Need some help with DTCs

[gssterl]

After a few years sitting, I got the 84 SVO (LA3 swap) back up and running. All was well for a little while, but it is having some intermittent misfires. Ran a KOEO test and here is what I got:

O Codes
54- IAT Sensor Open, Vane sensor out of range
81- Air diverter fault
82- integrated relay control module
83- EGR fault

For 54, I plan on cleaning out the VAM and replacing the IAT. If that doesn't work maybe a new meter is the way to go.

81, 82 and 83 all makes sense since the car has a gillis valve to control boost and the EGR is blocked off. Please correct me if I am wrong.

C Codes
27- vehicle speed sensor fault
54- IAT Sensor Open, Vane sensor out of range
72- system power circuit fault

The car has an LA3 swap, so the 27 code makes sense since its not installed.

For code 72, I have no idea where to start, open for suggestions.

I did do the normal tune up procedures. Motorcraft parts all around, new plugs, wires, cap and rotor, fuel filter, fresh unleaded 93 octane. I did do some research about this sort of problem and found that others have had a fuel line in the tank break and as the tank went down there were misfires around 3000 rpm. This kinda makes sense since the car did start missing as the most recent tank went down, but the above codes are making me think something is wrong under the hood. Especially since fuel pressure is steady at 39 psi when the engine is revved up.

Appreciate any help. Thanks

Greg

[Mike S]

Since your car is an 84, I would suspect a wiring issue with the insulation falling off.

From the interweb, code 72 is: (M) 2.3L T/C - PCM re-initialized. Possible electrical noise, case ground or intermittent VPWR problem

VPWR is an acronym for "Vehicle Power" on Ford models, which refers to the vehicles battery voltage.

Make sure your alternator is charging.

[gssterl]

Thanks Mike. I checked the battery with the car running and it was charging at 14.0 volts. I'll check the grounds and look over wiring. Is there any specific wiring areas I should pay extra attention to?

[Mike S]

The wiring to the TFI and anywhere that sees elevated temps due to engine heat.

[gssterl]

Thanks again Mike. I will look over those areas and report back.

[MikeFleming]

Another common (popular) heat damage area is the harness that runs from the center of the cam cover towards the passenger side - very close to the exhaust heat. Including the short stub that sticks out of the firewall-mounted wiring box going to the TPS / IAC.

Those areas see much higher temps than the TFI harness. The TFI harness is also exposed to more oils -a common place for power steering fluid to get into.

When I took my 84 apart for the restore, I spent about 60 hours repairing assorted engine area wiring harneses. It's a lot more work if the harness is still in the chassis with an engine in the way.

[gssterl]

Thanks MikeFleming, I will check those areas as well.

[rodster]

Another common (popular) heat damage area is the harness that runs from the center of the cam cover towards the passenger side - very close to the exhaust heat. Including the short stub that sticks out of the firewall-mounted wiring box going to the TPS / IAC.

Those areas see much higher temps than the TFI harness. The TFI harness is also exposed to more oils -a common place for power steering fluid to get into.

When I took my 84 apart for the restore, I spent about 60 hours repairing assorted engine area wiring harneses. It's a lot more work if the harness is still in the chassis with an engine in the way.

Now there's a pleasant thought. Will probably have nightmares tonight!! Or did you mean 6 hours? :stick_poke:

[MikeFleming]

Now there's a pleasant thought. Will probably have nightmares tonight!! Or did you mean 6 hours? :stick_poke: Nope. Sixty.

First I made a plywood board with assorted standoffs and tie-downs to keep the harness shape. Then removed the outer wrap and tape. Then insoected/repaired/replaced each individual damaged wire. And there were LOTS of them. Having a [similar] donor harness helps keep the colors correct. Some wires needed to be splice repaired (soldering/heat shrink tube) and that took some time. I also upgraded/improved the front light ground wiring, through-soldered all the factory bare-wire "crimps", etc.

Then tape wrap it back up, re-installing the assorted mounting tabs, new outer wire shields, etc.

