MYFYN79

Howdy,

I'm hoping this is posted in the appropriate spot, if not please let me know where it should be. I'm new to Honda's, so I have little knowledge of things which may be obvious to others. I apologize if this has been beat to death or not talked about in years.

I have available to me a 1990 Civic SI which the owner passed away, so the specs of everything are gone. The person managing the estate let me drag it home to see if I want the car or not. The only obvious mods I can see are a header, catback, fancy plug wires and MSD coil, aluminum rear control arms, and a D16A8 engine with a cold air kit.

The car has been sitting several years and wont start. I'm not familiar with how loud the fuel pump should be on the car but I don't hear it running with the key on. It did fire with starting fluid so it has some compression and I can imagine its not getting fuel yet.

What I would like to understand most is how I could ID the transmission in the car, and also to determine which ECU the car has. Reading swap info I see a lot of people mentioning you should run the ECU which the engine came from. The only info I got for the car is that it has an Acura engine in it, and some places say certain year Integra's came with the D16A8. Thank you for any information someone could offer!

MYFYN79

Had a little time to mess with the car and it has the classic ECU fuse blowing when I key on. The only thing I found on quick diagnosing was that if I pull the alternator solenoid valve fuse the ECU fuse doesnt blow. Once I get over to the shop I'll need to do more digging on that.

MYFYN79

I spent a couple hours today cleaning the car out a little and troubleshooting the ECU fuse popping when I turn the key to "run"

So far I've confirmed-

Main relay looks good (although I understand that shouldn't cause an ECU fuse to pop). With the main relay unplugged it doesn't blow the fuse.
It has a PG7 ECU in it. With the ECU unplugged it doesn't blow the fuse.
With fuse #14 (Alternator solenoid valve) unplugged it doesn't blow the fuse.
Unplugged the fuel pump harness in the car and it still popped.
Unplugged the 02 sensor and it still popped.

Trying to piece this together with a wiring diagram but finding conflicting info online with the wiring diagrams I've printed. Does anyone have access a wiring diagram for a 90 Civic SI?

Thanks

MYFYN79

Spent some time working on the car again today.

Points of interest-

-I jumped the fuel pump and got that to run.
-I plugged in ECU plug A and it makes the ECU fuse pop.
-I plugged in ECU plug B&C and the ECU fuse does not pop.
-Cleaned grounds under the hood.
-Unhooked several sensors under the hood and ECU fuse still pops.
-Fuse #2 (Starter signal) has .5 volts on it in either the run or crank position. This is with the main relay unhooked. Shouldnt that be 12 volts?

Key off no wires at ECU A have power
Key on, following wires have power-
A1
A3
A5
A7
A11
A12
A13
A14
A15

I dont see anything else obvious. The ECU looks perfect inside and doesnt have a bad smell. As soon as I plug in ECU A and power up the ECU fuse blows.

I confirmed this car ran fine when it was parked several years ago.

I'm by no means asking anyone to solve this for me, but anyone have advice?

Thanks

~sp33~

Download the "CRX workshop manual", it has wiring diagrams that'll be suitable for chasing your gremlins.

http://www.hondacrx.co.uk/downloads/downloads.htm

See if the download in that link works...

If you can't find it, PM me your email address, and i'll send it over we-transfer or something.

MYFYN79

Thanks a lot for the info SP! I'm gonna print some of that out and give it a go this weekend again.

~sp33~

No probs, post up how you go with it.

MYFYN79

I spent a bunch of time tracing wires and couldn't come up with anything. The most important info I feel is that with the main relay unplugged the ECU fuse doesn't pop, with fuse #14 out the ECU fuse doesn't pop, and with plug A out of the ECU the ECU fuse doesn't pop.

I let the person know where I was at with the car and he said there could be more extra parts laying around. We went and found two extra ECU's for the car. I swapped in what I believe to be the original ECU (I think they were both PM6, forgot to take a picture) that had 1990 written in marker on it. Turned the key, no fuse pop and it fired right up! It has a CEL and 9 code, but not worried about that at this point.

I have a lot of other work to do on the car before I'll worry about this, but what would be the best direction to go for an ECU when I get that far? I'll verify and reply back, but I'm guessing now I have two good "chippable" PM6 ECUs. I see there is someone on Ebay selling a socket/chip for PM6s with a ZC swap. Would that (or someone elses chip) be a better alternative than finding another PG7?

~sp33~

It'll run fine on a PM6 ECU, Ideally you could find a PM7, but honestly I ran my car for years on a PM6 and didn't notice any difference moving to a PM7 (other than the 180kph speed cut that it had).

jlicrx

true - it will run fine with PM6 - the only other difference between PM6 and PM7 is the fuel cutoff - on PM6 it is 7000 rpm and on PM7 it is 7500 rpm - forget chipping the PM6 - nothing to be gained, especially on a stock engine

FYI - the ECU Code 9 is for the Cylinder Sensor on the end of the exhaust camshaft - it would be extremely rare for the sensor to be bad - most likely a problem with the wiring

MYFYN79

Thanks for all the input and advice. This will be a slow project to get the car road worthy again. I'll post updates as I progress!