lbs_ft

Hello all, once again I come to you in need of help...

I had this problem with my last twin cam (nftuatn can vouch for this), and this is the second time I've had this same issue with the newly rebuilt motor, with only 1300 miles on the odo. The #2 injector won't 'seat' correctly, and, therefore, the motor will only run on 3 cylinders. I know this is absolutely terrible for the motor, it must put a lot of unnecessary strain on a lot of parts, so I always aim to fix it asap.

Seeing as this is becoming a common occurrence , I've come to a couple conclusions already:

1) The wiring harness/ECU is fully functioning, I used a diode to test, and all 4 injectors are receiving power correctly.
2) I have spark on all 4 plugs.
3) Compression is 190 across the board, perfect.
4) All 4 injectors DO fire correctly.

So, to provide basic information: car is a 1990 coupe, harness is 93 twin cam, engine is 96 KA24DE. Last motor was a 93 KA24DE, and I'm re-using the fuel rail from that engine.

So here's what happens: driving fine, all of a sudden, huge drop in power, car smells like gas, exhaust sounds like a boxer motor. Pull over, pull #2 spark plug boot, no change in shitty idle. Switch #1 and #2 injectors, car fires up after clearing the flooded cylinders, runs rough for a couple seconds, evens out, runs perfectly fine again. Eventually it happens again, like 500+ miles later.

SO! My question is: what do you think the issue is here?

Should I replace my fuel rail with another from a junkyard twin cam?

Should I buy new injectors? ($$$, very expensive so I want to avoid dumping money there when mine still work)

How do I clean my injectors? Keep in mind, these are the same injectors that were powering my last twin cam when it committed suicide, and I've never cleaned them because I don't know how.

How can I make the injector 'seat' better in the rail? When I pry the injector out, you can see and hear it decompress, and its a bitch to remove, so I know the outer o-ring is good. Any way I could replace the inside o-ring or something?

Any and all help is graciously accepted, I just want to fix this for good and not have to worry about it again.

I can answer any questions you guys have, and I'll add information as I think of it or as it comes to me.

I also posted this question on Zilvia, so I'll update this with information if it comes from there in case someone else has this issue down the road...

Thanks again!

Chris28

Sounds like your fuel rail is messed up. I tried putting an sr fuel rail on my ka (didn't realize it was an sr rail) and had some seating issues, never got to the point of starting it though. As far as putting injectors in I always use vaseline to make sure the o-rings don't tear. Are you still using those retarded phillips head screws to hold the injectors in or did you use hex head screws when you rebuilt it?

I have 2 spare fuel rails if you want to try one, as well as 8 spare injectors haha.

lbs_ft

I went to Lowe's and bought some nice new hex-heads after I spent a million hours getting the sealed/stripped screws out.

What exactly do you do with the Vaseline? And fuck yeah, let me get at one of those rails, I'm thinking that's the culprit...

Z33_Taxi

god damn it Trendy...

Spindrift

Did you change your oil after? I had a fuckton of gas in my oil after this happened with mine.

lbs_ft

Shit, no... How the fuck did that happen? And how to fuck should I check that? I'm using Royal Purple so I'm not too keen on dropping 50 bucks when I just changed it 1000 miles ago

Fabrik8

Filling the cylinder with fuel isn't an O-ring problem. Leaking fuel everywhere is an O-ring problem. If the fuel rail seal is the problem, fuel leaks everywhere. If the manifold seal is the problem, you'd have a vacuum leak.

If too much fuel is getting into the cylinder, the injector is probably sticking on and not turning off, or the valve seat is damaged inside the injector and the injector is pissing fuel out. It's also possible you have a bad injector driver in the ECU that is making the injector stay on all the time. An injector driver can be particularly shitty to diagnose because it sometimes only happens when it gets hot, then behaves great once it cools for a very short amount of time.

But, it's also possible that the spark plug is not firing properly. You're assuming that the problem is with too much fuel, but why aren't you considering a problem with the ignition (and consequent consumption) of the fuel?

So you pull the spark plug wire off and you have no change in idle. That might suggest that you might have an intermittent contact problem with that spark plug wire, and removing and reattaching the wire restores the connection.

I'm having a hard time believing that the problem is related to an injector, because the problem doesn't track a specific injector wherever you put it. If the problem was a bad injector, the problem wouldn't only occur at cylinder #2 if you switched injector 1 and 2. So I think it's more likely that you have an injector driver problem or a spark problem.



Edit: Crap, I forgot those are side feed injectors. So yeah, the O-ring could be the problem. But keep in mind the other stuff I said too. Side feeds are such a stupid design, they just don't have that many advantages.

lbs_ft

I see what you're saying, but the dizzy/wires/plugs are all brand new and they all work perfectly fine. I can switch everything around, take stuff off, put stuff on - the problem only clears when the injector is removed from the #2 slot and then replaced, whether it be the same injector or another.

Sure, the injector that fucks up is never the same, but its always been the #2 slot that gives me shit.

I'm gonna replace the rail, get new lower o-rings, and clean out the injectors, and see what that does.

And yes, side feed injectors are an incredibly dumb design hahaha

CHUBBS_09

have your injectors flow tested!

Chris28

It's either the rail or the injector driver, easiest way to tell is by swapping out the rail. When I install injectors I lather up the lower o-rings with vaseline to make sure they don't tear, that's the one that really matters. I'll put a little on the upper o-ring as well, but those tearing won't result in fuel leaking past into the combustion chamber.

For what it's worth, s14 and s13 rails are different. I'm sure injector spacing is the same, but the way that wiring harness cover thing bolts to the rail is different. If you took those dumb screws out while the rail was off of the intake manifold it's possible you bent the rail with the pressure you put on those screws.