North American Turbocoupe Organization

TPS Orientation - Does it Matter?
Randy Wilhite Offline
Junior Member

For those who were kind enough to respond to all my questions in the "Rebuilt Engine - MAFI Appears to Problem" message string, a huge THANK YOU!. VAM seems to work great and static timing issue is now fixed. Timing with spout jumper out is now set to 12 degrees BTDC and engine runs great - except that it just won't idle.

Engine starts perfectly with no throttle, runs for two or three seconds and suddenly drops to below 500 rpm and quits. Starts right back up but does the same thing unless I feather the throttle. Once above 1800 rpm runs perfectly with no sudden shutdown. I had previously set the TPS to .94 volts. Car drives great on the road unless you come to a stop light and then it dies.

I have checked every single vacuum line and they all hold air at 10 PSI with no leaks. New distributor cap and rotor, new plugs. Fuel pressure regulator (FPR) has no gas odor and no gas in the vacuum line.

When I had the engine out for a full rebuild, I disassembled the intake manifold including the TPS, sealed off all openings and bead blasted it to restore the new aluminum look. Flushed with water, air blasted dry and reassembled before re-installation. While I was trying to figure out why this thing won't idle, I was looking through a Haynes manual and in the section for fuel systems it states that the TPS must be installed with the wiring pointing up - for a 5.0L with central fuel injection - doesn't address the issue in the 2.3L EFI system. I checked mine and I have it installed with the wiring pointing down.

I assume the TPS will go in either way since only two small bolts hold it in place. Can you look at your 87 TC and see if the TPS wiring comes out pointing up or down? Does this have anything to do with not getting it to idle? I looked at the technical article on Idle and TPS adjustment and the picture shows the TPS being installed with the wiring point down.

Any and all suggestions are greatly appreciated and highly welcome.

Original owner 1987 Turbo Coupe 5 speed.

Pete D Offline
Tps wiring goes down.

Check you air intake system hoses like the vam and IC hoses. You may not have something completely seated and clamped. The VAM hose is hard to get seated and clamped on the back of the VAM and the lower IC hose is also hard to get seated and clamped properly.
Pete Dunham


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