Help Me Understand Timing

[DirtyD]

With the help of Dad (Brent) a couple of weeks ago, he helped me to put together the general pieces of the tuning puzzle for any car. I was very appreciative of this.

After running some more logs on a revised tune, my car is still pulling up to 3 degrees of timing from the knock sensors, ending up around 21-22° of final timing. The AFRs seem to be staying relatively spot on, however.

I know that air temp, fuel octane, and other factors influence the car pulling timing to protect itself, I just don't know the details on why/how.

I'm looking for help to further expend my understanding of this stuff, and to know whether I am still okay running my car hard in the colder weather now that it's hear, and that nothing will happen.

[McNastyGT]

Your good as long as you are not getting any knock

[DirtyD]

Your good as long as you are not getting any knock
Well it's hard to tell sound wise when I'm rolling the car up to 7k....

[wbt]

Your good as long as you are not getting any knock

That's not very helpful.....

He is getting knock which is why his car is pulling timing.

There are a few things to consider when discussing timing:

1. Quality of fuel being used
2. Commanded timing
3. Detonation
4. Cylinder pressure

Certainly not the whole picture but most of it.

Basically what happens is you command a certain amount of spark advance in the tune which can be RPM based. There is also a global spark advance modifier that works towards overall timing. When you hear of someone taking a few degrees out running nitrous for example, they are doing so on a global scale generally.

The knock sensors work to detect detonation. If they detect it, spark advance will be reduced and then ramp back in when it is back under control. Knock sensors can also allow timing to be added in vs. just for reduction.

Using a fuel such as e85 will allow for a greater amount of timing to be used as it is highly resistant to pre-ignition causing detonation. There are much deeper conversations that can be had about e85 and it's ability to resist detonation.

Then comes the whole discussion on octane rating and fuel. IMO you want to use the lowest octane fuel possible before detonation occurs. This ensures a more complete burn.

Cylinder pressure and dynamic vs. static compression have a lot to do with the detonation, timing, fuel discussion as well.

Not a cookbook by any means but a high level overview of what is happening.

[DirtyD]

I've filled up with 93 octane from 2 different Shell station in 2 different cities, and both datalog sessions showed up to 2.5-3° of timing being pulled from the knock sensor. This was denoted by a positive value under the knock sensor category. All the AFR were in check with what was being commanded.

I sent the datalogs to me tuner, who is one of the best ones in the Coyote platform (not AED), and his email back to me said that everything looked good and made small tweaks.

Both of these logs have come in colder temperatures than what my car was datalogging in the beginning, 65-75° now versus 80-85° before. Can that possibly be causing the issues?

I just want to know that my car is safe to drive hard, and that I won't screw anything up.

I will gladly forward someone my datalogs to look into if you supply an email.

[wbt]

I've filled up with 93 octane from 2 different Shell station in 2 different cities, and both datalog sessions showed up to 2.5-3° of timing being pulled from the knock sensor. This was denoted by a positive value under the knock sensor category. All the AFR were in check with what was being commanded.

I sent the datalogs to me tuner, who is one of the best ones in the Coyote platform (not AED), and his email back to me said that everything looked good and made small tweaks.

Both of these logs have come in colder temperatures than what my car was datalogging in the beginning, 65-75° now versus 80-85° before. Can that possibly be causing the issues?

I just want to know that my car is safe to drive hard, and that I won't screw anything up.

I will gladly forward someone my datalogs to look into if you supply an email.

Sending you a PM with my email address. I make no promises or guarantees but will look over it.

[JDBishopArts]

I'd try a different brand gas.

I've seen some cases where 93 with additives doesn't act like 93 without. Try it and see what happens. Your car should not be pulling that much timing. Doesn't sound like you're trying to give it too much timing. Try QT gas. Very high quality, the turnover in the gas in the tanks is good.

[DirtyD]

I'd try a different brand gas.

I've seen some cases where 93 with additives doesn't act like 93 without. Try it and see what happens. Your car should not be pulling that much timing. Doesn't sound like you're trying to give it too much timing. Try QT gas. Very high quality, the turnover in the gas in the tanks is good.
I've never had issues with shell before, but I will try another brand next tank and log what I find.

As far as I know, I should be commanding around 25° or so...

I ran QT gas a few times and it didn't go over well...

[re-rx7]

Chevron exxon/mobil. Wbt pretty much hit the nail on the head.

[JDBishopArts]

Stock plugs? Did you gap down?

[JDBishopArts]

And I don't know much about the correct timing for NA 5.0s but isn't 25 a bit high? I thought most were around 20-22 and the race tunes were 23-24. I'd either get another tune or back the timing off till it stops knocking. Some cars act different than others.

[TrueStreetTim]

I worked with aviation fuel for 9 years. Shell was the bastard son of fuel in that industry as well. It's funny that folks that feel they may have a fuel issue.....buys from Shell.

[wbt]

I have used Shell fuel for years without issue.

