1998 Silverado Tuning Question

[Mr.Bull]

Good morning everyone. I have a couple of questions regarding a tune for a 1998 Silverado with a 5.0 V8. First let me start with this, is it possible to tune without a wideband? I'm trying to help my buddy just clear up his truck after headers, CAI, and cat delete. It seems to be running a bit rich. I have only tuned my own built Camaro and it is SD only with no MAF so I'm not sure if I should start with his MAF or his VE table. If it's possible to do without a wideband, what histogram should I use? Again... I've only tuned my own car and it's in SD only with LTFT and STFT both disabled so this MAF and Fuel Trim stuff is kind of new to me. I tuned my car strictly off of my wideband based on what was commanded and what was actually read. His truck isn't a race truck or anything and his exhaust was custom made and has no bungs for a wideband so I don't think he's going to put one in. Sorry for the noob questions. I searched the forum but everything I was finding seemed to mention a wideband. I have attached his "As found" tune if anyone wants to see it. Thanks in advance.

[TheMechanic]

Can you do it without a wideband. Kinda. Should you tune without a wideband? Never. Wideband is critical in tuning. Everything fuel related is a guess without a WB. You have invested this much in a tuner, bust open the wallet and get a AEM on Amazon or Summit. Buy once cry once.

[Mr.Bull]

Can you do it without a wideband. Kinda. Should you tune without a wideband? Never. Wideband is critical in tuning. Everything fuel related is a guess without a WB. You have invested this much in a tuner, bust open the wallet and get a AEM on Amazon or Summit. Buy once cry once.

Well I bought the tuner for my own car which does have a wideband. A buddy I work with just had asked me to help him with his truck if I could because it was running rich after his headers, cat delete, and CAI install. He doesn't have a wideband nor does his exhaust have a bung to plug up a wideband. I'm not trying to charge the guy for tuning services, I'm so far from a pro it's not even funny lol. I'm just trying to help the guy out if I can. I told him that I only tuned mine with my wideband but surely there is some way to do this. How do some of these other shops tune cars without a wideband? Do they not use some kind of input from the ECU when someone brings a stock car in for a better tune?

A better question might be... If nothing with the fuel system was changed ie: injectors, fuel pump, fuel rails etc... Should fueling truly even be an issue? He basically just opened it up to let it breathe better right? Or is that an incorrect thought process. I'm just wondering why would it be dumping more fuel just from CAI and headers. Is it because more air is going across the MAF sensor so it calls for more fuel? I'm just trying to understand why it's doing what it's doing.

Thanks in advance.

[gtstorey]

Have you logged it to see what the fuel trims are doing?

[TheMechanic]

Well I bought the tuner for my own car which does have a wideband. A buddy I work with just had asked me to help him with his truck if I could because it was running rich after his headers, cat delete, and CAI install. He doesn't have a wideband nor does his exhaust have a bung to plug up a wideband. I'm not trying to charge the guy for tuning services, I'm so far from a pro it's not even funny lol. I'm just trying to help the guy out if I can. I told him that I only tuned mine with my wideband but surely there is some way to do this. How do some of these other shops tune cars without a wideband? Do they not use some kind of input from the ECU when someone brings a stock car in for a better tune?

A better question might be... If nothing with the fuel system was changed ie: injectors, fuel pump, fuel rails etc... Should fueling truly even be an issue? He basically just opened it up to let it breathe better right? Or is that an incorrect thought process. I'm just wondering why would it be dumping more fuel just from CAI and headers. Is it because more air is going across the MAF sensor so it calls for more fuel? I'm just trying to understand why it's doing what it's doing.

Thanks in advance.

Any shop that "tuned" any vehicle without a wideband or 5 gas should NEVER be trusted to tune even a stock vehicle.

Something was changed. Headers and CAI will change fueling. Maybe only a little maybe more than you think. The only time I don't use a wideband is when someone wants a limiter change or trans tune.
There are adapters that go into a tailpipe that are better than nothing at all. Just got to make sure they are REALLY secure and zip tied.

[Mr.Bull]

Have you logged it to see what the fuel trims are doing?

I did connect to it and do a log but I wasn't sure which histogram to setup for his truck. With my car it was easy, I just logged the AFR % difference from commanded/read. When I logged his truck and looked at the LTFT they were seemingly about +15 but I hadn't done any tuning changes so DFCO was still active and STFT and LTFT were both still active. Didn't want to make any changes until I knew what direction to go as far as what histograms to log without a wideband.

[Mr.Bull]

I'll have him check into those. That might be the best bet to get one that goes to the tail pipe for him. I appreciate it

[TheMechanic]

https://www.summitracing.com/parts/f...xoCva4QAvD_BwE

https://www.summitracing.com/parts/i...xoC8l4QAvD_BwE

Just make sure it is WELL secured. I usually safety wire the thing also. They WILL fall out if not and there goes your sensor, wiring, and adapter