cmarris2142

I have a 99 Camaro with a 408 lq4 and a Huron speed twin turbo kit the specs are
fic 1200H injectors
Dual 450 pumps, second pump comes on at 3 psi currently
Fast 102 intake, NW 102 TB
2.5 bar map sensor from dpe Corvette
return style fuel system with rising rate fpr base pressure set to 43
Br7EF plugs gapped to .021 and stock coils
On a manual trans
Factory PCM with 3 bar map OS
on e85 fuel

​​​​​​The car starts and runs fine, it drives great, wideband stays right around 1.0 lambda, I can give it some load and in vacuum it does fine, but as soon as it hits the threshold of 0
Vacuum and going into boost it will pop, studder and break up, but if you give more throttle and push it doesn't hang in that area long and goes into boost, it makes 5 pounds to redline smoothly, what could be going on or help that transition area? I attached a log where it broke up going into boost slowly, and made boost fine, and it also broke up really bad if you stab the throttle quickly, thankyou for any help!

NicD

iTrader: (7)

Yup, you definitely have a misfire so check plugs/wires. Start with bank 2 as I see O2 dropouts when you get into boost on that side. Also clear your fuel trims using your scanner, you have LTFTs disabled in the tune but it still has stored values so clear them out so they don't interfere.

cmarris2142

Alright I'll pull them out and check, it was a fresh set of plugs they might have gotten gunked up from the other tuning, and the car has a new set of msd wires but I'll check them with the multimeter and make sure they are all generally the same, should I go ahead and gap the plugs down a bit also while I have them out?

NicD

iTrader: (7)

.021 gap is not causing your issues that's for sure. I'm guessing cracked porcelain on a plug or a bad wire especially since you said they are MSDs.

cmarris2142

I'll pull everything out and have a look, probably just throw a set of plugs in it. What's odd to me is wouldn't that issue happen anymore in boost? Why was I able to roll into it moderately and make 5 pounds to redline cleanly? Or do you see the misfire in that as well

cmarris2142

And should I look into the dwell settings?

cmarris2142

Got everything done yesterday and still had the issue with breaking up, what's interesting is the didn't notice a boost pipe blew off after I left the house and when I went to make a partial throttle pull it still broken up really bad around the same area. Only was around 40% throttle and it started breaking up around 70-80kpa on the map. Being a SD car I would think it should be fine to run all motor since it won't ever see the boost area of the table, or boost power enrichment. I noticed in the log it looks like it started breaking up as soon as fuel system one status went into OL-ACCEL which I'm assuming is my power enrichment. Is it possible my PE is coming on too early and too heavy and and just smacking the cylinders with a ton of fuel too fast?

Full Power

WHat is your PE threshold ( KPa and TPS ) ?

cmarris2142

Min map-70kpa
Mik map hyst-6kpa
TPS cold
1200-51
1600-45
2000-45
2800-38
3200-36
3600-33
4000-28
28tps all the way from there

Full Power

.
. Are both fuel pumps on the same main power feed ( fuse or relay ? ) You might need seperate power feed and grounds for each pump..
Any possibility that the moment the second fuel pump kicks on at 3PSI Manifold the 30 amp start-up pulse KILLS the primary fuel pump for a split second, and fuel pressure actually DROPS briefly ?
Do you have a fuel pressure sensor that you can LOG ?

cmarris2142

The second pump is controlled by my boost controller I had it set to 3psi, and the last run I had it disabled completely to see if that was it, it's definitely not going lean, it honestly feels like its choking on gas. I'm fixing the boost pipe now. I might try leaning out the pe enrichment % a good bit and see if it still tries to break up at that transition between vacuum and boost, I still have my boost enrichment on

cmarris2142

Sorry to also answer your question better, the pumps have individual relays wired directly to the battery. One pump relay is triggered by the factory fuel pump wire, one is triggered by boost controller. Each pump has a seperate main power feed that connect to battery positive

Full Power

I am not playing turbo guy-yet.
My belt drive supercharger rig I have PE set to come in at 105kPa
Also, left the enrichment percent fairly low in the low RPM ranges, ie 1.10 or so. little heavier above 3000 rpm.

cmarris2142

i tried adjusting the PE values a bit to see and still no dice. Im going to go back into the ignition system. it seems to be getting worse the more the car is driven. this time when i tried to push it into boost where it was happy before, as soon as it hit positive pressure the cars started to pull then fell flat on its face and had a massive backfire. maybe a weak coil

cmarris2142

heres the log from the backfire, right around 18:12. has the lean spike on the narrowbanbds and hardly makes a pound and backfires

cmarris2142

Got to hand it to ya, after still fighting the car after looking at the wires and plugs, i put another set in and tested the wires on a different multimeter, 2 of the msd wires read 600ohms while the others read 30. just threw a set of wires in it from oreilys to test and the car pulled clean, thanks everybody for the help

G Atsma

OEM wires are still the best.....