Need help...breaking up

[Almighty-Si]

Ok guys need your help. This car belongs to a fellow eCtuner but he doesn't frequent this forum. He is having an issue with the car and is now talking about selling it because of it. I get where he is coming from especially afer investing all the money and time to put it together but at the same time it's a sweet ride and it would be a shame to see it go for the same reason. Here is his motor mod list.... Fully built/swapped 1.9 b16a2 Laskey Racing fully built engine: Benson 84mm sleeved blueprinted block Benson balanced and micro-polished crank 84mm CP pistons and rings Eagle rods ACL bearings OEM (Type R) oil pump PortFlow port & polish SuperTech Stainless Steel nitride coated valves SuperTech Dual valve springs SuperTech Titanium retainers Competition 3 angle valve job Re-surfaced to a mirror like finish Brian Crower stage 2 turbo cams BDL cam gears STR Cam seal RC 750cc injectors ACCEL 8mm spark plug wires AEM fuelrail AEM fuel pressure regulator AEM Wide-band OK now, he is experiencing a break up when he gets up in the higher rpm band on high boost. He has re-gapped the plugs and now he's down to .22 and it's still breaking up. He has changed coils, igniters, cap, rotor and plug wires. The only thing he hasn't done is change the distributor all together. I am running out of ideas and I thought I would post and see if anyone has any ideas to what might be causing this or see something in his set-up that might be an issue. The turbo on the car is a GReddy kit with a Tial 38mm wastegate running an open dump. It's still using the elbow on the exhaust housing which is causing boost spikes and hitting boost cut but I know if he fixes that part of the downpipe it will fix that problem. So that's it...any help is much appreciated !

[Bugermass]

gap them down to like .016 .. That should be good for about 800HP on stock ign.. Otherwise he'll need to get a good aftermarket coil. Also depending on the fuel if hes running it rich he can lean it out a bit, and if hes being conservative on timing he can try to put some back in it and it'll help the breakup.. Me personally I'd just gap the plugs way down and keep tunning. Its not gonna hurt anything.. I've had to run gaps down to .014 before on stock ignition to light up serious boost.

[DSMR]

Do those injectors require a resistor box? If so double check the wiring with a multimeter

[naturalalloy]

they don't.

[Almighty-Si]

No resistor box on the car. He is trying to run 20psi but it's from the GReddy 18G so yea a lot of boost but a smaller snail, didn't think it would be an issue. I will have him gap them smaller again. The air/fuel ratio under boost is low 11.1-10.8:1 highest reading to lowest reading, but pretty steady 11.1:1 and I thought about leaning that out but he is still running pump fuel and I don't want to risk that without being there to hear what's going on (i'm in NY he's in NC). I guess I could lean that out for him and make it 11.5:1 and it should still be pretty safe on 93 octane. Anymore thoughts are welcome...thanks !

[J. Mills]

I believe i know which car you speak of.. His name on the local web forums is \"DOHCIVIC\". Very clean car. What is the injector duty cycle when his misfire/breakup happens? I encountered a similar problem the other week with a car here at the shop. The gaps on the plugs were down to .018. The air/fuel ratio was 11.9 in boost (when the breakup occurred). Anytime the injector duty cycle reached 70..ish and up, the car was breaking up even though the air/fuels remained perfect. The customers quick fix was bigger injectors. His new injectors and more tuning fixed the problem, even though i feel that his first set of injectors should have suited him fine .

[Almighty-Si]

That would be the car I speak of...it is damn clean and he loves it, doesn't want to sell it but he is getting frustrated with it. I mean in a way I can't blame him but at the sametime its sad to see it go for something that is probably minor. I would have to check the logs again but I'm pretty sure they're in the low - mid 50's as far as duty cycle when it starts. I have the same thought as you, his turbo should max out before his injectors. I am thinking that this may also be happening because he is still using the GReddy elbow off the turbo into his 3inch exhaust. For anyone that doesn't know the GReddy turbo kit, the elbow off the turbo is a mere 1.8 inches and my thought is that there is too much pressure being built up between the head and exhaust housing on the turbo causing the issue, if that makes any sense? I know its causing his boost spike issue as I went through the samething but soon as I upgraded to the external wastegate and 2.5 inch downpipe right off the turbo, no more boost spike and I picked up a nice boost in power as well. Thanks for your thoughts and please keep them coming.

[naturalalloy]

wouldn't that elbow just cause more backpressure and promote reversion? That would just lower his knock threshold and would have been tuned around. The car wasn't knocking up top was it?

[Almighty-Si]

wouldn't that elbow just cause more backpressure and promote reversion? That would just lower his knock threshold and would have been tuned around. The car wasn't knocking up top was it?

That's what I thought. It's not knocking though, just blowing out the spark.

[Bugermass]

No resistor box on the car. He is trying to run 20psi but it's from the GReddy 18G so yea a lot of boost but a smaller snail, didn't think it would be an issue. I will have him gap them smaller again. The air/fuel ratio under boost is low 11.1-10.8:1 highest reading to lowest reading, but pretty steady 11.1:1 and I thought about leaning that out but he is still running pump fuel and I don't want to risk that without being there to hear what's going on (i'm in NY he's in NC). I guess I could lean that out for him and make it 11.5:1 and it should still be pretty safe on 93 octane. Anymore thoughts are welcome...thanks !

YOu only have a few choices.. Lean it out, Gap the plugs smaller, run more timing up top where it breaks up, or get a stronger ignition.. If your IATs are ok and your fuel curve isn't dropping off super fast on top end I'd say try leaning it out to like 12.0 or so. If you don';t feel comfortable with that, try adding 2-3 degree right before the breakup area and past. Otherwise you either have to gap the plugs waaay down, or get a better ignition.

[DyeceDic73]

I dont know... Im sure there are some fluids that will deteriorate seals and rubber. Maybe hes trying to let you know what you need to change before it breaks on you.... dunno Did he say What fluid was put in insted ?