I have a 98 civic that I recently put a b16 in and it runs great untill all of a sudden the main relay clicks and the engine stumbles for a brief sencond and then continues to run fine until the main relay clicks and the engine stumbles again it does it randomly and I cant figure out what it is
-tried a different ecu
-checked all the grounds, cleaned and made sure all grounds checked out
-checked my main relay and seems to look good
-has a brand new battery
and checked just about anything i can think of.... any help would be greatly appreciated

 

I would suggest soldering the main relay. The solder joints are known to go bad.

It's a cheap fix if it works.

 

Honda Acura Essential Electrical Repair Website. Troubleshooting Main Relay, Coil, Igniter, etc.

 

or just get a new mitsuba relay for 20 clams or so...

 

I checked the main relay n all solder spots seemed good but i l try a different relay n see what happens

 

 

Did you check the ECU ground wires on the thermostat? Start engine and wiggle those wires to see if that causes the problem. Really wiggle any wiring that you can reach.

 

Yea checked em about 15 times lol, i took em off cleaned the area and put em back good n tight and even jumped another ground to it just for the hell of it to make sure it had a solid ground, wiggled wires n nothin, i ve tried tryin to wiggles differnent wires to see if anything changes n yet to find anything

 

Bump i would really like to figure out this issue.... any ideas!?????

 

Intermittent problems can be really hard to troubleshoot. You almost hope it will get worse so that some definitive tests can be done.

It's not throwing any CEL codes?

 

It is throwin a cel for a o2 sensor so i changed that out and still the same thing, but than again there has been times where i ve ran with no o2 and had no other issues than just runnin rich, the weird thing is that my other motor ran just fine with no issues and i havent done anything different as far as wiring goes between this swap and the last so its got me scratchin my head as to what it can be.... most likely somethin right in front of my face to lol 😂

 

tried the spark plug non fouler trick?

DIY O2 Sensor Bypass / Spark Plug Non-Fouler Trick Installation (w/ pics) - Honda Civic Forum

 

You're likely to get codes, most of them false, when there is a basic electrical power supply issue.

 

thats exactly what I was thinken, i have a o2 code but thats definitely not the issue, do you have any pointers as to what I should be checkin cuz this thing is driven me nuts, it tends to cut out alot more when i am idling or driven around town, but when i am on the freeway or just smashin on it wot then it doesnt give me any issues whatsoever, really has me confused 🤔

 

Bump hopefully somebody can help 😂

 

So if your wiring is 100% good, you've already replaced the main relay, and you have an o2 code that will not go away even though you replaced it with a new one then your fault is in the ecu. Could easily have a fault in driver, processor or traces causing the intermittent issues, have seen it a lot I work on ECU's daily.

 

That was one of the first things i tried was replacing ecu and still the same issue so i am currently lookin for another harness to throw on there and see if anything changes

 

Ok well ill stay tuned for an update on the issue