The two wires to the brake fail switch on the top of the Prop valve were cracked every couple inches. Replaced them from a donor v-ate harness. The large brown power wire from the starter solenpid to the ignition switch was mostly completely fried: 90% of the insulation melted, 50% of the "shiny copper-color" wire was burnt toast in color. Replaced it with a new, 8-gauge wire and adapted the ends so it's fit the connectors at the ends. Some wires and insulation were perfect, some had random crumbled insulation along the length.

The front light grounds at the corners of the radiator core support were completely inadequate in size and each side ground cables ot the lights were crimped there (on each side - one outer marker, inner marker, high/low beam and fog light) on each side. I added a section of 10-gauge wire to each combo-crimp, soldered the assortment, and made a new eye lug end that attached to the radiator core on each side using the stock screw.

Fortunately I had a spare (new) EEC harness so not as much work was needed there. Then there were the mods to the fuel pump supply/return in the back harnesses.

After I finished the car, I burnt the wooden harness frames.to cast away all demons and recycled what was left of the rusty nails.

I have pics of the process somewhere.

[rodster]

Too bad you burnt the wooden frame, it would have only taken you 30 hours to do mine! :p

I'm afraid to even look at my wiring. The car is running and I don't see flames or smell anything hot, jump in and :runningdog:

[gssterl]

Had a few hours to work on the car. Checked the TFI harness starting at the plug to the distributor and working all the way up to behind the valve cover. Everything looked great, even the metal insulation was intact. I did however notice the ground strap on the firewall was loose. Cleaned that up and re-wrapped the TFI harness. Checked the connections on the computer as well as the ground. Looked good there too. Started the car and let it warm up. Ran a KOEO test and still got codes 54, 81, 82, 83 as well as CM codes of 27 and 54, but no 72 (i did disconnect the battery though). I tried to run a KOER test, but it wouldn't work. The code reader (innova 3145) displayed 00 and when i hit the test button the engine would rev for a second, but no codes were sent, just continuous 00. I disconnected everything and took the car for a ride. Unfortunately the problem persisted. Every time I got on the throttle at around 3000 rpms the car would start missing. No knocking or popping, just bucking like no combustion. Took the car home and tried another KOER test, again no codes. Turned it off and ran another KOEO test. Still codes 54, 81, 82, 83 and CM codes of 27 and 54. Pulled the alternator off and took it up to the auto parts store, checked out fine. Decided to check the timing and noticed something didn't look right. At idle it was reading above 30 BTDC, well above the top of the timing belt cover markings. Ran out of time, so that will have to wait until tomorrow.

[MikeFleming]

Pulled the alternator off and took it up to the auto parts store, checked out fine. Most auto parts store testers will not detect / report bad diodes. Find a local alternator rebuilder and ask them to test the diode set.


Decided to check the timing and noticed something didn't look right. At idle it was reading above 30 BTDC, well above the top of the timing belt cover markings. Ran out of time, so that will have to wait until tomorrow. Did you disconnect the SPOUT ot verify timing?

That is correct timing if SPOUT is not disconnected. Timing at closed throttle mode will be base + 20 (aka 30 BTDC). If part throttle is detected, the EEC adds another 15-20, depending on calibration and mode (prem/regular) so 45-50 total.

[gssterl]

spout was in when I checked the timing. Any ideas on why i can't run a KOER test?

[MikeFleming]

spout was in when I checked the timing. Then timing is correct.


Any ideas on why i can't run a KOER test? Perhaps your code reader is giving a pass with "00" (s/b code 11")? Did it ever prompt you with "10" (snap test prompt)?

The 54, 81, 82, 83 are happening because you don't have those components installed - the EEC doesn't see them. So they set a code.

Do you mean 25 and 72? You wull get these in KOER if the SNAP test is not performed.

In any case I do not see anything form the EEC that I would pursue further. Move on to things that can cause your symptoms.

Back to your symptoms: Cutting out under load at ~3000 RPM:
- Fuel supply not keeping up - get a fuel pressure gauge on it and see what happens under load. In this case as soon as the load goes down, "normal" operation will return immediately - when the fuel supply comes back after load / demand is decreased.

- weak valve spring(s) - test and replace. This symptom usually results in continued stumbling after load is reduced as the HLA(s) pump up. Can take several seconds for the engine to return to "normal".

- could also be weak ignition. TFI/PIP, spark plugs, spark plug wires, coil, cap, rotor, etc.

