Car falls on face at ~6000 RPM...
Thread Starter
Registered User
Joined: Jun 2001
Posts: 822
From: Lawrence, KS, USA
Car falls on face at ~6000 RPM...
Not sure what's causing this. It's a 93 Camaro Z28. I've got NGK TR-55 plugs, Accel 8mm wires, Delteq DIS, and only at extremely high RPMs (~6000 RPM) does the car seem to just fall on its face, sometimes will backfire. At WOT, it pulls hard from idle to 5900 RPM, but once you hit about 6000, it just falls flat on its face. This car has NO REV LIMITERS, not even the factory-equipped one (my rev limited "disappeared" after converting my car to an M6). This seems to only be a recent occurrence. Any clues anyone? One or more of the original Delteq coils going bad? I was thinking about buying some MSD replacement coils, but before I drop $180 on it, I'd like to know if that's even the problem...
Registered User
Joined: Jul 2002
Posts: 1,367
From: Burlington, NJ
do you have the stock opti? could be a crap opti. sounds like my first opti's experience. it would just basicly start sputtering and then shut down and die out...at least until about 3k rpm. once down there it was fine and would be good up till about 5500 rpm.
Registered User
Joined: Aug 2006
Posts: 922
What mods do you have on the motor to justify spinning it up that much? At the vary least you should have an aftermarket cam, heads and valve train to make any power above 5500RPM. Stock motors will not make power past 5500 RPM
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Joined: Aug 2005
Posts: 4,405
From: Kantuckee Yo'
Thread Starter
Registered User
Joined: Jun 2001
Posts: 822
From: Lawrence, KS, USA
Mods? Here ya go...
Now, back to my question...WHY is it doing this? This is a recently-developed problem, and just FYI, I've had the heads, cam, roller rockers, and valve springs on for about FOUR YEARS now. Do you STILL think it's the valve springs not keeping up???
Performance:
K&N Fuel-Injection Performance Kit (CAI)
1LE Intake Elbow
Edelbrock TES Headers
3" Exhaust (dumps out before the axle)
Dynomax 18" Bullet Race Muffler
Walbro 255 lph In-Tank Fuel Pump
Ford SVO 30 lb/hr Fuel Injectors
Aeromotive Adjustable Fuel Pressure Regulator
Hand Ported LT1 Intake
Holley Twin 58mm 1050cfm Throttle Body
Comp Cams XE Camshaft (224/230, .536"/.544", 112 LSA)
Comp Cams Pro-Magnum 1.6 Roller Rockers
Comp Cams Dual Valve Springs (PN# 987-16)
Comp Cams Hardened Pushrods (PN# 7608-16)
GTP Stage II Aluminum LT1 Heads (2.02" int/1.60" exh.)
March Underdrive Crank Pulley/Overdrive Alternator Pulley
Powerstat 160* Thermostat
HPS Z-Rated Brake Pads
Powerslot Slotted Disc Brake Rotors
Earl's Stainless Steel Braided Brake Hoses
Suspension/Chassis:
Eibach Pro-Series Springs (1.5" drop)
Energy Suspension Polyurethane Bushings
Kenny Brown Double-Diamond Subframe Connectors
Lakewood Lower Control Arms
Lakewood Adjustable Panhard Rod
MAC Floorpan mounted Torque Arm
Air Lift Rear Coil Spring Airbags
BMR Trunk-Mounted Battery Relocation Tray
Edelbrock Strut Tower Brace
Drivetrain:
Borg Warner T56 6-speed Manual Transmission (converted from a 4-speed automatic)
B & M Short Throw Shifter
SPEC Stage II Kevlar Clutch
Motive 3.73 Rear Axle Gears
RaTech Solid Pinion Bearing Spacer
Torsen T2 Limited-Slip Differential Carrier
Superior Hardened Race Axles
Jeg's T/A Aluminum Rear Axle Support Cover
Electronics:
Delteq Ignition System (converts Optispark to a 4-coil DIS)
Accel 8mm Spark Plug Wires
NGK Sparkplugs
Optima Red Top Battery
Taylor 1-gauge Trunk Battery Wiring Kit
Hypertech Manual Fan Switch
Racetronix Fuel Pump Voltage Booster
MSD Fuel Pump Booster
PCMFORLESS Custom PCM Chip
Griot's Battery Drain Protector
Power Antenna (replaced OE fixed mast antenna)
4-sensor Electronic Parking Assist System, with LED Distance Indicator Gauge
<<Upgraded to a 140-amp alternator from a B4C "Police Package" Camaro>>
K&N Fuel-Injection Performance Kit (CAI)
1LE Intake Elbow
Edelbrock TES Headers
3" Exhaust (dumps out before the axle)
Dynomax 18" Bullet Race Muffler
Walbro 255 lph In-Tank Fuel Pump
Ford SVO 30 lb/hr Fuel Injectors
Aeromotive Adjustable Fuel Pressure Regulator
Hand Ported LT1 Intake
Holley Twin 58mm 1050cfm Throttle Body
Comp Cams XE Camshaft (224/230, .536"/.544", 112 LSA)
Comp Cams Pro-Magnum 1.6 Roller Rockers
Comp Cams Dual Valve Springs (PN# 987-16)
Comp Cams Hardened Pushrods (PN# 7608-16)
GTP Stage II Aluminum LT1 Heads (2.02" int/1.60" exh.)
