EVO III GT/650cc FIC's/100%+ IDC's!!??

[sweet97]

If this is not the correct forum let me know and I will move it. A friend bought the EVO GT big 16G and a set of 650cc FIC's. At 22psi he is getting over 100% IDC's on his logger. His trims are right around 100%. Fuel pressure is set at 40psi base, hose off.
When I ran an EVO I had 550's and ran right around 100% IDC at 20-22psi so I thought 650's would be great for him. Now I'm confused. Does the GT copy of the MHI EVO flow that much more air? He has the MAF in the blow thru position. Also has a KEYIVER chip compensating for the 650's. Has the MAFT base set on 5 to get the trims at 100% which is leaning the inj's which should lower the IDC's wouldn't it? Has me stumped. Suggestions please? Thanks, mark

 

[1990EclipseGSX]

The MAFT in blowthrough configuration could be causing extremely high duty cycles. A lot of people that have DSMLink with the MAFT end up pulling out 20%+ airflow to get it to read correctly. I am pullling out 20% above 800Hz with DSMLink, and 5% more above 1000Hz on my MAFT, and this got my GM MAF in blowthrough pretty much dead on. But that is ~25% correction in airflow... When I finally got things dialed in, it dropped the IDC's on my injectors big time.

It is very possible that the GM MAF is reading high in blowthrough config, causing really high IDC's. What kind of airflow are you seeing at 22psi? Does it look absurdly high?

 

[sweet97]

Not sure he can log airflow but I can and was getting 3600Hz but if you check my mods I can flow a good amount of air. How can you tell when you have the settings "dead on"? I have a wideband and if I set the MAFT base to get my trims at 100%(1G) shouldn't the airflow then be correct?
The car with the EVO GT is getting 18* timing and just a few counts of knock so I am confused because if the MAFT was reading higher than the flow actually was then shouldn't the motor run lean?
Not directly related to my thread heading but I am a bit confused on the part that fuel trims play in performance of the motor. Can anyone explain or link me to the function of fuel trims? Searches are difficult bringing up every word, perhaps there is a way to check for phrases that I did not see. Then again I heard of a guy with a small 16G maxing 650's also with boost in the lower 20's.
Well the guy with the EVO GT leaned it out 15% more than what KEYDIVER compensated for and still 98% IDC. How about using the RPM feature of the MAFT to tune with? That should eliminate the airflow to some extent but maybe not because it is working on top of the airflow readings that would be set on the rough tune!! AARRGGHH!
Well how about a suggestion for helping this situation. Should he go with 750cc inj's?
I have a wideband and if it reads correctly then the idc is correct with the correct AFR's, correct?
You said you took out 25% and I take that to mean 25% airflow, correct?
With my friend with the EVO GT doing so then should have brought his IDC down but still it only dropped to 98% after he leaned the Translator 15%. That got his trims good so then he needs larger injectors. He has a Walbro 190 also. Not sure if it's rewired. Thanks and please keep some info coming here! Mark

 

[BlackbirdOfPrey]

THe only benefit RPM mode would net you is if you were only pulling over 100 INJD at a certain rpm, otherwise MAF mode is the way to go for global settings, RPM is just for specific point tuning. IF you are pulling that across the board, something else is amiss. I have never heard of a MAFT adding 25% more air. If anything I've seen most cars run overly rich as opposed to lean with them. BTW is the 40psi base fuel pressure done that way to tweak something? Because if I recall base fuel pressure on a 1g is supposed to be 37-38psi. As far as airflow on the EVO GT the extra airflow is supposed to be almost negligable compared to the MHI Evo 3, so I doubt that is the problem. Find out about the fuel pump rewire, because if your not getting enough voltage, that could make your injectors work harder to keep up with the bigger injectors/airflow.

 

[dsm-onster]

The MAFT in blowthrough configuration could be causing extremely high duty cycles. A lot of people that have DSMLink with the MAFT end up pulling out 20%+ airflow to get it to read correctly. I am pullling out 20% above 800Hz with DSMLink, and 5% more above 1000Hz on my MAFT, and this got my GM MAF in blowthrough pretty much dead on. But that is ~25% correction in airflow... When I finally got things dialed in, it dropped the IDC's on my injectors big time.

It is very possible that the GM MAF is reading high in blowthrough config, causing really high IDC's. What kind of airflow are you seeing at 22psi? Does it look absurdly high?

My MAFt in blowthru reports richer than stock, but not enough to max out 650s at 22 psi w/ stock cams . . .

Did you use a map sensor or a wideband to calibrate your maft? I used a wideband... I'm not questioning you at all. Just confused .

