1993 Cobra flooding

FireFoxCobra_SVT93

New Member
May 20, 2022
2
0
1
Hello everybody, this is my first post on stangnet. I’ve done my best to figure out what’s going on with my car by searching every forum I can find on flooding, but can’t seem to find anybody with the same issue. So here it is:

My 1993 Cobra runs a little rich and drives its best when cold or during winter. If I drive my car for let’s say 10 minutes after it’s been warmed up, it starts to flood at idle (or at least that’s what I think it does). It’s always when I’m stuck at a red light for a minute or two, or in stop and go traffic. The idle drops from about 950 to 550/600 and the car reeks of gas when it does. It sounds like it wants to die, but doesn’t. It becomes very easy to stall. But if I rev the engine high enough for a moment, or do a decent burn out, it burns off the gas and goes back to idling and driving normally. Also if I stall the car while in this state, it wont start unless I disconnect the fuel relay, try to start it (burn off what gas is left in the cylinders), and then plug it back in. Then it’s good to go.

What does this mean? Is it in the tune? My car will not idle for long before it starts to flood seemingly. Hot weather makes it worse I think. I’ve checked for all vacuum leaks, clean MAF, new IAC, etc. and can’t figure out the problem. My dad is the best mechanic I’ve ever met in my life. He’s the one who figured out the fuel relay trick. He too is curious as to what’s causing this.

What I can say is this car was tuned with the stock Cobra intake along with long tube headers. Right now I have a Holly Systemax II upper and lower intake, and unequal length BBK Shorty’s. Those are the only changes since it was tuned. Any idea what might be causing this? I keep thinking it’s in the tune.. Here’s most of the mods that my car has:


Ford 306 ci / 5.0L Crate Motor
FRRP Engine Block
GT40X Aluminum Heads M-6049-X306
B303 Camshaft
1.6 Roller Rockers
Holley SysteMax II Upper & Lower (72mm)
BBK Cold Air Induction
75mm Mass Air Flow Meter
75mm Throttle Body
Forged Mahl Aluminum Pistons (9:1:1)
Forged Steel Connecting rods
Forged Steel Crankshaft
Aluminum Flywheel
McLeod Super Street Pro Clutch
Tremec 3550 Transmission
Pro 5.0 Short Throw Shifter
Moser Aluminum Driveshaft
4:10 Gear
MSD 6AL Ignition
Cobra ECU (EEC-IV) Rebuilt & Updated
24 lb Injectors (Adjustable)
3 Core Aluminum Radiator/Electric Fan
Original Radiator
Rear Battery Conversion
Underdrive Pulleys (smog bypass)
SCT Chip with Tune

Exhaust:

BBK Shorty Headers / 2.5" Collectors
BBK Off-Road H-pipe / 2.5"
Flowmaster 40 Series / 3" In & Out
Turndown Pipes / 3"

Brakes:

Baer 13" Front Disc Brake Setup
11" Rear Disc Brakes from 1997 F-Body / Corvette

Suspension:

Steeda Anti-Roll Bars (Front & Rear)
Steeda Ball Joints
Steeda Lowering Springs (Front & Rear)
Baer Outter Tire Rods
Welded Subframe Connectors
Moser Axles
FRRP Control Arms (Front)
BBK Upper & Lower Control Arms (Rear)
BBK End-Links
Ford 8.8"

Wheels:

1995 Cobra R 17 × 9
5 Lug Conversion
Cooper RS3-A Tires:
Front 255/40/17×9 94W
Rear 275/40/17×9 98W
 
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Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
39,493
15,335
224
I’ll have to circle back to helping troubleshoot, but wanted to mention this.

Modern EFI cars have a “flood clear” mode. It definitely sounds like you are flooding the engine and they can be difficult to restart.

When this happens, depress the gas pedal tp the floor and crank the engine over. This activates flood clear which turns off the fuel injectors. They will not spray fuel while the engine turns over.

This will usually get the engine started. Just be ready to let go of the gas pedal of it starts while you have the pedal down.

Should make it easier than pulling the fuel pump relay each time. I use this trick for priming the oil filter after an oil change on all cars. The engine won’t start with the pedal down, unless it’s flooded.
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
39,493
15,335
224
Did the car ever run well post tune? I’m assuming the tune took into account the mass air meter?

The x3z Is specific to the 24# injectors and the correct F1SE 70mm mass air meter.

So want to be specific about what mass air meter is on the car and was it tuned for the meter or is one of those meters calibrated for 24# injectors, which would not be correct to use with an X3Z ECU?
 
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FireFoxCobra_SVT93

New Member
May 20, 2022
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Did the car ever run well post tune? I’m assuming the tune took into account the mass air meter?

The x3z Is specific to the 24# injectors and the correct F1SE 70mm mass air meter.

So want to be specific about what mass air meter is on the car and was it tuned for the meter or is one of those meters calibrated for 24# injectors, which would not be correct to use with an X3Z ECU?
That’s a very good point you bring up. I’m not much of a fan of it’s ECU. All I know is this car was tuned about 10 years before I even bought it.. The original owner did all the mods with the exception of the intake and headers. The guy I bought it from did that and never re-tuned the car.

But I’m confident that the original owner properly tuned the car after he installed the MAF considering he really did know what he was doing. He truly build it from the bottom up, the correct way. It definitely has the stock meter calibrated for 24 lbs still on it, but whether or not it was tuned for 75 mm, I don’t know. And no, I haven’t checked the codes yet, but definitely will. I’ve had it non-opted, but now it’s almost summer. :)

One thing I can say is that this car drives absolutely perfect under wide-open throttle. It’s probably making 315-330 at the wheels. Not very streetfriendly though. I know it’d make more power if I had 30 lb injectors and a new tune for the exhaust and intake.
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
39,493
15,335
224
Let’s assume for the moment that it ran great with whatever tune was on it and the combo was dialed in.

