[Ray Green]

I mentioned this in my other thread started on behalf of our wonderful '96 GC! Anyway, I'll get it all fixed up soon.

While it's been laid up and I've been driving my wife's '02 Caravan Sport (3.3L), it developed a miss. I pulled plug wires and found #1 cylinder dead. I pulled the plug and it had something blocking the spark gap so I cleaned & re-installed. No help.

I put in a new set of plugs and checked all the wires with an ohm meter. I cleared all the codes I generated by pulling wires and went for a road test. When the engine is loaded, such as heavy acceleration or a bridge/hill, the check engine symbol blinks. While on level ground and holding your speed, it's off. I've only went about 2-3 miles with it doing this.

Have any of you had this happen before? Maybe I need to drive it farther and see if it codes up. At this point, I'm thinking an injector problem. An electrical/sensor fault should code up pretty quickly and this doesn't.

 

[ImperialCrown]

A blinking 'ck eng' light means that cat damage is possible if you continue to drive like this. It is explained in the owners manual. Severe cylinder misfire means unburned fuel can reach the cat and destroy it.
Are you getting a P0301 fault code? This would narrow it down to a single cylinder and ease diagnosis.
An ohmmeter will confirm wire continuity, but can't guarantee that the wire won't leak (arc) or otherwise breakdown under high voltage. Spark voltage soars under engine load. Any coil/wire/plug arcing seen or heard under briefly 'power braking' the engine? Stand to the side and not in front of the vehicle when trying this with a helper.
You could try to swap the #1 fuel injector with an adjacent injector to see if the fault code follows the injector if you suspect a fuel supply issue (too much or too little) to that cylinder.
You don't want to drive with a dead cylinder.

 

[chuzz]

Check that spark plug connector at your coil pack. I bought a 94 New Yorker several years ago for a hundred bucks and a used DVD player. It had a severe miss it. After making the deal and taking the guy home, I found two plug wires weren't even connected to the coil pack and one of them was full of corrosion. A set of wires later and she was running great!

 

[Ray Green]

Crown & Chuzz, thanks for the guidance. All plug wires looked good and while the ohm meter was attached I bent & twisted in hopes of shaking out an intermittent break. No P0301 or any other faults except for the ones I set while pulling plug wires. I cleared those and no codes have surfaced since. Maybe I need to run it til it "codes up".

 

[ImperialCrown]

Fault codes may not return for awhile after an erase and the vehicle may need a road test. A real misfire will set a code and hopefully point to the affected cylinder.
P0300 is a multiple cylinder misfire that can be frustrating to diagnose as it affects all cylinders.
If it is in one cylinder (P0301 through P0306), that makes it easier to find.

 

[Ray Green]

If it is in one cylinder (P0301 through P0306), that makes it easier to find.

When I pulled plug wires one at a time, it was #1 that didn't change anything. That's also the plug that was fouled and discolored compared to the others. It was brownish on the electrode porcelain where as all the others were pretty white & clean.

 

[chuzz]

I'm guessing that either your plug wire isn't holding up under the load or you have a broken wire on the injector harness. It sure sounds more like an electrical problem to me, but then again, I'm not that smart.

 

[ImperialCrown]

Fuel fouled as in a black carbon tip? That could be too much fuel.
Try a compression test?

 

[chuzz]

IC, would the injector still dump gas into the cylinder even if it's not getting a signal? I'm not all that familiar with fuel injection, as I'm sure you can tell.

 

[ImperialCrown]

If the injector pintle was being held open, fuel could leak from it all the time. This could make the one cylinder run rich.
http://auto.howstuffworks.com/fuel-injection3.htm

 

[Ray Green]

Fuel fouled as in a black carbon tip? That could be too much fuel.
Try a compression test?

A compression test can show if an injector is stuck open? Cool. I got a compression gauge and I can do that.

 

[ImperialCrown]

No. but a compression test will show the general mechanical condition of the valves, etc to rule that scenario out.
Fuel injector testing may be easiest by swapping with an adjacent cylinder as stated in post #2.

 

[Ray Green]

No. but a compression test will show the general mechanical condition of the valves, etc to rule that scenario out.
Fuel injector testing may be easiest by swapping with an adjacent cylinder as stated in post #2.

That makes sense of course, but if the intake has to come off to get the injectors out, I'll just replace it.

 

[Ray Green]

Ok, new plugs and wires. While idling out of our park it coded up and stayed. P0301 (cyl #1 misfire). Is an injector the primary suspect or that ignition module thing that takes the place of a distributor cap?

A compression test indicates no valve or piston problem.

 

[Ray Green]

I took a shot and replaced the #1 injector but miss is still there. After having bad dreams about this thing, I started to second guess if I was dealing with the proper cylinder. I went outside between rains a minute ago and began pulling plug wires again. The #1 cylinder is definitely the dead one. I noticed that when pulling the wires for #3 and #5, when I put them back onto the module, I could see the spark fly when I got the wire close. #1 terminal doesn't do that so ...... module time, right? $52.99 at AAP.

 

[ImperialCrown]

When the PCM fires one coil (there are 3 in the coil pack) to spark the #1 plug, it also has to spark another plug on the backside of the same coil to complete the circuit.
The #1 spark has to be going somewhere because it is getting to the companion spark plug, maybe to ground from a leaky #1 plug wire insulation or leaky #1 coil tower insulation?
It would be good if you could prove something like this before buying a coil pack.

 

[Ray Green]

The #1 spark has to be going somewhere because it is getting to the companion spark plug, maybe to ground from a leaky #1 plug wire insulation or leaky #1 coil tower insulation?
It would be good if you could prove something like this before buying a coil pack.

I already got it but haven't installed it yet. Plugs and wires are all new. What else can I do?

 

[Ray Green]

I replaced the coil pack this morning and the miss is gone.

 

[chuzz]

Congratulations, Ray. Glad to hear you finally got it fixed.