I have a d16z6 boosted on 16psi, street tuned by Vega. I had it street tuned 2 years ago and after a long road trip in my car, about 200 miles round trip, now the car is misfiring like crazy, in every gear when in boost except 1st. I checked the spark plugs and it still looks good, only 9k miles. I swapped the spark plug wires and still nothing. Could timing skip a tooth or two? When i went into wot, the wideband was at 12.2 then will go up to 13.5 and thats when the misfires happen. Idk could the injectors cause this or there's a vacuum leak somewhere cause after the wot run, the vacuum was at -18psi and now its at -12psi. Any ideas what to check or test?

 

If it's only in boost then it's probably the gap on ur spark plugs buy if that fine try to do some vacuum leak diag

 

Vega gapped them to .22 but when i guess i might of bent them a bit when i dropped them in instead of actually using the spark plug socket. But could that cause the -12psi vacuum at idle?

 

Anyone?

 

yeah, check your bank account..




cause youre going to need some $ to play with forced induction bro.

 

Maybe do a compression test??????

But looking at the valve cover for a long time usually helps

 

200 miles is a long road trip? i drive more than that on a typical day lol.

driving cross country is a long road trip lol.

check the basics

fuel filter, injectors, coil, cap, rotor, wires, plugs, tune/ecu, do a compression and leak down test, check mechanical and electrical timing, check valve lash, do a leak test on piping, intake manifold, couplers, check that the bov isn't leaking, etc.

those are things that could cause your issues. if you don't look in those areas then we can't tell you what's wrong. start with a compression test... if those numbers are off/low then there's no need to look further, you have a motor issue.

if the numbers are normal then keep looking.

 

I found why the vacuum was too high, the greddy type s have an adjusting screw at the top and it must of fell off and leaking there. I plugged it up with some tape and it seem to seal up the leak but it still misfires. So im thinking theres a boost leak there since the screw tightens the spring but its gone. Would a boost leak cause a misfire? I changed the fuel filter last night, and new wires and plugs and still does it.

 

A boost leak would not cause a misfire because we do not run maf sensors so the car will run with or without boost ... it just won't build as much boost

 

I sold a car with misfires bc of the same issues

 

I bet whoever you sold it to really appreciated that...

 

So would it or wouldnt cause the misfires? I looked at my wideband at wot and it fluctuates from 13.3-14.5, before the issue, it was at 12.5 which was were my tuner set it. Maybe bad injectors or fuel pump?

 

Maybe compression test?

Sometimes injectors get stuck. Best to replace them all.

The ignitor could be going bad swap that out to while you're there.

The vtec solenoid could be getting stuck change that out really quick