misfire... really bad after warming up
 

I've got a misfire that isn't that bad when the car is cold. After it warms up, it gets worse. After drivign for like 15/20 min, it get horrible... giving it any gas make is miss, and you can hear it missing really bad at idle. What would cause a miss like this? It feels fine for the first few minutes of driving and gradually gets worse.

Re: misfire... really bad after warming up (servion)
 

List mods and anything repaired/replaced recently

Or worked on.

Re: misfire... really bad after warming up (Spade)
 

Ya, also any trouble starting the car?

Re: misfire... really bad after warming up (Dutchie)
 

well, car starts fine. ('95 JDM h22a in '97 civic cx)

Since this misfire problem, ive changed rotor, plugs, wires, added known good MSD SCI-L /w blaster 2 coil. I first tried using a NEW USDM cap /w my external coil, and then have modified the JDM cap to work with the external coil.

The misfire did not happen when I first installed the motor, and it gradually started and got worse about 2 weeks after the swap.

I've checked to make sure all the injectors are clicking at idle (when its missing) byt putting a screwdrive on top of the injector and putting my ear to the screwdriver... all the injectors click at idle at the same rate (none of them skip a clik when the exhaust pops).

I changed my ICM last night... no difference. I also ran the helms manual tests for the 3 sensors that run wires into the distributor (mainly checking for resistence and lack of continuity to body ground), and they all checked out. Any thoughts at all? I'm getting despearate... after warming up its undrivable

Re: misfire... really bad after warming up (servion)
 

How is your fuel pressure? Looks like you've ruled out ignition unless it is the distributer itself. My guess is the fuel pump or the regulator, no codes right? Have you cleaned the throttle body and IACV valve?
Btw H22 turbo hatch = badass http://images.zeroforum.com/smile/emthup.gif .

Re: misfire... really bad after warming up (Dutchie)
 

Well, I don't remember the fuel pressure exactly, but I think its about 34psi. ( I remember checking the helms manual on the fuel pressure and it is about 1-2 psi high, but I heard that 1-2 psi high is ok...)

The car likes to miss right when you give it throttle at idle... and this inparticular miss only happens when you optn the throttle plate quicky.... but it sounds like it misses (it's 'trying to catch up with itself') as the rpms rise past a certian point. If I open the plate slowly, then it doesn't happen. (this is different from the constant miss at idle, that problem still exists no matter what). Here's the thing: I installed a walrbo intank 255 high-pressure pump from my old setup... and this 'catching up' problem started happening as soon as I installed that pump. I switched back to the stock civic CX pump, and it still did it. BNecause it still did it, I again switched back to the aftermarket intank pump.

FPR is stock... I installed an adjustable fpr off my old b18c just to try it, and it didn't make a difference.

Thanks man.. I hope that the turbo h22 hatch will be badass.... if I ever get tha damn thing to work. Its been missing for weeks. Just got a 3" exhaust done yesterday... Any ideas on where I can get a manifold? That's all I need to install the kit once I fix this miss.

Re: misfire... really bad after warming up (servion)
 

are you getting any CEL's and does it surge at idle? i'm guessing that since it gets worse when it gets hotter, it must be a sensor that has something to do with temperature like the IAT or ECT.

Re: misfire... really bad after warming up (Salvatore Leone)
 

that's the ECT sensor? I'll try another IAT (i've got a spare). No CEL, and what do you mean by surge? It pops (hou can hear the exhaust popping) just like a misfire at idle.

Re: misfire... really bad after warming up (servion)
 

yeah try swapping the IAT. test it first though to make sure it's good. by surge i mean does it fluctuate at idle. like 750 rpm to 1500 rpm back down to 750 and so on. check if there's a test for the ECT in the helms too.

Re: misfire... really bad after warming up (Salvatore Leone)
 

no it doesn't fluctuate. What's the ECT? By test it, do you mean test the new IAT or the old one?

thanks

Re: misfire... really bad after warming up (servion)
 

test the one that your going to use. the ect is the sensor on the thermostat housing. it has a yellow plug.

