robx7fcna

Hey guys, here's the story, I know someone will be able to help.


I recently did a 1st gen b16 swap on an 89 civic si. We didn't have an engine harness for it, but we did have an 88 crx si harness, which as you guys know has a different plug on the drivers side shock tower. I de pinned the 89 chassis harness plug and added an 88 plug so the engine harness would plug into the chassis harness, but 2 wires weren't used in this process (fast idle solenoid) just thought I would share that infor just invade that may be an issue.

Anyhow, key on engine off, the fuel pump primes, relay clicks, and the car starts fine. When it's driven cold, the car runs normal.

Once the car is fully warm, then randomly the main relay will click off, then on for a fraction of a second, which causes the car to suddenly die, then come back to life.

When you try to take it to redline, around 5500 rpm the problem becomes much worse and the relay will click on and of 2 or 3 times in a 2-3 second timeframe. Also sometimes I will try to do a second pull to replicate it, and vtec won't come on.

What I have tried to remedy this is the following

1) remove and test main relay

2) replace main relay with known good relay

3) test for power/ continuity in main relay harness

4) test continuity on ecu grounds (both black wires, black with red stripe, brown with black stripe.) i also ran a new ground wire from all 4 grounds to thermostat housing to bypass any potential broken wires (since the problem only surfaces during driving I wanted to be sure that I had solid grounds from the ecu to the thermo housing

5) removed, cleaned, reinstalled all chassis grounds (battery ground, valve cover ground, tranny ground, also added a ground from the drivers side front of the block to the chassis (paint was ground off on chassis side) all points were checked for continuity after and yielded less than .8 ohm.

All of this and it still does the intermittent clicking while driving. It is so random, it can happen under any throttle load, and can happen 2 times in 5 seconds or can go a few minutes before clicking on and off again.


Any info or suggestions would be greatly appreciated!

Also, let me know if I need any more specific info.

Thanks, rob

robx7fcna

One thing I should add, I did have a brain fart when I did the first start after the swap. I had the battery ground going from the battery to the block and only the valve cover ground running to the chassis. I tried starting it this way and my buddy said a big spark shot out from around the battery area. I was thinking I might have killed somthing in the dash and/or engine harness because of this.

EF9_TryMe

Battery ground should directly be placed to the chassis.

Did you check all of your connections? Fuses ? How did the car run before the swap was done ?

robx7fcna

Thanks for your reply.

Yes, since the "brain fart", I moved the battery ground to the chassis. Then I have the transmission ground running to the same point on the chassis as the battery ground.

The car ran great before te swap, but it also sat in a garage for 2 years without a motor before I performed this current swap.

It previously was an obd 1 built b16 swap 2 years prior and was turbo. Back then I added a walbro 255lph pump amd it has seen maybe 4000 total kms, but I have heard of these pumps failing prematurely.

Anyone think that te pump could be causing this?

robx7fcna

Oh and yes, fuses are all fine. Connections seem to be good.

I have also replaced the plugs, wires, distributor and no change (even though I knew they wouldn't)

CRX Si69

if it was sitting in gas for 2 years, service it or get a new one.

Canadian_EF

did you check your thermostat housing ground? mine was loose and my relay was clicking all over the place.

robx7fcna

Good call. I am going to drop the tank and take a look at it tonight. What can I do to service the pump? Or should I just replace it?

robx7fcna

Yeah, I've triple cleaned and tightened. I have cleaned all grounds in the engine bay

EF9_TryMe

It's not the pump.

Relays: I don't know how they actually work in hondas, but regardless, it's one of the two

ways explained. Here goes: The reason why the relay is clicking is because it's either

being energized constantly by a voltage to close up the other side of the switch inside

the relay and apply a voltage path for current to flow, and it's getting annoying or it's

just a ground that's lose somewhere and has a tendency to affect the energized circuit

path of the relay completing the switched circuit inside the relay in which would create

current to flow.

Sorry to get all technical, trying to help ya out here buddy and it's kind of late for me to think, bare with me.

Did you double check those grounds ?

robx7fcna

robx7fcna

Whoops kinda screwed up my last post and put it smack dab in the middle of the quote. Please bare with me as it was posted from my phone haha.

sstupid

When you get over 3K miles, you are at high demand on the electrical system. You might also want to get a new battery and check the alternator, and see if that helps.

robx7fcna

I bought a new battery and new altenator when I did the swap. Battery has 12.6v and alt has 14.5v. So I think I'm good there.

CRXcaliber

Relays work by using current to create a magnetic field in a coil which makes a plunger of some sort bring the contacts together (as in a solenoid, which is a relay). They are mostly used in applications where high current flow is needed, to prevent damage to other circuitry from current spikes associated when the relay circuit is energized. The ONLY thing that can make a relay "click" on and off is loss of applied voltage or ground. Check ALL the current paths in these diagrams. I guarantee you have a bad connection somewhere or you are losing the 12v needed to energize the relay due to something killing the 12v. Keep in mind a 12v relay needs 12v to energize. Nothing else, possibly even 10v or so will keep the contacts closed sometimes. Probably not the case here, but if you have like 6v, you may have a problem. Depends on how the circuit is designed. Also, if you notice, the ignition switch is part of the circuit so you may want to check it for bad or dirty contacts which could cause the applied voltage to be intermittent. Pick something common to that leg (such as the wipers) and turn it on, If they shut off when it happens you may have a bad ignition. You are looking for 12v at pins 5 and 4 and ground at pins 2 and 8. Notice the diode in the circuit (the triangle with a line beside it). The side with the line is ALWAYS the lower voltage side, in this case ground. Its purpose is to prevent spikes in the circuit from damaging other things when the voltage is removed and the magnetic field in the coil collapses inducing a current in the line. Hard to troubleshoot not being there so just use your common sense and you will find the problem, I'm sure. Hope this helps.

