For starters, I already have an LT4 knock module but my mail order tune was not set up for roller rockers, headers, etc.

Is there anything additional I need to do in the tune to make sure I'm not getting "false knock".

I am picking up some knock here and there, and thinking about throwing in some 111 octane and see if it goes away. If it does then I know it was real, if not I'll just tune it out.

Next, I am only pulling a max of 80Kpa at WOT, why is this? I thought it would go to 100. Obviously something is causing it to still pull a vacum, how can I start chasing this down?

Then I am getting 40-41 deg of timing shown on the scanner at WOT, when the tune only commands 38 in the 75-80kpa area for that rpm....

The correction Spark Correction vs MAP vs Coolant Temp is zeroed out in the 80deg C row, and the engine was at 82.3C when I was did the log.

Here's the datamaster log if anyone wants to check it out.

Thanks for any help,

Greg

 

In doing some reading looks like other at my altitude only see 80Kpa max at wot so that makes sense.

That doesnt explain what is modifying the RPM to read much higher than what is commanded. I'll throw up a few screen shots...

 

It shows higher timing in the logs because thats part of the lt1 pcm firmware. It adds timing incrementally as rpm increases above about 3000rpm. Imo you have to much timing especially when you consider that you're only at 80kpa wot.

 

Thanks for the reply. Any ideas on. What I should pull it back to? Was thinking 1deg and relog

 

In looking at this more I have compared it to a few stock files and the timing at 80kpa is stock...

The modifiers in the spark correction vs coolant temp table are a little different but they're also the same at 80deg C where the engine runs.

It has been brought to my attention that I have B body tables in there, so I was gonna rewrite my tune starting over with a stock F body calibration file, but I really dont see where this will help considering the stock file has the same timing in that area of the map.

Is there something I'm missing?

 

Timing varies on every motor. You already know my answer but find out where it makes the most power on the dyno while still being safe.

I have tuned one lt1 that actually liked 40-41 up top. Most are not that high. I do not have any experience at your altitude.

 

The part your seem to be missing is that the timing being added vs rpm is hard coded in there is no table for it it cannot be changed that I have seen.

I would just pull the timing back 2 degrees at a time across the 80kpa column from 2500 on up and do the same on all columns to the right and one column to the left of it. I would not dial it in below about 36 degrees max on datamaster. What you will end up with to have steady timing at high rpm is the numbers will get smaller as the rpm increases above aprox 3000. Although without a dyno or drag strip I dont know how you're going to determine max power, all you can do with what you have is get rid of indicated knock/retard which really there should not be at high altitude with a mildly modified engine anyway.

If you have a way to post the logs and the tune it would really speed things up since i could look at what you have instead of you looking and telling me what you see.

 

I understand that, I was just thinking it was odd that a stock tune at 80kpa would be causing KR, esp at my altitude. It does though.

The part of the spark at 85 or less kpa was STOCK in my mail order and was causing 41-42 deg at WOT and a good amount of knock retard.

The way I plan on arriving at what timing to set it is both dyno tuning and reading the plugs.

I updated the tune based on a stock F body file, like it should have been in the first place. I kind of reshape the curve with the understanding that 80kpa is my WOT and lowered the tables down to read 39 indicated on the scanner and no KR. Not saying that's where I'm going to leave it, just that it runs great and pulls smooth with this tune and zero KR.

Here's the tune if you want to give it a look and make any suggestions. I'll datalog the new tune more and post that when the roads clear up, slick and snowy out there right now but I did get to go WOT in 3rd and 4th and no KR at all...

http://forddieselpower.com/grfiles/gregbase.bin

 

I'd like to chime in if you don't mind.

Mail tuning is a big ripoff! I went through the same thing awhile back with my PCMforless mail order. Once I realized the car felt slower after installing my mail order, I got curious and decided to give tuning a try. Downloaded datamaster, reset PCM, put 50 miles on the car, then logged. I was getting 10+deg of retard at 4000rpm and hence the car was a dog up top. Next step was to download Tunercat to see what the hell was going on. Got a autometer wideband on order and spent the next few weeks reading everything I could on tuning these machines.

