Jim R.

Hi All,

Took the 89 GT out for a ride to settle the new suspension tonight, and on the way home lost power. Ran very rough, and felt/sounded like it was running on 4 cyl. Got home and checked fuel pressure-45 lbs at idle. Shut car off, no obvious loose coil wires or connectors. Restarted car and it ran fine for about 90 seconds, then went back to limp home mode. The relay next to the lh/ezk boxes shows a green led.
I searched the archives, and it looks like I should:
1.check the coil wires
2.switch final ignition stages to see if one is bad
3.check exhaust temp senders

Any other ideas? Any help is greatly appreciated-that loss of power miles from home with a total change in the sound of the motor was nasty!

Thanks
Jim R.

worf928

Start with the big picture: which cylinders are not firing? (I don't remember this instant which half of the motor is shut down when the green LED lights. Archives will say...)

At that point look at everything that contributes to spark. You've already started the list. Which of the components in the list might have been disturbed by work on the suspension?

Add to your list:

coil ground wires
coils themselves
ignition stage ground
distributor cap (cracked?)
rotor

Jim R.

Dave,

The left coil, and cyl 5,8,2,3 are on the green circuit. The caps and rotors are only four months old, but I will check them anyway. The only electrical issue with the new coilovers was a broken brake pad depth sensor. I will also check to see if any injector connectors on 5,8,2,or 3 came loose after the intake R&R last month.

Thanks
Jim R.

worf928

If the cap somehow got cracked it can lead to limp home. A friend dropped a cap during a t-belt R&R and spent hours chasing limp mode to the dropped cap.

Quote:

...after the intake R&R last month.

Hmmm... what could have gotten tweaked... lemme think...

The harness to the EGT sensors ties into the main harness under the throttle cable pulley. And - if memory serves - there's a connector behind each head.

Plug wires are good and tight I assume - along with other obvious stuff...

One thing you might do is swap some components from side-to-side and see if the other LED lights. Coil wires, caps, etc.

John Speake

Obviously an ignition misfire will trigger the system, but also if one injector is not flowing properly this has also been known to trigger "limp home".

It is possible to link out the system to enable you to fault find, at the risk of damaging the cats if you persist if the misfire is very bad.

Regards,

Jim R.

Thanks guys. I will check all connections and swap sides/parts to see if I can activate the red led and make an easy fix. I hope it is nothing under the intake-I did that job about a month ago and had no problems until now.

John- I don't think on the '89 and newer cars the cats get overloaded with fuel since the injectors are not firing(I hope not!).

I'll give an update later after swapping parts around.

Jim R.

wds928

Jim:

Good luck with locating the problem. I had the same thing happen to me weekend before last when I replaced rotors and distributor caps. The passenger side coil wire was not quite on correctly. The engine went into "limp home" mode the next day and the sound sent a chill up my spine and gave me a lump in my throat. Not to mention the possible damage to my wallet.

I removed the coil wire and re-attached it and haven't had a problem since.

John Speake

Hi Jim,
I meant that if you bypass the relay to fault find, then you "might" damage the cats...............