99 L29 454 build

[L31MaxExpress]

It's confirmed, I am a moron. I just realized I can open the data log on the efi live scan tool app and see the numbers myself. That same run has a peak airflow of 25 lb/minute. At 12:1 afr, thats about 2 pounds of fuel per minute, so a gallon would last a little over 3 minutes. At 60 mph it would go 3 miles in 3 minutes for 3 miles per gallon! Another way to look at it is 2 pounds per minute is 120 lb/hr. Divide that by 8 gives 15 lb/hr per injector, which confirms the 36 lb/hr injectors were running at 40% duty cycle. This is fun!

Be happy, lol. At 70+ mph in 2nd gear my 383 can drop to 2~ mpg when it is really pulling hard.

 

[Scottm]

My ecm is on the way back from black bear. They did add 3 deg of timing at cruise and wot. They said I may have a vacuum leak due to fuel trims doing things at idle and deceleration.

 

[Scottm]

Ecm with new tune installed and tested today. They fixed 2 out of 3 things. First the hard starting is cured. It had something to do with the idle air control. The very first start was rough and it surged up and down til it found the happy IAC setting. All other starts were great. So I took it for a drive and a data log. The first pic is of a cruise moment, 53 mph, showing a big boost in part throttle timing as I requested, now 35 deg. The second pic is a full throttle moment - 4,200 rpm, 57% injector duty, etc, but still only 23 deg of timing. I said at wot, I wanted 30 at 3k, and a max of 34 by 3500 and up. They didn't fix that. Is there a reason? Are they trying to protect my trans? Or did they forget? I will write them tomorrow.

There is something else weird though. Notice the MAP numbers. At cruise, it says 47 in hg, and at wot it says 89 inches. That's impossible, full atmosphere is 27 inches. Plus it's actually moving backwards, it should be low at wot and high at cruise. But the ecm is doing everything else right, like advancing timing at cruise and reducing it at wot. What is going on? Could I have wired the map backwards?

 

[Scottm]

Also the wot run shows 32 lb/min air and 57% of 36 lb/hr injector duty. That fuel equals 164 lb/hr. I have a chart in a Holley book somewhere that shows a graph of hp vs fuel burn.

 

[Scottm]

A quick search shows the hp estimate is easy. Brake specific fuel consumption for a gasoline engine is typically .4 to .5 pounds per hour per horsepower. So that moment at 4,200 rpm and 164 lb/hr at .5 lb per hp/hr means 164/.5 = 328 hp at the crank. That could be right. Now a healthy, modern efi engine (got that) could be tuned to run leaner, since the knock sensors will prevent damage from detonation. So if my engine could get to a bsfc of .4, the power at that moment would be 164/.4 = 410. I'm going to get a chassis dyno run on it some day. I would love to see 350 at the wheels at 4800-5000.

 

[Supercharged111]

It runs what it runs. Who cares what the number is? Whatever it is, it's not 350 wheel.

 

[Scottm]

I keep going around with BB on the timing issue. They insist 22 is the right amount at wot, and what I want, 34, would be immediate engine destruction. Nonsense. Carbed engines with stock heads and wandering conventional distributors can run 34 no problem. Guy said the stock L31 350 van tune is only 16 deg wot. Can anyone confirm that? If that's true, it has to be to reduce emissions and maybe protect the trans from idiots driving fleet vans around full throttle.

 

[Supercharged111]

I keep going around with BB on the timing issue. They insist 22 is the right amount at wot, and what I want, 34, would be immediate engine destruction. Nonsense. Carbed engines with stock heads and wandering conventional distributors can run 34 no problem. Guy said the stock L31 350 van tune is only 16 deg wot. Can anyone confirm that? If that's true, it has to be to reduce emissions and maybe protect the trans from idiots driving fleet vans around full throttle.

Are you logging for knock? If you can provide him datalogs with zero knock I can't see a reason in the world he wouldn't be willing to bump you 2 degrees at a time.

 

[BeXtreme]

Ecm with new tune installed and tested today. They fixed 2 out of 3 things. First the hard starting is cured. It had something to do with the idle air control. The very first start was rough and it surged up and down til it found the happy IAC setting. All other starts were great. So I took it for a drive and a data log. The first pic is of a cruise moment, 53 mph, showing a big boost in part throttle timing as I requested, now 35 deg. The second pic is a full throttle moment - 4,200 rpm, 57% injector duty, etc, but still only 23 deg of timing. I said at wot, I wanted 30 at 3k, and a max of 34 by 3500 and up. They didn't fix that. Is there a reason? Are they trying to protect my trans? Or did they forget? I will write them tomorrow.

There is something else weird though. Notice the MAP numbers. At cruise, it says 47 in hg, and at wot it says 89 inches. That's impossible, full atmosphere is 27 inches. Plus it's actually moving backwards, it should be low at wot and high at cruise. But the ecm is doing everything else right, like advancing timing at cruise and reducing it at wot. What is going on? Could I have wired the map backwards?

Those numbers would be right for KPa, which is normally what you would be reading MAP in. The MAP reading is an absolute pressure reading, which means it does not read relative to atmospheric pressure. 14.7PSI is standard atmosphere, which is roughly 101KPA of pressure. So if you are at sea level and full throttle, you should have roughly 0PSI of vacuum in the manifold, which means it is roughly atmospheric pressure, which means the MAP should be reading close to atmospheric pressure(100KPa). If you have the throttle closed and the engine is creating a vacuum in the manifold, you would need ~14.7PSI(~30 in/hg) of vacuum for the absolute pressure to read 0 KPa at sea level. That's a huge amount of vacuum and I've never seen an engine get close to there unless the throttle is fully closed and it's decelerating(being back driven by transmission).

My guess is that you were at 47KPa MAP reading at cruise. I was just tuning my VVE on my 2011 Suburban last night and MAP was sitting around 20-30KPa at idle. It dropped lower than that only while decelerating and got up near 100KPa at full throttle. I'm at 200ft elevation and it was ~40 deg F at the time.

 

[BeXtreme]

Ecm with new tune installed and tested today. They fixed 2 out of 3 things. First the hard starting is cured. It had something to do with the idle air control. The very first start was rough and it surged up and down til it found the happy IAC setting. All other starts were great. So I took it for a drive and a data log. The first pic is of a cruise moment, 53 mph, showing a big boost in part throttle timing as I requested, now 35 deg. The second pic is a full throttle moment - 4,200 rpm, 57% injector duty, etc, but still only 23 deg of timing. I said at wot, I wanted 30 at 3k, and a max of 34 by 3500 and up. They didn't fix that. Is there a reason? Are they trying to protect my trans? Or did they forget? I will write them tomorrow.

There is something else weird though. Notice the MAP numbers. At cruise, it says 47 in hg, and at wot it says 89 inches. That's impossible, full atmosphere is 27 inches. Plus it's actually moving backwards, it should be low at wot and high at cruise. But the ecm is doing everything else right, like advancing timing at cruise and reducing it at wot. What is going on? Could I have wired the map backwards?

That tune looks like hot garbage. Why aren't your O2 sensors cycling properly... and why are your LTFT's almost 20%?!?!?

Do you have a wideband? Just off hand it looks like your VE and MAF are way off and need some good iterations of tuning. It also looks like they went ham on the PE... you are getting 11.8:1 under PE... which is pretty dang rich for an NA motor. Looks like they also have your commanded AFR at 14.1:1? Is that because they are assuming you are running E10 fuel?