Having spent the last month adding a considerable arsenal of instruments to my MINI, with absolutely no performance improvement, I have a greater appreciation of how the air moves through my engine, and how difficult it is to really understand the complex processes that generate those data.

That said, I thought I'd start a separate thread about these instruments, and how we use them. At the moment I have the following instruments installed in my car:
1. Davtron IC gauge and 2 probes, sold by Virtual Racing. This is a package sold specifically for measuring in- and out- IC temperatures, the digital gauge showing both in- and out- temps and the difference between the two. The probes are short and fat, which is probably not the best probe for measuring IC airflow temps, especially as heat soak of the probe body is a problem with a big fat Al body on the IC and runners/horns, whereever you mount the probes. They are fast response though, which is a good thing, and the system is very accurate over the relevant temp range.
2. Reasonably priced tethered thermal probe connected to a self-powered digital gauge, accurate to 1.8F over the entire -40F to 300F range. It's surprisingly fast, but isn't for the IC since the probe is mounted in a plastic body. Great for reading general engine bay temps, and I use it to measure temps in the airbox.
3. A ScangaugeII, which reads all the OBDII outputs (as well as act as a trip meter and a scanner for error codes). It shows in real time things like IAT, water temperature, MAP, all of which are good for comparisons with other probes. Unfortunately, the OBDII seems to have a slow update cycle (2-5 secs I'd guess), so the readout jumps around wildly compared to the smoother increases and decreases of faster measuring instruments.

The problem with all these instruments is that while they indicate temperatures in real time, they do no allow data logging, which allows for more reflective and intense analysis of the data using statistical methods.
Ultimately what we'd need is a multi-probe/input logger which can display values in real time, but can be downloaded as a data log for analysis.

All that said, I'd say that my observations of the last few weeks are quite consistent with those that have been reported here on NAM over the last 4 years in various threads. Unfortunately it takes a lot of searching to find them all, and they are disparate in many ways, not just in time and space. Nearly every time I report an observation someone points to the same finding from a thread in the past. Eg airbox temperatures near ambient (obehave), the heat cost of the VGS (MSFITOY), IC TEs (DrObnxs), and others.

Maybe I'll try a meta-analysis if I ever get some free time...

cheers,

 

May I assume you set the ScanGauge's reaction speed to the fastest setting?

It has three speed positions. On the second fastest (or second slowest, for that matter), I agree it does take too long. The slowest one is slooow indeed.

On a related note, do you equate the ScanGauge II MAP readings with boost?

Because in our much colder recent weather (20 degrees), the MAP readings were significantly higher than "normal" - which is maybe 17.5 under full throttle at 55 degrees or so ambient. But it was north of 21.5 in the deep cold!!!

 

Yes, I was going to ask about the SGII's MAP readings--they seem to be way too optimistic. Where does it take the readings, and how does it measure the pressure? How does this compare to the more standard boost gauge readings from the fuel rail, or the IC?

cheers,

 

Hey, I was asking you!

I don't know for sure, but I did think the MAP readings were a bit too high, especially on what would appear to be only part throttle applications.

I don't have a boost gauge to compare it with.

DMH uses the SG 2 as well...

 

Matt will know, for sure! We just have to wait for him, or another of the major gurus to chime in. I saw 22psi at WOT on the SGII this afternoon--at 5000ft elevation, I find that hard to believe...

While I'm at it--how does one interpret the advance/retart output on the SGII? I've read the manual, but do I have to have some "reference" angle (or value) to measure against to determine advance or retard? I've seen values ranging from 0 to 50ish, with little constancy. I haven't seen a negative reading yet...

thanks

 

All the ScanGauge II does is read your OBDII like just as a monitor works with a computer. The MAP/boost reading is taken from the MAP sensor on the intake manifold. You need to subtract your starting pressure to see your vacuum/boost. Turn the key on and take that reading; 14.7 is sea level, I'm at 14.5, your lower because of the altitude. I have an '03 and must keep the reading on slow. Newer cars can use a faster setting.
The ignition timing is how it looks in the ecu tables; it's like a code for a code. It is hard to use that data.
I use the gauge to monitor IATs, MAP, water temp, and usually timing. The IAT and MAP readings are what I have been using to test intercoolers at the road race track (the only place possible to safely and accurately test them).

 

One thing is for sure.

The IATs will not come down if the car has been sitting waiting for the next run at an auto-x, especially on a hot Atlanta day, staging on pavement.

I've noticed that cooling is certainly longer than the 45-55 seconds for the typical run. So it doesn't ever come down.

Part of that is because you're at full throttle a lot of the time, and part is that the top speed may reach 60 or so, but only momentarily, but then under full throttle (with attendant high heat fron the SC).

I want to try spraying the IC and see if it really makes a measurable difference. We all do that dance at the auto-x.

But does it really matter except in our heads?

