Different plugs/gap for more boost?

[Neejay]

RB25 S2

I'm currently using bcpr6es @ .8mm gap @ 10-11psi (also have a walbro + fpr), but I get a "slamming into a wall" cut out when going WOT in 3rd/4th. Idle, partial throttle, normal driving: engine purs like a kitten, no rough idle, no violent shaking. I can even partial throttle all the way through redline from 1-4th gears.

I'm gonna use bcpr7es, but I'm not sure what to gap it too. Should I use .8mm on the bcpr7es too? Or should it change since I'm running higher boost on the stock turbo?

EDIT: Here is exactly what's happening: Ok, what happens is that in 3rd and 4th, I'll be going WOT, boost will hit 11psi and then it will it cut out. If I leave the pedal pressed down, it will take like 2-3 seconds and build boost again and cut out. Another 2-3 seconds and it will build up and pull strong without cutting out.
Modified by Neejay at 11:30 AM 12/21/2009

[eh?]

11 psi on a stock turbo isn't much. Have you checked your coils? When you part throttle does boost still hit 11psi?

[Neejay]

11 psi on a stock turbo isn't much. Have you checked your coils? When you part throttle does boost still hit 11psi?

I was thinking coil(s) at first, then I read the symptoms of spark plug blow out and they pretty much match mine. So I got back confused.

I haven't checked my coils yet (30F + on/off rain + no garage + apartments), and no, I don't make it to 11psi when going part throttle.

[eh?]

Sounds like coils to me but I have my bcpr7es at .8mm. I've always had them like that regardless of boost level and turbo size.

[RustspecS13]

When I swapped in my rb20 I didn't hook up my 4/5th gear sensors.

During long 3/4/5th gear pulls my fuel would cut out for a good 5-10 seconds until the ecu returned fuel/power. If I started in 3rd it cut out mid/top of 4th and if i started in 4th it would do it top of 4th or any where in 5th.

It does this because it thinks its in neutral all the time and the ecu doesn't want the engine at full load in "no gear" so it cuts fuel.

If it was spark blow out it would be more inconsistent, but a solid lack of all power is more likely a fuel cut.

~Alex

[Neejay]

Sounds like coils to me but I have my bcpr7es at .8mm. I've always had them like that regardless of boost level and turbo size.

Ok, I'll change my plugs to bcpr7es @ .8mm and while I'm in there examine the coils.

When I swapped in my rb20 I didn't hook up my 4/5th gear sensors.

During long 3/4/5th gear pulls my fuel would cut out for a good 5-10 seconds until the ecu returned fuel/power. If I started in 3rd it cut out mid/top of 4th and if i started in 4th it would do it top of 4th or any where in 5th.

It does this because it thinks its in neutral all the time and the ecu doesn't want the engine at full load in "no gear" so it cuts fuel.

If it was spark blow out it would be more inconsistent, but a solid lack of all power is more likely a fuel cut.

~Alex

See, initially, fuel cut is what I was thinking (from the VERY beginning). It's in 3/4/5th gears only @ WOT.

Meh, might just pay a reputable shop here to figure it out.

[WhatsADSM]

yea full out cutoff in power is typically not spark blowout. Spark blowout is more of a random miss feeling at WOT.

[Neejay]

yea full out cutoff in power is typically not spark blowout. Spark blowout is more of a random miss feeling at WOT.

Ah, ok. So it'd basically be like a "skipping" feeling vs. a instant drop in power?

[RustspecS13]

Exactly, I was going to say something to that effect. But I god distracted lol.

~Alex

[GSDKinked]

Exactly, I was going to say something to that effect. But I god distracted lol.

~Alex

Do you have the stock intake tubing? Cause it is probably collapsing in on itself. My SR used to do that until I changed it. Felt like hitting a brick wall.

[Cjmartz2k]

Ignition is always about the weakest link. I don't feel like typing everything again, so search coil packs and look for a LONG post I made about ignition. If you need a set of SII coil packs, email me. I've got some.

[Neejay]

Ignition is always about the weakest link. I don't feel like typing everything again, so search coil packs and look for a LONG post I made about ignition. If you need a set of SII coil packs, email me. I've got some.

Ok, I'll do that.

Ok, what happens is that in 3rd and 4th, I'll be going WOT, boost will hit 11psi and then it will it cut out. If I leave the pedal pressed down, it will take like 2-3 seconds and build boost again and cut out. Another 2-3 seconds and it will build up and pull strong without cutting out.

[TwoJayZee240]

I had the same problem. I am running bosch platnum 4001 plugs now. I had them gapped to .8mm and still had the problem at 12psi. I gapped them down even more to .025" and it runs mint under boost now. Just try gapping them down to .025", it cant hurt anything by trying this before you start buying parts. And it dosent matter how big the gap is as long as you get that initial spark in the time sequence the ECU needs it to be. From my exsperience the Rb coils seem to be weak, but i have heard of people running them to 500hp. I see some Splitfire coils in my future. Hope this helps.

[ST240]

I know you think it isnt the coils but did you check them? Make sure there's no cracks in the coating on the coil "frames". If there is or it's flaked off wrap them up in e-tape.

[Cjmartz2k]

From my exsperience the Rb coils seem to be weak, but i have heard of people running them to 500hp. I see some Splitfire coils in my future. Hope this helps.

There is no difference between new splitfire coils and new OEM coils. I've never run anything but junk yard RB coils coming about of everything from an RB26dett to a RB20de. They are all the same, except the RB20de ones tend to be in better shape since they never really got heated up and beat on like the RBxxdet(t) ones. The reason people see an improvement and think splitfires are better is because they are replacing old worn out coils with brand new ones. OEM RB coils in good shape are good to WELL over 600+rwhp.

[Neejay]

Updating thread (for future searches) to say my coils *looked fine*, and I changed the spark plugs to BKR7E @ .028. This was the solution. No more cut out, smooth power delivery.

[RustspecS13]

Good to know, Ive had a miss fire in my bolt on ka24e, and I just looked at my plugs 2 days ago. The gap was at an astounding .055"+!! And they were gapped at .044 when they were new around 5K miles ago.

The weird part is that it only missfired off idle and at 4500rpm+ and only some times so i really couldnt even guess what the problem was before i checked gap. So I regapped them and got rid of 99% of my missfire.

Any way point is i HATE this particular KA, as all the ka specific parts on this car are JUNK and I cant wait to put my rb back in.......

~Alex

[marshallpre1]

Just to bump a semi old thread back up...

I just picked up my first RB25DET S13 yesterday from CT. Mods are stock ecu, stock turbo, Greddy Profec B (garbage), new Splitfire coils...

Anyways, it ran well during the first leg of the trip (1.5hrs) to grab lunch. After lunch, I was boosting a little, maybe 9psi (greddy setting), and everytime i hit 3k rpm or so (not sure on boost, maybe 9?) it would basically get really sluggish and sound/feel like ignition break up or fuel/boost cut (only experienced fuel cut in my Supra when I was BPU). Has anyone had this experience? I turned the car off when I got home, and then acouple hours later, went on another drive with the BC off, and no more problems... what do you guys think it is? Do you think its sparkplugs or the maf?

Thanks,
Jeremy