5.0 runs horrible

ishootstuff

New Member
Apr 15, 2013
8
0
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Tucson, AZ
Hey everybody, first post here. I'm at a loss and I figured you Fox body peeps could point me in the right direction.

First off, I'm no mechanical noob. My daily drivers are a 1999 F150 that I successfully swapped a 6.8 V10 into & a 1995 Lexus SC300 that I turbo charged.

I'm swapping a 5.0 speed density EFI from an 89 Lincoln Town Car into a 72 convertible Mustang and I can't get the thing to run good. I didn't install the smog stuff and the only codes I'm getting are related to purge solenoid, and EGR. The EGR valve is still installed and I just wired it in today to see if there was any change. Nope.

I have new Motorcraft plugs, wires, cap & rotor. Timing is set at 10 BTDC with the little goodie unplugged. Firing order is correct. I have tried swapping TFI, PCM, and MAP, none of which made any difference. I don't have a fuel pressure gauge, but the inline pump from summit is rated at 45 PSI and lots of fuel squirts out of the schrader valve on the fuel rail.

It runs rough through all the RPM range and has so little power that at full throttle, the engine really doesn't rev up all the way. The engine ran great in the donor car, so I obviously messed something up - I just don't know these motors well enough and I'm hoping you do.

Here's a VID for your viewing pleasure.

 
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The 5.0 HO computer uses a different firing order than the non HO engines. This means that even though you have the spark pug wires setup according to the 5.0 HO order, the injectors are squirting at the wrong time. All three (camshaft, ignition firing order and computer) must match to get a smooth running engine.

Putting the distributor back in and setting the timing.


You can forget about anything beyond this point if you don't have access to a timing light. You will never get the timing set right without one.



Putting the distributor back in is fairly simple. Pull #1 sparkplug, put your finger in the sparkplug hole, crank the engine until you feel compression. Then line up the TDC mark on the balancer with the pointer on the engine block.

The distributor starts out with the #1 plug wire lined up at about 12:00 with you facing it. Align the rotor to about 11:00, since it will turn clockwise as it slides into place.

Align the distributor rotor up with the #1 position marked on the cap, slide the distributor down into the block, (you may have to wiggle the rotor slightly to get the gear to engage) and then note where the rotor is pointing.
If it still lines up with #1 position on the cap, install the clamp and bolt. If not, pull it out and turn 1 tooth forwards or backwards and try again. Put the #1 spark plug back in and tighten it down, put the clamp on the distributor, but don't tighten it too much, as you will have to move the distributor to set the timing. Note that there is no such thing as one tooth off on a 5.0 Mustang. If it doesn't align perfectly with #1 position, you can turn the distributor until it does. The only problem is that if you are too far one way or the other, you can't turn the distributor enough to get the 10-14 degree optimum timing range.


Setting the timing:
Paint the mark on the harmonic balancer with paint -choose 10 degrees BTC or 14 degrees BTC or something else if you have NO2 or other power adder. I try to paint TDC red, 10 degrees BTC white and 14 degrees BTC blue.

10 degrees BTC is towards the drivers side marks.

Note: setting the timing beyond the 10 degree mark will give you a little more low speed acceleration. BUT you will need to run 93 octane to avoid pinging and engine damage. Pinging is very hard to hear at full throttle, so it could be present and you would not hear it.

Simplified diagram of what it looks like. Not all the marks are shown for ease of viewing.

ATC ' ' ' ' ' ' ' ' ' '!' ' ' ' ' ' ' ' ' ' BTC
---------------- > Direction of Rotation as viewed standing in front of the engine.

The ' is 2 degrees.
The ! is TDC
The ' is 10 degrees BTC
Set the timing 5 marks BTC. Or if you prefer, 5 marks towards the driver's side to get 10 degrees.

To get 14 degrees, set it 7 marks BTC. Or if you prefer, 7 marks towards the driver's side to get 14 degrees.

The paint marks you make are your friends if you do it correctly. They are much easier to see that the marks machined into the harmonic balancer hub.

At this point hook up all the wires, get out the timing light. Connect timing light up to battery & #1 spark plug. Then start the engine.