To make a long story short, I asked for these things to be in my mail order tune-
5200ft altitude, intake/full exhaust, modified MAF, delete emission SES codes, 3.73 gears, fan on at 180. I downloaded the tune in the car to the laptop and this is what I found- a couple constants/switches had been clicked for SES/fans/gears, my AFR was targeting 12.6 til 4k, 12.8 to 5k and 13.2 to 6k rpm (why would you REMOVE fuel with more RPM !?!), and ONLY 100kpa timing values were set to 35. Every other table was still just as stock, including my MAF tables.

Just like you, I see around 80-85kpa at WOT. Those timing values were still 37-39, so the car was trying to run 41-42deg advance. With the modified MAF and no update done to the MAF tables the car was hitting 13.4-13.6, obviously too lean. I set my 80-85kpa timing tables to 35, changed AFR to 12.8, and borrowed a stock MAF- sure enough most of my timing retard went away, still getting traces in logging from the LTs and RRs (I'm assuming). The ported MAF would work fine too with some tweaking of the MAF tables, didn't waste the time trying though.

A stock tune will not knock with 39-41deg in higher RPM because target AFR is set pretty rich, roughly 12.6-11.7.

Reading plugs and dyno tune will help you squeeze the most out of it, but I highly recommend putting in a wideband too. Very helpful tool.

 

Removing fuel beyond peak tq is a common practice and is actually desirable in many cases because it will increase hp beyond peak tq. Of course you also should be adding to fuel after peak hp to help out with shift recovery.

The rest of that mail order tune story sounds about right, and a ported maf usually takes anywhere from .5-.8 ratio richer target to get what you want. The dirty secret of tuning is that many maf cars would run decent on a stock tune with only the idle and idle timing turned up due to the way the car functions; sadly the mail order tuning customer generally has neither the knowledge or the tools to figure this out and the majority of the time never attempts to run on the stock tune at all.

Some things to keep in mind with the knocking is that gm did not develop their cal with an older and worn engine with carbon deposits. Also keep in mind if you have changed the camshaft you have improved the cylinder filling at those levels; where the stock cam is starting to have trouble filling the cylinder and as a result you're seeing more power/pressure and thats causing knock issues.

 

Thanks for chiming in! Interesting that you've been down the same road.

I have talked to another well-respected mail order tuner and was simply told "it will correct itself for altitude, nothing needs to be changed". BS!

You and I both know that is simply not the case, [i]especially[/b] with regard to the spark tables. In fact the tune gets more aggressive because we never make the transition through the part of the table at 80 kpa and on to "WOT" like the sea level guys do, because our "WOT" IS 80 kpa lol.

I'll post a log of a 1/4mi run here in a second so you can check it out. Hit my current tune to and let me know what you think.

 

WS6, all good feedback. I appreciate it all. The point you made about more efficiently filling the cylinder with the cam (and other engine mods) is spot on, and will help me with my tuning from here on out.

I also know exactly what you mean about the part in bold. I couldn't believe how much of a difference simply tuning the idle in my car made in terms of throttle response and just the whole feel of the powerband was smoother and more crisp. Idle and low / part throttle tuning is huge.

Here's a copy of a 1/4mi log I did tonight. Wasn't really on a drag strip, but I just ran the car out the back like it feels on the track, and turns out I was right on. It traps 100 and I let off at exactly 100 lol.

Here's the log, any suggestions or comments you might have are appreciated.

http://forddieselpower.com/grfiles/log3.uni

 

Set your 75kpa-85kpa timing the same in the upper rpm ranges, your map is not giong to be 100% stable at wot and the pcm interpolates between the values based on map to figure out what timing so if they are the same timing will be rock solid instead of bouncing around like it does. Everything else seems to be just fine as far as I can tell. Nothing looks wacky to me. For future reference turn the speed that it takes records at up as high as possible (shortest record) so you get the maximum amount of data since things are happening quickly where you're doing your testing. Car is moving ok air mass when you consider the altitude. I cant comment on rich or lean at wot with any certainty with narrow bands but from what I see you aren't going to hurt it with the tune you have in it.

If you make a simple change to the idle spark overspeed and underspeed tables you can make the idle more stable if you want because timing wont be bouncing around. You can search my name here and find info on doing that. I'm too lazy to type it up yet again.

 

I'll adjust the timing like you said and see how it runs. I agree it should stabilize it as it moves from the 75 to 80 columns.

I'll search your posts for the idle tuning.