New to Tuning...

[Bullitt5566]

Just a quick introduction. I have a 2001 Bullitt with a Vortech pushing 11 psi of boost into a stock long block with MHS Stage I blower cams. Since the car was retuned three years ago I've chased an idling problem where the car will run rich at idle and anytime the oxygen sensors are not warmed and reading. It will stall if you don't coax it with the throttle and has even refused to start a few times.

I've replaced the oxygen sensors, MAF, COPS, plugs, and checked for leaks everywhere. I eventually data logged injector pulse width the reading from the O2 sensors. At cold startup the Inj PW is around 500 and the STFT is .75. The car is stupid rich, misses, and the AFR drifts to 8:1 and then pegs at 18:1 because the engine is missing and not burning fuel. As soon as the O2 sensors warm, STFT swings to 1.25 and the Inj PW drops to ~300. The car immediately idles fine, does not stall, and the AFR reads steady 14-15.

The tuner has been utterly useless during the past three years. Right after it started happening I contacted him and he eventually agreed to look at it. I drove 2+ hours to his shop. And with the car repeatedly starting, missing, and stalling right in front of him, he said "it's a supercharged 2v with cams and it will do that". Three years later after tracking down every possible cause outside of the tune, I finally decided to order the SCT Pro Racer software and fix it myself.

I've already used the search function and have an idea of what needs to be done, but any suggestions to avoid beginner mistakes would be greatly appreciated. The software will be here in two days.

 

[gmcconn1]

New Tuner

Highly recommend purchasing Don LaSota's book. Everything you need to know and more is covered.

Beyond that, Greg Banish has a couple books on Amazon that do a great job of teaching the "whys" of what is going and how to tune.

You will get more solid information from those books than anywhere else.....

 

[lowranger96]

what injectors are you running? how big are your cams? reasons for these questions:

if the injectors are older large injectors, they are very hard to control at idle when the injector is not it's optimal working range. basically.. if the pulsewidths required to idle where you want are too low, and the injector cannot switch open and closed fast enough, they'll cause driveability issues for sure. this is the reason that everyone is using the high dollar bosch style (ID/deatswerks) injectors.

depending on the cam size, it will fool the o2 sensors (including the wideband) into giving a false lean condition. this happens when the cam has large overlap and pulls a bunch of fresh air into the exhaust. the o2 see this as a lean condition and add fuel. the tuner sees this as a reason to add fuel by increasing the maf transfer. this is not correct procedure. if the cams are the root cause here then the best thing to do would be basically forcing open loop just at idle and tune the air/fuel mix during idle by using a vac gauge. the most possible vac is where the engine is most efficient. then your o2's cant "fix" what it thinks is a problem. once you are out of the idle range, if properly done, you'll use closed loop again for cruising (best gas mileage).

so.. first thing i'd do is put the car in open loop and get a vac gauge. get the idle to be steady and get it to pull the most vacuum. once you do this, put it back into closed loop and see what the fuel trims and idle behavior do.. if it surges or the fuel trims add a fuel then you'll know that you are pulling a bunch of air into the exhaust and you'll need to keep it in open loop for idle to correct this.

get the tune from that guy if you haven't already so that you'll at least have a good starting point

 

[U LOSE]

I read both of Greg Banish books, both of them cover pretty much the same thing. I highly recommend them. He also has a DVD set that is really good.

I also downloaded a lot of tunes off the web and studied their mods and what they changed in the tune vs factory.

AND a LOT of reading on the forums.

I recommend the books more than the DVD, that might just be me though.

After reading the books and watching the DVD. I started to play with my car and now I tune my car and most of my friends cars.

 

[Bullitt5566]

I have both of Greg Banish's books and I'll definately order Dan LaSorta's book.

I'm running Deka 60lb injectors and Modular Head Shop Stage I blower cams. Since they are blower specific cams they don't have excessive overlap. I don't have the spec card handy right now.

The reason I think it is the tune is because it idles fine once the oxygen sensors warm up and start sending signals to the ECU. The problem is exacerbated by the at fact that the long tube headers put the O2 sensors further from engine so they not reading all the time. In fact when idling after driving, I can watch the AFR drift from 14-15 AFR to 8 AFR, then it starts to stumble and swings to 18:1 AFR.

The software dongle will be here Monday. My game plan is to put it in open loop and remove fuel at idle until it idles near 15 AFR and pulls max vacuum. I think the current tune is dumping so much fuel at idle that the engine cannot burn it causing the 18 AFR. The spark plugs support this as they are black and soot covered.

I have so many questions.

