My 1988 LFX F40 build. (Page 43/68)
Rickady88GT JUL 23, 05:27 PM

quote
Originally posted by Will:


Right... they required you to make it exactly the same as the original certified configuration.



Not really, the ref wanted the vin numbers to match because he could force me to.
The computers that needed to be reflashed included:
Electronic Control Module
Transmission Control Module
Body Control module
Anti-Lock Brake Control Module
Radio
Heater Ventilation Air Conditioning head unit
Satellite receiver
I understand the ECM and TCM but the rest is hard for me to explain or understand. He just wanted to see all of the computers have the same vin. I did not see what information he had access to, or if he could even verify the reflash was done, but he was very clear on taking the car to the Chevrolet dealer and have all the systems flashed with the vin number that I had the pinkslip for. I had to provide the receipt to prove I did the reflash. BTW I had the pink slip for the donor car for proof that it was not a theft. This ref hopefully is not typical of all refs.
Again I won't argue that a tune can fail your inspection, be on the safe side and don't do it. But what is tuned and how it is tuned may not necessarily be an automatic fail.
Joseph Upson JUL 23, 07:02 PM
There must have been some ignorance on the emissions agent's part, the modules will not communicate unless they are vin matched for the modules that require it, and some modules will deadline the car if they don't match up, which is why late model swaps are so complicated to begin with. If they're in the car working, they match. I identified the chip in my radio that contains the vin for direct matching, but if the programming is not the same, you'll have more, or fewer functions. This approach was used to add navigation, bluetooth and or backup cameras to stock radio boxes that did not have it, as the dealers often will not attempt the RPO add on, or don't have the skill on hand to do it. I have a few important backup modules in case an onboard module fails.


quote
Originally posted by Daryl M:

ChuckR
I realize that there is a vent on the filler neck, but there is another vent . According to Guru, it goes to a charcoal canister. What I am trying to determine is where it goes from there and if the canister can be deleted and the vent can go directly to the device pictured. I think it is called a purge valve. The second photo shows the vent I an referring to. The first photo is the purge valve.



Are you planning to modify the pump assembly to adapt all of the appropriate stock components from the donor car? GM added a fuel pump control module to the 3.6L system around 09-10 so be sure to check into that if you are not aware of it.

[This message has been edited by Joseph Upson (edited 07-23-2020).]

msweldon JUL 23, 10:51 PM
Yes, the lfx, as does the lf3/lf4, requires a fuel pump control module (fpcm) that receives a CAN signal from the ecu which tells the fpcm what pressure to maintain from the low pressure in tank fuel pump, by way of a PWM signal so the high pressure mechanical fuel pump just off the front head has exactly what it needs. This is all for keeping the direct injection system happy.

Make sure your fpcm is vin matched to the ecu.

Make sure your in tank fuel pump is PWM capable as well.

Make sure you use sheilded twisted pair wire from fpcm to fuel pump for the PWM signal.
Daryl M JUL 23, 10:54 PM

quote
Originally posted by Joseph Upson:

There must have been some ignorance on the emissions agent's part, the modules will not communicate unless they are vin matched for the modules that require it, and some modules will deadline the car if they don't match up, which is why late model swaps are so complicated to begin with. If they're in the car working, they match. I identified the chip in my radio that contains the vin for direct matching, but if the programming is not the same, you'll have more, or fewer functions. This approach was used to add navigation, bluetooth and or backup cameras to stock radio boxes that did not have it, as the dealers often will not attempt the RPO add on, or don't have the skill on hand to do it. I have a few important backup modules in case an onboard module fails.


Are you planning to modify the pump assembly to adapt all of the appropriate stock components from the donor car? GM added a fuel pump control module to the 3.6L system around 09-10 so be sure to check into that if you are not aware of it.




Not using the donor bcm or transmission control module . Just the ecm . Not using the donor fuel pump either.

[This message has been edited by Daryl M (edited 07-23-2020).]

ChuckR JUL 24, 09:11 AM
Daryl, I keep seeing your adjustable coilovers. I went back through this thread again and I do not see if you ever said where they came from. I either am missing the post or it is not called out. In your pix i do not see them when you are asking about the rear sway bar, and then they are there in pix after. I am just curious as I want to get a parts list for replacing / refreshing my 88' suspension. Thanks!
Will JUL 24, 09:26 AM

quote
Originally posted by msweldon:

Make sure you use sheilded twisted pair wire from fpcm to fuel pump for the PWM signal.



I find it hard to believe that anyone's actually had problems with this. The PWM is delivering motor power. Electronic noise is not going to have a measurable effect on the power delivered to the fuel pump.

I find it hard to believe that even crank sensor wiring needs TWSP... 10,000 RPM on a 58x wheel is only a 10kHz signal.

[This message has been edited by Will (edited 07-24-2020).]

pmbrunelle JUL 24, 01:33 PM
Shielding and twisting has two use cases:

1. Reduce the possibility of a victim from receiving unwanted interference.
2. Reduce the possibility of an aggressor from emitting unwanted interference.

It's hard to imagine that a fuel pump (and its wires) could be a victim, but the "high" power involved means that it could become an aggressor quite easily.
Will JUL 24, 02:03 PM
I'm not sure at what frequency the PWM for the fuel pump operates, but PWM solenoids (e.g. auto transmission line pressure control) are typically in the 100-200 Hz range; I would expect anything that rejects 60 Hz powerline noise is safe from that.
pmbrunelle JUL 24, 03:17 PM
The PWM may nominally switch in the audio frequency range, however, every time the switch transitions from on to off (or vice versa), the hit can excite resonant modes in the tens or hundreds of MHz. Of course, this is implementation-dependent.
msweldon JUL 24, 09:23 PM
I figured if gm went through the effort to twist and shield the pwm wires they did it for good reason.

Granted the electronics are far more sensitive and numerous on modern vehicles.