eng92

iTrader: (3)

Are those insulating gaskets you are using much thicker than stock?

Jime

iTrader: (10)

No, they are pretty thin, 1/16" at the most if that.

DandyMax

iTrader: (7)

If you saw the list of to-do items I have... lol

Picked up a cheap GM pressure sensor yesterday though, planning on rigging that up with the EU soon. The car is driveable now though at least which is more than I could say 3 days ago. Got the seat in now too, cutout is next. It's gettin' there.

Coming back from the alignment I realized they gave me -2 on the camber even though I asked for -1. Not sure how much effect that'll have on the launch with slicks. Car corners great though!

Sorry to go OT...

virgilio7

Jime. I have a 3.5 intake made by cp-e with the maf adapter hole. you want it?

Jime

iTrader: (10)

[QUOTE=virgilio7][QUOTE=Jime]Stock MAF and JDM cams.

I'm still going to mount a 4g MAF in a 3.5 tube but just have to finish up some other stuff first. I'm like Dan I think he dropped off the face of the earth since he got his car out of storage.
Thanks but it won't fit the 4g MAF, its integrated into the plastic tubing its not just held in by 2 screws. I bought one from the junkyard and cut the whole thing out so now I have to epoxy it into the aluminum tubing. The new Altima/Maxima one would have been too easy.

virgilio7

No problem. i hope you get it right. not easy at all.

eng92

iTrader: (3)

I connected the analog voltage input on the EU to the TPS output on the electronic throttle so I could measure the flap position directly instead of going through the OBD-II port.

Results are below. As long as the pedal was to the floor, the throttle plate never moved even after I bounced it off the rev-limiter a few times. The OBD-II data which indicates a gradual closing throughout the rpm range now makes absolutely no sense.



I have also mapped the VTC duty cycle vs rpm and could use the additional injector function to control them, but I have a feeling the 5.5g ecu would quickly go into failsafe mode when the cam phasing started to deviate too far from the target value.

nismology

iTrader: (8)

Isn't the TPS on the pedal though?

eng92

iTrader: (3)

There are 2 APP sensors on the pedal and 2 TP sensors on the throttle body. I am monitoring 1 of each type.

nismology

iTrader: (8)

Well perhaps TPS voltage and throttle position aren't directly related. I don't see why they'd be related in a DBW system. From what i've read about most DBW systems 50% throttle, for instance, doesn't necessarily mean the throttle itself will open 50%. It just means that around 50% of the available torque at that particular RPM will be delivered. Something to that effect...

eng92

iTrader: (3)

That would make no sense. What's the point of having a position sensor if it is not related to position?

You need position sensors for feedback otherwise how does the ecu know when to shut off the throttle motor?

nismology

iTrader: (8)

I edited my last post for clarity.


The ECU determines how much torque you want via the TPS, not how much you want the throttle to be opened. It takes RPM, MAF voltage, TPS voltage and w/e else to determine the throttle opening. It's not like a mechanical linkage system.

eng92

iTrader: (3)

a more definitive answer

eng92

iTrader: (3)

You are confusing the TPS on the throttle with the APPS on the pedal. The TPS is whatever the true throttle opening is and the APPS measures the true position of the gas pedal. The ECU determines how one affects the other.

My simple experiment just shows that the throttle plate remains wide open through the rev range when the pedal is floored.

nismology

iTrader: (8)

Interesting info but that still doesn't definitively say that pedal position directly corresponds to throttle flap angle at every RPM, at every engine load etc. Referring to the ESM snippet BTW...

Edit: Your new TPS curve and pedal position percentage jumped up at precisely the same RPM. What are the odds that the throttle valve could respond so quickly? Also it seems as if the pedal percentage dropped a bit around 5300 RPM while the TPS voltage didn't waver. I don't get it...sorry. Break it down for a n00b please...

eng92

iTrader: (3)

For all driving conditions ... of course not. That was never implied.

For the specific case of a WOT run through the rev range it does.

I am sure there are other conditions where the ecu may regulate the opening rate of the throttle for smoothness. Also IIRC in failsafe mode it takes about 5 seconds for the throttle to open to a maximum of 10 degrees no matter how far the pedal is depressed.

nismology

iTrader: (8)

Does this mean that everyone that got the TS L-spec ECU with the "throttle flap fix" got ripped off?

I guess this myth has been debunked until further notice.

eng92

iTrader: (3)

You really need to sit in a car with DBW where you can see the throttle plate move as you press the accelerator (ie. ignition on - engine off) The response time of this electro-mechanical system is far quicker than you might think. IMHO there is no perceptable delay.

That negligible drop was from 100% to 99.7% - exaggerated by the relatively coarse resolution of the graph

Jime

iTrader: (10)

DBW is a lot better than people realize. I have always driven a cable driven throttle until I got the 2k2. I couldn't tell the difference in throttle response from cable. About the only thing I noticed is that on cruise the throttle doesn't get held down on the DBW like the cable.

I did get the TS L-Spec and there was no measurable difference I could find with the electronics I had and no difference in performance.

Aceman

Interesting Read

Anything else come out of this?

Later
Aceman

eng92

iTrader: (3)

This thread is not dead. I have just moved temporarily onto VTC control to try and improve my airflow.

eng92

iTrader: (3)

I found out something unexpected about the DBW system tonight. I was trying to get some VTC timing information for other engine loads by holding a fixed accelerator pedal position and sampling the crank and cam signals at various rpm points. I placed some metal blocks under the accelerator to limit its maximum travel and logged the actual throttle blade position vs rpm

The throttle plate actually opens further the longer you keep your foot on the pedal.

The purple data below is the TPS voltage for a maintained 53% pedal position. The black data is the TPS voltage for a floored pedal position.

NOTE: The top black arrow is pointing to the wrong axis. The sensor voltages are both on the RH axis.



The plate started to open further at about 2800 rpm and was fully open by 4500 rpm.

Incidentally the changeover from closed loop to open loop occured at 4000 rpm consistently for this accelerator pedal position.

IceY2K1

iTrader: (3)

So, you've shown it doesn't close as it approaches redline like TS says, but it also doesn't open 100% of the way according to your graph, correct?

eng92

iTrader: (3)

As noted above, the top arrow (black data set) is pointing to the wrong axis. I apologize for the confusion.

The two throttle plate position sensor outputs, purple and black, are shown as voltages on the right hand scale.

My TPS voltage when the plate is fully open (verified physically with engine off and ignition on) is about 4.1V (FSM spec is <4.75V).

The left scale is the accelerator pedal position. I placed it on there so that I could show that the pedal position was constant and the throttle plate was opening with no addional user input.

IceY2K1

iTrader: (3)

Gotcha...

So you just tapped ECU pin #83, correct?

eng92

iTrader: (3)

That is correct.

NmexMAX

iTrader: (22)

Keep in mind, I'm using a larger MAF housing & am probably @ much lower ambient pressure (5500' elevation, ~615-620 mm Hg)

krismax

iTrader: (15)

just saw this thread and like i posted in another thread my scan tool does lb/per minute

and actually none of my readings were WOT ill get some tonight.