I've been getting constant engine misfires since the past month.

I've replaced the o2 sensor, tried out my factory ecu, checked and replaced my spark plugs and yet the problem is still occuring.
The car is not giving any CE lights either. All other sensors seem to be fuctioning correctly. I've pulled the spark plugs while the motor was running and all the cylinders seem to be up and running. Also the car is not smoking or tapping. I haven't got a clue why its misfiring so badly.

I will be replacing the cap and rotor this week to see if that would work, but its a pretty frustrating problem since i dont know where to start.

 

mine was doing that too , but i was getting cells, it turned out it was my AEM fpr, i had to change the orfice inside to a bigger one ebcuase it was too much pressure becuase my Walbro pump . i dont know if that'll help you, but thats what fixed my problem

 

my cars been running good for the past 6months, just started while i was driving. By looking at the fuel pressure gauge, seems like i'm getting the same amount of fuel from my fpr.

 

do you have the aem fpr and the walbro pump>?

 

stock fuel pump with a vortech FPR (not the boost dependent fmu) Runing 21psi static with 440cc injecotors on hondata stage 2b.

 

You can look at the rotor and tell if its bad. My car was misfiring in EVERY cylinder and I replaced the cap, rotor, and coil assembly and everything is fine now. Good luck.

 

could it be that that fuel pressure it too low and causing probs?RC told me you have to run at l;east 30 or 35 fuel pressure , i forget which one , but i think its 35 for thme to work efficiently . . . its a stab in the dark , but i dont think thats helping the situation


[Modified by itr206, 9:20 AM 2/10/2003]

 

What size orifice did you end up using? I have the same FPR and fuel pump and I don't want to run into any problems.

 

i doubt its the fuel pressure because my car has been running perfect for the past 6months.

 

yea and that just means that your injectors/fuel system took it for a little and are crapping out over time. . . trust me man , that would be the 1st thing to check out , pump up the fuel within specs and go from there. . . . stock fuel pump and super low pressure =
whats prob happeneing is it isnt getting a constant pressure and causing like surges and drop offs that are causing the missfiring and stumbling
my FPR issue with the missfires happened about 6-8 months after i put in the pump and it was the pump that was maxing out the fpr . . . so thats food for thought , trust me , try it and see what happens
im using the middle orfice now . , it was causing dipram flutter due the the fpr high pressure of the smaller orfice(the one that came in it )


[Modified by itr206, 9:49 AM 2/10/2003]

 

so what did you replace?? the FPR?

 

i replaced my orfice in my fuel press reg for that , but thats not your issue, becuase you dont have that regulator nor do you have a big pump like i do . . . . pump up the pressure man .
with Fi you are taking chances big time for problems down the line .

 

21psi static fuel pressure is REALLY low, try adjusting at least up to oem specs, 36-38 psi fuel pressure.

 

tried higher pressure, still it does it at 40psi. The car was tuned at low pressure, dont know why.

 

Hmm.. I'm getting constant misfires as well. I get misfires once every 5 seconds
at 12:1 a/f ratio.. . and constant misfires any leaner than that.

The misfires go away when I get on the throttle though. Maybe my fuel system
is shot too.. I used to run inline+FMU.. and maybe that screwed up the stock FPR
and fuel pump.

 

Holy F you might have solved my problem, I got random CEL misfire codes, hopefully what you did will fix my situation because its what I did. Was running stock/then AEM fpr (small orifice), and walbro. Now I stepped up one size on the orifice and seeing how that will work out.

Whats your fp set at if I may ask? (idle with vac connected)

 

ummmm, i think it was like 45-48 idle. my car was higher pressure though from the factory.
yea try it ma , i bet itll work , mine drove me nutts for freakign weeks , seriously many weeks . i was soo fuckingpissied replaced everything int he car and thne aclle aem becuase i thought the FPR was bad, i narrowed it down to that at least and thne we talked for a while and figured it was that . . . i replaced it and never had a prob since.

AEM Tech in my book. i was ready to start breaking ****

 

I'm sure my problems isn't fuel related, fuelpressure gauge is constant. Unless my new RC eng injectors are defective.

 

try retuning it for higher pressure.
my guess is that . ,, ,. . . double check with Vaprotrail , SGT, or Eb18c i think thats his scrren name . . from RPM . they will give you a better idea. but im telling you , RC reccomends nothing less than 35 psi for there injectors,in that case yes you might havebroken them .

 

you know if RC engineering has warrenty of them?

 

Do you have any aftermarket ignition upgrades like MSD? If so, try removing it and test it again with stock componets.

 

nope all stock ignition. dynoed at 216hp at 13psi on a td04-15G. Everything worked perfect for so long, thats why i'm confused where it went wrong.

 

and thats the thing with fuel it will work for a while under retarded loads and then one day start giving probs intermittently until you decide to fix it .

 

Of course one thing that will cause misfires is sticking/bent valves or
bad rings etc.

 

wouldn't i see alot of smoke or hear valve tapping??