#1 |
My 87 TC is still experiencing a slight drivability problem where there is an intermittent miss while driving and an occasional struggle to pull past 4K RPM.
A little bit of background. Car has 44K original miles and is unmolested. Have known all but the last owners (4 total) personally. Last owner was meticulous with records, but did little maintenance wise and only drove the car 1500 miles in roughly 13 years.
When I first got the car last summer, it would not pull past 4K RPM- engine would build full boost, but would lay over like it was against a rev limiter or fuel was getting cut off.
I stored the car over winter and recently set about doing a tuneup in order to get a quality baseline from which to solve my driveability problem.
So far I have replaced:
Plugs- Motorcraft gapped to 0.034
Wires- Taylor Spiro Pro ( these wires have historically been as good or better than Motorcraft amongst our group that have ran them for 25+ years)
Cap/Rotor/TFI/PIP- all new Motorcraft Parts
O2 sensor- new Motorcraft
Timing Belt- new Dayco
Fuel Filter
One concern I had was that after all of the years of being a garage queen, that either the cam or tappets may have prematurely worn out, so I pulled the valve cover and both looked fine. I also pulled the IAC and cleaned it with Carb cleaner while apart, along with removing the injectors just to check their status while the upper plenum was off replacing the oil sending unit ( unrelated but it was fluctuating badly).
Put a fuel pressure gauge on the car and baseline w/o vacuum was 39 psi. While driving pressure would come up to roughly 45 psi under max boost.
I did all of the tune up items except for the PIP ( couldn't get the gear off myself)so I had a new dizzy that was supposed to have a new PIP in it, so I put that one in the car with the new TFI and the car ran decent, but still had the intermittent miss but was pulling up to redline. I pulled codes and got an erratic PIP code. Yesterday, I got the new PIP installed in the old dizzy and swapped it back into the car, reset base timing with spout out to 11 BTC, replaced the spout and drove the car.
Curiously, the tach got lazy between 3-4K rpm, like it broke or something. Also, and unfortunately, the intermittent miss was still there. After driving a few miles, the car start driving fine, but still had the intermittent miss. Without a load, the engine would rev freely to redline.
At this point, my only thoughts are either the coil- can't handle the demand, VAM - possible dead spot, or PCM are malfunctioning.
I would be indebted at this point on a direction to go in or something to test. My friend suggested pulling the VAM and making sure the contacts in there were clean and replacing the 28 year old coil. Aside from that I'm stumped.
Thanks!
A little bit of background. Car has 44K original miles and is unmolested. Have known all but the last owners (4 total) personally. Last owner was meticulous with records, but did little maintenance wise and only drove the car 1500 miles in roughly 13 years.
When I first got the car last summer, it would not pull past 4K RPM- engine would build full boost, but would lay over like it was against a rev limiter or fuel was getting cut off.
I stored the car over winter and recently set about doing a tuneup in order to get a quality baseline from which to solve my driveability problem.
So far I have replaced:
Plugs- Motorcraft gapped to 0.034
Wires- Taylor Spiro Pro ( these wires have historically been as good or better than Motorcraft amongst our group that have ran them for 25+ years)
Cap/Rotor/TFI/PIP- all new Motorcraft Parts
O2 sensor- new Motorcraft
Timing Belt- new Dayco
Fuel Filter
One concern I had was that after all of the years of being a garage queen, that either the cam or tappets may have prematurely worn out, so I pulled the valve cover and both looked fine. I also pulled the IAC and cleaned it with Carb cleaner while apart, along with removing the injectors just to check their status while the upper plenum was off replacing the oil sending unit ( unrelated but it was fluctuating badly).
Put a fuel pressure gauge on the car and baseline w/o vacuum was 39 psi. While driving pressure would come up to roughly 45 psi under max boost.
I did all of the tune up items except for the PIP ( couldn't get the gear off myself)so I had a new dizzy that was supposed to have a new PIP in it, so I put that one in the car with the new TFI and the car ran decent, but still had the intermittent miss but was pulling up to redline. I pulled codes and got an erratic PIP code. Yesterday, I got the new PIP installed in the old dizzy and swapped it back into the car, reset base timing with spout out to 11 BTC, replaced the spout and drove the car.
Curiously, the tach got lazy between 3-4K rpm, like it broke or something. Also, and unfortunately, the intermittent miss was still there. After driving a few miles, the car start driving fine, but still had the intermittent miss. Without a load, the engine would rev freely to redline.
At this point, my only thoughts are either the coil- can't handle the demand, VAM - possible dead spot, or PCM are malfunctioning.
I would be indebted at this point on a direction to go in or something to test. My friend suggested pulling the VAM and making sure the contacts in there were clean and replacing the 28 year old coil. Aside from that I'm stumped.
Thanks!