Fuel from the local Exxon comes from the same refinery as the local Shell station. The differences are the additives used.

One thing to be on the lookout for is general age of said gas station. I don't buy gas from an older facility. Jobbers can mess up and put the wrong fuel in the wrong holding tanks as well. It happens more often than one might think.

Find a station of your choosing and monitor logs periodically to see how the car is doing.

DirtyD's problem isn't fuel. He has too much timing in his tune for the fuel he is using. My recommendations via PM were to reduce timing and richen it up a hair.

[46Tbird]

Shell is fine, QT is fine. Stay away from RaceTrac gas.

http://www.toptiergas.com/retailers.html

[DirtyD]

Stock plugs? Did you gap down?
I've never so much as touch the COPs with my fingers, let alone taken the plugs out. LOL

[DirtyD]

Stock plugs? Did you gap down?

And I don't know much about the correct timing for NA 5.0s but isn't 25 a bit high? I thought most were around 20-22 and the race tunes were 23-24. I'd either get another tune or back the timing off till it stops knocking. Some cars act different than others.
I've spoke with other people, and 25-27 is used a lot in tunes that are "track tunes" for people, but that is very aggressive. I originally had 22-23° of timing before I asked Kevin @ JPC to bump it up a little bit. He said it may hit the knock sensors, and it appears he was right. I'm getting back in touch with him shortly.

I have used Shell fuel for years without issue.

Fuel from the local Exxon comes from the same refinery as the local Shell station. The differences are the additives used.

One thing to be on the lookout for is general age of said gas station. I don't buy gas from an older facility. Jobbers can mess up and put the wrong fuel in the wrong holding tanks as well. It happens more often than one might think.

Find a station of your choosing and monitor logs periodically to see how the car is doing.

DirtyD's problem isn't fuel. He has too much timing in his tune for the fuel he is using. My recommendations via PM were to reduce timing and richen it up a hair.
Thanks again for looking them over, wbt.

Shell is fine, QT is fine. Stay away from RaceTrac gas.

http://www.toptiergas.com/retailers.html

RaceTrac is just nasty period. Their drinks from the soda fountain aren't even good. I would never buy gas from them.

[JDBishopArts]

My recommendation is get Kevin @ Dunn Tuned to tune it. haha

My Dad was an petrol engineer for Exxon. While yes, most of the petroleum comes from the same place, the refining process and additives each gas producer adds are much different.

Most tuners prefer Exxon/Mobil, BP and QT gas. A lot of people having tuning problems were using Shell gas.

I learned a lot of this because when I went to tune my old Cobra at Gearheads I had filled up with Shell and it was pinging really bad. Luckily there wasn't a ton of fuel in there. We drained it and I filled up with QT and there was no problems.

Ford even recommended BP gas for years. I think they still do.

[DirtyD]

My recommendation is get Kevin @ Dunn Tuned to tune it. haha

My Dad was an petrol engineer for Exxon. While yes, most of the petroleum comes from the same place, the refining process and additives each gas producer adds are much different.

Most tuners prefer Exxon/Mobil, BP and QT gas. A lot of people having tuning problems were using Shell gas.

I learned a lot of this because when I went to tune my old Cobra at Gearheads I had filled up with Shell and it was pinging really bad. Luckily there wasn't a ton of fuel in there. We drained it and I filled up with QT and there was no problems.

Ford even recommended BP gas for years. I think they still do.
But then how can Shell produce a inferior consumer gas but make one of the best race gases in the industry (URT)?

I've tried a few tanks of QT in my car, and the last one I did gave me horrible mileage, so I didn't go back. That could've been a number of factors, but who knows.

The guys at JPC have been great working with me, so that's why I'm giving them my business. I'm hopefully going to have Kevin tune it when I convert to corn, but I'll stick with them for now.

I'll try another gas next go around this weekend when I head down to Austin for a JDRF walk.

[JDBishopArts]

It's not that it's an "inferior gas". It's good fuel for normal cars. Not tuned performance cars. From what I read and have heard from 2 tuners they think it has something to do with the additives. Most tuners don't like it because it causes knock retard. Same thing you're experiencing. Look it up. You'll see tons of cases where people are having knock issues and using shell gas. They switch and it goes away.

There are very few things that can cause knock retard. But if you're commanding a certain degree of timing and the car is pulling it in my experience it can only be fuel or heat. It's not hot so that leaves fuel.

[JDBishopArts]

Buy Exxon. We have a lot of Exxon stock. lol.

[wbt]

So for the armchair quarterbacks who haven't seen his logs, explain to everyone how you have his issue nailed down to bad fuel. Basically you guys are guessing at the issue but have no data to back it up with. Just Internet hearsay. Makes sense.

[DirtyD]

As far as I'm aware, I wasn't pulling timing on the previous tune revisions and datalogs prior to the temperatures changing around here. But, I was not monitoring KS. Brent reviewed one of the logs in the warm air time period and said everything looked pretty good. These problems didn't surface, to my apparent knowledge, until I started doing these logs in cooler weather.

