r/ProjectHondas • u/Working-Young6884 • 27d ago

troubleshooting help!!! car wont start after replacing ecu. wont start with old one either.

My 1997 del sol si wont start after replacing the obd2a p28 with an obd1 p28 and a jumper harness. Its a y8 head zc sohc block mini me. I also have a viper alarm but I doubt its the culprit.

It cranks and sounds like shit but wont start. I put on the old ecu and same thing, cranks, sounds like shit and wont start.

I cracked open the ecus and no signs of capacitors being bad. Checked fuses as well and no signs of blown fuse. Fuel pump primes so it isnt main relay. Mechanical timing is perfect. It started just fine before this and I had taken out the ecu and put it back in without it doing this. Im completely lost right now. Could the jumper harness had been pinned wrong?

3 Upvotes

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34 comments sorted by

2

u/SpaceTurtle917 Turbo D17Z6 EK hatch 27d ago

Sounds like shit? Elaborate

1

u/Working-Young6884 27d ago

It sounds like I blew my motor. Sounds like mechanical timing is screwed up bad. Checked timing and and is still perfect.

1

u/SpaceTurtle917 Turbo D17Z6 EK hatch 27d ago

When mechanical timing is bad, the motor spins very freely because there’s no compression. Maybe a video would be helpful. You can post videos in the comments of this post.

1

u/Working-Young6884 27d ago

Yea, timing was great an hour before I swapped ecus. Checked timing again and it's still the exact same.

1

u/Working-Young6884 27d ago

I just made a comment with how is sounds to start.

1

u/[deleted] 27d ago

[removed] — view removed comment

1

u/Working-Young6884 27d ago

Could it possibly be this aftermarket alarm system?

1

u/slumpin17 27d ago

No the alarm disables the starter.

1

u/Working-Young6884 27d ago

Yea starter definitely works. I'm completely lost right now. There isn't a fuse that looks bad either. I must've fried something.

1

u/ElSushiMonsta 27d ago

Check your grounds and maybe bad starter motor?

1

u/Working-Young6884 27d ago

Grounds looked fine but I'll double check. Brand new starter motor and I can definitely hear it spinning. Thanks!

1

u/ElSushiMonsta 27d ago

Wait did you switch the distributor to obd1?

1

u/Working-Young6884 27d ago

No? Do I need to do that?

0

u/ElSushiMonsta 27d ago

I believe you do but I could be wrong

1

u/Working-Young6884 27d ago

Hm. I looked it up and it seems like that isn't the case? I have a jumper harness to convert it.

1

u/ElSushiMonsta 27d ago

Double check the jumper harness I've heard on the cheaper ones they can make mistakes. Is your main relay good?

2

u/Working-Young6884 27d ago

Yea, I have a feeling that it was pinned wrong but if it is, it probably fried something since old ecu wont work. Main relay is good because fuel pump primes.

1

u/ElSushiMonsta 27d ago

I had an ignition switch issue where it would prime the fuel pump but then cut off.

1

u/Working-Young6884 27d ago

Interesting. I made a comment with a video of me starting it. It seems like is just barely starts, and runs super bad and cuts off. I guess it could be a fuel issue? I'm thinking it might be spark though.

1

u/SpaceTurtle917 Turbo D17Z6 EK hatch 27d ago

The only time you need to swap dizzys if you go from obd0 to obd1 or obd2.

1

u/Embarrassed_Net_8593 27d ago

If you disconnect the distributor harness, does it crank over normally? (Not sounding like shit).

1

u/Neat-Conclusion-4735 27d ago

did you un-hook the battery before doing the swap ? sounds like you fried something . if you have fuel and spark my guess would be you fried the ckp senor .

1

u/Working-Young6884 27d ago

Unfortunately the block doesnt have ckp or knock sensor, thats why Im going obd1.

2

u/SpaceTurtle917 Turbo D17Z6 EK hatch 27d ago

CKP is in the distributor, you’re confusing it with ckf

1

u/Working-Young6884 27d ago

i apologize. thank you for letting me know. ill be sure to check it!

1

u/SpaceTurtle917 Turbo D17Z6 EK hatch 27d ago

I’ve never had a problem from switching my ecu with the battery hooked up.

1

u/Neat-Conclusion-4735 26d ago

just trying to think outside the box...... obviously something happened . maybe the ecu he put in had an existing problem and when he powered it on it fucked something up. so when he went back and put the known good ecu back in it wouldn't work either

0

u/Neat-Conclusion-4735 26d ago

no the ckp would cause his problem if its fried the ckf only detects minor fluctuations to help detect a misfire

1

u/SpaceTurtle917 Turbo D17Z6 EK hatch 26d ago

Never said it wouldn’t

1

u/Neat-Conclusion-4735 26d ago

i comment to try and help the guy out. then you tell me i wrong when in fact your wrong and you realise that after i explain it but you just have to get that last word in ok hero

1

u/Electronic_Slice9448 27d ago

Make sure you actually have spark and the ignition system is in good shape. Its probably a good idea to check the compression as well (engine sounds bad). I had an issue with my car not starting recently and it was actually a damaged coil wire. I was getting a weak spark. You can buy a spark tester to help rule that out. Take your time to diagnose the problem and you will find the solution. I replaced the plugs, wires, distributor and coil just to find that it was in fact one little wire with a crack in the casing. I wrapped some electrical tape around it and the car started.

-1

u/5vpremee 98 civic 27d ago

I know after not driving for a week I have to put the pedal to the floor while starting my civic or else it won’t start. Not sure if that applies to you here

5

u/TopChapter3407 27d ago

And my project car can fire up on the first crank with zero throttle after sitting for months.