 

[sweet97]

I will check about the rewire but lets say that has been done. Aren't 650cc's enough for an EVO 16G? That is what has me stumped. Guys with 50 trims are getting away with 650cc inj's.!!! He is running 40 psi to help bring the IDC's down. He was running 50psi base to get them around 90% or so. I told him that was not the thing to do and if anything he needs 750cc injectors but that is a lot of fuel for a big 16G in my opinion. Thanks, Mark

 

[dsm-onster]

Not sure he can log airflow but I can and was getting 3600Hz but if you check my mods I can flow a good amount of air. How can you tell when you have the settings "dead on"? I have a wideband and if I set the MAFT base to get my trims at 100%(1G) shouldn't the airflow then be correct?

The airflow at the lower hertz ranges will be accurate. But when you throw more air in the engine in blowthru, the maft gets less and less accurate at the higher hertz or higher airflow (higher boost and higher rpms). The MAFt in blowthu is not linear w/ respect to the stock maf.

The car with the EVO GT is getting 18* timing and just a few counts of knock so I am confused because if the MAFT was reading higher than the flow actually was then shouldn't the motor run lean?

If the MAFt is reporting higher hertz than there really should be, then it is telling the ecu that there is more air coming into the engine than there really is. The ecu will add fuel for a larger amount of air than there is, and so you're running richer.

Not directly related to my thread heading but I am a bit confused on the part that fuel trims play in performance of the motor. Can anyone explain or link me to the function of fuel trims? Searches are difficult bringing up every word, perhaps there is a way to check for phrases that I did not see. Then again I heard of a guy with a small 16G maxing 650's also with boost in the lower 20's.
Well the guy with the EVO GT leaned it out 15% more than what KEYDIVER compensated for and still 98% IDC. How about using the RPM feature of the MAFT to tune with? That should eliminate the airflow to some extent but maybe not because it is working on top of the airflow readings that would be set on the rough tune!! AARRGGHH!
Well how about a suggestion for helping this situation. Should he go with 750cc inj's?
I have a wideband and if it reads correctly then the idc is correct with the correct AFR's, correct?
You said you took out 25% and I take that to mean 25% airflow, correct?
With my friend with the EVO GT doing so then should have brought his IDC down but still it only dropped to 98% after he leaned the Translator 15%. That got his trims good so then he needs larger injectors. He has a Walbro 190 also. Not sure if it's rewired. Thanks and please keep some info coming here! Mark

What are the settings on the MAFt now?

 

[sweet97]

My MAFt in blowthru reports richer than stock, but not enough to max out 650s at 22 psi w/ stock cams . . .

Did you use a map sensor or a wideband to calibrate your maft? I used a wideband... I'm not questioning you at all. Just confused .

Matt I am really confused! How do you use the wideband to calibrate the MAF? I had him use the base knob to get his mid and high trims to 100% and that required him to lean the base by 15%. He has a keydiver chip compensating for the 650's. Jeff said that usually users of the MAF have to lean his chips by 10% or set the base on 470cc's instead of 450cc's. I have a wideband and MAF so "calibrating" it is something I need to know what you are talking about as you are not physically doing anything to the MAF and that is what I would call calibrating something. What would I do to calibrate my MAF using my wideband? I am really stumped as we got his trims to 100% and with 40psi base fuel pressure he is getting 98% IDC's on his logger at 22psi on the EVO GT 16G!!! What could be wrong? Please help with the calibration part and thanks very much, Mark

 

[sweet97]

His AUX is on "0", BASE is on "5", IDLE is on ?, MID is on "f" and the WOT is on "0". He is in Las Vegas and runs a cold air intake so the sir could be a little cool and denser. He has 91 octane fuel. With the BASE on "5" he gets his mifd and high trims about 100%. At WOT he gets no knock but taking the WOT knob to "F" leads to 10 counts of knock. He is willing to buy 750cc inj's but I say that an EVO 16G should NOT require 750cc inj's at 22 psi!!! Mark

 

[dsm-onster]

Matt I am really confused! How do you use the wideband to calibrate the MAF? I had him use the base knob to get his mid and high trims to 100% and that required him to lean the base by 15%. He has a keydiver chip compensating for the 650's. Jeff said that usually users of the MAF have to lean his chips by 10% or set the base on 470cc's instead of 450cc's. I have a wideband and MAF so "calibrating" it is something I need to know what you are talking about as you are not physically doing anything to the MAF and that is what I would call calibrating something. What would I do to calibrate my MAF using my wideband? I am really stumped as we got his trims to 100% and with 40psi base fuel pressure he is getting 98% IDC's on his logger at 22psi on the EVO GT 16G!!! What could be wrong? Please help with the calibration part and thanks very much, Mark

You can only calibrate a maf with dsmlink. Or another setup that allows you to go into the ecus memory and tell it that you have maf that reads airflow at a different hertz curve...

