5.0 running poor in a 49 f-1

Gdog3225

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Oct 27, 2009
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:(Any of you ford gurus out there that can help me?? Right now in our garage we are working on a 49 f-1 with a 5.0 HO. We have built the engin and put trick flow twisted wedge heads, cam, rockers, push rods, lifters, 70mm throttle body and egr plate, msd 6al box, wires, coil, the truck will sit there and idle just fine, if you try to quick rev it it will shake and hesitate like its out of time or loosing fuel, it has 24lb injectors in it, the rail pressure is 42 psi. We have double checked the timing and everything even internal timing, readjusted valves, the list goes on and on. LOL. Anybody have suggestions??
 
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How can a chip be burned if the mass air sensor and EEC are not known?

The stock MAF would be unlikely on that combination (bottleneck), and other wise to run 24's, you'd need a tune or a Cobra EEC.

That's not to say this is the issue but it will need to be known at some point.

Has anyone tried to retrieve codes yet? They might supply a clue.

Double check the timing. See if it will run with the SPOUT connector removed. Be sure the dizzy is not installed 180* out.
 
Is the engine physically shaking like something is out of balance? Or is it just running rough?

I would ask are you running the correct flywheel balance and what is the condition of the harmonic balancer?
 
it was running the same before we put the 24 lb injectors in, they hooked up to it and checked codes but i am not sure what they were cleared them and none came back. had it in two shops that were "supposed" to know what was going on. helped some but still cant get it out, it has a stall in it, we took balancer and flexplate off an engine one year older, is there difference in them or anything?? the balancer was running fine on the other engine. wouldnt it be doin like a carb if the dizzy was 180 out??
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This is going to break out in to 2 separate steps: information gathering and diagnostic testing. In order for you to get good help there on Stangnet, you need to do both. If we don't have a clear picture of what you have, getting your problems fixed will be very difficult. Don't skip or shortcut any of the steps. You might just skip over the thing you need to find and fix the problem.

Information gathering
The computer code is on a tag taped to the end of the computer. That is the first piece of information we need to help you. An 89-93 5.0 Mustang computer would be the best one for your purpose.

The 89-93 5.0 Mustang computers have one of the following codes:
1989 MANUAL A9L, A9S
1989 AUTO A9P, A9T
1990-92 MANUAL A9L
1990-92 AUTO A9P
1993 MANUAL A3M
1993 AUTO C3W
1993 COBRA X3Z (uses a 70MM MAF and 24 lb injectors stock from the factory).

The 24 lb injectors will require a 1993 COBRA X3Z computer and matching Cobra MAF, or an aftermarket MAF customized for the 24 lb injectors and one of the computers from the list above. We need a description of the MAF, its internal diameter and the part numbers on the MAF housing and sensor to be sure there isn't a mismatch between them.

Diagnostic testing

Computer power ground:
Check the computer power ground to make sure it did not get disconnected. Since you have a Painless wiring harness, you will need to find the installation instructions to help identify it. The stock Mustang harness uses two black wires with a white or green stripe. The Painless wiring harness will probably be different. The computer power ground is very important: the computer will not work correctly without it.


Firing order check:
Remove the #1 & #3 spark plugs. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Slowly turn the engine until the TDC mark and the timing pointer line up. Mark TDC on the balancer with chalk or paint. Put your finger in #3 spark plug hole and crank the engine 90 degrees. You should feel pressure trying to blow past your finger. If you do not feel pressure, repeat the process again. If you feel pressure, it is a HO engine.

No pressure the second time, remove spark plug #5. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Put your finger in #5 spark plug hole and crank the engine 90 degrees. If you feel pressure now, the engine is not a HO model, no matter what it says on the engine.

Using a small carpenter or machinist square to mark the harmonic balancer off into 90 degree sections may be helpful here.

A 15/16 deep socket & breaker bar or ratchet may be used to turn the engine.

The HO firing order is 1-3-7-2-6-5-4-8.

Non HO firing order is 1-5-4-2-6-3-7-8

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Checking codes and finding cylinders that aren't firing :
Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a
jumper wire or paper clip to put the computer into test mode. Start
the engine and let it go through the normal diagnostic tests, then
quickly press the throttle to the floor. The engine RPM should exceed
2500 RPM's for a brief second. The engine RPM's will increase to about
1450-1600 RPM and hold steady. The engine will shut off power to each
injector, one at a time. When it has sequenced through all 8 injectors,
it will flash 9 for everything OK, or the number of the failing cylinder
such as 2 for cylinder #2. Quickly pressing the throttle again up to
2500 RPM’s will cause the test to re-run with smaller qualifying figures.
Do it a third time, and if the same cylinder shows up, the cylinder is
weak and isn’t putting out power like it should. See the Chilton’s Shop
manual for the complete test procedure

Dump the codes and see what the computer says is wrong…Codes may
be present in the computer even if the Check Engine light isn’t on.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check
engine light, or test light or voltmeter. I’ve used it for years, and it works great.
You watch the flashing test lamp or Check Engine Light and count the flashes.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.


Dumping the Engine Running codes: The procedure is the same, you start the engine with
the test jumper in place. Be sure the A/C is off and the transmission is in neutral.
You'll get an 11, then a 4 and the engine will speed up to do the EGR test.
After the engine speed decreases back to idle, it will dump the engine running codes.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the
check engine light, or test light or voltmeter. I’ve used it for years, and it works great.
You watch the flashing test lamp or Check Engine Light and count the flashes.

See Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical

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If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method.
There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

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The STI has a gray connector shell and a white/red wire. It comes from the same
bundle of wires as the self test connector.


89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

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The STI has a gray connector shell and a white/red wire. It comes from the same
bundle of wires as the self test connector.



WARNING!!! There is a single dark brown connector with a black/orange wire.
It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector.
If you do, you will damage the computer.


What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's
internal workings are OK, and that the wiring to put the computer into diagnostic mode is good.
No code 11 and you have some wiring problems.

Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder
balance test. Low compression on one of these cylinders rules out the
injectors as being the most likely cause of the problem. Look at cylinders
that fail the cylinder balance test but have good compression. These
cylinders either have a bad injector, bad spark plug or spark plug wire.
Move the wire and then the spark plug to another cylinder and run the
cylinder balance test again. If it follows the moved wire or spark plug,
you have found the problem. If the same cylinder fails the test again,
the injector is bad. If different cylinders fail the cylinder balance test,
you have ignition problems or wiring problems in the 10 pin black &
white electrical connectors located by the EGR.

How to do a compression test:
Only use a compression tester with a screw in adapter for the spark
plug hole. The other type leaks too much to get an accurate reading.
Your local auto parts store may have a compression tester to rent.
If you do mechanic work on your own car on a regular basis, it would
be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the
throttle wide open, crank the engine until it the gage reading stops
increasing. On a cold engine, it will be hard to tell what's good &
what's not. Some of the recent posts have numbers ranging from
140-170 psi. If the compression is low, squirt some oil in the cylinder
and do it again – if it comes up, the rings are worn. There should be
no more than 10% difference between cylinders. Use a blow down
leak test (puts compressed air inside cylinders) on cylinders that
have more than 10% difference.

See the link to my site for details on how to build your own blow
down type compression tester.