lq9 engine transplant

[lq9nissan]

tun file

[lq9nissan]

hello all, long time no talk. my vehicle has been on hold for a few months. I managed to get things running quite smoothly after many many hours. However perfection still has not been achieved. I feel it is not achievable without the clutch and brake switch being connected for a start. Also having dificulties getting return to idle decay rate to speed up, any ideas.

[joecar]

You do need the clutch switch.

[Mr. P.]

+1; was just reading the post on tuning idle, and the clutch switch informs the PCM when to use the "P/N" columns or the "Drive" columns in all of the idle parameter tables - you won't get a clean idle without the clutch switch and (additionally) tuning those columns.

Mr. P.

[lq9nissan]

the clutch switch, the switch in the vehicle is paralled with seperate brake switch it is 12vdc+ only when the cruise is enabled. connector c1 pin 33 i believe is fine for cruise. what about c1 pin 35 cpp switch signal, it it required and if so +vdc hot on ignition ??. or are you talkin about c2 pin 18 clutch start switch ?

[Taz]

OK … should confirm a few things before making any further suggestions.

You stated previously that the engine is a 2005-2006 LQ9 crate motor. What / where are the following components from:

• TB (Throttle Body)
• APP (Accelerator Pedal Position) or “gas pedal”
• TAC (Throttle Actuator Control)
• Engine wiring harness

The reason I ask is that theTB / APP / TAC and PCM tune must be mutually compatible for the DBW system to function properly. You had indicated that you were using OS 12592618 (2005 OS). You also indicated that you had used OS 12587811 (2006 OS) to “copy and paste” some parameters.

Here is where I’m going …..

On 2003 to 2005 Gen III trucks (i.e. LQ9) the APP used 3 sensors (sometimes referred to as “pots”). This APP had 9 pins. This APP had a 10 way connector which used 9 of the 10 available cavities. The other end of this harness plugged into the TAC via a 10 way connector. The TAC featured a 16 way connector for output – to TB, PCM, Cruise, power, ground, etc.

On 2006 and early 2007 Gen III trucks (i.e. LQ9) the APP used 2 sensors. This APP had 6 pins. This APP had a 6 way connector which used all 6 available cavities. The other end of this harness plugged into the TAC – which I believe used the same 10 way type connector as was used with the 3 sensor APP. The TAC featured the same 16 way connector for output – as was used with the 3 sensor compatible TAC.

The 2003 to 2005 TB / APP / TAC and PCM tune should be mutually compatible – and the DBW system should function appropriately.

The 2006 to 2007 TB / APP / TAC and PCM tune should be mutually compatible – and the DBW system should function appropriately.

Any intermixing of these two groups of components will cause problems with the DBW system – which could manifest as complete dysfunction, or idle issues, or driveability issues, or any or all in combination.

Regards,
Taz

[lq9nissan]

ok, dbw 10 pin conn. 9 in use. tac 10 pin connector. dbw 8 pin all in use.
dbw came with engine, app and tac came from harness & pcm supplier/ builder. i see where your coming from.
still need to sort the cpp switch and tcc brake/cruise switch out as well. i cant do that until i find out for sure what signal the pcm requires, +vdc hot on ign n/o or n/c. or -vdc no/nc


just finished going through 2003 & 2006 circuit diags. it is quite clear what Taz is saying about the App to Tac module wiring, basically there is no sense wire returning to the tac module from the first pot on 2003. the tac sends 2 serial class data transmissions to c1 pins 14/15. 2006 clearly shows the 2 pots only and the 6 wires.
so its most likely recieving currupted or unsupported data.(well spoted Taz).

[Taz]

From your description, the APP you are using is a 2003 to 2005 variant. Try using a 2003 to 2005 truck tune - if the DBW is appropriately functional - then use that tune as your "base" for future tuning. If the DBW system still does not appear to function properly, then it is possible that the TAC is from a 2006 / 2007 - and would need to be replaced with a 2003 to 2005 TAC.

Hope some of this helps ....


Regards,
Taz

[lq9nissan]

ok got 2003 silverado base modified and loaded, all functioning well, just need to get case relearn to take and im pretty sure i'll be well on my way to a much better drive, will keep posting with results as i go. if all is clear ill post the modified tune up. cheers

[lq9nissan]

case relearn will not function no matter what i do, is the splash supposed to open in a seperate window as the efi tutorial suggests ?