To do it w/ dsmlink, you log your target a/f ratio that dsmlink does for you while logging the actual a/f ratio froma wideband. Then at the hertz points were the actual A/F ratio is higher than the target you modify (to the positive) in the "maf compensation" box (w/ dsmlink).

Of course, none of this is relevent to your friend. He isn't running dsmlink . So you'll have to go into the MAFt box and lean her out more than you would if he were in drawthrough, the mode for which the MAft was designed. I guess for most, this means leaning out WOT significantly, but not I. Mine wasn't off this much.

Don't worry about any of this stuff. You have a wideband. Just use that. If he's really rich then lean him out. Target 11:1 and be done w/ it. If he is at 98% idc at 11:1 then he dhould get larger injectors... But I will wager my own wideband o2 that, if he has stock cams and running 22 psi on a MHI EVO3 or EVO GT or even a 50-trim, he is not maxing out his 650s. He's probably running rich, at least a little rich.

Keep in mind that since you're a MAFt that is tuned will never give the user an accurate airflow reading for purposes of study... This is why DSMLink guys calibrate the gm maf or hacked maf. So that we can look at our grams/rev and know that it is really what is flowing into the engine. We bought DSMLink not to fool the ecu. So we don't want to be fool either... But None of this is a concern if you're jus ttrying to get the engine to run as sharp as it can. All you need is your wideband, and this whole problem will go away.

 

[GVR4592]

Not to be a dick but why does everybody with a 16g think they need the MAFT? I can see no real benefit from having it except for a slightly less restrictive intake. You aren't going to get anywhere near maxing out a 2g maf with a 16g so why not just use that? It's a lot easier to tune.

 

[sweet97]

You can only calibrate a maf with dsmlink. Or another setup that allows you to go into the ecus memory and tell it that you have maf that reads airflow at a different hertz curve...

To do it w/ dsmlink, you log your target a/f ratio that dsmlink does for you while logging the actual a/f ratio froma wideband. Then at the hertz points were the actual A/F ratio is higher than the target you modify (to the positive) in the "maf compensation" box (w/ dsmlink).

Of course, none of this is relevent to your friend. He isn't running dsmlink . So you'll have to go into the MAFt box and lean her out more than you would if he were in drawthrough, the mode for which the MAft was designed. I guess for most, this means leaning out WOT significantly, but not I. Mine wasn't off this much.

Don't worry about any of this stuff. You have a wideband. Just use that. If he's really rich then lean him out. Target 11:1 and be done w/ it. If he is at 98% idc at 11:1 then he dhould get larger injectors... But I will wager my own wideband o2 that, if he has stock cams and running 22 psi on a MHI EVO3 or EVO GT or even a 50-trim, he is not maxing out his 650s. He's probably running rich, at least a little rich.

Keep in mind that since you're a MAFt that is tuned will never give the user an accurate airflow reading for purposes of study... This is why DSMLink guys calibrate the gm maf or hacked maf. So that we can look at our grams/rev and know that it is really what is flowing into the engine. We bought DSMLink not to fool the ecu. So we don't want to be fool either... But None of this is a concern if you're jus ttrying to get the engine to run as sharp as it can. All you need is your wideband, and this whole problem will go away.

Well he leaned the base 15% with the maft and has the WOT set on "0" because if he leans it 1 click he gets 10 counts of knock because of the base leaning which brought his trims to 100%. He says no leaks. 98% IDC on his logger. I thought 650's would work fine also. He probably is going to 750's. mark

 

[GVR4592]

I have FIC 650's, 2g maf, EVO 3 16g, and DSMLINK on my Galant. I see 88% IDC at 24-25 psi on pump gas with 10.5:1 a/f. So the issue isn't the injectors, could be fuel pump related, but I'm still betting it's the MAFT.

 

[sweet97]

Not to be a dick but why does everybody with a 16g think they need the MAFT? I can see no real benefit from having it except for a slightly less restrictive intake. You aren't going to get anywhere near maxing out a 2g maf with a 16g so why not just use that? It's a lot easier to tune.

Well how would someone tune the fuel if he had the 2g mas? Remember he has no SAFC. What would he tune with running 650 or 750cc inj's? Even with a DSMchip compensating for the inj's someone would still need something to tune with wouldn't they? The MAF-T is not difficult to tune. I use it and run high 11's at 120. Mark

 

[GVR4592]

My mistake, I didn't see that he had nothing to tune the fuel with.

