I bought a 1999 Civic Si last summer from auction, sight unseen. This is my first Honda project; most of my automotive experience is with BMW. I'm finally getting around to being able to spend some time on it to hopefully get it back on the road. Best I can tell, the car has been sitting since 2008 or so, and had a lot of early 2000's period correct modifications. It's still a B16a2, but has an Edelbrock Victor Jr intake manifold, different injectors, and an MSD ignition setup as well as your typical exhaust modifications. At one point, it was converted to an OBD1 (P75?) ECU with a jumper harness. I'm making the assumption that cams and basically everything else is stock (plastic cover is intact and present).

In my limited research, it seems that the Victor Jr. intake is way overkill for a stock B16A2, and is probably hurting power throughout a lot of the rev range, and it looks like the ECU was swapped to OBD1 to support this manifold. I purchased a stock B16a2 intake manifold as a replacement as the idea is just to get this thing in drivable condition first. Am I best off also swapping this car back to the stock OBD2 ECU? What other steps will that require? I'm assuming there is reprogramming involved to get the ecu to match the immobilizer. This car is in bad shape cosmetically (painted at least twice) and has a rebuilt title, so keeping costs down is a priority as I tend to get bored with cars quickly and don't want to be completely upside down in this.

 

As long as no one hacked up the harness and/or removed anu emissions equipment, swapping back to the stock P2T ecu should be plug and play. The injectors will need to be replaced with stock ones. Might as well remove the MSD ignition stuff as well, it's not of any use on a stock B16 (or really and Honda, in my opinion) and the external coils aren't terribly reliable.

It's likely just a chipped ecu in there, you can open up the lid to see what it's got but unless there's a cutout for a USB port you won't be finding an S300 or Demon board or anything. If it's been sitting since 2008 the board would be way outdated anyway. Nothing really lost by pulling that ecu, but OBD1 ecus in good condish are worth a decent amount on the market these days.

You are correct on that manifold being way overkill for a stock B16A. The OE P2T mani is pretty decent, you could also go up to a P73 (type-R) mani if you want to run ITR/CTR cams in it. It's worth popping the valve cover off to check what you've got. There are ways to identify different OEM cams. Hoepfully you are able to find the OEM evap purge valve and hoses for your P2T manifold.

FFS | Tech -- DOHC VTEC CAM ID (ff-squad.com)

 

Appreciate the reply/link. I did pop the OBD1 ecu open a while ago and didn't see anything of note- was not expecting any sort of modern chip/software/etc.

Should I anticipate having to get the ECU coded for the ignition/vin/etc (again- BMW background, specifically E46, and they're very finicky about what looks for vin numbers, security, etc)? Also, is it worth tracking down a factory service manual for this chassis? I usually buy them for other cars I've owned that I'm unfamiliar with, but they're usually a lot cheaper than the $150 price I'm seeing for used on ebay/etc.

 

I'm pretty sure these did not have the ECU coded to the ignition. there's no transponder in the key- it's all mechanical. part of why they tend(ed) to get stollen often.

FSM like this one include the info for the EM1 along side the EJ6 and EJ8. this is about what I paid for mine 14 years ago. I'd pay $100 for a new, in wrapper example if that's what I felt I needed. But anything over that is silly.

 

Okay, good to know. I'll try buying an ECU- worst case is that there are additional steps.

Thanks for the link as well- everything else I was seeing was $150.

 

Correct. US market Civics didn't get immobilizers until 2001.

 

Make sure the sensor at the crank pulley for the t-belt is intact if you plan on revert back to OBDII. The sensors, bump guard, and harness clips are not the easiest to come by. The harness to that location is very near a lot of belts so it cant be left flopping around.

 

As a follow up- ended up buying an EM1 ecu on ebay. Swapped back to the stock B16A2 intake manifold and the car is back up and running.