COBRA cumputer
- Thread starter coupecop
- Start date
It's not a matter of differences in performance. It's a matter of having an EEC program that matches the fuel injector, induction, and engine combo that you're running in your car.
I see that you're running an 80mm meter. What meter is it? What size injectors and EEC is it calibrated for? What size injectors are you running?
Cobra computers are designed to run with a stock Cobra meter and 24 lb fuel injectors. If you run an after market meter then it needs to be one that is calibrated for a Cobra computer and 24s. If it's a meter that you've been told (incorrectly) that is calibrated for xx sized injectors (with no other information) then it's a meter that was designed for the A9x family of EECs. Not a Cobra.
Most after market meters are calibrated for different sized injectors and assume and A9L (or equivalent) EEC is being used. Unless you bought that meter specifically for the calibration of a Cobra computer and the injectors that you're using, then it's mismatched.
You may want to hit the search function in this forum and read up on mass air meters and Mustang ECUs.
I see that you're running an 80mm meter. What meter is it? What size injectors and EEC is it calibrated for? What size injectors are you running?
Cobra computers are designed to run with a stock Cobra meter and 24 lb fuel injectors. If you run an after market meter then it needs to be one that is calibrated for a Cobra computer and 24s. If it's a meter that you've been told (incorrectly) that is calibrated for xx sized injectors (with no other information) then it's a meter that was designed for the A9x family of EECs. Not a Cobra.
Most after market meters are calibrated for different sized injectors and assume and A9L (or equivalent) EEC is being used. Unless you bought that meter specifically for the calibration of a Cobra computer and the injectors that you're using, then it's mismatched.
You may want to hit the search function in this forum and read up on mass air meters and Mustang ECUs.
C&L meters are the junk of the meter making world. hehe
They take electronics from an OEM meter and slap it into a new housing with a sample tube to fool the meter into sending voltages that you "hope" are similar to the voltages necessary for the EEC to properly adjust the pulsewidth for your injectors.
Take into account, the effort put into tuning the electronics of a mass air meter vs. trying to do it mechanically through a larger housing and machined sample tube. What's going to be more accurate? The machining of these two pieces of metal or the lazer tuning perfomed on the electronics of an OEM meter sensor?
I would love to one day put 3 different C&L meters on a flow bench and see how they do. My guess is that the quality control necessary to duplicate a transfer function is near impossible to replicate with any accuracy on a machine piece of metal. If that quality control were accomplished, the part would cost more money than any meter currently ont hte market. hehe
Who knows though... you might get lucky.
By the way... You need an A9L computer for the setup that you've described so far. A Cobra EEC is not even an option.
They take electronics from an OEM meter and slap it into a new housing with a sample tube to fool the meter into sending voltages that you "hope" are similar to the voltages necessary for the EEC to properly adjust the pulsewidth for your injectors.
Take into account, the effort put into tuning the electronics of a mass air meter vs. trying to do it mechanically through a larger housing and machined sample tube. What's going to be more accurate? The machining of these two pieces of metal or the lazer tuning perfomed on the electronics of an OEM meter sensor?
I would love to one day put 3 different C&L meters on a flow bench and see how they do. My guess is that the quality control necessary to duplicate a transfer function is near impossible to replicate with any accuracy on a machine piece of metal. If that quality control were accomplished, the part would cost more money than any meter currently ont hte market. hehe
Who knows though... you might get lucky.
By the way... You need an A9L computer for the setup that you've described so far. A Cobra EEC is not even an option.
Well... like anything else, there's always an exception to a rule. The two that I can think of, off the top of my head are:
A) You have a custom tune for the meter you're running (i.e. a custom transfer function created for your meter).
B) Tolerances are close enough that EEC is within its ability to adapt.
DMAN302
My mom says thanks for the pearl necklace.
....just kidding.
Daggar covered things pretty well, so I'll just offer up my thoughts.
I have run both the A9L and the X3Z.
I switched to the X3Z to utilize 24lb injectors with a stock setup.
The difference between the A9L and the X3Z are very minimal.
You won't feel any difference in power due to the tune.
The only significant difference I have found through tuning is in how fuel is controlled during decel.
The X3Z cuts fuel pretty aggressively during decel. For most applications this is insignificant.
Keep in mind that a stock (un-tuned) calibration X3Z uses a specific MAF/MAS and Injector setup, which is different than the A9* cars.
Switching to an X3Z computer (without a tune) REQUIRES converting the MAF/MAS and Injectors.
I have been happy with my 73mm C&L for the last 10yrs.
I am of the opinion that the accuracy of all 'calibrated' MAF meters should be scrutinized.
A custom tune is the best solution, regardless of the brand of MAF.
jason
I have run both the A9L and the X3Z.
I switched to the X3Z to utilize 24lb injectors with a stock setup.
The difference between the A9L and the X3Z are very minimal.
You won't feel any difference in power due to the tune.
The only significant difference I have found through tuning is in how fuel is controlled during decel.
The X3Z cuts fuel pretty aggressively during decel. For most applications this is insignificant.
Keep in mind that a stock (un-tuned) calibration X3Z uses a specific MAF/MAS and Injector setup, which is different than the A9* cars.