 

Having spent some time with the SGII now, I have figured out a few things. The MAP reads 12.1 psi before the engine starts, and varies considerably while driving around town. I really need to get a boost gauge on the DFIC-out to compare readings with.
I asked LinearLogic, who make the SGII about the Timing readout, and it's reading timing degrees, sort of. I start off reading about 50 just taking off slowly, and then as I get on it, the number falls, (retards timing). When I backed off at speed, and got the backfires in my exhaust, the reading when to -11! (I think that's as good as going to 11, just in the other direction.)
It's nice to see the actual water temperature, as opposed to the silly on-ff gauge on the dash board, and intake temperatures compare well with those I'm reading with my therm probes.
All-in-all, I like the SGII a lot!

cheers,

 

Prof -- You're only getting 9.9 psi of boost! You ought to check for a leak.

 

I was told by Randy Webb that here at 5000ft altitude, about 10psi was all we were ever going to get. Is he wrong?
thanks

 

I just recently returned from tuning cars out west and in Denver I was seeing 12 psi with a 15% pulley (measured with the ScanGaugeII).

 

So Don,

If the a.p. here reads, say 14.2 on the ScanGauge II, then to see 15 lbs of boost, it oughta read in the range of 29?

And if I thought I should be getting 17+ pounds that should simply be in addition to the a.p. as read with the ScanGauge switched on, but the car is not started, right?

So I ought to see 31+ in an instance of max boost of +17?

The reason I ask is that during the 7 days or so I've been using this tool, I've never seen boost over 22.7...

But I haven't actually TRIED to get a high reading for the sake of a high reading.

Hmm...

 

Correct.

 

I took the car out and purposely concentrated on the MAP/boost readings only from the ScanGauge II.

Ambient temp was 66.

Atmospheric pressure here was 14.2.

Max MAP reading I saw was 30.2.

So I had 16 lbs. of boost.

This is with a 15% SC pulley and a 2% crank pulley.

Compared to some highly modified turbo cars I've had in the past, I'm depressed at how long it takes the car to get to full boost.

Guess that's the nature of SC cars. But man, it takes much longer to get to full boost than the turbo cars I had.

At the moment, I'm bypassing the Unichip. I know the Unichip would help in the acceleration, therefore reaching full boost slightly quicker, but it's depressing to watch it climb, not with throttle position, but with revs...

I suppose this boost and time to full boost is normal for non-turbo'd cars. Or not?

 

The boost seems normal.

 

so would the reading be set on slow also for my 2002 mcs?
i just ordered the scangauge II. online.

 

i have an 2002 mcs would the setting be on slow also?
for the scangauge II.

 

Keep the setting on slow as our ecus are not a sophisticated as later cars that may be able to run faster speeds.

 

I'm setting up an Innovative DL32 as a base for data logging. I also have an AEM A/F gauge. Going to use that Unichip P&P cable to tap into! Hitching it all up to a Mac MINI running Windoz XP (currently running IGuidence GPS). I'm using the APEXI diagram as a start and the Bentley manual for other info. Any advice would be appreciated especially where to tap into the exhaust for EGT. Doc, were you able to tap into the knock sensor? Does anybody have a good list of known working tap points (pin#) for the ECU??? It would be nice to have all of that in one spot on this thread (what a lazy ***).

 

pmello:
Sorry, you're way beyond me. Perhaps Dr Obnxs will know, and there are others on the board who have ripped into the wiring to get signals for data. But I'm not help, sorry.

 

I've been doing a lot of work finding wiring pinouts with the Unichip harness so I can hook up a Innovative DL-32 datalogger. I'm getting a better appreciation of what is possible with it. It uses Throttle Potentiometer, Crank Position and T-Map to do it's work. Some of these wires feed the Unichip and others are interrupted and fed from the Unichip. I can post my findings if anybody wants.

What pinouts on the ECU (or other places) have people been tapping into and for what??? Just a general question to the forum.

 

Anyone know about the crank position sensor? What I'm looking for is a closeup picture of it. I'm trying to figure out where the trigger point is in relation to TDC on #1 Piston (in degrees). I Know from reading Bentley's that it has 60 teeth with 2 missing (thats the trigger). It's suppose to be a Hall effect type not a VR (variable reluctance type)? I need this to measure timing with the Innovative DL-32. Trying to get all my ducks in a row for the install. It's cold (21deg) , but I may still do it this weekend.

 

So with it on slow, is there any way of accurately determining peak MAP (thus boost)? Is there a peak hold function or something of the like so you can just go driving and check the highest MAP value when you get home?

 

I wish! No, the SGII does not have any logging capability at present. Peak or over-time would be fantastic, but not on the one I have which is about 2 months old. I have an '05 and use fast, and the output varies quite quickly, but smoothly so there must be some smoothing/averaging going on with the display.

cheers,

 

Really? I am at 6200', and usually see 10-11psi. That is typical on most of the cars we test with the 15%. Of course, that varies with ambient, and with the ubercold air, I am seeing the higher side of 11 these days (too bad the roads are too crappy to use that horsepower!).

Randy