No boost?

[Rhinopolis]

Wild. Love the boost plot. It's like it was trying it's little heart out to make positive pressure but the big bad leak had other plans.

Haha. Yeah and I can't wait to seal that sucker up on Saturday and enjoy the new tune plus FMIC kit

 

[opusmonday]

Haha. Yeah and I can't wait to seal that sucker up on Saturday and enjoy the new tune plus FMIC kit

You're gonna looooooove it. Capital L. I had some boost loss due to the factory leaving loose boost clamps on the charge pipe-throttle body connection. From birth. Tightened those up and found the torque steer love with the stage two tune.

 

[dyn085]

As painful as I'm sure it was to drive, it's kinda neat to see so much ETC angle with non-existent boost. Fwiw, it looks like you have pretty decent fuel as well. Add the ignition corrections of the other three cylinders to your datalogging monitors; you'll want to know how well they all act together and if any one trends out in the future to be weaker than the other three.

 

[Rhinopolis]

F

As painful as I'm sure it was to drive, it's kinda neat to see so much ETC angle with non-existent boost. Fwiw, it looks like you have pretty decent fuel as well. Add the ignition corrections of the other three cylinders to your datalogging monitors; you'll want to know how well they all act together and if any one trends out in the future to be weaker than the other three.

As I am on mission to learn, would you mind please explaining why I need to monitor ignition correction on all the cylinders, what I need to watch out for, and also why you found it neat that I had as much ETC angle with a boost leak?

Feel free to point me in the direction of searching the forum or whatever other resources you know of where I can read about this stuff. Thanks for your time

 

[dyn085]

F

As I am on mission to learn, would you mind please explaining why I need to monitor ignition correction on all the cylinders, what I need to watch out for, and also why you found it neat that I had as much ETC angle with a boost leak?

Feel free to point me in the direction of searching the forum or whatever other resources you know of where I can read about this stuff. Thanks for your time

Monitoring all four cylinders is important in the beginning for a couple of reasons-mostly in the fact that if you have a weak cylinder or if the four don't play well together, you'll know. Once you've watched/logged all four to have an understanding of if any of them are statistically weaker, then you can drop three of them and only monitor the weakest cylinder. If they're not all showing basically the same corrections, you can also look into why and how to address it. You're basically looking for linearity and positive numbers, and if you're seeing non-linearity or aggressive negative numbers then you could have either a mechanical problem or an overly-aggressive tune (or bad fuel, or a multitude of other issues depending on the situation).

As an example, you'll see that most people monitor Ign Corr Cyl 1 in their datalogs and on the gauge. That's probably great for them, but in my FoST it's cylinder 4 that's the weakest and most prone to having issues. The only way that I know that is by having spent time monitoring and logging all four, so now I monitor cylinder 4 90% of the time because I know that if it's doing well then the others are doing well.

As for the ETC angle, it's not going to be funny to anyone but me I'm sure. If you're at 82 degrees ETC then your car is trying to give you full power, regardless of your accelerator input. Because you're not building boost your throttle plate is maxed trying to compensate. In the data perspective, it's just mildly amusing to see 82 degrees ETC and 0 boost because you don't see that that often. Or almost ever, really.

In the Self-Tuning/Datalogging section, I have a few write-ups that might be worth your time to read. Start with Datalogging-101 and it should basically lead you through the process as there are clickable links in all of them and it's a redundant system.

 

[rexdriver85]

If you see positive pressure then switch to map 1 and see if you have full-boost-there's always a possibility that the system just needed reset. Once the car is warmed up you should read -9.5 psi or less pressure at idle if you have a good seal. If you're reading higher (-9 or above) then you probably have a leak.

What exactly are we looking for here? I am assuming if the negative pressure is higher there could be a vacuum leak?

 

[dyn085]

What exactly are we looking for here? I am assuming if the negative pressure is higher there could be a vacuum leak?

Correct. Imagine sucking 3 psi worth of air through a straw, then imagine sucking that same flow rate (not the 3 psi) through a straw that you just cracked trying to get it out of the wrapper and now it's useless for the bottom 3" worth of drink. It's easier to draw through in the second scenario because there is another opening for which air can pass through. This effectively lowers the negative pressure within the tube, and also makes you drink the rest straight out of the cup.

In a normally-aspirated motor you would want to reduce the amount of negative pressure, so long as it didn't come post-MAF sensor. It's also the same principle that will allow a SRI to flow better than the exact same design that is maybe longer-the external air has less area to force itself through.

This gets complicated really fast when trying to discuss and while I understand the principle I can't explain it very well.

 

[rexdriver85]

Correct. Imagine sucking 3 psi worth of air through a straw, then imagine sucking that same flow rate (not the 3 psi) through a straw that you just cracked trying to get it out of the wrapper and now it's useless for the bottom 3" worth of drink. It's easier to draw through in the second scenario because there is another opening for which air can pass through. This effectively lowers the negative pressure within the tube, and also makes you drink the rest straight out of the cup.

