Quick question about cruising speed timing for L67

[e85grandprix]

Honestly I'm not sure how much to tell you to add with E85. I know with gasoline, running 26* at WOT is not real good. Anything over about 21-22* offers no gains for for those that can even get that high.

yea, tis ok with e85. Car pulls like a monster, and its working very well, best trap of 105.8 with simple bolt ons. Couple cammed cars i was with barely trap that. What timing are you running during cruising? Do you take the same route as wot, add until you see knock and back off 2-3, but eventually stop at 40?

[Eddie-98GTP]

http://www.hptuners.com/forum/showpo...30&postcount=2

I run about 15-16* WOT right now, but I'm running 87 octane.

[japslpr]

Eddie,
I have the 2005 timing tables, but should I wait to put those in until after I finish with my VE tune? Will bumping the timing in the cruise area affect the VE tune?

Currently my timing tables are stock running 26-29* crusing.

[Eddie-98GTP]

Will bumping the timing in the cruise area affect the VE tune?

It might. I'd wait until you finish tuning your fuel tables before messing with timing anyway. I'm a fan of the "one change at a time" method (even if I don't do that a lot of the time )

Did you reset your timing tables before the VE tune? I'm surprised with the mods in your sig that you're running stock timing.

You'll like the 05 tables, big difference from the 99.

[japslpr]

Did you reset your timing tables before the VE tune? I'm surprised with the mods in your sig that you're running stock timing.

This is the first time I have got to try to mess with all these tables. First time I have attempted tuning myself. Most of my PCM's were box tunes. So I got a lot to learn, but I have a good idea about it and I have been doing tons of reading.

It kinda goes with my profession to learn this stuff.

[starks]

Eddie98gtp...


how come you skewed your cylinders fueling?

[Eddie-98GTP]

I flow tested the injectors and skewed them based on the results. This is the average each injector flowed in cc's., I tested this using an injector tester set to pulse the injector for 10ms for a total of 400 ms. I used the fuel pump in the car to provide pressure.

These are the results of the injector flow test...

1 - 34.5
2 - 35
3 - 33
4 - 35.5
5 - 34.5
6 - 32.5 <- I tested this one 4 times to be sure it was really that much lower

[starks]

So much for flow matched out of the box huh?

makes since. im going to try using the 05 GTP AE tables, and your timing tables to see if i can see any difference in mileage.

the AE tables were ALOT different then the tables i had...ill give it a try though.

[Eddie-98GTP]

Well, they were not flowmatched injectors. That may not have been the most scientific way of measuring injector flow, but it seemed like a good idea at the time

[IndeedSS]

Bringing this back up. Eddie, are you still runing 40+ timing in the crusie cells and are you still getting the good mpg you once were? I noticed you recommended mctrusan only bump his timing 1-2*. May I assume to just start at 40 is a bad idea? I only ask because a lot of your cells are well beyond 40.

[Eddie-98GTP]

Are you talking about this...

I would raise the timing in 1-2* increments in the 1400 to 2800 RPM range and .12 to about .44 g/cyl range for cruise. 5* increments are a lot, I would not try that although you may enmd up being able to raise your cruise timing as much as 10*.

I would raise timing in smaller increments than he as going to. He was talking about raising timing by 5* at a time, I think that's too much of an increase in one shot to be safe. He (or you) may be able to do it, but I would rather make smaller changes.

As far as my timing, I have not touched my high octane spark table in a long time, except for the WOT areas when I ran lower octane fuel. I don't get on the highway much, so I really can't comment on my fuel economy there,but I get about 18 in town with a LOT of stop and go traffic. My average commute is about 23-25 miles and takes about 45 minutes with an average speed of about 25 MPH.

IIRC, I was getting about 25-27 MPG on the highway running 70 MPH. If I ran over 80 my mileage increased to about 29. That's not fantastic, but as I said I don't really get on the highway so I have not really tuned this area as much as I would have if I drove on the highway more. All in all I'm OK with the fuel economy. I'm running about 75 HP above and 2 seconds faster in the 1/4 over stock and getting the same 18/27 that was advertised on a stock 98 GTP.

[murphinator]

I have found that my car cruises effortlessly with extra timing in the cells i cruise at , I commute over 1,000 miles a week mostly between 70-75 mph

it is unbelievable how little throttle input is needed to climb a slight grade where before the convertor may unlock to climb the same grade.

disregard my timing at wot though as i had to de tune my timing to get rid of some KR due to my powerlog cracked and I am temporarily on a stock front mani as well as my stock catback during the winter to save my 3" hogan from the salt with a 3.5 pulley

I added 5* ar first but once kr started showing up I cut back to 2* at a time and stayed away from the areas that i knew kr had shown up

basically highlight a group of cells in the area your timing histo revals you are spending a lot of time driving in by clicking on th "C" (counts) which shows how many times you hit that cell during your log , I always scan after any changes with a HUGE kr guage to the left margin (about 2" wide by 6" tall ) with alert set to 2*

I used copy with labels on the max kr histo then paste special subtract in the high octane table to get rid of the kr in those cells

[IndeedSS]

Eddie - Yes, what you quoted was what I was referring to, thanks. Your results are very good.