March Underdrive Crank Pulley/Overdrive Alternator Pulley
Powerstat 160* Thermostat
HPS Z-Rated Brake Pads
Powerslot Slotted Disc Brake Rotors
Earl's Stainless Steel Braided Brake Hoses
Suspension/Chassis:
Eibach Pro-Series Springs (1.5" drop)
Energy Suspension Polyurethane Bushings
Kenny Brown Double-Diamond Subframe Connectors
Lakewood Lower Control Arms
Lakewood Adjustable Panhard Rod
MAC Floorpan mounted Torque Arm
Air Lift Rear Coil Spring Airbags
BMR Trunk-Mounted Battery Relocation Tray
Edelbrock Strut Tower Brace
Drivetrain:
Borg Warner T56 6-speed Manual Transmission (converted from a 4-speed automatic)
B & M Short Throw Shifter
SPEC Stage II Kevlar Clutch
Motive 3.73 Rear Axle Gears
RaTech Solid Pinion Bearing Spacer
Torsen T2 Limited-Slip Differential Carrier
Superior Hardened Race Axles
Jeg's T/A Aluminum Rear Axle Support Cover
Electronics:
Delteq Ignition System (converts Optispark to a 4-coil DIS)
Accel 8mm Spark Plug Wires
NGK Sparkplugs
Optima Red Top Battery
Taylor 1-gauge Trunk Battery Wiring Kit
Hypertech Manual Fan Switch
Racetronix Fuel Pump Voltage Booster
MSD Fuel Pump Booster
PCMFORLESS Custom PCM Chip
Griot's Battery Drain Protector
Power Antenna (replaced OE fixed mast antenna)
4-sensor Electronic Parking Assist System, with LED Distance Indicator Gauge
<<Upgraded to a 140-amp alternator from a B4C "Police Package" Camaro>>
Thread Starter
Registered User
Joined: Jun 2001
Posts: 822
From: Lawrence, KS, USA
Hard to believe it'd be the Optispark when the only part that's used on it is the optical sensor, since I upgraded to a Delteq Distributorless Ignition System...
Thread Starter
Registered User
Joined: Jun 2001
Posts: 822
From: Lawrence, KS, USA
Guess what? I've got all of the above...AND they're not recent mods. The entire upper half of my motor was replaced FOUR YEARS AGO with all aftermarket parts. I'm by no means a guru when it comes to automotive performance, but don't mistake me for a novice...
Thread Starter
Registered User
Joined: Jun 2001
Posts: 822
From: Lawrence, KS, USA
Do what I did and swap out those 987's for some 918's. 
Thread Starter
Registered User
Joined: Jun 2001
Posts: 822
From: Lawrence, KS, USA
How could this be a recent development, though? Also, does this explain why it cuts out at other RPMs sometimes, like tonight, it happened once @ 4800 RPM, and another @ 5400 RPM. I don't think it's the valve springs, but I could be wrong...
Registered User
Joined: Oct 2004
Posts: 365
From: Long Island, NY
correct me if im wrong, but doesnt backfiring at high rpm indicate a running lean problem? My experience with fuel related problems is backfiring, however most times its as soon as you command more fuel by putting the accelerator down.
Have you checked what kind of fuel pressure your getting? Could be as simple as a clogged fuel filter...
Im by NO means an expert on the lt1 though..
have you yanked a plug and checked what they look like after this problem occurs?
Have you checked what kind of fuel pressure your getting? Could be as simple as a clogged fuel filter...
Im by NO means an expert on the lt1 though..
have you yanked a plug and checked what they look like after this problem occurs?
Thread Starter
Registered User
Joined: Jun 2001
Posts: 822
From: Lawrence, KS, USA
correct me if im wrong, but doesnt backfiring at high rpm indicate a running lean problem? My experience with fuel related problems is backfiring, however most times its as soon as you command more fuel by putting the accelerator down.
Have you checked what kind of fuel pressure your getting? Could be as simple as a clogged fuel filter...
Im by NO means an expert on the lt1 though..
have you yanked a plug and checked what they look like after this problem occurs?
Have you checked what kind of fuel pressure your getting? Could be as simple as a clogged fuel filter...
Im by NO means an expert on the lt1 though..
have you yanked a plug and checked what they look like after this problem occurs?
I'll check the plugs today and see if I find anything there...
Registered User
Joined: Oct 2004
Posts: 236
From: Tampa, FL
I'm fighting the SAME issue right now with a 350 and the delteq!!! Its like it just loses sync at about 6000 and falls flat on its face, even the datamaster dyno logs show the same thing. I have LE2 heads and a much larger cam that should be making peak at about 7000rpm. I have a MSD DIS-4 box as well and also have a fuel pressure gauge that doesnt drop, the AFR even stays ok up there....well its gets a little rich on the wideband. I'm about ready to yank the delteq and try a OPTI again!!! 
Jason
Jason