my B16 started misfiring like crazy. ive replaced the spark plugs, gapped to .44, plug wires, cap and rotor, the distributor is brand new only 2 months old. not throwing any codes. last week it would randomly start misfiring while i was driving it. but when i would turn it off and let it sit for a while then start it back up it would stop. but not it does it constantly, at idle, under load, under light throttle and heavy throttle. any ideas?

 

I would try to check for spark at each cylinder when the problem starts happening. If you are getting spark it might be a fuel issue. Are the injector clips loose? Also maybe an injector is stuck. You could try having them cleaned professionally or try a fuel system treatment like lukoil. Sometimes problems like this are harder to diagnose since its pre-obd .Hope this helps.

 

i had this happen to me an i had 2 injectors that were cracked.

 

it might be a fuel issue. i changed the fuel filter but that didnt change anything. would the ecu throw a code if an injector is stuck open? this swap also only has 30k miles on it. so i dont see why ive been having so many problems recently. bad luck i guess... any other input will be greatly appreciated

 

also, are D16A6 injectors the same flow rate as ob0 B16A injectors? because i have an 89 Si parts car that i can pull them from.

 

yes. i am running d16a6 injectors in my b17a1. runs great.

 

ok i swapped the injectors and changed the spark plugs again but its still misfiring... i really have no idea where else to look

 

maybe the timing jumped a tooth

 

yeah but its an intermittent problem
correct?

ur ignition can be caused out because u have replace the whole assembly unless it wiring

im assuming something with ur feul
ive had the same preoblem on my em1 everytime i would go over 3k rpm
then i took out the spark plug wires and they had water in them.


and the 89 injectors fit the clips or did u modify the clips to fit.

 

Did you change your spark plug wires?????

 

i didnt have to change the clips. its definitely a fuel issue because its running super rich and thats causing the spark plugs to foul out so quickly. i thought maybe the injector resistor box was bad, since i have 3 spares, i swapped different ones on and it still didnt change a thing. i really have no idea what else to look at. its still not throwing any codes.

 

also changed the fuel pressure regulator today. it ran a little bit better for about an hour. then started spitting so bad it wouldnt even accelerate...

 

have you looked at both the electrical and mechanical timing to make sure they are both on time?

 

possibly the ECU. i had this issue once in the pass on my DOHC ZC, i changed the ecu out and never had the issue again.

but it also sounds like a timing issue, check the timing on the distributor and on the cams. id also suggest u use a timing light when checking the timing on the distributor.

 

I am telling you its the spark plug wires

 

my buddy let me borrow his spark plug wires from his car and it didnt change anything. they werent brand new, but they work perfectly on his car. i set the timing with a light for the distributor, i pulled the timing cover off a few weeks ago and the timing wasnt off, but ill check it again. im also going to check the resistance on the injectors with an ohm meter.

 

could be the ecu, try swappin the computer from your parts car it will throw a code but if it is the ecu your car should run good on the si ecu.

 

there is one thing about my ecu that makes me wonder... the car hits vtec at about 4800. i thought that all b series ecu's engaged vtec at 5800? so i took the cover off of it and it didnt look like it was chipped. its a PR3. the ecu thats in the parts car is a PR4, which is an LS ecu. but the PR4 looks like its chipped. i know the parts car was boosted at one point. so if i swap the LS ecu in my car it might still run rich...

 

anyone else who is running a PR3 ecu?

 

anybody at all? i dont want to spend a hundred or two on an ecu when its not the problem... like i did with my distributor

 

problem fixed. it was the main relay...

 

Wow.

That is like no main relay problem I've heard of. Ever.

Noted.

 

exactly what i thought the entire time... also i had just replaced it about a month or two ago. so it never crossed my mind. i got a stock LS PR4 ecu from a junkyard, changed the spark plugs again. didnt fix anything. put the PR3 back in it, it ran a little better. couldnt think of anything else. then i thought i might as well swap the main relay, just to be safe, the old main relay was getting really hot when the car was running. runs perfect now...