 

[sweet97]

I have FIC 650's, 2g maf, EVO 3 16g, and DSMLINK on my Galant. I see 88% IDC at 24-25 psi on pump gas with 10.5:1 a/f. So the issue isn't the injectors, could be fuel pump related, but I'm still betting it's the MAFT.

Well he could rewire the pump but he has had a couple of guys aay they needed lrger thn 659's for their EVO's. One guy runs 850's at 70% duty and another said he maxed his small 16G on 650's. I'll let you guys know what results he fets, thanks, mark

 

[GVR4592]

They have fuel pump problems if they are maxing 650's on a small 16g. If there isn't enough flow then IDC's shoot way up. Definitely rewire the pump. I was seeing 9 volts at the pump before I rewired it. Not that this is a great comparison but my cousin is running 25 psi on pump gas with his EVO 8 with stock 550's and just a fuel pump.

My buddy has 550's and an EVO 3 on his 2g GST. He's at 21 psi with 70% IDC. He runs the Supra pump which has a bit of an advantage over the Walbro at higher pressures, usually 20-30 l/ph at 70 psi.

Another issue is going to be running 750's with a piggyback, you are probably going to see too much timing advance.

 

[sweet97]

They have fuel pump problems if they are maxing 650's on a small 16g. If there isn't enough flow then IDC's shoot way up. Definitely rewire the pump. I was seeing 9 volts at the pump before I rewired it. Not that this is a great comparison but my cousin is running 25 psi on pump gas with his EVO 8 with stock 550's and just a fuel pump.

My buddy has 550's and an EVO 3 on his 2g GST. He's at 21 psi with 70% IDC. He runs the Supra pump which has a bit of an advantage over the Walbro at higher pressures, usually 20-30 l/ph at 70 psi.

Another issue is going to be running 750's with a piggyback, you are probably going to see too much timing advance.

He will have a chip burned to cover for the 750's but perhaps he does not need the inj,s his pump could need a rewire. Mark

 

[dsm-onster]

Well he leaned the base 15% with the maft and has the WOT set on "0" because if he leans it 1 click he gets 10 counts of knock because of the base leaning which brought his trims to 100%. He says no leaks. 98% IDC on his logger. I thought 650's would work fine also. He probably is going to 750's. mark

The WOT does not affect his fuel trims.

So you're saying that, if he leans out his WOT knob by turing it 1 click counter clockwise, he knocks.

When Does this occur? IF this is the case, then go to the "click" at WOT that he knocks, and switch over to rpm mode and fine tune by richening up at the specific rpm he knocks. . . It's that simple. I still can't believe that you havn't hooked up your wideband yet. He IS your fiend, right ? You can give him an excellent tune with a wideband and the MAFt...

 

[dsm-onster]

Well he could rewire the pump but he has had a couple of guys aay they needed lrger thn 659's for their EVO's. One guy runs 850's at 70% duty and another said he maxed his small 16G on 650's. I'll let you guys know what results he fets, thanks, mark

Who the He!! is tuning these cars!!!!!??????

ShapeGSX. EVO3 16G. 30 psi . 264/272s. 11.825sec @ 117.550mph.

Click here: Shape is running 84% IDC w/ his 660s.

 

[tstkl]

The MAFT in blowthrough configuration could be causing extremely high duty cycles. A lot of people that have DSMLink with the MAFT end up pulling out 20%+ airflow to get it to read correctly. I am pullling out 20% above 800Hz with DSMLink, and 5% more above 1000Hz on my MAFT, and this got my GM MAF in blowthrough pretty much dead on. But that is ~25% correction in airflow... When I finally got things dialed in, it dropped the IDC's on my injectors big time.

It is very possible that the GM MAF is reading high in blowthrough config, causing really high IDC's. What kind of airflow are you seeing at 22psi? Does it look absurdly high?

you had to change your fuel trims based on airflow and not rpm's?

I currently have my maft set to -25% at wot and +5% at mid and +25% at idle.... blow through does seem to screw with the readings of a gm maf a lot...

I too see really high idcs and hit fuel cut at 20-21 psi while doing a third gear pull at around 4k rpms. I want to get a wideband o2 sensor before I go to rpm based tuning with the maft. dsm link is just too expensive for me at the moment, so I think I'll sit and wait til version three comes out since I'll probably have the money by then anyways.

 

[dsm-onster]

They have fuel pump problems if they are maxing 650's on a small 16g. If there isn't enough flow then IDC's shoot way up. Definitely rewire the pump. I was seeing 9 volts at the pump before I rewired it. Not that this is a great comparison but my cousin is running 25 psi on pump gas with his EVO 8 with stock 550's and just a fuel pump.