Murphinator - good info. I get acceptable mpg but was also interested in correcting the low TPS low RPM response. Your info and table will likely be helpful.

[murphinator]

Murphinator - good info. I get acceptable mpg but was also interested in correcting the low TPS low RPM response. Your info and table will likely be helpful.

I havent noticed a significant gain in mpg , but I started working on this right at the time we start getting the crappy winter blend gas here in new england and cold temps which will cause longer warm up times and command higher afr's

the change in light throttle response though was worth the effort

[IndeedSS]

I messed with this quite a bit over the weekend and finally got to test it out on the stretch of road I travel 10 times a week. Basically I took the cruise range from ~30 to 40*. I saw no real gain in mpg and could tell no difference in throttle response.

I thought it a nice experiment, however, I've read multiple places not to adjust timing based on knock sensor(s) input. Needless to say advancing the timing even this far seems risky without appropriate means to very engine health.

Other than those that say, "I've done it without any problems", is there any real data showing where this is safe and actually is making the most power? There is another thread discussing the max torque timing table (MBT). As I understand it this is the lowest amount of timing required to achieve the max power. The numbers being changed in the cruise range are well beyond the MBT table, even if it's theoretical, and therefore a bit of a concern.

[murphinator]

I have only increased timing down low based on others doing similar on vehicle specific forums.

if you go too high in cells it will cause KR.

I am all ears if it has any negative impacts that can be substantiated as you are suggesting with some type of difinitive data

as for me feeling the light throttle difference maybe its the placebo effect ?

[bilemke]

You can discuss a change being safe all you want.. How many people here do long term studies of any onecange they make to the PCM in their cars and can say it is for sure "safe"?

The MBT table has been noted as a mean for calculating a theoretical value that is used for torque management.. Right off the bat, we know that is not intended to be a limit. Go grab a 04+ GP GTP file.. You will notice the stock High Octane spark table is quite a bit higher then the stock MBT table in several cells.

Concerning spark, there are other changes I would be more concerned about that seemed to be considered safe by a few (reducing the knock attack rate or increasing the recovery rate because it is supposedly false knock).. Notice GM didnt really change these values over the years..

Just look at the variation in people trying this timing advance change.. How do you know it will be "safe" or lead to "good" results for the variation in hardware (parts) that so many of you are running. However, GM changed it in a stock 04 and 05 and I imagine that much timing advance was not simply a slip of the hand.

[IndeedSS]

The differences are only really big in a couple of areas. This is a 04 series II and a 04 series III compared.

[murphinator]

You can discuss a change being safe all you want.. How many people here do long term studies of any onecange they make to the PCM in their cars and can say it is for sure "safe"?

The MBT table has been noted as a mean for calculating a theoretical value that is used for torque management.. Right off the bat, we know that is not intended to be a limit. Go grab a 04+ GP GTP file.. You will notice the stock High Octane spark table is quite a bit higher then the stock MBT table in several cells.

Concerning spark, there are other changes I would be more concerned about that seemed to be considered safe by a few (reducing the knock attack rate or increasing the recovery rate because it is supposedly false knock).. Notice GM didnt really change these values over the years..

Just look at the variation in people trying this timing advance change.. How do you know it will be "safe" or lead to "good" results for the variation in hardware (parts) that so many of you are running. However, GM changed it in a stock 04 and 05 and I imagine that much timing advance was not simply a slip of the hand.

so do you (Bilemke) feel it is or is not OK to increase timing in low load areas of the high octane tables provided you eliminate any areas with knock that might appear ?

or is there something else that should be the determining/limiting factor in the adding of timing in cruise areas that this thread has yet to discuss ?

[IndeedSS]

I have only increased timing down low based on others doing similar on vehicle specific forums.

if you go too high in cells it will cause KR.

I am all ears if it has any negative impacts that can be substantiated as you are suggesting with some type of difinitive data

as for me feeling the light throttle difference maybe its the placebo effect ?

Your throttle response results may be, like mentioned above a result of your mods versus mine.

I'll see if I can find the book reference about tuning in areas not as prone to KR. I'm not saying this is right or wrong because I don't know the answers.