What changed when the issues started? The exhaust and intake swap?

Have you dumped codes to eliminate anything that the ECU would see as a fault?
 
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manicmechanic007

5 Year Member
Sep 26, 2017
1,903
537
133
Monitor the ECT sensor voltage
That is what brings the injector pulse width down (when the processor sees hot)
Want to see the ECT around .64v hot (at operating temp) 195F
Your big radiator may be preventing it warming up completely
Give it some air
See how much better it runs with a vacuum leak, then put an altitude compensator on it (on the fender apron of old Escorts or order one)
You could also put a hot idle compensator on it and bend the tab so it leaks vacuum constantly (the old brass ones in the air cleaner)
 

manicmechanic007

5 Year Member
Sep 26, 2017
1,903
537
133
Smog will be half the rash and throw in both rich and lean codes for the camshaft
Tab and tad solenoids the evp, the works. That is why a rash
Once the processor thinks it's in the dark it will run like chit
The EGR especially
 

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,388
3,091
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Smog will be half the rash and throw in both rich and lean codes for the camshaft
Tab and tad solenoids the evp, the works. That is why a rash
Once the processor thinks it's in the dark it will run like chit
The EGR especially
If someone pulled the rest of the smog “junk”, I absolutely agree it will puke codes and can run pig stench rich. (I rescued my car from the track this way. It ran great a WOT, but was not fun otherwise.)

@FireFoxCobra_SVT93 have your found, absorbed and closely followed the Surging Idle Checklist? It made my car streetable and worked on far more than the idle.
I don’t see anything super radical here. I have a non Cobra 5.0 computer, but do not suspect anything but trouble shooting and keeping the computer happy with expected part inputs will be needed.
 
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manicmechanic007

5 Year Member
Sep 26, 2017
1,903
537
133
Used to see cars and trucks come in with a bb stuck in the rubber end fitting of the green EGR vacuum line
Would run like puke. Was sometimes hard to figure out before pids came around in 1992
If the processor did not see any EVP movement it would run like %$#@ Limp mode or worse
 

Mindseye007

Active Member
Oct 21, 2020
162
18
28
Hello everybody, this is my first post on stangnet. I’ve done my best to figure out what’s going on with my car by searching every forum I can find on flooding, but can’t seem to find anybody with the same issue. So here it is:

My 1993 Cobra runs a little rich and drives its best when cold or during winter. If I drive my car for let’s say 10 minutes after it’s been warmed up, it starts to flood at idle (or at least that’s what I think it does). It’s always when I’m stuck at a red light for a minute or two, or in stop and go traffic. The idle drops from about 950 to 550/600 and the car reeks of gas when it does. It sounds like it wants to die, but doesn’t. It becomes very easy to stall. But if I rev the engine high enough for a moment, or do a decent burn out, it burns off the gas and goes back to idling and driving normally. Also if I stall the car while in this state, it wont start unless I disconnect the fuel relay, try to start it (burn off what gas is left in the cylinders), and then plug it back in. Then it’s good to go.

What does this mean? Is it in the tune? My car will not idle for long before it starts to flood seemingly. Hot weather makes it worse I think. I’ve checked for all vacuum leaks, clean MAF, new IAC, etc. and can’t figure out the problem. My dad is the best mechanic I’ve ever met in my life. He’s the one who figured out the fuel relay trick. He too is curious as to what’s causing this.

What I can say is this car was tuned with the stock Cobra intake along with long tube headers. Right now I have a Holly Systemax II upper and lower intake, and unequal length BBK Shorty’s. Those are the only changes since it was tuned. Any idea what might be causing this? I keep thinking it’s in the tune.. Here’s most of the mods that my car has:


Ford 306 ci / 5.0L Crate Motor
FRRP Engine Block
GT40X Aluminum Heads M-6049-X306
B303 Camshaft
1.6 Roller Rockers
Holley SysteMax II Upper & Lower (72mm)
BBK Cold Air Induction
75mm Mass Air Flow Meter
75mm Throttle Body
Forged Mahl Aluminum Pistons (9:1:1)
Forged Steel Connecting rods
Forged Steel Crankshaft
Aluminum Flywheel
McLeod Super Street Pro Clutch
Tremec 3550 Transmission
Pro 5.0 Short Throw Shifter
Moser Aluminum Driveshaft
4:10 Gear
MSD 6AL Ignition
Cobra ECU (EEC-IV) Rebuilt & Updated
24 lb Injectors (Adjustable)
3 Core Aluminum Radiator/Electric Fan
Original Radiator
Rear Battery Conversion
Underdrive Pulleys (smog bypass)
SCT Chip with Tune

Exhaust:

BBK Shorty Headers / 2.5" Collectors
BBK Off-Road H-pipe / 2.5"
Flowmaster 40 Series / 3" In & Out
Turndown Pipes / 3"

Brakes:

Baer 13" Front Disc Brake Setup
11" Rear Disc Brakes from 1997 F-Body / Corvette

Suspension:

Steeda Anti-Roll Bars (Front & Rear)
Steeda Ball Joints
Steeda Lowering Springs (Front & Rear)
Baer Outter Tire Rods
Welded Subframe Connectors
Moser Axles
FRRP Control Arms (Front)
BBK Upper & Lower Control Arms (Rear)
BBK End-Links
Ford 8.8"

Wheels:

1995 Cobra R 17 × 9
5 Lug Conversion
Cooper RS3-A Tires:
Front 255/40/17×9 94W
Rear 275/40/17×9 98W
How do you like those 4.10 gears?