interesting OBD II live enginedata from a run

[mmag1982]

hey guys,

here are snap shots of my log files using my innovate 02 OBDII scanner

please tell me what do you technically think of the trend. I have some interesting observations

light green is MAP, red is spark advance BTDC, violet is RPM, etcc

the 1st log was recorded while i was gunning it full throttle through a 1-2-3 shift

- why is my throttle position sensor not reading more than 74% at WOT??
- my MAP sensor as well wont reach the 14.7 psi atmospheric even at WOT. I know that MAP reading at WOT should nearly match atmospheric.
- spark advance is a little bit retarded maybe? ranging from 15 to 22 degrees BTDC, it stays at around 10BTDC at idle and jumps to 35 BTDC sometimes during mid throttle.
- calculating my gauge vacum reading at idle from the MAP reading I have around 17.8 in-HG at 14.6psi atmospheric. is that healthy enough?
-Intake air temp is ranges from 120F to 160F
-short and long term fuel trims are very stable.
- The jeep generally running very well now after I installed the famous bosch 4 hole 22lb/hr injectors. smooth idle and reduced pinging and improved throttle response

and my XJ is a 2001 4.0 with an NV3550 and a 3.55 rear DANA35C. ( export version) .I cant get my 0-62mph time under 8.5 sec with 255/60R15 tyres.

and I have all the performance bolt ons I can think of, complete exhaust system with tube headers, intake, 62mm throttle body, etc, etc.., I am even running 92 octane currently .

shouldn't I be at least 1 sec quicker with that higher, rear axle ratio?

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[Talyn]

Can you convert that to show voltages instead of PSI/%? The PSI and % really won't tell you much. For instance, the MAP sensor takes a quick snap shot of the atmospheric pressure right before you turn the key to start. It then compares that voltages to the voltages when running to calculate the engine load. So, you would want to view the voltage when its not running and compare that to WOT. Similar for the TPS. WOT would be x# of volts above closed throttle position.

 

[seanyb505]

Run the lowest grade fuel you can without pinging. High octane does nothing in our engines. Is yours 2wd or 4wd? Do you have anything installed that adds unnecessary weight? Do you have a shielded intake?

 

[mmag1982]

talyn,i get your point, i think there is an option in the logworks software to do that, I'll check.

but, i checked the manifold pressure reading I get from my AEM FIC (it has its own MAP sensor with a vacum line to the intake ), The readings are about the same 14.7psi at key on, which is atmospheric pressure, 6.5 psi at idle, etc... The readings are nearly the same as the innovate. I haven't wired the rest of it yet to compare TP.

what do you think of the spark advance values?

@ seanyb: for pinging , anything lower than 92 in mine it starts pinging like crazy, dont ask me how, and i tried everything. the final thing that killed it was the NGK FR-1 spark plugs and the bosch injectors.

mine is 4wd with country suspension package.

 

[Talyn]

but, i checked the manifold pressure reading I get from my AEM FIC (it has its own MAP sensor with a vacum line to the intake ), The readings are about the same 14.7psi at key on, which is atmospheric pressure, 6.5 psi at idle, etc...

6.5psi at idle? Maybe -6.5psi @ idle? Even then that is only 13.2 in hg, which I don't think is normal for a stock engine. I suggest you try with a mechanical gauge and see what it is really doing at WOT. If there really is a vacuum at WOT you need to look at possible restrictions such as the throttle body, air filter, etc.

 

[gradon]

If in psi units, then anything less than 14.7 at sea level would indicate vacuum(your 17.8"-HG is a good idle value) . I still haven't used the AEM's onboard MAP(waiting for my brother to get his welder so I can get rid of my exhaust leaks before I spend time tuning it). I don't know about your LM-2, but mine can only monitor and/or datalog 5 high-priority channels before it bogs down and makes all data useless(it's like a pc needing ram).

 

[Talyn]

Ahh.. i usually see it refereed to in in hg, not usually PSI. Going off the AEM MAP it would translate to something like 16.69 in hg then?

As far as bogging down, I think its the OBD II bus. All live data scanners I have used bog down when you start adding more than 4 or 5 readings.

 

[offroadordnance]

Regarding the 74% TPS and vacuum reading at WOT. Have you verified the throttle blade is opening all the way with the pedal to the floor? Maybe cable slack or pedal travel is restricting it from fully opening?

 

[mmag1982]

what about spark timing, do you think its normal? i starting to think there might be a small gain if I relocated the IAT sensor to a cooler spot.

the torque curve of the engine now is kind of odd, all power comes at 2800 to 4000 rpm range, below that choke , above that just noise.
somehow mid to 3/4 throttle opening gets the most acceleration. if I go full throttle it just picks up slowly in an elastic way.