU is having to compensate as little as possible.

[asshanson]

Injector duty cycle won't matter what injectors you have, it should be accurate. I believe it's based on what percentage of the time they're on, not a factor of how much they're actually flowing.

If you're just using an AFC or something like that, you can't really adjust the closed loop A/F ratio, the ECU will shoot for 14.7 automatically and adjust fuel trims to reach that.

Edit: looks like Shane beat me to it.

[Gravy]

Thanks for the info, may end up swapping the 550's back in than if i run into any more problems with the 450's. Sounded like a good idea, better control and able to make smaller adjustments but maybe not. Now i've just gotta figure out how to log the wideband 02 with the unit i have. May need a different cable.

[niterydr]

Originally Posted by Gravy

Thanks for the info, may end up swapping the 550's back in than if i run into any more problems with the 450's. Sounded like a good idea, better control and able to make smaller adjustments but maybe not. Now i've just gotta figure out how to log the wideband 02 with the unit i have. May need a different cable.

Since you are using an air flow correction you want the closest injectors to factory as possible, aka the smallest ones you can get away with. 80% IDC's is fine for most injectors, when you are constantly running them around 90+ is when you can see failures over time.

The 450's will allow for more degree of control over the 550's. Most of this has been covered on 3si.org, very specific information to the 3s.

[Shane@DBPerformance]

Most factory ecu mitsu dataloggers are off on their duty cycle calculation anyways. Some of the ECUs give out Injector Pulse Width(IPW) and dataloggers use a guesstimate calculation based on IPW, RPM, and dead time to try to give a duty cycle, but they are usually off. Like Evoscan is a good 15% off at high duty cycle. 115% duty cycle in Evoscan is more like real 100%. Systems like the AEM EMS give true duty cycle, but a box like that can do it because it is actually controlling the injectors.

The whole 80% duty cycle thing that books and injector makers recommend is BS. Even some OEMs run them well past 80% on stock cars.

As Josh said, with an airflow tricking system like an SAFC, you want as small of injectors as you can get away with. The more you have to deviate from 0% in the SAFC, the more unintended sideeffects start happening.

[Gravy]

I think tonight i'm gonna set the MAF translator to -20% across the board, i'm running around -15% to about -18% so i'll be able to run closer to 0 on the safc, but i'm pretty sure that's still gona give me the same results as setting the safc to -20.

And the reason i went with the 450's is i had to run e-85 on the 550's to prevent running around -30 to -40 to keep the AFR correct. I've almost wondered if they are larger than 550cc's but a run of the part number confirmed it twice now.

[Shane@DBPerformance]

Originally Posted by Gravy

I think tonight i'm gonna set the MAF translator to -20% across the board, i'm running around -15% to about -18% so i'll be able to run closer to 0 on the safc, but i'm pretty sure that's still gona give me the same results as setting the safc to -20.

Yea, the SAFC and MAFT trick the factory ECU in exactly the same way, so it doesn't matter which you pull 20% out of.

[Gravy]

E-85 keeps sounding better and better. Found out part of my problem, plugs gapped at .038-0.40 is giving me some MAJOR spark plug blow out. Got the knock under control, but the WOT is hard to keep happy with the blow out happening.

Got the new set of plugs, going back to the original wires that were on the car, new one's i'll hold till i need them for now.

[Gravy]

Double posting over making another thread since it's in the same ball park, but i ran into some interesting issues tonight on the stealth. To lay out a quick run down:

Car stock injectors are 360cc, i have 450's on there.

I've switched back over to e-85 and can NOT get it running right. Last year on 550's i still had the settings around -20 all the way down the RPM range. This year trying it on 450's, I'm +20 just to keep it semi happy running at low throttle or cruising. It runs at idle around 14.9-15-5 at that point, but my high settings are -10% and when i get under WOT it goes to 9.9 and i hit fuel cut even as low as -25%. For the life of me, i didn't have the logger to check IDC but does this make ANY sense to anyone else? I'm about ready to drop the 550's back in cause i know they didn't have any issues really last year on it.

[Shane@DBPerformance]

Too lean at cruise and too rich at WOT usually means a boost leak.

[Gravy]

Yeah, i'll run though it tonight, but i've got a feeling it's been there the whole life of the car while i've had it. The AFR also jumps alot, and after reading Josh's tuning bit on 3si.org, i have much to work out.

[niterydr]

Originally Posted by Gravy

Yeah, i'll run though it tonight, but i've got a feeling it's been there the whole life of the car while i've had it. The AFR also jumps alot, and after reading Josh's tuning bit on 3si.org, i have much to work out.

It is much better to tune a solid vehicle versus trying to tune around mechnical problems and limitations. I always recommend boost leak tests, spark plug tests, and vehicle inspections for all "tuners" atleast once a year. Saves on headaches.