Btw, I've used these diagrams for other things with other people so the colored notations may or may not apply to your situation.

robx7fcna

Excellent info, thank you sir! I will soak all that info in and apply it to the car when I get a chance. I still havent got back to working on the car yet, I have been working overtime like crazy right now.

Anyrate, thankyou for sharing that with me, much appreciated, I'll report back with an update when I tackle all of the paths in those diagrams

CRXcaliber

EF9 PM'd me asking to explain relays more in depth and why they are used. I figured I would post my reply to him for others that would like to know.


Quote:
Originally Posted by EF9_TryMe
Relays work by using current to create a magnetic field in a coil which makes a plunger of some sort bring the contacts together (as in a solenoid, which is a relay). They are mostly used in applications where high current flow is needed, to prevent damage to other circuitry from current spikes associated when the relay circuit is energized. The ONLY thing that can make a relay "click" on and off is loss of applied voltage or ground. Check ALL the current paths in these diagrams. I guarantee you have a bad connection somewhere or you are losing the 12v needed to energize the relay due to something killing the 12v. Keep in mind a 12v relay needs 12v to energize. Nothing else, possibly even 10v or so will keep the contacts closed sometimes. Probably not the case here, but if you have like 6v, you may have a problem. Depends on how the circuit is designed. Also, if you notice, the ignition switch is part of the circuit so you may want to check it for bad or dirty contacts which could cause the applied voltage to be intermittent. Pick something common to that leg (such as the wipers) and turn it on, If they shut off when it happens you may have a bad ignition. You are looking for 12v at pins 5 and 4 and ground at pins 2 and 8. Notice the diode in the circuit (the triangle with a line beside it). The side with the line is ALWAYS the lower voltage side, in this case ground. Its purpose is to prevent spikes in the circuit from damaging other things when the voltage is removed and the magnetic field in the coil collapses inducing a current in the line. Hard to troubleshoot not being there so just use your common sense and you will find the problem, I'm sure. Hope this helps.


Very well explained. Learned something new there. Could you just go more in depth in how
relays prevent damage to other circuitry from current spikes ? Like which circuitry ? Energized ? Or bridged side ?


My reply:

No problem, glad to. Here goes. The relay is used in high current applications (usually). Ohm's law states that Voltage is equal to current times resistance. E=IxR where E is voltage, I is current, and R is resistance. This can be transposed to I=E divided by R. This is the equation we will be dealing with mostly. We'll use your fuel pump circuit as an example and also the starter circuit. First, the fuel pump. Since the fuel pump circuit is essentially a motor and some wire with 12v on one side and ground on the other, it can be thought of as a short (1 Ohm resistance or less). If you measure across the terminals on the pump you will find that it has virtually no resistance. It is basically a coil that creates a magnetic field which deflects the magnets in the armature and causes rotation since magnets will repel like poles. The magnets constantly try to find equilibrium within the field and thus the motor turns. A/C motors are a little different, but that's not important here. The same principles are used. The coil in the motor windings is just a very long wire wrapped in a loop fashion to create a very strong specific magnetic field. Since it is just wire it offers very minimal resistance. Here is where Ohm's law comes into play. With 12v at one side and ground at the other we can find the current values for this circuit. I=E/R.. I=12v div by we'll say 1 Ohm for practicality and ease. I=12Amps. If this was just connected to your ignition switch you would quickly fry the puny contacts in the switch passing 12A through it. A heavier duty application is needed. This is where the relay comes in. Allowing a low current to switch the circuit on without burning up the switching circuit. All that is needed is a resistor in the coil side to dissipate the current flow and keep the relay closed using low current. Say a 100 Ohm resistor is placed in line with the coil in the relay. Now we have I=12v/100 Ohms. I=.12 or 12 mA (milliAmps). Big difference! The same applies to the starter circuit except the windings in the starter are designed to provide maximum torque and probably are only about .05 Ohms. Using Ohm's law we can see how much current is in this circuit: I=E/R I=12v/.05 Ohms I=240A This would definitely smoke ANYTHING in its current path! By using a solenoid (relay), this current flow can be isolated to only the starter motor circuit and nothing else is in danger. The current in this circuit (actually it's more like 280A or so, which actually gives us .0429 Ohms rather than .05, since R=E/I) would melt your ignition switch into a glob of metal as soon as you turned it, not to mention it only takes 5mA (.05A) to kill you under the right circumstances. Much safer to use a relay for switching. Hope this helps you. Glad to share the knowledge with anyone willing to learn something new.

sstupid

Ah, the good old G101. What a bastard.