PlanktonBB

Currently trying to log/tune my AFR. However, I'm not able to boost over 4K rpm
"10PSI" Car seem like it being held back and with multiples popping noise.

So I did some research, and came across a post from DaleClark/Crewrx7r1 in the Rx7Club, mention that.

"Here is a quick test to determine if it is the secondary injectors.
Lowering the Settings 5 Pri/Sec transition % lower would cause the problem sooner.
Raising it higher will cause the problem later."

Originally 50% transition = can't pass 4K RPM
Set to 30% transition = can't pass 3K RPM
Set to 70% transition = can't pass 4.5K RPM
What I have done:
1) Check continuity in the harness for the F/R Secondary injectors. Make sure the connector are seated correctly.
2) Open the PFC for an inspection to see if the driver is okay. But I cant seem to tell if it's actually bad.

My question is:
Are there any other alternative method to test secondary driver.
Are there any schematic out there for PFC repair?
Does anyone have a spare UPA1556AH driver that I could buy off?


Setup:
750/2000 New Injector Dynamic
Fuel lines are ran in parallel configuration.
Gtx3582r .82AR
Aiming for 14PSI max boost, Currently at 10 PSI
External boost controller set at 10PSI

PlanktonBB

Any EE here?
Are there any alternative driver that is better than NEC UPA1556AH??

Thank you

Turbo II FC

iTrader: (14)

This would definitely be beneficial as there are still quite a few Power FC owners out there and its a common failure for the injector drivers to have issues as these ECUs are getting up there in age. I do see that youre located in Arlington and Rotary Performance does replace failed injector drivers on PFC so thats one option but I would like to see this procedure discussed more in detail. If youre looking to replace the driver yourself a quick google search shows the NEC driver for less than $5: https://www.utsource.net/itm/p/982140.html?digipart=1

PlanktonBB

Turbo II FC,

Thanks, I just ordered two from ebay for 7 each + 3 for shipping.
I'm going to reach out to some EE to see if there are any alternative replacement for this particular driver.

I might run a noid light to see if it the driver are actually firing.
Because during my log, from 1-4k RPM my voltages for "Front Prim Inj" was fluctuating according to the throttle response, while Voltages for "Front Sec Inj" was 0.
Right when I hit over 4k "Front Prim Inj" was increasing, but "Front Sec Inj" was stuck at 5v.

I hope the driver will come in soon.

scotty305

iTrader: (2)

I spent a few minutes searching on digikey, it looks like that style of chip (10 pins with 4 circuits inside) has fallen out of favor as technology improved. I think your best bet is replace your damaged driver with the exact same part and then try to avoid damaging it again.

It might be possible to build something like a small adapter board to use modern transistors, but I don't have a PFC to know the space constraints and it would cost a lot more then $5 to use transistors that can handle harness faults without getting damaged. You should still find and fix the cause of the problem, even with a fault-tolerant chip the injectors are likely shutting off or stuck on by the type of harness problems that could kill that chip.

PlanktonBB

Scotty305,
When I first bought the car, I only drove it for roughly 20 miles prior to the engine rebuild so I'm not exactly sure, if the Secondary injector driver ever work?
Originally car came with the 550/1300.. "1300cc was the oem one that got bored out"
During my rebuilt, I went ahead and replaced everything, even made my own custom harness.
ID 750/2000 FE primary/sec fuel rail.

I wonder what underline condition could've cause this chip to fail Nothing within the PFC itself is melt or have any sign of issue.

scotty305

iTrader: (2)

How do you know the chip is damaged? Did you test with a noid light? Are you sure the injectors are getting power in the harness? I'm not familiar with how to test the PFC, but for other ECUs there is often a way to manually trigger an injector output to make sure everything is working as expected. Do you have a wideband to see if the fuel mixture is showing lean or rich when you adjust the secondary settings? If you only swapped injectors without changing the ECU calibration it might be simply adding so much fuel the spark plugs can't ignite it.

H_M

iTrader: (7)

The injector driver won't show any signs of damage if it's blown. This happened to me a couple of years ago when one primary injector stopped firing. It takes a steady hand and some soldering skills but it's not too had to replace. If you don't feel comfortable replacing it, you can mail your PFC to Michael Gagne and he can test/repair it for you.

PlanktonBB

I did a continuity test for the harness to ensure it was good, from the ECU itself to the connector.
Checked the connector make sure it's all good.

This is what I did to test the secondary injector.

DaleClark/Crewrx7r1 mentioned
"Here is a quick test to determine if it is the secondary injectors.
Lowering the Settings 5 Pri/Sec transition % lower would cause the problem sooner.
Raising it higher will cause the problem later."

Originally 50% transition = can't pass 4K RPM
Set to 30% transition = can't pass 3K RPM
Set to 70% transition = can't pass 4.5K RPM

PlanktonBB

Ahh okay, do you happen to remember which driver did you replaced?
UPA1556AH?