Remove the SPOUT connector (do a search if you want a picture of the SPOUT connector) It is the 2 pin rectangular plug on the distributor wiring harness. Only the EFI Mustang engines have a SPOUT. If yours is not EFI, check for a SPOUT: if you don’t find one, skip any instructions regarding the SPOUT
Warning: there are only two places the SPOUT should be when you time the engine. The first place is in your pocket while you are setting the timing and the second is back in the harness when you finish. The little bugger is too easy to lose and too hard to find a replacement.

Start engine, loosen distributor hold down with a 1/2" universal socket. Shine the timing light on the marks and turn the distributor until the mark lines up with the edge of the timing pointer. Tighten down the distributor hold down bolt, Replace the SPOUT connector and you are done.

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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Yup, I got that part. I'm sure the firing order is correct because there is a sticker on the Lincoln that told me the correct firing order. It's not backfiring either, so I'm fairly confident it's not ignition related, but I'm open to anything right now. I really appreciate the detail too!
 
If you don't hold the clutch pedal down, the engine running codes will not dump.
What codes did you get with the engine not running?
 
If you don't hold the clutch pedal down, the engine running codes will not dump.
What codes did you get with the engine not running?

It's an automagic, but I don't have the transmission harness hooked up yet. I'll hook that up and try again. I don't remember the code numbers, so I'll pull those again later today.

It's definitely, air/fuel related. Yesterday I sprayed some brake cleaner in the throttle body while it was running and it made a huge difference. The engine was responsive and smooth - well as good as can be expected under the circumstances.

Here's a little vid of my fuel pressure. I have never run a fuel pressure test, but I don't think it should bounce around so much. Opinions?

 
That uper intake manifold is on backwards. :rlaugh:

My assumptions:
The CPU is from the same car the engine came from.
The wiringharness is from the same car and not damaged.
Thus injector timing/sequence should be good

1989 5.0 original fuel injectors?
Go over firing order one more time with a helper. Why not?

You could remove the vacume line from the fuel regulator and the fuel pressure should jump up. With a stock pump in a Fox 5.0 I ussually see 44 PSI at idle when I do this. This should not change your running condition but lets you know the regulator is working. Your reading at idle of ~34 PSI seems normal.
 
I tried flipping the instake around, but then the engine ran backwards:p

Yes, the harness, transmission, PCM, etc is all from the donor 89 Town Car.

I have checked the firing order no less than 13 times, but it wouldn't hurt to have another set of eyes.

The fuel pressure regulator is working, the pressure goes up when I disconnect the vacuum line.

I hooked up the tranny harness, and I still get codes I wouldn't expect to see and it still won't complete the KOER test. At one point DTC 34 showed up twice, dunno why - that's why some pics say there are 5 codes and some say 4.

Thanks again for the help and suggestions!

dtc29.jpg


29

Vehicle Speed Sensor problem - VSS

dtc34.jpg


dtc67.jpg


dtc85.jpg
 
I tried flipping the instake around, but then the engine ran backwards:p
It did? Well than you need to get one of those Austrailian rear gear sets where the pinion engages the left side of the ring gear.:lol:

Oh, and I did clean the injectors with my sonic cleaner. It worked awesome for my turbo Lexus.
So, it's possible you have a very clean non-working injector...?
Try removing the plug from youir injectors, one at a time while running and see if you have one that when you unplug it, there is no change in idle, vacume and throttle response. Back Yard Mechanic's Cylinder Ballance Test.
 
So, it's possible you have a very clean non-working injector...?
Try removing the plug from youir injectors, one at a time while running and see if you have one that when you unplug it, there is no change in idle, vacume and throttle response. Back Yard Mechanic's Cylinder Ballance Test.

I actually tried that and I can't hear a difference - of course I can't get to some of them because of intake design. I guess it's back to basics. Time to read the plugs. It feels like the issue is affecting all cylinders, but I could be wrong.
 
OK, all fixed. I must have gotten some crud in a fuel line when I was routing new lines. Some of the injectors were dirty, some didn't even click. Another trip through the sonic cleaner, some technical tapping, and she's running great! I shouldn't have ignored basic troubleshooting. Thanks everybody.