Newly Purchased 1986 LX 5.0

Hardwerk

Member
Apr 21, 2022
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Recently purchased an '86 LX with 26k original miles (really).

When I purchased it (at an estate sale) I knew the heater core needed to be replaced (famous coolant stain in the passenger floorboard). It ran rough (rich) and brakes were trash. It's basically sat for 15+ years so throw in tires and a bazillion other problems as well. Got the brakes going (for the most part but still have some work to do).

Dropped the fuel tank, emptied out the bad gas, replaced the fuel pump, fuel filter, and fuel injectors. Threw in some fuel system cleaner (chevron). Checked the air filter (clean). Cleaned out the fuel rail. The car still runs the same. Plugs are heavily carbon fouled (cleaned them up and put them back in).

The car acts like it has a cam (but doesn't - entire car is original). At idle it struggles not to die. Give it a little gas to keep it running. After it's hot, it will die at idle without gas. Black smoke out the exhaust.

I finally drove it about 7-8 miles yesterday. Once it gets over 1500 rpm's and I push the gas pedal in more than ~5% it runs ok. Less than 5% pedal it bogs and jerks.

I checked for vacuum lines not being plugged in yesterday. I think they all are.

The only thing I can think of is possibly the throttle body is stuck. So, at idle, it's starving for air. But, if I get into the gas it pushes open. Is there anyway to test this?

Anybody have any better ideas?


When
 
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Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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At the lenght of time sitting and dry-rotting, I would build a smoke machine and smoke test everything. These 86-88 speed density cars are VERY sensitive to vacuum leaks
 
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Hardwerk

Member
Apr 21, 2022
21
2
13

Here is a video of it running

I replaced the TPS, did a smoke test for leaking vacuum lines, and confirmed the IAC is functioning (I started it with it unplugged and then plugged it in and noticed a significant difference).

It still bogs down when I push the gas pedal and idle sounds like it has a cam with black smoke (rich).
 

Hardwerk

Member
Apr 21, 2022
21
2
13
At the lenght of time sitting and dry-rotting, I would build a smoke machine and smoke test everything. These 86-88 speed density cars are VERY sensitive to vacuum leaks
Yeah, I did a hand pump sucking on a cigarette. I'm assuming that is enough smoke. I didn't see anything. I've felt around all the vacuum lines I can see and made sure they were there. Vacuum leak was my gut but just can't prove it yet.
 

Cheapskate207

The left one hangs a little lower
Jan 12, 2020
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Auto zone sells the odb1 scanner for cheap. If you’re going to own one of these cars it would be a good investment. Alternately, you could manually dump the codes and count the flashes. I’m not familiar with the procedure but I can be found here, on stangnet.

If the o2 sensors are “bad” it will throw a code.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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