My condolences on the loss of your friend.
I got my '86 GT from, my BFF.
We went through college, then grad school, then even moved to the same area out of State.
My friend bought the '86 GT brand new, custom order the options he wanted. I drove him to pick it up.
I know the history of my car very very well. I also know a lot about the engine/concerns/etc the '86 5.0.
About the '86:
Congratulations, it sound like it's an
authentic '86 Stang GT.
And, not some fake China clone. ;-)
About the
'86 5.0L Stang engines:
In order of likely-hood for producing a hunting idle problem:
1) The IAC gets filled with carbon from the EGR valve, and sticks.
Get a new **FORD OEM** IAC.
Note: A
short-term solution is to clean it out with Acetone.
2) The EGR valve may not fully seat. Get a new **FORD OEM** EGR.
3) There were a
few TPS units that were bad, and moisture would get in, and they would produce erratic signals
If it's original, get a **FORD OEM** TPS.
The
'86+ TPS units are
not adjustable. Sorry, only fools can adjust a
non-adjustable part. :-)
4) Sorry, the program storage in PROM(like a write-once flash-drive) was very very very very limited. The did a lot of hacks to get fit, what was fitted.
What they did not have room for was the ability to limit the "integrator" wind-up in the "PID" control loop that controls the IAC and idle speed.
So... even on a
100% perfect '86 5.0L engine, there is that
chance that the idle will hunt. This is from a classic "Integrator wind up in the PID control algorithm". I think I learned that, and they teach that, in the 3rd year of engineering in a Control Systems class.
The hunting idle will
most likely happen when the engine is cold, or warming up.
But, without that "Integrator" limit, or a more advanced control algorithm (that there isn't room for), even when the engine is warm and happy, the idle
can go into hunting mode.
The solution?
Shut off the engine, and restart the engine.
Even after my engine was rebuilt, and I had a new IAC, new EGR, etc, etc, the idle would hunt when the temperature was below ~70F->60F.
Some people move to the MAF-based setup.
That cures that hunting - assuming stock engine, and no other problems, of course.
I did that for a number of years. But, when it was time for an engine rebuild, I decided I wanted to go back to SD. My coil is relocated to the passenger-side. And, that had some impact on my decision. Not much, but not zero.
Btw:
Any pictures?
Any pictures?
Any pictures?
Yea, we leg-hump cars like mad in these forums. Just like it should be!
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