I'm going to switch to another gas this weekend and see what the logs show.

But I wonder if the whole nitrogen additive that SHell uses is partly to blame...lol

[JDBishopArts]

So for the armchair quarterbacks who haven't seen his logs, explain to everyone how you have his issue nailed down to bad fuel. Basically you guys are guessing at the issue but have no data to back it up with. Just Internet hearsay. Makes sense.


lol This guy.

I'm trying to help him find a solution based off of the information I was given by Derek.

It's not internet hearsay. It's fact. Backed up by a million Elvis's.

Never said I had it 100% nailed down to fuel. It's a good place to start. There are a few things that can cause knock retard. Fuel being one of them. Shell gas caused knock retard on one of my own cars.

Cooler weather also means more dense air which means it can lean out a car which could also cause knock. Unless it's on a poor tune it shouldn't go so lean due to colder air to cause knock, which would also indicate fuel.

Either way, just trying to help a guy out with a problem.

[DirtyD]

lol This guy.

I'm trying to help him find a solution based off of the information I was given by Derek.

It's not internet hearsay. It's fact. Backed up by a million Elvis's.

Never said I had it 100% nailed down to fuel. It's a good place to start. There are a few things that can cause knock retard. Fuel being one of them. Shell gas caused knock retard on one of my own cars.

Cooler weather also means more dense air which means it can lean out a car which could also cause knock. Unless it's on a poor tune it shouldn't go so lean due to colder air to cause knock, which would also indicate fuel.

Either way, just trying to help a guy out with a problem.
I appreciate the help Josh.

[BERT]

So for the armchair quarterbacks who haven't seen his logs, explain to everyone how you have his issue nailed down to bad fuel. Basically you guys are guessing at the issue but have no data to back it up with. Just Internet hearsay. Makes sense.



It's the American way

[46Tbird]

Ford even recommended BP gas for years. I think they still do.

Pretty sure this message was in the gas tank of every S197 Mustang up until the 'incident' in the gulf.

http://www.allfordmustangs.com/forums/attachments/2005-2010-mustang-talk/12398d1132509133-bp-ad-gascap-06-stang-gas-cap-002.jpg

[kdanner]

But then how can Shell produce a inferior consumer gas but make one of the best race gases in the industry (URT)?

It had their name on it, but they didn't make it. It also no longer exists. All that spamming of forums constantly and they still couldn't keep that program going.

I've had my best luck with Exxon. BP is good too but nearly nonexistent here. HEB has some nice E85 that always tests 85 to 90% here.

[TrueStreetTim]

I have used Shell fuel for years without issue.

Fuel from the local Exxon comes from the same refinery as the local Shell station. The differences are the additives used.

One thing to be on the lookout for is general age of said gas station. I don't buy gas from an older facility. Jobbers can mess up and put the wrong fuel in the wrong holding tanks as well. It happens more often than one might think.

Find a station of your choosing and monitor logs periodically to see how the car is doing.

DirtyD's problem isn't fuel. He has too much timing in his tune for the fuel he is using. My recommendations via PM were to reduce timing and richen it up a hair.

Ditto. Probably the best thing you can do (regardless of refinery/company) is to use the more crowded stations. Stations off the beaten path dont get as many deliveries and fuel sits longer etc.

[DirtyD]

It had their name on it, but they didn't make it. It also no longer exists. All that spamming of forums constantly and they still couldn't keep that program going.

I've had my best luck with Exxon. BP is good too but nearly nonexistent here. HEB has some nice E85 that always tests 85 to 90% here.

We only have one HEB up here, but no E85. Hell, back in Houston is don't think many or any of the HEBs have E85.

Kroger is always good for E85 when you find a station that has it.

Opinions on Kroger gas? I'm running a tank right now and might see what my logs tell me.

[BV600]

It had their name on it, but they didn't make it. It also no longer exists. All that spamming of forums constantly and they still couldn't keep that program going.

I've had my best luck with Exxon. BP is good too but nearly nonexistent here. HEB has some nice E85 that always tests 85 to 90% here.

A friend that runs E85 here tested the HEB here and I believe it was 94%, and its like 60 cents cheaper than the other option around here which test lower.

[KungFuHamster]

Something else to think about D, is just because you're having to pull timing doesn't necessarily mean you're losing power...the opposite is true.

If you're running too much timing and the knock sensors are pulling timing, then you are losing power. You want the car to run to where it makes as much power as it can without any knock. Most cars I've had made more power with less timing. Every car is different.

[Dan12GT]

Although I don't have a custom tune I fill up with QT gas almost 90% of the time. I get great gas mileage, usually averaging 22-23mpg on normal driving highway/city. I too stay away from Shell, one because its so damn expensive, and two because of the things Tim and Josh are talking about.