So i recently did something i'm sure cant be reversed without completely swapping in a new "completely functioning" OBD1 ECU.

I believe I miswired the purge solenoid harness plug to my IAT and viceversus, now the motor will start w/out the check engine light but it idles below 11:1 where as the idle was at 14.7-15.7 as of recent fueling changes I applied to the rom. The check engine light may be staying off in lieu of this issue since the rom is set to debug most check codes and features that would otherwise keep the motor from starting too. I'm NOT driving on this just to make it clear

My ECU was a JDM P30 already socketed and setup for datalogging. My replacement ECU happens to be a Phearable bought socketed P28, or P30, or possibly P75. I say this because the form factor is a USDM however the stickers were pulled off to identify the specific board type.

Here's a pic of my old Phearable ECU....


My question is, most reference's say that the pinouts on OBD1 ECU's (JDM/USDM/EDM) are all the same?

In the example below even Katman of FF-Squad notes this however if I take the SST Crome written chip out of my JDM P30 and place this in the USDM unit and try starting the car it wont start or so much as trigger the fuel pump to prime......
http://www.ff-squad.com/technet/wiring.obd1.htm


I'm just trying to identify where the hangup is.....I've tried importing the tables of my current rom into a P72 USDM ROM in Crome to see if this would work but I had the same issue as mentioned however I can put the chip back into my damaged P30 JDM ECU and it starts fine with the P72 image with the exception that I'm still having fuel enrichment issues.

I've also swapped in a spare good working IAT and no change was seen.

 

Well after about a week worth of testing I've come to the conclusion that my Rich Idle AFR's are the result of a Vacuum leak. I've tested a replacement IAT sensor, I checked the voltage coming from the plug i miswired and the output was less than 5 volts that the IAT normally see's so I seriously doubt the sensor or circuit for the IAT was damaged....

I tested a tweaked ROM that had the fueling corrections for colder and hotter temps leveled to the same multiplier of 1.00 at any temp and also leveled post cranking fuel corrections so that these adjustments wouldn't infer on the idle.....

None of these changes hindered the overly lean condition until I took the fuel values out of the far left column on the fuel table and copied these into the 2nd and 3rd mBar columns where then I saw the AFR's stabilize or go above 14.7.

I've come to the conclusion that the newly installed Hondata gasket could be the root of a Vacuum leak that is causing the motor to see less vacuum at idle speeds which would explain the higher fueling the motor is undergoing......


This problem began after recently installing a catch can which tapped the back of the block instead of the valve cover so this required removing the intake and replacing the intake gasket, only I figured why not reuse my old Hondata thermal gasket that ran fine on my old NA LSV, but i still had suspicions of rather it might cause a boost/vacuum leak potentially

 

Indeed, the ECU was not damaged thankfully......A vacuum leak was the issue and was the result of leftover gasket that wasn't fully removed from around certain harder to spot intake studs.....I removed nearly all the studs that had any trace of leftover composite gasket still stuck to the surface and scraped it off with a new gasket scraper.

I also had a buddy who had a spare USDM P30.....I threw my chip into his and the engine fired right up so I'm certain my old USDM P30 that I bought from Phearable.net has checked out strangly......theirs no reason this ECU shouldn't still work since it worked perfectly fine before being placed in storage for a few years so its a bummer because thats $175.00 im down but my idle is back to normal and I am using the Hondata gasket with no issues.