In a normally-aspirated motor you would want to reduce the amount of negative pressure, so long as it didn't come post-MAF sensor. It's also the same principle that will allow a SRI to flow better than the exact same design that is maybe longer-the external air has less area to force itself through.

This gets complicated really fast when trying to discuss and while I understand the principle I can't explain it very well.

I do understand the concept you are getting at, what I don't get is the -9.5psi. Why is it that number specifically? See, all these little tidbits I pickup stick with me, so when I am out in the FiST and if/when I happen to see the negative pressure deviate from -9.5psi at idle, I'll remember this and know I have a possible vacuum leak.

Just trying to learn more from those who know more.

 

[dyn085]

Ah, I see what you were asking now. I've always been taught that a healthy engine will idle around 19-20 in hg, and so that's what stuck. I've never looked into it much more than that, quite honestly.

 

[rexdriver85]

Oh I see now where you were going. If you take 9.5psi and convert it to inches of mercury you get about 19.34.

So really anywhere between -9psi to -10psi at idle should be pretty good.

 

[dyn085]

Yup, exactly.

 

[Rhinopolis]

I finished resolving my boost leak (intake FMIC/charge pipe connection) yesterday, and this morning using the stage 1 91 octane tune I went on a long drive. I use 93 octane but want some margin in case of any bad gas. Maximum boost peaked at 21.62 psi and maximum estimated torque peaked at 250 lbs/trq.

I have the COBB FMIC with upgraded COBB charge pipes. The car at present at 770 miles on it. I also data logged two 3rd gear 1500-6000 pulls and will share the logs later on today.

The logging feature is great, and I am learning what to log and how to interpret the data. Thanks to dyn085 for some very useful post throughout the forum. Thank you.

Ryan

 

[Rhinopolis]

2015 FiST 770 miles, COBB AP OTS Stg 1 w/91 octane setting being run on Chevron 93 octane gas. I am concerned as knock appears on both of my logs shared below. Can someone please explain to me what might be happening and if this is normal? Also, cylinder 1 appears to be doing different things than the other cylinders on the correction monitor. How should I interpret what cyclinder 1 is doing and why?

Second 3rd gear pull after car had been run for at least 20 minutes and maybe longer

http://www.datazap.me/u/rhinopolis/6...a=4-8&mark=280

First 3rd gear pull after the car had been driven a little over 5 miles since cold

http://www.datazap.me/u/rhinopolis/6...log=0&data=4-8

Thanks,

Ryan

 

[dyn085]

Knock happens, but just because it does doesn't necessarily indicate anything bad. Maximum torque is located at the knock threshold, and occasionally we bump into it. Back before fuel injection made fuel delivery so much more precise, it wasn't uncommon to be driving next to a car that was pinging the entire time, so don't be worried about seeing the occasional blip because that's what the system is designed to see and protect us against. Definitely step up your tune and see how it goes as you're giving up a ton of timing with the 91 tune.

When it becomes a concern is when it's happening repeatedly or is resulting in high negative corrections-especially in the upper-rpm range. If you were running into either of those scenario's then it would be advisable to run a lower-rated tune. Neither of those appear to be the case here, so I wouldn't worry. I would note that you should probably ramp-into boost at that low of an rpm, and that punching it that hard, that low, could have been the main cause in that scenario.

If cyl 1 is a repeat offender, your first step is to pull your plugs and verify or re-gap them, and if they all check out then swap them around to see if the problem still exists in the cylinder or if it follows the plug. There's always the possibility that it is just temperamental, and if so there generally isn't much that can be done if a plug-swap doesn't take care of it. I haven't really seen those types of issues on the FiST though, but it doesn't mean that they don't exist-maybe the trend hasn't been established.

Your log list seems like an odd combo, btw.

 

[Rhinopolis]

What would you suggest me logging?

 

[dyn085]

Well, it really all depends on what you're logging/looking for. For general-purpose logs, I only log default parameters plus ignition correction on all cylinders. This is probably where I would (did) start until you get more familiarized with what you're looking at as it paints a whole-picture.

Outside of that, there's a wealth of knowledge once you start logging the correct parameters-of which I don't even understand the full breadth yet. Typically (if you were tuning) you would want to separate what you're evaluating into air, fuel, or spark (and I guess you could add turbo). You would then log the applicable parameters and adjust within that single area of the tune. Outside of general curiosity though, there's not much that you can really do with the info.

 

[Rhinopolis]

I just like to understand what's going on. Thanks for the explanation!

Ryan

 

[Rhinopolis]

Definitely step up your tune and see how it goes as you're giving up a ton of timing with the 91 tune

I uploaded the stage 1 93 this morning and will take your advice to ramp up my acceleration the next datalog that I do.