RB20DET 'MISFIRING'??

[BSRJIRONMAN]

Hi. I recently bought an rb20det powered 240sx and ive got a few questions. every morning at a cold start, it takes about 3 trys to start her up. once it starts, it seems to run fine. The other thing i noticed is when i really 'get on it', is sounds and feels like its misfiring at high rpm's. I sorta hear popping and the power cuts out. Then when its warm, at idle it a has a subtle 'miss' and occasionally bogs down. Any Ideas??? Thanks in advance!

[Coolwhip]

what plugs are you using and what are they gapped to?

Are the boots to your coils dried out and cracking?

And what type of voltage are you seeing on to the coils?

[BSRJIRONMAN]

hmmm, havent checked these things. ill check them out for sure. You really think plugs would do that? I havent replaced them but....well maybe, ill check 'em, thanks.

[Coolwhip]

plugs would cause high rpm misfire, yes.

[Carl H]

check yo timing.

[Eikon]

Hi. I recently bought an rb20det powered 240sx and ive got a few questions. every morning at a cold start, it takes about 3 trys to start her up. once it starts, it seems to run fine. The other thing i noticed is when i really 'get on it', is sounds and feels like its misfiring at high rpm's. I sorta hear popping and the power cuts out. Then when its warm, at idle it a has a subtle 'miss' and occasionally bogs down. Any Ideas??? Thanks in advance!

I've been having a similar issue.. I have driven the car so little that I haven't made it a priority, but it's time to do something about it.

I have trouble starting the motor as well after it's been sitting for a while. I can hear the fuel pump and I wait until it's done priming. Then I try to fire it and it has a hard time catching.. Sometimes it won't catch at all the first turn of the key. Then I turn the key again and it usually catches and starts to sputter like it's hitting on 2 or 3 cyl. only. It will choke and sputter for a few seconds, then finally start to fire on all cyl.

I can pull it out of the garage and it runs decent while it's still on closed loop. But after it's warm (say 5 to 10 minutes) it starts to display a bit of a miss when cruising and wants to bog and die on idle.

I've been meaning to change my plugs and I have a set already gapped and ready for install. So i'll do that tonight.

I know that I have a couple broken exhaust manifold studs, and that might be a small issue.

BSR - do you have a fuel pressure gauge? I have a feeling it's my fuel filter or fuel pressure that is the issue.

Another idea might be a new 02 sensor. You can get one from a local parts store under a 1984 Nissan 200sx turbo (CA18et) I think???

[BSRJIRONMAN]

Let me know how the plug change goes. I have a pressure gauge that i can hook up to the car, maybe inline with the fuel line, but it wont be until this weekend. Im thinking the warm running miss is a timing or igniter issue. The cold start problem.....timing.....or solenoid. I have a couple things im going to check this weekend. Ill let you know how they go for sure.

[PorkChopExpress]

i have the same problem, when cold the moter takes a while to start up. arent the fuel lines supposed to stay pressurized? i know right when my fuel pump turns off the pressure drops right to 0. maybe a leaky injector?

im using a accufab fpr

[craz4240]

Sounds like cold start enrichment isn't hooked up...I put mine on a toggle switch also makes it harder to tel...

[Eikon]

Well.. i've been around RB's for a while and I haven't heard that term tossed around for the RB20.

I know what it means, but didn't know it was something that could be hooked up or not hooked up. Am I missing some wiring somewhere?

I know i've seen a 7th injector in the crossover pipe for that intent...

What would I do to ensure this system either was or was not hooked up?

[BSRJIRONMAN]

GOT IT!! Eikon, check the plug behind your glove box...it should be a rectangular brown plug. In one corner of it there should be an orange wire pinned in (should be on the dash harness side). What color is the wire that is connected on the other side (ecu side)?? Is it orange?

[drifter92sx]

mine feels like its missin when i get to like 6 to 7 rpm on 13lbs of boost thats wat my mine;s vx-rom ecu is tunned for

[BSRJIRONMAN]

Wow, its weird that you reply now, because I just got it fixed this weekend (the high rpm misfire. I fixed the cold start problem a long time ago). I just replaced the fuel filter...thats it. I bought a replacement fuel filter for a 300zx n/a, and it works wonderfully no more misses @ high RPM. Hope this helps!!

Oh yeah, Eikon if you're still having that cols start problem, just shoot me an email and Ill walk you through it.

[drifter92sx]

i

Wow, its weird that you reply now, because I just got it fixed this weekend (the high rpm misfire. I fixed the cold start problem a long time ago). I just replaced the fuel filter...thats it. I bought a replacement fuel filter for a 300zx n/a, and it works wonderfully no more misses @ high RPM. Hope this helps!!

Oh yeah, Eikon if you're still having that cols start problem, just shoot me an email and Ill walk you through it.

i installed a new n/a 300zx fuel filter but im think it might be cause on the rpm signal tap in like they say on this forum to get the dual cam stock rpm tach to ready right with the 10k resistor from the signal wire to the ground to change the current flow of the signal i think its cuz the ecu is reading a lower rpm signal that it really is at could it be that? when you did your swap did u tap into pin 49 for the signal or did you just calibrate the tach in the cluster its self?