Re: misfire... really bad after warming up (Salvatore Leone)
 

well, I tested both. The IAT was bad... no coninuity in the sensor pins. I swapped it with a good one (test it too), and no change. I mean, the tip was melted ofthe bad one... I put in the good one and the damn thing still misfires when its warm. Anyu other thoughts?

Re: misfire... really bad after warming up (servion)
 

look into an electrical component that is failing when the car is hot.. i'll say it again and again.. heat = resistance, resistance = component failure..
I would concentrate on the ignition side and suspect..

plug wires
spark plugs
coil(s)
cap and rotor
ignitor

Re: misfire... really bad after warming up (BreakStuff)
 

I agree with Breakstuff that it seems like an electrical problem, but it looks like you have changed everything that has to do with ignition except the distributer and ECU. I think you have something in your fuel line or clogging an injector. I know you said that the injectors click but there could still be something disrupting flow. Since it happened right after you installed the pump there is a good chance that you sucked something up. Did you remember to put the sock on the end of the pickup? There was a post on here awhile ago about a fuel system cleaner that does a better job than the stuff you get in the bottles. You should try to do a search or instant message Teken about it.
I still think you should try throttle body cleaner on the throttle body and the IACV valve. Might as well since it is cheap. It could still be the ECT sensor. It could test fine but the sensor could still be messed up. Same goes for the O2 sensor, it could be messed up but if it doesn't throw voltage that is out of the ECU's tables it won't throw a code. One more thing you should do. Replace the PCV valve since they are only about $10 max or test it. With the car running pinch the vacuum line from the block that goes to it. If you hear a click than it is okay.

Re: misfire... really bad after warming up (Dutchie)
 

In my last tank (that I just finished burning) I had a can og BG 44k... amazing stuff. $20 a can and its the best fuel additive money can buy. So unless the injectors are bad or there's a pebble stuck in them or something....

I have a warlbro 255lph intank pump. I was thinking of installing my turbo inline pump too to see if it makes a difference. I have replaced the PCV valve a little bit ago, and I have also used some TB cleaner on the iacv and tb.

By sock at the end of the pickup, do you mean that flat plastic fuel-filter on the fuel pump itself? Yeah.. .I've got that. Plus, if the lines were clogged, why would it not miss that bad when its cold?

Re: misfire... really bad after warming up (servion)
 

what is the ignitor... is it the ICM? I replaced the icm....

Re: misfire... really bad after warming up (servion)
 

Ya the ICM and the ignitor are the same thing.
Well, I'm out of ideas other than the O2 sensor. Although you say it is like that when it is cold too so I doubt that is your problem.

Re: misfire... really bad after warming up (Dutchie)
 

Changed the o2 2 weeks ago... the old one was bad, but it still misses. Id take it to a shop, but there is no one in this area who knows anything about this stuff

Re: misfire... really bad after warming up (servion)
 

Shit, I'm running out of ideas http://images.zeroforum.com/smile/emsmilep.gif .
What about a valve adjustment or has that already been mentioned?
I think you troubleshot pretty well, I feel bad for you, lol.

Re: misfire... really bad after warming up (Dutchie)
 

I did a valve adjustment... actually I went to do one and they were adjusted perfectly when I got the motor

this sucks

Re: misfire... really bad after warming up (servion)
 

what happens with a different ecu? same thing?

Re: misfire... really bad after warming up (Salvatore Leone)
 

have you checked the map sensor?

Re: misfire... really bad after warming up (minime)
 

I'm using my old map sensor of a d16z6... and it worked fine on that motor. Different ecu yields the same results... I think that I am going to change my entire engine wiring harness and see what happens. I've got a new 97 ex one in the mail so hopefully that'll make a difference. I don't know what else to do.