[gssterl]

Perhaps your code reader is giving a pass with "00" (s/b code 11")? Did it ever prompt you with "10" (snap test prompt)?

No, I power it on, hit test. 00 comes up, engine revs a bit and nothing happens after that. 00 still shows and there is no little triangle in the lower right to show connection to the computer. 10 never comes up.

The 54, 81, 82, 83 are happening because you don't have those components installed - the EEC doesn't see them. So they set a code.

Understood.

Do you mean 25 and 72? You wull get these in KOER if the SNAP test is not performed.

Nope. Never seen a 25. 72 was in CM codes, but after I disconnected the battery and checked some grounds it hasn't come back.........yet (fingers crossed)

In any case I do not see anything form the EEC that I would pursue further. Move on to things that can cause your symptoms.

Agreed. I'm going to mount my fuel pressure gauge outside the window and monitor while driving. Its currently underhood and shows 39 psi with vacuum connected and 42 psi with vacuum removed. When the engine is revved, fuel press is constant at 39 psi.

Back to your symptoms: Cutting out under load at ~3000 RPM:
- Fuel supply not keeping up - get a fuel pressure gauge on it and see what happens under load. In this case as soon as the load goes down, "normal" operation will return immediately - when the fuel supply comes back after load / demand is decreased.

see above

- weak valve spring(s) - test and replace. This symptom usually results in continued stumbling after load is reduced as the HLA(s) pump up. Can take several seconds for the engine to return to "normal".

Will test ASAP.

- could also be weak ignition. TFI/PIP, spark plugs, spark plug wires, coil, cap, rotor, etc.

plugs, wires, cap and rotor are all new. Coil checked out okay with a resistance test. TFI/PIP may very well be the culprit. Know how to check that?

[gssterl]

Timing is reset at 10 BTDC spout out. Put spout back in and timing was at around 27 BTDC and moved higher when throttle was advanced. Still can't run a KOER test, KOEO test runs just fine with same three codes of 54, 81, 82 and 83. Took the car for a ride and issue is still there. Anytime I slowly advance the throttle it starts missing at 3000 rpm. If I goose it at all it misses regardless of rpm. Just cruising below 3000 rpm, with small throttle application the car runs fine. I pulled in the garage and checked the fuel pressure. 42 psi with vacuum disconnected, 39 psi with vacuum connected. Revved the engine a few times and fuel pressure was constant at 39 psi. The readings all came off my gauge attached to the FPR (Aeromotive). I'm going to mount the fuel press gauge outside the windshield and monitor the pressure when driving. Right now its mounted underhood. If that checks out i'll move onto a compression test unless any one else has a better idea.

[gssterl]

Did a little more research and the thread below sounds somewhat like my issues.

https://www.svocop.com/forum/showthread.php?1236-Engine-stall-at-3000-RPM

Runs much better after filling up the gas tank. As the gas is used it runs worse.



BINGO!!!

There's a crack in the fuel hose between the pump and the fuel pump bracket. When the fuel level drops below the crack, the pump spews the gas out of the crack and back into the tank, rather than going to the engine. Been there, done that. We went through this together at the Best Western parking lot in Richmond Ky with Gyrhead's car when you and I met the first time.

Funny thing is my car ran great wen i topped the tank off with 93 octane and as the tank went down it all of this started. Maybe worth a try.

[rodster]

Good luck, I hope that solves your issue. I was thinking about it and thought maybe a weak coil even though it passes the resistance check.

Keep us posted on your findings.

[MikeFleming]

There's a crack in the fuel hose between the pump and the fuel pump bracket. When the fuel level drops below the crack, the pump spews the gas out of the crack and back into the tank, rather than going to the engine. Been there, done that. We went through this together at the Best Western parking lot in Richmond Ky with Gyrhead's car when you and I met the first time.

Funny thing is my car ran great wen i topped the tank off with 93 octane and as the tank went down it all of this started. Maybe worth a try. Do you have a dual-pump installation (stock for 84)?? Or has it been "converted to single??

It's possible that a crack/hole/leak there with the dual pump system will prevent/reduce the dual-pump system from sucking air from the tank with a higher level in the tank but not with a single-pump system as it's pressurized at that point and will easily blow out the hose venting to the tank - at all times (full or empty tank).

