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Hickory-NC-2Ggsx

Supporting VIP
310
129
Dec 27, 2018
Lincolnton, North_Carolina
hello everyone I hope yall are having a good day!

So I've been battling this afr roller coaster affect. if I add or take out fuel like it says it needs and I try it again it has no change to the afr so I'm wondering if its a fpr problem. The car has a 255 fuel pump fic 650 injectors and a stock 240k fpr don't roast me if that's the problem. LOL but its always at the same rpm 3200-3900.

@v8s_are_slow do you have any idea?

Also I switched from a 16g to a 20g, And I've noticed my mafraw goes crazy after 3400rpm. It didn't do that until I switched to the 20g. But Ive always had the rich-lean-rich issue.

Thanks in advance!
 

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You are out of fuel pump and injectors badly. Well over 100% IDC and if you logged fuel press i bet its falling off. Almost all 255 pump cars i tune max out around 45-47lb/min. I think that is causing you to overinflate ur MAF table to compensate for fuel pressure dropping off. What fuel is the car running on? I also suspect that because your mph is not climbing at a rate a car logging a real 54lb/min does. My own car when around mid 50lb/min is pulling 10-11mph per second yours is more like 8mph.
 
Yeah Ive been trying to get the boost undercontrol and I just now realized I didnt disable error corection on the wgs tab. so I've been battling the target and duty to lower it.

Here a log I just did before I found that out that I was fighting the target boost. And even though it says 31psi its 20psi on my mechanical gauge. But I do agree its not flowing what it says. Ive been trying to get a grasp on all of this again since I've now moved from a 16g to a 20g.

So even with this lower psi log why is the mafraw being erratic like that?

Ill definitely put a bigger pump, injectors and a fpr on the list. but for now id like to just get it dialed in for what I got eve if i have to lower it more.

And I forgot to mention its 93 pump gas.
 

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I would start with a better regulator before wasting time on a fuel pump. You idc's in the first log were screaming. Not as bad in the 2nd one. A fuel pressure increase and a regulator that controls the pressure might be all you need. I see you smoothed out the mafcomp sliders in the second log and that looks to have helped. I'm totally ignoring your map sensor though. Not sure if the sensor is bad, wired incorrectly, or what. But it's not reading correctly unless you just have a really bad boost leak.

Anyway, increasing fuel pressure will help get the idc's down. If the pump can't handle it, then it'll just go lean on the big end and no amount of adjustments will give you more fuel. That's when you'll know that you're out of fuel. Till you get things sorted out, I would lower the boost.
 
You can add a T to the injector rail feed with extra line that deadends to increase VOLUME that is available when needed if you go lean and don't know what to do. I've even thought of putting a T on BOTH ends of the rail to test
It's just a test but will give you data.
It may not help or you may see a difference. Its just a test tho to see if you need to get bigger lines or a rail/both.
I have a setup like that just to see if I need more fuel than the pump can deliver at the instant moment.
Just thoughts.
Pops
 
Ive been meaning to just take the map sensor off the log because I bought a cheap "3bar" and I think its just a regular map sensor. Yeah I change the mafcomp slider back to the way they was the 16g and that helped alot as well as the lower boost levels. Ill do another pull in the morning on my way to work and see what I can put together. But its like I said I dont know why now on the 20g the mafraw is freaking out.
 
Following along.....
 
Ive been meaning to just take the map sensor off the log because I bought a cheap "3bar" and I think its just a regular map sensor. Yeah I change the mafcomp slider back to the way they was the 16g and that helped alot as well as the lower boost levels. Ill do another pull in the morning on my way to work and see what I can put together. But its like I said I dont know why now on the 20g the mafraw is freaking out.

Well, the stock regulator doesn't do the best at "regulating". If fuel pressure is all over the place, the tune results will follow. I also wonder if either your grounding of the electrical system is crap, or just a crap voltage regulator. In the first log, the voltage is dropping through the pull. Goes back up as soon as you let off the throttle. On the second log there's a nice little dip right there in the middle of the log for no apparent reason unless your fans maybe came on at that time as well.
 