[Gravy]

Cracks around my waste gate lines on both sides, fixed the leak and now the afr is much more stable. Took it for a few spins and got 111% and 115% IDC on e-85. Either i'll have to stick to 92 or upgrade to the 550's again.

One thing i have noticed, and i'm not sure if it's something i havn't been able to find or just isn't out there. But both of my 02 sensors cycle the way they should, but on the wideband, since the day i've had the car/wideband in there. It will start off cruising fine at around 14.5-14.9 and than as i've heard nytrider describe in the tuning post on 3si, it "Switches" from 14.8 or so down to 11.4-11.5. It will continue to run at that range untill i let off the gas and register 0.0% on the tps, than it resets and runs there for a minute or so, than will switch back. I tried tuning for the higher afr range and the lower. But it still switches no matter what.

So if i try and tune it to run on the "High" setting as i'll call it, it runs great for a minute or so after getting in gear. When the minute is up, it switches to the "Low" setting. If i tune for the low setting, it starts off in the high, than switches to the low and runs great. The problem is it is runing super lean to start with and i can't get on the gas at all without terrible knock and a heavy miss. Everything on the logger looks fine, i throw no codes and the only lite on the car is the SRS for the airbag.

The only thing i can think of, and it still doesn't make sense, is the car is set up to vary the voltage to the fuel pump, but i have a rewire done. So it just sees a higher voltage than it probably wants to see. I've tried re-setting the ecu(pulling the battery over night) and trying to get the car to relearn the fuel curves but with no luck. The EGR system is removed from the vehicle, but i've had that on and still had the same problem as i do now.

Any ideas on what to check? Full out boost leak test is coming, i just have to get a couple 1 3/4" caps to put on the turbo's and tap a tire valve into them.

[niterydr]

Originally Posted by Gravy

Cracks around my waste gate lines on both sides, fixed the leak and now the afr is much more stable. Took it for a few spins and got 111% and 115% IDC on e-85. Either i'll have to stick to 92 or upgrade to the 550's again.

One thing i have noticed, and i'm not sure if it's something i havn't been able to find or just isn't out there. But both of my 02 sensors cycle the way they should, but on the wideband, since the day i've had the car/wideband in there. It will start off cruising fine at around 14.5-14.9 and than as i've heard nytrider describe in the tuning post on 3si, it "Switches" from 14.8 or so down to 11.4-11.5. It will continue to run at that range untill i let off the gas and register 0.0% on the tps, than it resets and runs there for a minute or so, than will switch back. I tried tuning for the higher afr range and the lower. But it still switches no matter what.

So if i try and tune it to run on the "High" setting as i'll call it, it runs great for a minute or so after getting in gear. When the minute is up, it switches to the "Low" setting. If i tune for the low setting, it starts off in the high, than switches to the low and runs great. The problem is it is runing super lean to start with and i can't get on the gas at all without terrible knock and a heavy miss. Everything on the logger looks fine, i throw no codes and the only lite on the car is the SRS for the airbag.

The only thing i can think of, and it still doesn't make sense, is the car is set up to vary the voltage to the fuel pump, but i have a rewire done. So it just sees a higher voltage than it probably wants to see. I've tried re-setting the ecu(pulling the battery over night) and trying to get the car to relearn the fuel curves but with no luck. The EGR system is removed from the vehicle, but i've had that on and still had the same problem as i do now.

Any ideas on what to check? Full out boost leak test is coming, i just have to get a couple 1 3/4" caps to put on the turbo's and tap a tire valve into them.

Do you see the vehicle bounce around on the tuning software (forgot what you are using)? Is it grabbing two maps possible? How do the plugs look? A really good wideband can actually show a missfire, I've see them show as lean or rich, depends upon the load and sensitivity of the wideband.

How old are the 02 sensors? You are watching the wideband switch correct? It sounds like you are running between closed and open loop.

[Gravy]

That's what it sounds like but my throttle almost doesn't change more than 1% the whole time while cruising. And i stay out of boost while it's happening, even if i step on it and put it in open loop, it still returns back to whatever state it was in. I.E. if it was early in the gear or if i'm ripping on it i'll get a good 11.5-12.1 AF when i get on it in the high setting. If i wait for i to switch, it likes to run 9.9-10.3 as it's set up now under WOT in the low setting.

Car has the following, to give you a full idea:

Stock 9b turbo's
450cc injectors
SAFC-II
GM MAF translator set at 0 for everything for now and using the SAFC only
MBC
3" turbo back with WB on the front bank
AEM WB 02 sensor
MMCD logging software used on palm
FPR set at 38psi no vacuum last i checked
Vacuum line reduction
Dejon 3/S intake splitter with Maf in blow though
Fuel Pump rewire
Battery relocated to the trunk
New plugs
Wires were new, but didn't make any difference so i went back to the after market ones i had on originally.

