Timing, the Vec and the AEM

[Jack B]

When the timing is set with the AEM, is there any cross check that verifies what the timing is. In other words, if you could use a timing light, would it match the aem setting?

The reason I am asking is that it has always bothered me on the VEC that we are sort of blindly adding timing and don't know what actually is happening. This is not taking away from Sean, he has done as much or more than anyone to support the viper community. To go one step further some minor issues still remain with timing and high speed misses.

With all that said, about one year ago a friend and I started trying to log true timing. It turned into the search for the holy grail, we are finally at a point where we can accumulate some data. It seems to be working and just needs a bit of fine tuning. We are using an optical sensor on the damper and comparing it to cylinder #1 coil pack, therefore, it is exact. We just did my Gen 2 and are going to do a Gen 1 next.

I would be willing to bet that some of the high speed misses can be linked to a timing anomaly and the logging will be able to catch it.

 

[Hisserman]

PM EarlH, he has a good handle on these issues.

 

[FE 065]

Earl_H to be exact

 

[Joseph Dell]

Jack -

The answer is that there is no explicit cross-check. when you install the AEM and set the base timing, they suggest (highly suggest, that is) that you manually check it w/ a timing light to make sure your base is correct. So maybet the answer is yes. but you gotta use a light.

W/ my set-up, I had ZERO angle to get a light in there. so i guessed. I hope it was right!

JD

 

[Earl_H]

Jack -

The answer is that there is no explicit cross-check. when you install the AEM and set the base timing, they suggest (highly suggest, that is) that you manually check it w/ a timing light to make sure your base is correct. So maybet the answer is yes. but you gotta use a light.

W/ my set-up, I had ZERO angle to get a light in there. so i guessed. I hope it was right!

JD [/quote ]

 

[Jack B]

Joe:

the base timing is only one issue, if you remember when the VEC came out, it had a bad algorithm and there was the V-Notch at about 5000 rpm. My reason for asking, I am wondering whether there is a market for the ability to log timing. I am using the Innovate to record, so this would be an accessory kit to the Innovate system.

 

[Joseph Dell]

my opinion and mine only: there is a level of trust that we have w/ the equipment. if we can't trust the equipment (such as the AEM, to adjust timing properly) then we have a different issue. for me personally, i'd love to be able to check the actual timing, but i don't need to know it that badly b/c I tune not just with the timing numbers but also w/ the performance results. So if my car thinks it is running 15 deg of timing and it is actually running 17 or 18, i don't really care... so long as i've tuned it optimally for what i think is 15 deg.

then again, it is all a cost thing too... show me a $10 way to check the timing and i'm all over it. a $500 way... not so much.

JD

 

[Jack B]

Joe:

Let me rephrase the question, there have been numerous cars on this forum that have never able to fix their high speed miss. They end up pulling timing and therefore hp, does the ability to log timing now become important. There have been multiple cases where thousands of dollars and and mass time has been spent trying to fix this problem to no avail. I just thought that the ability to log timing was a crucial trouble shooting tool.

I guarantee when I start the serious logging I will find some interesting timing issues.

 

[Joseph Dell]

Jack -

In this case, then yes: it is badly needed. I can't tell you the number of times I have wanted to log actual timing when that stupid VEC2 V-notch happens.

Back to the "trusting the equipment" issue... VEC2 as a culprit? maybe. Sean was pretty sure it was a IAT issue. but it may be more than that.

hum...

keep up the research!

JD

 

[PowerKraus]

Having used HPTuners, EFI Live, LS1 Edit, Direct Scan, etc....I certainly would be very interested in seeing the actual timing table(s) used by the PCM. Sean is very helpful in providing the WOT timing in summary form for certain RPM ranges, but engine timing based on engine load/rpm would certainly help, especially when looking to tune around town driving. Specifically, I'd like to program custom timing curves for my own vehicle in various trims, i.e. N/A pump gas, N/A 100 unleaded, nitrous shots at 100 and 200 HP levels.

I understand from your post that you are actually logging the 'net' timing to the engine; the 'net' of a combination of a various number of timing tables. By that, tables that not only account for load/rpm, but tables that also adjust timing for inlet temperature, water temp, throttle postions, etc.

However, your results would be useful for us DIY tuners using the VEC II, especially if you are logging rpm, engine temp, inlet temp, engine load (kpa or vacuum). So please keep us posted and good luck with your project !