Switching to an X3Z computer (without a tune) REQUIRES converting the MAF/MAS and Injectors.
I have been happy with my 73mm C&L for the last 10yrs.
I am of the opinion that the accuracy of all 'calibrated' MAF meters should be scrutinized.
A custom tune is the best solution, regardless of the brand of MAF.
jason
tunedin302
I AM the law!!!
When it comes to tuning, a lot of the Cobra guys will ditch the Cobra computer in favor of the A9L due to the ease of tuning (especially with chargers and turbos).
To further the meter discussion, I ran a Pro-M 75mm bullet MAF once I did the charger on my GT. The car ran ok but was kind of choppy at idle. I spoke with Pro-M and they suggested dumping the bullet in favor of the 80mm non-bullet. This made a world of difference. Immediately after install the car idled so smoothly and drove much better. Don't skimp on a good meter - definitely not the place to try to save a buck.
To further the meter discussion, I ran a Pro-M 75mm bullet MAF once I did the charger on my GT. The car ran ok but was kind of choppy at idle. I spoke with Pro-M and they suggested dumping the bullet in favor of the 80mm non-bullet. This made a world of difference. Immediately after install the car idled so smoothly and drove much better. Don't skimp on a good meter - definitely not the place to try to save a buck.
This could be a couple of things, the discussion of which could get pretty involved.
It would be best to start a new thread for this issue.
I am sure someone can help you out.
jason
Cranks OK, but No Start Checklist for Fuel Injected Mustangscoupecop said:
Revised 18-Oct-2006 to include TFI fault during crank/run cycle
All text applies to all models unless stated otherwise.
Note: 94-95 specific changes are in red
1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park and set the parking brake. Remove the coil wire from distributor & and hold it 3/8” away from the engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.
No spark, possible failed items in order of their probability:
A.) MSD or Crane ignition box if so equipped
B.) Coil
C.) TFI module
D.) PIP sensor in distributor. See paragraph 3A - a noid light will tell if the pip is working by flashing when the engine is cranking.
E.) No ECC or computer power - ECC or computer relay failure
86-93 models only: ECC relay next to computer - look for 12 volts at the fuel injector red wires
94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
F.) No ECC or computer power - fuse or fuse link failure
86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid.
94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire.
H.) Computer
J.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI.
See the following links for wiring diagrams...
http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp for 79-88 model cars
Computer/fuel pump/ignition wiring diagram, 86 model http://www.autozone.com/images/cds/gif/large/0900823d80167158.gif
Computer/fuel pump/ignition wiring diagram, 87 model http://www.autozone.com/images/cds/gif/large/0900823d8016715e.gif
Computer/fuel pump/ignition wiring diagram, 88 model http://www.autozone.com/images/cds/gif/large/0900823d80167162.gif
http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp for 89-93 model cars
Computer/fuel pump/ignition wiring diagram, 89-90 cars http://www.autozone.com/images/cds/gif/large/0900823d8019595f.gif
Computer/fuel pump/ignition wiring diagram, 91-93 cars
http://www.autozone.com/images/cds/gif/large/0900823d80195960.gif
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-98 model cars
2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability:
A.) Moisture inside distributor – remove cap, dry off & spray with WD40
B.) Distributor cap
C.) Rotor
D.) Spark Plug wires
E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil
3.) Spark at spark plug, but no start.
Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.
Two reasons:
1.) If it backfires, the chance for a serious fire is increased.
2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.
If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t, then it is a computer or timing issue: see Step 4.
Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the Upper RH corner to ground.
If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. Beware of fire hazard when you do this. In pinch you can use a tire pressure gauge to measure the fuel pressure. It may not be completely accurate, but you will have some clue as to how much pressure you have.
No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – Coupe & hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) 86-93 models only: Blown fuse link in wiring harness. Look for 12 volts at the Orange/Lt Blue wire on the fuel pump relay. The fuse links live in the wiring harness near the starter solenoid.
94-95 models only: 20 amp fuel pump fuse in the engine compartment fuse box. Look for 12 volts at the Dark green/yellow wire on the constant control relay module.
F.) Fuel pressure regulator failed. Remove the vacuum line from the regulator and inspect for fuel escaping while the pump is running.
Fuel pressure OK, the injectors are not firing.
A.) A Noid light available from Autozone, is one way to test the injector wiring.
B.) I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles. Cheap if you have the stuff laying around, and works good too.
a.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
b.) No power, then look for problems with the 10 pin connecter (salt & pepper shakers at the rear of the upper manifold).
c.) No power and the 10 pin connections are good: look for broken wiring between the orange/black wire on the ECC relay and the red wire for the 10 pin connectors.
4.) Spark & fuel pressure OK.
A.) Failed IAB (no airflow to start engine). Press the throttle ¼ way down and try to start the car.
B.) Failed computer (not very likely)
C.) Engine ignition or cam timing off: only likely if the engine has been worked on recently).
D.) Firing order off: HO & 351 use a different firing order from the non HO engines.
HO & 351W 1-3-7-2-6-5-4-8
Non HO 1-5-4-2-6-3-7-8
E.) No start when hot - Press the throttle to the floor & try starting it if you get this far. If it starts, replace the ECT.
Similar threads
