Strange performance issue (long)

[thudson]

1989 limited
4.0 non-HO
AW4 auto
165,000 miles
Renix FI

I had an odd performance issue this morning. Perhaps some of you may have experienced it. I drove 30 freeway miles to the gym next to the office with no problem I was there an hour. When I got out of the gym to finish my commute, the jeep started just fine and idled just fine. As soon as the gas pedal is pushed the jeep started missfiring. It would not get any RPM past 1200 indicated. Under that was no problem. It felt and acted like a RPM limiter.

I had the beast towed to the local dealer and it did the same thing for the porter when he drove it to the mechanic's bay. When the mechanic started it up it was perfect, no issues at all. He drove it around and tried several restarts to no avail. If the service writer and the porter had not experienced it themselves I would have been the loose nut behind the wheel.

After an inspection, the mechanic found the TDC sensor wire laying on the exhaust manifold. I had him replace it because I was paying for an hour anyway and the sensor was at least 70,000 miles old. No wires were exposed and the heat sheathing was only a little burned.

The mechanic is unsure if that is the real issue. Time will tell.

Anyone have any ideas?

Regards,
Tom Hudson

 

[Matthew Currie]

That's actually a pretty common problem on those. Wire routing is critical.

 

[Markm80521]

Does it run fine now that the wire was removed?

I had similar issue when I replaced the long block in my 88. Put everything back on it. Ran fine for a month, then one day it would crank fine, idle fine, but any gas would cause it to miss. Soon it just wouldn't start. Found that the old harmonic Balancer was the culprit.

 

[thudson]

It ran fine the last 10 miles to work. I havent left for home yet. If you stick your head out the door about 4:30 PDT and hear a howl, it is just me biting myself