In any case I'd suggest to replace the pump and hose while you're in there. If you're going to convert to a single-in-tank pump system, do not fail to fix the wiring to/from the in-tank pump. You can use a second fuel filter to replace the chassis-mounted pump or make up a section of 5/16" nylon hose with two male 5/16" quick-connect ends.

[gssterl]

Do you have a dual-pump installation (stock for 84)?? Or has it been "converted to single??

It's possible that a crack/hole/leak there with the dual pump system will prevent/reduce the dual-pump system from sucking air from the tank with a higher level in the tank but not with a single-pump system as it's pressurized at that point and will easily blow out the hose venting to the tank - at all times (full or empty tank).

In any case I'd suggest to replace the pump and hose while you're in there. If you're going to convert to a single-in-tank pump system, do not fail to fix the wiring to/from the in-tank pump. You can use a second fuel filter to replace the chassis-mounted pump or make up a section of 5/16" nylon hose with two male 5/16" quick-connect ends.

Its a stock 84 dual pump setup. What all do I need to convert to a single pump system? I'm guessing i'll need a new hanger assembly, 255 lph pump for a 87-93 5.0 and a ranger filter to replace the chassis mounted high pressure pump (part # would be nice if someone has it).

[MikeFleming]

Yes, you will need pump and hangar for the larger pump. Wiring is same.

You will also need to locate and bypass the ground wire resistance element (1 Ohm), add a larger ground wire ).+14ga in parallel with the existing 14Ga). And then run a ~10Ga positive wire from the chassis-mounted pump's harness back to the power feed wire that's part of the in-tank harness. In both the car side and the short pump/level sender harness. You can use the same 4-pin connector, just with larger wires for the pump +/- sides.

Reference:

https://www.svocop.com/forum/showthread.php?1740-Fuel-Pump-Resistance-Wire-Bypass

[Raven855]

If you have trouble finding a pump hanger Pro M makes a nice one.

[gssterl]

Ran a compression test tonight. 98, 95, 97, 95. Engine was cold and throttle closed. Numbers seem low, but consistent. Thoughts?
Oh and keep in mind those numbers came off a cheap harbor freight gauge

[Under Pressure]

Pull the head off. Probably a bad head gasket and the head may need to be resurfaced.

[MikeFleming]

Ran a compression test tonight. 98, 95, 97, 95. Engine was cold and throttle closed. Numbers seem low, but consistent. Thoughts?
Oh and keep in mind those numbers came off a cheap harbor freight gauge Cold is not good, hot (just after a ten+ mile run is more better); while closed throttle makes the test useless. Using a known-good meter is more better but even-ness is more important than actual number(s).

Cranking speed and intake valve closing point (cam profile) will have major effect on cranking PSIG.

Prop the throttle wide open and repeat the comp test. Be sure to have a charger on the battery too.

[gssterl]

Had some more free time this weekend. New in tank and external pumps went in. I wanted to check the fuel tank and decided why not upgrade the fuel pumps since they are 30 yrs old an all. Stock replacement in tank and walbro 255lph on the frame rail. That didn't fix the, issue, but peace of mind going forward.

I decided to do a check spark again. Put a timing light on each plug wire and revved the engine. Solid light on all. Did a cylinder balance test as well, pulled the plug on each injector and idle changed the same on all.

Decided to do a base idle adjustment and check the tps. TPS was way high, like 1.12 at idle. Set it back to .94 and adjusted the idle to 800rpm IAC unplugged. Went for a drive and it ran GREAT! I'm hoping that was the problem. I'll be driving it a few more times this week to see if that was the cure.

From now on, TPS adjustment is going to be part of my tune up process.

[gssterl]

Unfortunately, the problem is back. It's sporadic, not occurring every time I drive it, but when it does happen the engine cuts power at 3000rpm consistently and backfires in the exhaust.

I don't know where else to look. I upgraded the coil and replaced the alternator. Fuel pressure is solid at 39 psi, rising 1:1 with boost. Plugs,wires, cap and rotor are all brand new motorcraft.

Maybe the tfi module or the PIP? There has got be something wrong with spark. Need help!

[Under Pressure]

Pull the distributor and see if the gear is chewed up or has very thin teeth.