That pull was better. Still to rich maf comp needs to come down. I see the random voltage dip. From a quick look appears 2-7% needs pulled out of maf comp to get it to line up.
 
so here is a new log I've been working on. it seems to not like 11.0 afr since the knock sensor is picking it up. so I may try to turn it down to 10.8 target? this weekend I'm going to try to add more grounds to the engine, hopefully that will solve the jagged data I've been getting.
 

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If going richer does not help pull a degree. For pump gas its not uncommon to end up in the low teens sometime high single digits. But you have to find the spot where car feels best. Some cars will pick up minimal knock sensor activity but when reading the plugs they show no signs of knock.
 
yeah I guess ill have to get some new plugs and read them this weekend. Because in one log with the same timing, afr and everything its looks pretty good with 0 knock and the other has 1.8-2.5 halfway through the whole thing. But in the morning I'll pull some timing and see what it does.
 
You are out of fuel pump and injectors badly. Well over 100% IDC and if you logged fuel press i bet its falling off. Almost all 255 pump cars i tune max out around 45-47lb/min.

I’m coming to this party late. I’m def not questioning anyone’s timing ability as mine is very limited and quite outdated. I’m not sure how a 255/660cc Combo is maxed out on a 20g on pump gas. I’ve run an old version FP Green at 25psi on 93 octane with that same fuel setup (only difference is I had an AFPR). I didn’t have DSMLink at the time. Just a good old pocketlogger and an AFC (showing my age here). At most I would see 1 deg of knock retard. Time was good enough for mid 11’s@120mph.

I’m all for learning About tuning methods, as I haven’t tuned a car in almost 15yrs and need to learn V3, since my new car has it. I’m just in for the discussion and information
 
@jed344 i believe it was around 5500. But ill double check when I get home. I havent updated because first my cam sensor took a dump on me so Ive been waiting on the new one to show up.
But Ive been thinking and what if the surging in the maf raw is from my blow off valve surging open and close? Also ill be ordering a fpr friday and a sensor so i can log it.
 
I’m coming to this party late. I’m def not questioning anyone’s timing ability as mine is very limited and quite outdated. I’m not sure how a 255/660cc Combo is maxed out on a 20g on pump gas. I’ve run an old version FP Green at 25psi on 93 octane with that same fuel setup (only difference is I had an AFPR). I didn’t have DSMLink at the time. Just a good old pocketlogger and an AFC (showing my age here). At most I would see 1 deg of knock retard. Time was good enough for mid 11’s@120mph.

I’m all for learning About tuning methods, as I haven’t tuned a car in almost 15yrs and need to learn V3, since my new car has it. I’m just in for the discussion and information
Many people make good power on 255 walbro. But if fuel pressure is logged you will see it dropping off and then the MAF comp or SD table ends up inflated to compensate for drop in fuel press. From my personal experience that is around 450-500whp on e85. I am not sure on pump gas as ours is garbage here and E85 is everywhere so almost no one stays on pump gas for long.
 
Yeah i noticed one at the 02 housing to downpipe flange is leakeing So I ordered a gasket for that as well. Its like my car is falling apart all of a sudden. :cry:
So this weekend will be full of installing new parts. Its just crazy because i checked all of this when i installed the new turbo. And everything checked out fine. Hell i mights as well boost leak test it again this weekend too. Lol
 
You are out of fuel pump and injectors badly. Well over 100% IDC and if you logged fuel press i bet its falling off. Almost all 255 pump cars i tune max out around 45-47lb/min. I think that is causing you to overinflate ur MAF table to compensate for fuel pressure dropping off. What fuel is the car running on? I also suspect that because your mph is not climbing at a rate a car logging a real 54lb/min does. My own car when around mid 50lb/min is pulling 10-11mph per second yours is more like 8mph.
Jed, You might want to take a step back and reevaluate if you are ready to be giving tuning advice or not. You missed quite a few key details in the OP's post, and make a lot of assumptions, possibly sending the op in the wrong direction. While I will agree that on E85 500hp is getting nearing the limits of a 255, that's 100% not a hard and fast rule. There are 3 different 255 fuel pumps, the op did not specify which one he has. Also boost has a huge influence on fuel delivery limits, at 5psi of fuel pressure a 255 can probably support 6-700whp on E85, but at say 100psi, it's effectively zero hp.