My buddy has 550's and an EVO 3 on his 2g GST. He's at 21 psi with 70% IDC. He runs the Supra pump which has a bit of an advantage over the Walbro at higher pressures, usually 20-30 l/ph at 70 psi.

Another issue is going to be running 750's with a piggyback, you are probably going to see too much timing advance.

I'm sorry but no. The ecu does not know he has a stock fuel pump or a dual 255HPs. The only time the ecu knows there is not enough fuel flow is in closed loop where it monitors air/fuel ratios via the narrow band o2. During open loop, which is closer to WOT, the ecu ignores the o2 sensor and relies on the programmed maps and the MAF and nothing more. If he was getting screwy fuel trims that would be one thing... that's closed loop issues. If hes getting peak IDCs of 98% then that is an open loop issue. The ecu will go ahead an fry your engine in open loop if you have weak fuel pump and you go to WOT or open loop. Unless it can retard timing in time!!!!!

I'm telling you, if you wire up the frickin' WBO2 that you have IN YOUR POSSESION, then chances are you will figure out your problem.

 

[dsm-onster]

He will have a chip burned to cover for the 750's but perhaps he does not need the inj,s his pump could need a rewire. Mark

Neither a bigger pump nor bigger injectors will solve his problem. Only a wideband will. No one with an 18G or less running stock cams needs 750s running 22 psi. 650s flow enough for 380 horsepower at stock 40 psi base fuel pressure at only 80% injector duty cycle!

See the DSM_Tuning_Sheet_v2.1.xls.

 

[GVR4592]

I'm sorry but no. The ecu does not know he has a stock fuel pump or a dual 255HPs. The only time the ecu knows there is not enough fuel flow is in closed loop where it monitors air/fuel ratios via the narrow band o2. During open loop, which is closer to WOT, the ecu ignores the o2 sensor and relies on the programmed maps and the MAF and nothing more. If he was getting screwy fuel trims that would be one thing... that's closed loop issues. If hes getting peak IDCs of 98% then that is an open loop issue. The ecu will go ahead an fry your engine in open loop if you have weak fuel pump and you go to WOT or open loop. Unless it can retard timing in time!!!!!

I'm telling you, if you wire up the frickin' WBO2 that you have IN YOUR POSSESION, then chances are you will figure out your problem.

You're right I don't know what I was thinking.

 

[sweet97]

I'm sorry but no. The ecu does not know he has a stock fuel pump or a dual 255HPs. The only time the ecu knows there is not enough fuel flow is in closed loop where it monitors air/fuel ratios via the narrow band o2. During open loop, which is closer to WOT, the ecu ignores the o2 sensor and relies on the programmed maps and the MAF and nothing more. If he was getting screwy fuel trims that would be one thing... that's closed loop issues. If hes getting peak IDCs of 98% then that is an open loop issue. The ecu will go ahead an fry your engine in open loop if you have weak fuel pump and you go to WOT or open loop. Unless it can retard timing in time!!!!!

I'm telling you, if you wire up the frickin' WBO2 that you have IN YOUR POSSESION, then chances are you will figure out your problem.

Yeah Matt, he's my friend and I have the wideband. I am in central, NY and he lives in Las Vegas! We're still friends. Sorry I didn;'t say he was a forum friend long distance.
I started this thread because I could not believe he was maxing out 650's when I know that 650's would be fine for a 50 trim. With the MAFT the first step is to set the BASE for good fuel trims, in his case being a 1G that would be 100%. He leaned the MAFT 15% to get those trims correct. What he was doing is setting his base fuel pressure at 50psi to get the IDC's down and that resulted in erratic misfires at WOT, probably rich knock. I had him lower the fuel pressure to 40psi and then get the trims correct. Doing this he eliminated the misfire and it runs great but he does not like the 98% IDC and I am still stumped as to why the cycles are so high. Like I said he has WOT set on "0" and gets no knock but leaning WOT by 5% yields 10counts.
This is why I posted this thread. What could be wrong with this set-up? The chip came with the EPROM ECU he bought and it was advertised as having compensation for 650cc inj's, just what he had at my suggestion. So you guys believe he should buy a wideband rather than injectors? That sounds good to me because there are factors that could be off. The CHIP, Fuel pump, maybe even the logger but he gets 18* timing advance at WOT and 7000rpm's. Any suggestions will be passed on. I have mentioned the wideband and will stress that to him. He is running 91 octane. Could 22 psi just be too much boost for the turbo with 91 octane. He could have to run quite rich to stop knock with that fuel. Thanks, mark