Need a good ECU Detective...

Background: We (me and my son, yes I’m that old) bought a 92 GSR for parts (price was cheap but registration was FUBAR and I didn’t want to deal with that headache + car was abused and hit in the front).

The ECU is an original P61 (says the tag on the side) but something is not right. VTEC doesn’t kick in and the car sometimes runs rough. We swapped a SOHC P28 VTEC ECU and VTEC worked, so I know it’s the ECU and not wiring or the VTEC solenoid.

Problem: I don’t know enough to tell if the ECU is stock or if it has been chipped and messed with. I recognized that it has a ZIF socket but I also read somewhere that some stock ECU’s came with ZIF. I think it has been chipped and then for some unknown reason had the 74HC373 chip removed. I’m assuming that the car is running on limp mode and that’s why I have no VTEC but I also don’t have a CEL.

Investigation: So, for those of you familiar with chipped and stock ECU’s, take a look at these pics I took of the ECU and tell me what you think…

Exhibit A:

Exhibit B:

Exhibit C:

Exhibit D:

Thanks in advance

Well had a local guy who mods ecu’s look at it. For some unknown reason a previous owner removed the 373 chip. He also said there was more stuff that was broken. It will be easier to buy another chipped ecu than to pay someone to repair this one. So off to craigslist to look for a chipped ecu. I already have my eye on one. I’ll keep this one and try to repair it myself…with time. Eventually I want to learn how to do this stuff myself.


Well, the good news is that you have a genuine p61 (which is rare).

The bad news is that it’s been modded by someone who clearly did not know what they were doing… They attempted to chip it, but didn’t do a very good job. I’m sorry to say, but the soldering job looks like crap.
I cant tell that the 74 HC373 was previously installed, but then removed later (have no idea why…).

If your intent on fixing it, the first thing you need to do is cut j1 and see if it runs normally (it should allow the ecu to run as if it was stock). It should act exactly was if it was never tampered with (make sure everything works including VTEC).

If it still works normally (after cutting j1) then you’re in luck. you can just get a chipping kit from xenocron or phearable and just follow the regular chipping procedure. the only caveat is that you’ll have to desolder the components already soldered into the board. Desoldering is a little bit more difficult that soldering. I suggest you to get a small spool of 5mm wide desoldering wick to make your life easier. Pumps work too, but they are harder to use.

Good luck, I hope that you can save that board.

Thanks for the info W.O.D. I’m going to try cutting J1 and see what happens. Hopefully it works like OEM. Weird how the ecu works now even without a chip in the ZIF socket and the sabotage job the previous owner did on it. But it is rough and VTEC does not engage. No CEL either. Worst case scenario I will buy one of those chipped P28 clone ecu’s that are available locally. I’ll update what I find later.


Checked J1 and it has been cut. I’m guessing that the ecu has been running in limp mode. I’m going to pick up a clone P28 tomorrow. I’m going to see if I can repair the P61 and hopefully use it for later on.


ya if j1 was already cut and it doesn’t work properly like oem, chances are that the ecu is bad.

That’s what I’m afraid of. Regardless, I’m going to give it a shot and worst case is I’ll get some practice on soldering and desoldering. First, any recommendations on a good soldering iron for the job?


The iron isn’t as important as you may think. I just use an old 45w iron. I don’t even know where i got it from or what brand it is. Probably stolen from my friend a while ago haha. Just make sure you have a clean damp sponge with you to keep the tip clean. A more expensive iron will heat Up faster and have a consistent temperature, but that’s about it.

Soldering really easy. The key to good soldering is to make sure the area is clean. I use 95% rubbing alcohol to clean the board before soldering. Also make sure you use rosin core solder that is thin. I use a spool of 0.032" diameter solder for ecus. Make sure your iron is up to temperature before you touch the components. You want to use the least amount of heat to get the job done. Once your iron is hot, ‘tin’ the tip of the iron with a small bit of solder, this helps to transfer the heat faster. Just touch where you need solder for a few seconds and dab with some solder. If the trace is hot enough, it will draw the solder in. Be careful not to damage the components with too much heat! You can attach some pliers to some of the transistors as a heat sink if you want.

Desoldering is harder. If you have a desoldering pump, use the pump to pump out the majority of solder. Rarely will you be able to suck out all of the solder with a Pump. Use desoldering braid to clean up the rest of the solder. Make sure you do not pull on compOnents as you can lift the traces and damage the board. If you tried to desolder something but it won’t break loose, just resolder and then try desoldering again.

Good stuff W.O.D. This will be a long term project for me. I already bought a chipped clone P28 ecu from a local. I’m going to learn how to chip with Crome first since I already have a chipped ecu. Once I get a good feel on how to burn chips I’ll move on to the hardware stuff.