Oxygen sensors look fairly new, but i have never replaced them myself. But logs do show that both are cycling going back and forth on voltage.

Old plugs looked good, had about 2,500 miles on them and they were still ok, but while i had everything apart i was just gonna toss a new set in for $8. Using NGK part number 5553, i believe they are BKR6ES-11 thought of going platinum but no one can ever give me a good reason why to, copper seems more liked for boost, and i know the eclipse liked them much more than the plats.

Gap is set at .028, i get blow out at .032 but still get a miss slightly at .030 and .028 pulls hard under WOT. And it's running about 14lbs of boost atm and holds about 10 to red line.

[niterydr]

Originally Posted by Gravy

That's what it sounds like but my throttle almost doesn't change more than 1% the whole time while cruising. And i stay out of boost while it's happening, even if i step on it and put it in open loop, it still returns back to whatever state it was in. I.E. if it was early in the gear or if i'm ripping on it i'll get a good 11.5-12.1 AF when i get on it in the high setting. If i wait for i to switch, it likes to run 9.9-10.3 as it's set up now under WOT in the low setting.

Car has the following, to give you a full idea:

Stock 9b turbo's
450cc injectors
SAFC-II
GM MAF translator set at 0 for everything for now and using the SAFC only
MBC
3" turbo back with WB on the front bank
AEM WB 02 sensor
MMCD logging software used on palm
FPR set at 38psi no vacuum last i checked
Vacuum line reduction
Dejon 3/S intake splitter with Maf in blow though
Fuel Pump rewire
Battery relocated to the trunk
New plugs
Wires were new, but didn't make any difference so i went back to the after market ones i had on originally.

Oxygen sensors look fairly new, but i have never replaced them myself. But logs do show that both are cycling going back and forth on voltage.

Old plugs looked good, had about 2,500 miles on them and they were still ok, but while i had everything apart i was just gonna toss a new set in for $8. Using NGK part number 5553, i believe they are BKR6ES-11 thought of going platinum but no one can ever give me a good reason why to, copper seems more liked for boost, and i know the eclipse liked them much more than the plats.

Gap is set at .028, i get blow out at .032 but still get a miss slightly at .030 and .028 pulls hard under WOT. And it's running about 14lbs of boost atm and holds about 10 to red line.

What are your throttle settings for high and low for the s-afc? Is it configured correctly? When did the problem start to occur?

[Gravy]

Low is set at 35%, high at 50%. Have tried raising and lowering the throttle point on both high and low. Looks like everyone has an opinion on where to set it, and i've found this works well for me, anything under 35% throttle is normally out of boost, or low boost, and runs the afr good for how i drive. Anything over 50% throttle i start seeing a good amount of boost, and anything inbetween the low and the high has a varying amount of boost.

The car has always had this switching problem since i got it. I would notice after getting up to 55mph i couldn't get on the throttle unless i waited a little bit, than i could give it hell when i first got it. After getting the wideband it was much more clear as to why i couldn't do that. But not why it was happening.

The car also does it at idle every once in a blue moon. It doesn't happen when fans turn on or off, or change with the voltage coming out of the alternator either. It's got a mind of it's own as far as i can tell. Speedo has been off since i got the car, i just havn't got around to trying to replace the speed sensor, i just drive to the corrected speed.

[niterydr]

Originally Posted by Gravy

Low is set at 35%, high at 50%. Have tried raising and lowering the throttle point on both high and low. Looks like everyone has an opinion on where to set it, and i've found this works well for me, anything under 35% throttle is normally out of boost, or low boost, and runs the afr good for how i drive. Anything over 50% throttle i start seeing a good amount of boost, and anything inbetween the low and the high has a varying amount of boost.

The car has always had this switching problem since i got it. I would notice after getting up to 55mph i couldn't get on the throttle unless i waited a little bit, than i could give it hell when i first got it. After getting the wideband it was much more clear as to why i couldn't do that. But not why it was happening.

The car also does it at idle every once in a blue moon. It doesn't happen when fans turn on or off, or change with the voltage coming out of the alternator either. It's got a mind of it's own as far as i can tell. Speedo has been off since i got the car, i just havn't got around to trying to replace the speed sensor, i just drive to the corrected speed.

Sounds like an internal pcm issue if all the sensors are correct and wiring is good (and no aftermarket stuff is mucking it up). Can you swap out a stock ecm with someone to test?

[Gravy]

I can see if anyone has a spare i can borrow. I'll post up on the local 3/s forum. But i have had my caps replaced before they went bad, and i don't imagine them going bad already again. Still does it now, but runs much better than it has in the past.