Optimal Gauge Readings

ejb2112

ejb2112

Greenie N00B Member
So I've looked around both forums, and I'm not finding what I need. And that is a quick-and-easy reference guide that tells me the optimal readings for the most important gauges, and what it means when you stray from those readings.

For example, HPFP. Mine idles around 425 psi. I assume this is normal, but how do I know for sure?. Or KR. I believe it's best at 0. But what does it mean when it goes to +5? Or -5?

I think you get my drift here. I'd love to be able to glance at my AP and see that readings are within acceptable ranges.

P.S. I'm fully aware that everyone will have different readings based upon their car and modifications. But I have to assume there are some that are optimal across the board.

P.P.S. I would also appreciate knowing what you guys think are the best 6 gauges to show on the AP v3.
 
KR is technically the amount of timing retard due to detected knock count. It's always a negative value because the whole purpose of it is tracking how much the timing is retarded (in other words, subtracted). It appears as a positive value in my datalogs, but just remember that the figure always represents what's being subtracted. It's almost like the reverse of an absolute value in mathematics, if that makes sense...

~400-430 idle HPFP actual is normal. Sometimes while coasting down to a red light, you may see it go to ~280 also. Again, totally normal.
 
I monitor KR, BATs, Actual HPFP Pressure, Coolant temp, LTFT, and boost.

During WOT you want 1600+ HPFP and optimally zero KR. Values while cruising around will vary.
 
ejb2112, a better question to ask before you go worrying about what value everything should be is what parameters are even important?

I don't live monitor HPFP actual pressure at all. I have upgraded internals, so if I'm not meeting targets, one of two things is going to happen: ZZB, or I won't accelerate at all. I use WOT logs that I take periodically to check up on my HPFP...and haven't seen a single problem since I installed my autotechs.

Here's my top 10-ish list of parameters to monitor, in alphabetical order:
1) AFR - When I go WOT, especially when I'm running a methanol/ethanol mix, I'll periodically verify that I'm achieving my target AFR (11.5 at WOT, 14.7 or 17.0 depending on what map I'm running at all other times). Too rich or too lean, something's wrong and I need to sort it out ASAP. Going mega rich at WOT when SWAS and TCS are disabled are the classic signs of a boost leak. Too lean at WOT is usually a tuning issue, but can also be caused by a bad flash of a map in my experience.

2) Boost - This is good to monitor to watch out for boost spikes, and boost leaks. It also tells me at a glance how cold/hot the temperatures are outside since I'm load tuned, so the ECU will add/subtract boost to meet my target loads. When it's really cold outside and I see boost go really low, I know I might be getting close to territory where the wastegate dynamics system will run out of ability to adjust WGDC enough to bring my calculated load down. At this point I'll usually massage the WGDC table a little bit to make sure it has room to adjust so that my load targets aren't exceeded (you can also recalibrate the IAT Comp table).

3) BAT - This is a good one to live monitor when you're running a gas tune. Personally, I just don't go WOT when my car is heatsoaked and I'm running gas. It's going to knock no matter what.

4) Calculated load - This parameter is equal to mass airflow divided by RPM times 40. It it directly proportional to torque output. I monitor this parameter at all times since any deviation from my target values at WOT can mean either a catastrophic overrun of torque, or conversely, significant loss of power. This parameter will vary car to car depending on power level, turbo, etc. In general on the stock engine I don't like to see calculated load values of more than 2.50 at low RPM's, however on a spike-happy K04, you may see higher than this in the 3000-3500 vicinity and in this case you should reduce timing in this vicinity for safety.

5) Coolant temp - Gen2 folks who don't have a coolant gauge should monitor this. If it's below 176 or above 217°F while driving, you probably have a thermostat issue. When cruising at normal loads, it should nominally be 190°F. Mine usually sits a little lower.

6) Knock Retard - This is the one you watch while at WOT, if nothing else. In my opinion seeing more than 1.5 consistently at WOT is unacceptable. The engine can handle a hell of a lot more than that (I've personally seen a 3.8 before at somewhere in the 2.20-2.30 calc load vicinity - the engine is still alive and well somehow!). Part throttle, you will see a lot of knock on gas tunes, especially when heatsoaked, and this is when I will usually try to take it easy until things cool off. On E85 or methanol mixes, generally it will be zero pretty much all the time unless your tune is really aggressive and you are well beyond your turbo and/or IC efficiency.

7) Fuel trims (long and short term) - Add these together and you will have your total fueling error. I like to see within +/- 5% at calculated loads above 0.30 or so, all the way to where it goes into open loop. If you see high values at idle, like say +25%, that could indicate a vacuum leak or pre-turbo intake leak. If you see really low values, especially as load increases, like -20%, that could indicate a boost leak between the turbo and the throttle body.

8) Throttle position at WOT - Watch for values that sit significantly below 74%-ish at WOT for a long time (more than 1500 RPM's or so). This means the load error comp system is really getting involved and your WGDC values are probably too high.

9) WGDC at WOT - This isn't one you really need/want to monitor, just one that you should always be comparing in your logs to your corresponding values in the WGDC table. Any significant deviation, after taking into account IAT, probably means you need to patch up your tune. Really high WGDC values combined with low calculated load values usually indicates a problem somewhere, either hardware (clogged cats/intakes, WG problems) or otherwise, as the ECU is trying to add lots of WGDC and still isn't reaching targets. Conversely, really low values could indicate a problem with your EBCS hardware, for example a leak in the lines between the turbo, EBCS, and wastegate, and this could be a serious problem.

This is not a complete list, just the stuff I feel is most important.
 
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VTMongoose, that is incredibly helpful. Thank you for spending the time writing that up. In fact, I printed it out so I can have it as a reference.
 
Watching idle/fully warmed-up boost (technically vacuum) can help you know how strong your compression is, and if you monitor it long-term can give clues to boost/vacuum leaks. *Note that changing idle speed affect this, in my experience.
 
DISIFTW said:
I monitor AFR, boost, coolant temp, BATs, KR, and HPFP actual. Huge thanks to @VTMongoose for the post, very informative.
Click to expand...
This is exactly what I'm monitoring real-time as well on the Cobb AP. I will switch out the AFR reading for intake temps as the weather gets warmer though, specially during the Texas summer.
 
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