likely cause of misfiring and no idle

I recently acquired a 1999 Grand Voyager with 3.3L engine and 124,000
miles. It will start only if the accelerator is pressed, and it will
not run at idle. Also, it runs roughly and without full power, as if
one cylinder is dead, but I'm not so sure it has a dead cylinder because
I removed the plug wires one at a time and it seemed to make the engine
run worse in every case.

Everything else on the van works great.

I think I remember reading on this forum that the later model Chrysler
vans will not display fault codes on the dashboard the way the older
ones do. Is this true? Anybody have any suggestions that might shed
some light on this, or should I cough up the cash for a diagnostic scan?

 

Sounds like it could be a fuel pressure problem. If you're lucky a clogged
filter, but could also be a failing pump. If it was mine I'd definitely get
a diagnostic, including fuel pressure. Diagnostics are cheap compared to
other ownership costs.

 

New clue: I notice a strong smell of unburned gasoline in the exhaust.

 

Low fuel pressure could cause this, but so could other causes i.e. low
ignition voltage, sensor malfunction etc. But there really is no way for
someone to diagnose this over a newsgroup. Today's vehicles are just too
complex. And oh yes I would NOT drive it very far that way. You could get a
damaging backfire.

 

Unburned gasoline in the exhaust could be caused by LOW fuel pressure?
I was thinking that it would be caused by a broken regulator resulting
in too much gas.

I drove it home about thirty miles a couple of days ago and it drove OK.
It just felt like it was lacking power, but everything seemed to work
just fine.

I'm getting ready to take it in for a diagnostic check.

 

When were the ignition wires last changed? If original, replace them and do
the plugs too if it has been a while and see it that helps. Those wires
will only give about 5-6 years/100K of service from my experience.

Bob

 

burn't valve or fouled plug?? a compression test is in order

 

An excessively rich mixture produces black smoke, which you did not mention.
An excessively lean mixture can result in partial burning, leaving raw gas
in the exhaust.