Hello! I need some help diagnosing my civic and would be extremely happy if any of you could share your experience with me if you've ever had the same issue.

SYMPTOMS:
- Works great most of the time. Runs perfecly, but then randomly stops starting good (cylinder by cylinder) or doesn't start at all. Just cranks. Last time i checked it had spark, fuel and pressure!
- It usualy doesn't start when its a bit humid and/or cold.. It starts easier/more often if it is parked under a roof or inside a garage..

WHAT I'VE REPLACED:
- Distrubutor (original kit), new throttle body with all of the sensors, spark plugs, spark cables, CPS-variability sensor (the one behind the timing belt),
- I've checked the intake air temp sensor also (even though this wouldn't prevent it from starting).
- Did a service while i was at it.. nothing changed.

---- None of these parts have made any difference at all. As said.. The car runs great / perfect most of the time.. but then sometime just doesn't want to start even after standing for just 2 hours in not so cold or humid weather.

I'm now waiting on a main relay to arrive to replace that aswell but im not sure anymore if that's the issue.

- (example of it starting cylinder by cylinder) --->
Picture of the car:

 

sometimes these intermittent starting issues are caused by bad electrolytic capacitors in the ECU. They leak their electrolyte onto the board and corrode the traces on the inside. Once it gets bad enough it will not start. I would attempt to pop the ECU open and inspect for any gross substance/corrosion under the cylindrical components. You will need to repair any traces, and replace the capacitors. This may not be the issue, but just an idea. I'm seeing it more and more often and its now become a preventative maintenance IMO... You might be able to narrow it down by seeing what your scan tool is telling/not telling you when it start or doesn't start. again, a suggestion, these issues are tricky.

 

Hi! Thanks for the reply. I took my ecu out and it looks pretty mint.
I've also recieved/replaced the main relay and it didn't fix the issue. Car worked fine for a week but then barely started on monday :/.
Would't it be possible that the issue is caused by a bad harnes? Im now thinking of replacing the engine harness next..


Anyways I'm attaching pictures of the ECU if you wouldn't mind to take a look! (is it normal for all the components to lean on the side like this?
Thanks again.

 

Yeah that board looks pretty clean. I don't see anything wrong myself.

I wouldn't expect it to be the engine harness myself. I would expect some anomalies when it runs/drives. Maybe if you suspect the harness, try to jostle the harness when you have it running and see if you're able to induce a fault.

I'm not a experienced diagnioser, but If you hook up a scan tool and look at engine data when cranking... do you get all data like crank position, cam position... ECT.... preferably when it won't start

you mentioned you had fuel, what did you check exactly?

i suspect you already know this, but Honda ignition systems can be picky when it comes to parts. ensure oem or recommended equivalent from others in the forum for the distributer, wires, plugs. I hadn't had too much experience myself in this area, so im not sure if any of it would cause an intermittent fault such as this. Also of course, fake parts exist and i wouldn't trust much of anything from eBay or similar...

 

I checked fuel pressure at the fuel filter under the hood. It had 40psi and held it after the car was off (so no leaks).
After the post i did some more diagnosing and found that when the car cranks but doesn't start, there's fuel only in the first cylinder (and the spark was also the strongest in the first clynder) (not sure if that's a hint to anything)..

I then started listening for the injectors actuating but before I got to the second injector the car decided to start (after cranking for quite a long time while diagnosing)..

When the car starts it starts off very weird, first running on 2clynders, then picking up the third and only after a minute it starts to run smooth.

I first thought about the injectors being faulty but that would surely effect the car while driving right? (missfires ect..)

I also tried shaking and budging the harness while the car is running with no luck .

Any suggestions help.

 

Would it turn over on starting fluid?

I do find it odd how you mention that it seems to start like it’s only firing on two cylinders before the others pick up. Unfortunately i’m not experienced enough to pick up any clues from that.

Other than making sure you have all your bases covered with grounds, oem ignition parts, strong battery/voltage, other basics… im not sure i’d be useful. hopefully someone can chime in.

 

Check fuel pressure, might be a bad fuel pump, or a bad fuel pressure regulator.

 

I've experienced something similar before on my old 00 EX. In my case when it would start rough when cold. When warm it would hesitate to start but eventually would catch. Ultimately the issue was the head gasket as coolant was getting in the cylinders causing hard starts. Are you losing coolant? Does your engine overheat?

 

Thanks for all the replys.
I've gone over all the basics (Batery, fuel pressure..) and had a professional civic mechanic/restorer check over it.

The car doesn't burn coolant (Has been on the MAX line since i've bought the car almost 2 years ago, but I'll still check over it! (was your intermintent no start super random and rare like mine?) )

I've also come to the conclusion of the fuel pump and regulator acting up and I'm now waiting for my replacement parts (original).
I'll post my findings soon Thanks agian

 

It acted up again yesterday so i had the chance to diagnose some more. I found out that the injectors weren't pulsing! I had fuel pressure, compression, spark, bu tno injector pulse (they weren's spraying fuel and they werent clicking (they're usualy really easy to hear when listening to them with a screwdriver so Im really sure they arent firing)

I then checked them and they were getting power, but no signal i suppose. (On my honda they're supposed to have a constand flow of 12v and then the signal grounds them, I got the 12V but didn't check for signal because I assumed it's the only thing missing now..)

What's my next step? The harnes? the computer? One of those has to be it. That must be it! (I plan on checking the harness this weekend for any damage at the firewall port behind the ac filter box. I'll keep you updated)

 

When that happened to my car, it was the immobiliser.

 

im glad you found the issue, i would be probing with a test light on each injector to see what else you can find. If you're having an issue across all cylinders, then perhaps its an issue with the computer. Maybe if you have another PGMFI relay, go head and change that and see if you're getting any change? Double check ground for the relay, voltage in... i think there's some troubleshooting steps for the pgmfi system in the factory service manual