Regardless, the op is on pump gas and that means he can probably support at least 25% more hp than if he was on E85.

As for the OP, well and all, remember that widebands are not some all seeing eye. Think like all seeing eye with a heavy pair of beer goggles on. In response to a step fucntion, you could see over a second delay in the wide-band reading the correct value. Meaning like a nlts, full boost 11AFR, push clutch in, and it goes to straight air, widband will show full lean. Let the clutch out car goes back to 11 AFR, but the wideband can take forever to settle back to 11. Maybe people get caught up in "why is my car lean after a shift" when it fact it's not. Couple this with the fact that LITERALLY EVERY EXTERNAL WIDEBAND ON THE MARKET HAS UNACCEPTIBLE CONTROL OF THE NERNST CELL TEMP, and they really are not a lot better than a narrowband. Also remember that a widebands reading is strictly based on assuming normal combustion, throw in anything abnormal and all bets are off, detonation for example usually shows up as a spike in the afr. I rarely look at the wideband on my 800hp 9 sec 1g anymore.

On to the FPR deal, I still use stock n/t FPR's on my car. I use 2 since I have 2 sets of injectors, and I also have 2 255 external fuel pumps. Yes it overruns at idle some, but remember injector output goes with the square root of pressure. The difference between 47 and say 55 isn't very much change in fueling - as long as they work properly. As long as the regulator functions correctly, a little bit of overrun at idle won't hurt you.
 
@bastarddsm I havent said anything about it going lean when i shift. I understand how that works. What im saying is at 11.0 afr mid pull and on Im getting black smoke not just a little bit either. But i think im reading 11.0 because of a slight exhaust leak that i just found yestrday. Because now my idle afr is around 16.0 afr.
 
Jed, You might want to take a step back and reevaluate if you are ready to be giving tuning advice or not. You missed quite a few key details in the OP's post, and make a lot of assumptions, possibly sending the op in the wrong direction. While I will agree that on E85 500hp is getting nearing the limits of a 255, that's 100% not a hard and fast rule. There are 3 different 255 fuel pumps, the op did not specify which one he has. Also boost has a huge influence on fuel delivery limits, at 5psi of fuel pressure a 255 can probably support 6-700whp on E85, but at say 100psi, it's effectively zero hp.

Regardless, the op is on pump gas and that means he can probably support at least 25% more hp than if he was on E85.

As for the OP, well and all, remember that widebands are not some all seeing eye. Think like all seeing eye with a heavy pair of beer goggles on. In response to a step fucntion, you could see over a second delay in the wide-band reading the correct value. Meaning like a nlts, full boost 11AFR, push clutch in, and it goes to straight air, widband will show full lean. Let the clutch out car goes back to 11 AFR, but the wideband can take forever to settle back to 11. Maybe people get caught up in "why is my car lean after a shift" when it fact it's not. Couple this with the fact that LITERALLY EVERY EXTERNAL WIDEBAND ON THE MARKET HAS UNACCEPTIBLE CONTROL OF THE NERNST CELL TEMP, and they really are not a lot better than a narrowband. Also remember that a widebands reading is strictly based on assuming normal combustion, throw in anything abnormal and all bets are off, detonation for example usually shows up as a spike in the afr. I rarely look at the wideband on my 800hp 9 sec 1g anymore.

On to the FPR deal, I still use stock n/t FPR's on my car. I use 2 since I have 2 sets of injectors, and I also have 2 255 external fuel pumps. Yes it overruns at idle some, but remember injector output goes with the square root of pressure. The difference between 47 and say 55 isn't very much change in fueling - as long as they work properly. As long as the regulator functions correctly, a little bit of overrun at idle won't hurt you.
That was a earlier post. He sense posted a log and the tune looked much better and didn't go lean up top like before. Yes there is a ton of factors. I usually recommend logging fuel press to show fuel supply issues, but to the OP what is your fuel trims saying at idle.
 
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