Can I use my current tune as a starting point? I have the .cef files from my SCT programmer.
Once I get the tune open. How do I put it in open loop? I've read that the engine ECT can be used.
What table/function should I use to adjust the fuel at idle. I don't want to mess with WOT right now because it seems fine. 12 AFR out to 12 psi.
Is there a way to force open loop at just idle? Long term this my be a viable solution because the oxygen sensors just are not working at idle because they cool off quickly.

I think tuners are good at getting the WOT fuel set correctly, but they just don't take the time to tweak the idle and drivability settings. I hate taking my car that I've worked hard on to someone else to finish with a tune. Especially a half-assed tune. I'm really looking forward to being able to do this myself.

 

[lowranger96]

I'm running Deka 60lb injectors and Modular Head Shop Stage I blower cams. Since they are blower specific cams they don't have excessive overlap. I don't have the spec card handy right now.

Ok you shouldn't need to do what I posted above, should idle fine in closed loop.

The reason I think it is the tune is because it idles fine once the oxygen sensors warm up and start sending signals to the ECU. The problem is exacerbated by the at fact that the long tube headers put the O2 sensors further from engine so they not reading all the time. In fact when idling after driving, I can watch the AFR drift from 14-15 AFR to 8 AFR, then it starts to stumble and swings to 18:1 AFR.

You can adjust for the long tubes by adjusting the HEGO delay settings

The software dongle will be here Monday. My game plan is to put it in open loop and remove fuel at idle until it idles near 15 AFR and pulls max vacuum. I think the current tune is dumping so much fuel at idle that the engine cannot burn it causing the 18 AFR. The spark plugs support this as they are black and soot covered.

18afr is lean not rich, your plugs would not be soaked.

I have so many questions.

Can I use my current tune as a starting point? I have the .cef files from my SCT programmer.
Once I get the tune open. How do I put it in open loop? I've read that the engine ECT can be used.
What table/function should I use to adjust the fuel at idle. I don't want to mess with WOT right now because it seems fine. 12 AFR out to 12 psi.
Is there a way to force open loop at just idle? Long term this my be a viable solution because the oxygen sensors just are not working at idle because they cool off quickly.

You cannot open or edit the .cef file. you have to have the mtf file from the guy who tuned it. if not you'll be starting from scratch. you have much to learn... i suggest starting my reading all the write ups on efidynotuning.com

yes there are ways to force open loop full time, open loop at idle, ect. this is done differently depending on the particular ecu being tuned and it's era. If you cant get the mtf file from the guy who wrote the tune then i'd suggest taking some cruising and WOT datalogs to reference while you're building your new tune. you can datalog all the maf, load, spark, etc which you can then use to get your wot spark/afr back in a safe range where you were before. the rest is going to be up to you to tune.

I think tuners are good at getting the WOT fuel set correctly, but they just don't take the time to tweak the idle and drivability settings. I hate taking my car that I've worked hard on to someone else to finish with a tune. Especially a half-assed tune. I'm really looking forward to being able to do this myself.

It just depends on the tuner and how much time they were willing to spend on the car. a lot of guys will get the wot stuff right and leave the o2s to try and do the rest for them once the ecu "learns". this will work on SOME stuff, but it's not the right way. best part of tuning yourself is you can dial it in as much as you want, until you're satsified. the dyno is good for numbers and loading the motor for timing table adjustments. other than that, it's just a tool. it sounds like your current tune has a half-assed maf function on the low end. those 60lb injectors shouldn't be giving you ANY idle issues so it sounds like idle just needs to be leaned out using the proper points on the maf curve.

 

[Boosted-Cobra]

nice

 

[Bullitt5566]

Software will be here today and the tuner has agreed to send me the MTF file provided I don't share it. I understand and will respect that.

BTW, I know that 18AFR is a lean AFR ratio, but if the engine is not burning the fuel (misfiring) it will read lean not rich.

The WOT is fine, I think the cams are throwing the idle off. I looking forward to dialing the car in.

 

[Bullitt5566]

Received the software dongle and the tune file from the tuner today. Made three adjustments. First, fixed the fan temps so that the cooling fans are not on all the time. Second, I increased the O2 delay by 15%, and Last I added 25% to the O2 sensor heater. The idle is better, but it seems to hunt instead of stalling for the first minute or so. I haven't touched any AFR yet.

 

[DHG1078]

I don't know how to tune, but would love to learn how in the near future. I was reading through one of the links posted above, and it sounds to me like this is the page you want to be reading. It is specifically for cold starts.

http://info.efidynotuning.com/startup.htm

 

[U LOSE]

I haven't touched any AFR yet.

I know that with HPTuners you just data log (run the scanner program). and it will tell you how much to adjust the AFR. Once everything is setup its pretty much just a copy and paste from the scanner to the tuner program. I had a car that would hunt for the idle once also. Problem ended up being it had to little timing in the idle area of the table. I added some timing it it smoothed out. Every situation is different though.