I've just replaced the motor in my CRX with the D15B7 from my 1993 Civic daily driver. The car works fine, however if I let it sit it's warm/humid outside, and I go to try and start it, the main relay and the IAVC click rapidly. I just spent $175.00 a new main relay and that didn't fix it. The ECU came from a perfectly working car I had for 2 years. I just replaced all of the grounds on the vehicle, and it only happens when the temperature gets above zero it seems. Any ideas?

EDIT: I also made a new ground for the ECU and the main relay right to the body of the car and that didn't make a difference. Battery is brand new and the cranks over very fast. With the main relay unplugged the car starts fine (until it runs out of fuel pressure and dies). I'm not sure how the injectors are getting power with the relay unplugged but it seems to start. I checked the prongs of the main relay, the power wire on the far right gets 12.65V, but the one in the middle only gets 11.5V.

 

$175? You got ripped off... really bad. Like 400% markup on top of retail bad.

Usually it's the ground wires on the thermostat housing not being tightened down.
They run into the engine harness and are often overlooked.

 

Thanks. I just replaced these grounds, however I will double check.

And yes I know I could have got one online for $40.00, but I was pretty confident that it was the main relay seeing how it was dependent on the weather, so I decided to spring for one locally.

 

Okay well it was fine for about a week despite parking in my heated garage (70 degrees) and going outside where it was well below zero (-25 ish) multiple times per day. Now suddenly it wont start in my garage again.

-> Brand new main relay (old one, and one from my other car also click)
-> All new grounds everywhere, when I replaced the corroded bolt on the thermostat ground the clicking got much louder.
-> both the IACV and the main relay click
-> intermittent, seems to be effected by temperature
-> Putting the batter booster (which used to fix it) only makes it worse now

 

Main relay rapidly clicking is usually caused by a blown fuse. Check all of them, not just the ones you think could cause it. I believe it was an underhood fuse though

 

Checked all of them with a multimeter, only one that was bad was the radio fuse (and I don't have a radio). The car starts fine when I tried it now. Garage temp dropped down to about 40 degrees, no other changes.


Maybe a bad ECU? I pulled it from a daily driver...

 

its early right now,and my brain isnt quite with me yet...lol,But it kinda sounds like an ignition switch problem to me if it isnt a ground issue or something shorting out..

 

This sounds really likely to me, I will buy a new ignition switch and report back.

 

No luck with the new ignition switch.

When I unplug the IACV (which also clicks with the main relay), the clicking goes away but the car doesn't start, it just cranks with a CEL on even if I give it throttle. I checked, and the valve is wired up correctly (yellow power wire, and blue wire going to A9 on my ECU).

If I jump the power wire directly to the battery it just clicks louder.

This only happens when it's warm, and the car idles fine when it starts a few hours later. Should I buy a new IACV?

EDIT: Dear god, $400.00 for an IACV... Any testing I should do or should I take the plunge?

 

Where are you buying parts??? $175 for a main relay, and $400 for an IACV? This place is taking your money and laughing at you.. I can get a main relay for less than $20 and an IACV for $155 at advanced.

It is either low battery voltage or a ground issue (and by ground issue I mean shorting to ground OR a bad/loose ground). Those are your only 2 options.

 

chances are something is getting shorted..



for the iacv,no need to pay $400..and thats just crazy.Salvage yard,man,salvage yard.lol.or ebay.local parts cars etc..
you could just remove/clean the iacv,they dont typically go "bad",they just get dirty, for the most part..

 

Problem = fixed. Took it to a shop who though it was the ECU, so I decided to take it home and put this issue to rest.

Sometimes it's the dumbest thing. The "power wire" I was testing was actually the fuel pump output (I think). The REAL 12v constant wire was not getting any power. Trace it up through the firewall and yup, it was cut.

Apparently not having a 12v constant wire will cause your car to run most of the time, except when you let it sit for 2 - 5 hours, or leave it out in warm weather. This also fixed my IACV clicking.

For future reference here were the pins that I think are correct for the main relay:

1 - Always +12V (from ELD)
2 - Ground
3 - Fuel Injector Output
5 - +12V Run and Start (from ELD)
6 - +12V During Start only (from Ignition Sw via interlocks)
7 - Fuel Pump Output
8 - ECU Fuel Pump Signal FLR1 & FLR2

 

That was my issue after replacing: fuel pump, main relay, distributor cap, tempering with ignition switch…
“ Usually it's the ground wires on the thermostat housing not being tightened down.
They run into the engine harness and are often overlooked “.

It was the ground wires !!!