ECMlink 1g - oxygen sensor issues messing with tune?

[CrackedDSM]

Hey guys, I’m at my wits end here. I’m having issues with this car refusing to let me tune it. When I’m driving from like 2500-3000RPM it goes like 17.0:1 lean. Before and after that is fine. No amount of mafcomp, fuel tab sliders, or global helps.


When I posted the log a couple members pointed out my oxygen sensors(both wideband and OEM narrowband) are “acting funny”.


If they are, how would I fix this? Both are brand new and exhaust has no leaks. Do I buy new sensors or is this a ground/wiring issue? Any suggestions or advice is helpful.

Here’s the log.

https://www.dsmtuners.com/attachments/log-2024-10-05-04-elg.745683/

Hopefully that link works if not then I’ll post the log later, if it doesn’t work in the meantime you can check my build thread for the log. It’s my second most recent post.

Thanks for any and all help.

 

[Imback]

Your MAF is bad. Your IAT is 137 from the start. The ECU needs pressure, temp, and volume from the MAF to make it's calculations.

 

[CrackedDSM]

Your MAF is bad. Your IAT is 137 from the start. The ECU needs pressure, temp, and volume from the MAF to make it's calculations.

Kinda weird on my part but that’s great news? Now this forces me to plug my SD stuff in and switch to SD.

It doesn’t surprise me. This MAF is very old and came off of a junkyard car anyway.

 

[1990TSIAWDTALON]

Once you get the hang of SD, I doubt you'll ever want a MAF again. I blew my turbo to IC piping coupler off of my Red Talon the other day (it refused to stay on at 30lbs but I did get that remedied) and the car drove me home just like a normal (but a tad spunkier) 4 cylinder car. No issues at all other than NO Boost. Good luck, it's not hard and I think you'll agree.
Marty

 

[CrackedDSM]

So, kind of bumping this because I feel like this is a better spot for this question than my build thread.


I've been chasing a sudden lean spike on both MAF and now SD. I'm just gonna think out loud here and ask those in the know to correct me if I'm wrong.

BUT, would it be stupid to increase my base fuel pressure to say...50psi...to put more pressure into the rail, and just adjust global and deadtimes to get the idle normal?

My thought process is this would allow more pressure in the rail to combat the sudden drop in rail pressure when the injectors open. Because I think I'm running into the problem where the 1050cc injectors are opening and causing a drop in fuel pressure to the point that its causing a brief lean spike. IDK, someone correct me if I'm wrong.

I'm still going to take advice and do all the tune things, but I feel like this may be my problem. Also gonna test my fuel pump and make sure it rises to 80+psi with the vacuum source off per Kevin Jewer's pre-tune checklist.


@1990TSIAWDTALON did you ever fix the lean spike issue you were chasing a few years ago? I think we are having very similar problems. You had a sudden lean spike and I'm curious if it ever got fixed and how you fixed it.

 

[jed344]

Fuel pulse issue? Raising pressure would likely not help as when pressure goes up pump flow flow goes down. When you look at a chart for a fuel pump it shows that at xx pressure it flows x. This number goes down as more pressure is needed. I would suspect if it comes back right on target fine that then it could be a fuel press regulator issue.

 

[1990TSIAWDTALON]

Kevin Jewer and I were tuning and he was thinking Big Pump, Stock Lines so I went with AN feed and used the stock feed as the new return line. That, on top of the filter element getting "twisted" somehow in the canister, made for not enough flow when I was demanding it. I also went to Hi Z injectors, then the trans gave me issues and we had to stop tuning.

 

[CrackedDSM]

Kevin Jewer and I were tuning and he was thinking Big Pump, Stock Lines so I went with AN feed and used the stock feed as the new return line. That, on top of the filter element getting "twisted" somehow in the canister, made for not enough flow when I was demanding it. I also went to Hi Z injectors, then the trans gave me issues and we had to stop tuning.

The fuel lines on this car are giant. They’re like if -9AN was a size. They’re bigger than -8 but a tiche smaller than -10.

 

[1990TSIAWDTALON]

It's not that then. I run 8AN on the Red Talon, no issues.

 

[jed344]

8AN is more then enough for 99%. We have 8AN feed and 6AN return on a car right now with a magnafuel 750 4303 pump. This car has seen around 40 psi on a 6466 and logs 80lb/min+. Have not seen any logged fuel pressure issues yet with it.

 

[CrackedDSM]

8AN is more then enough for 99%. We have 8AN feed and 6AN return on a car right now with a magnafuel 750 4303 pump. This car has seen around 40 psi on a 6466 and logs 80lb/min+. Have not seen any logged fuel pressure issues yet with it.

Only reason I even consider the -8AN PTFE specifically, is because the -6AN PTFE is smaller than regular -6. Don't wanna accidentally do a downgrade.

 

[jed344]

Only reason I even consider the -8AN PTFE specifically, is because the -6AN PTFE is smaller than regular -6. Don't wanna accidentally do a downgrade.

What pump and still in stock hanger ect? Normally when the pump has a sealing issue though it shows up much more from what we have found. I assume you have a bulkhead fitting done if it is a in tank pump.

 

[CrackedDSM]

What pump and still in stock hanger ect? Normally when the pump has a sealing issue though it shows up much more from what we have found. I assume you have a bulkhead fitting done if it is a in tank pump.

Aeromotive Stealth 340. Stock hanger but I have the "Bell" cut-off and have their included hose and better clamps doing the clampin'.


Ever since doing this and replacing the diaphragm in my 10-15 year old Aeromotive AFPR, the map is now lean everywhere. Same base fuel pressure, etc. So I'm pretty sure the aging diaphragm was part of the culprit. I'm also gonna send off the injectors to be flowed and cleaned by FIC, because they're about 10 years old and sat for that long as well.

 

[jed344]

Aeromotive Stealth 340. Stock hanger but I have the "Bell" cut-off and have their included hose and better clamps doing the clampin'.


Ever since doing this and replacing the diaphragm in my 10-15 year old Aeromotive AFPR, the map is now lean everywhere. Same base fuel pressure, etc. So I'm pretty sure the aging diaphragm was part of the culprit. I'm also gonna send off the injectors to be flowed and cleaned by FIC, because they're about 10 years old and sat for that long as well.

For sure get the injectors cleaned and flowed.