I have a '98 Ford Windstar with the 3.8L and about 152,000 miles. For the last few months I have had a miss fire on cylinder #5 and system too lean on bank 2 trouble codes. Occasionally I will also have a code for the o2 sensor circuit, sensor 2 bank 2. I have a rough idle and it stumbles on acceleration, almost to the point of not running. The problem comes and goes, but is very frequent. There is no trend to when it has a problem and when it doesn’t.
I think I can hear a vacuum leak, but vacuum tests come out just perfect around 20 inches of mercury. I have replaced the plugs at the specified .056" gap. New wires, and I’ve double checked the resistance of them and they are within spec. Fuel filter is new.
I’ve also checked the coil and the primary coil has perfect impedance. When I checked the secondary coils they were all around the same resistance, but it was above spec at around 13k? with a specified max of 11k?. I don’t believe this to be the problem though since the impedance is the same across the three secondary coils.
I have also done a compression check which was just fine as well, cylinder #5 was around 170 and #4 and #6 were around 180. All three cylinders reached peak compression quickly, but four and six took one more revolution.
This engine has a two piece intake and they are common to have gasket leaks, so I replaced the lower intake gaskets, the upper plenum gaskets, throttle body and iac gaskets. There is also a system called the intake manifold runner control, which is basically another set of throttle bodies in the lower intake to help performance, but these are operating perfectly too.
I have checked the temperature of the catalytic converter to see if it was clogged, but it wasn’t horribly hot and even if it was plugged it wouldn’t explain the miss on cylinder 5, but it would explain the lean condition on that bank.
The oxygen sensor code is questionable, but as far as I know the downstream sensor doesn’t affect the fuel ratio.
So what now? I think I’ve pretty much checked everything but this van is on my last nerve and very close to being driven into lake Michigan.
Coil 1 fires sparks for #1 and #5 cylinders, yes? This is what’s called a waste-spark design, isn’t it? That is, coil 1 fires BOTH sparks at the same time…one spark is wasted, the other spark fires (either) #1 or #5 cylinder cylinder. Next time around, they switch spark and waste spark.
It’s not rational; but, the one side of the coil, for #5 cylinder, could be misfiring. I had this to happen on a Mercury Cougar. I switched the wires around (primary and secondary ignition wires), and the coil tower, now, misfired on the the other cylinder. So, it was that one side of the coil which had the misfire; but, not the other side. Changed the coil, and all was light and happiness!
It’s easier to do with your waste-spark coil (testing good with a multimeter isn’t enough assurance). Just switch the spark plug wires from #1 to #5, and vice versa. Erase the DTC trouble code. Drive for two, or, more, “trips”. If #1, now, shows misfire (P0301), then, it’s the ignition coil.
If it’s not the ignition coil, the next suspect is the fuel injector. You could do the swap test of #5 fuel injector for another. IF the other cylinder now misfires, it would be that fuel injector which is defective.
Here are pictures and stuff of the Windstar’s ignition system: http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800adf78
I checked the coil pack for cracks, and there was one by the #1 post which I repaired with JB weld as a temporary fix. I pulled the #5 wire from the coil and ran a ground to it and it has a good spark, but then again I don’t know if it’s timing is off. Just a few minutes ago I found a dried up vacuum line which I replaced. Repairs to the coil and to the vacuum line didn’t make a difference.
I’m starting to suspect the fuel injector wiring harness or pigtail, only because when I replaced the intake gaskets I pulled and cleaned the injectors and replace the o-rings on them. I didn’t put them back into the spot they came from, but I suppose I could have put the #5 injector back into the #5 cylinder. I’m going to go check the resistance of that injector and see if I’m getting any voltage from the pigtail. One VERY interesting thing though, which leads me to believe it’s an injector is that when I pulled the #5 wire from the coil and started it up it ran the same. I even moved the end of the wire over to the coil with insulated pliers to get a connection and it didn’t make a difference either.
Well I just checked the injector, resistance is good and I’m getting power from the pigtail. The injector is also ticking the way it should. I can hear a vacuum leak, but I can’t find it. The only way I know how to is by spraying the suspected areas with starting fluid, which I’ve done. But regardless, the test comes out just fine. It’s obvious that the #5 cylinder isn’t working properly because if I pull the pigtail off another injector there is a noticeable stumble, but nothing with #5.
“I checked the coil pack for cracks, and there was one by the #1 post which I repaired with JB weld as a temporary fix.”
That’s like putting a band aid over a bullet wound. If there’s damage down in that coil covering the crack probably won’t help. Not even temporarily. Try Hellokit’s advice of swapping wires #1 and #5.
Easier than driving into a lake would be to trade it in because you are in a fine position to start on a parts replacing project with lots of guesswork. We know the odds against a repair shop fixing it without taking six months if it is even possible. The guesswork goes as far as suggesting that an intake valve has large deposits on it to changing the injectors and the engine computer. Just don’t be driven to flood the car and the engine. How many miles was a Windstar designed to go anyway. I will bet that it has exceeded all design expectations. We know that it could go farther; but will it be worth it? If you are repairing cracked coil packs with JB WELD, I don’t believe you will pay for what may be necessary anyway. It’s time to think things over.
I just put jb weld on the cracks to rule out the problem, if it solved it the coil pack would be replaced. But I understand what you’re saying and trading it in is a possibility that I’ve been considering. I’m a tech, but I’m young so I don’t have years and years of experience. The only thing left to check is the valves, but I’ve lost my ambition for today.
Say that the intake valve has a lot of carbon deposits on it restricting air flow when the valve is completely open. This would restrict performance on that cylinder. The only problem with this theory is that it would cause a rich condition, not a lean condition.
It could even be a bad ground since the problem comes and goes. I ran a new ground wire to the block today to help rule things out.
I did swap #1 and #5, but I haven’t driven the van long enough to throw a code. I’m doubting that it will change anything though. When I checked, #5 has a pretty healthy spark. I’ve ordered a coil pack regardless though since the resistance is 2,000 ohms above spec.
Have you checked to see if #5 injector is actually spraying fuel? You have good compression and spark, fuel is the only thing missing.
To help locate the air leak try holding a length of heater hose up to your ear and move the other end around to suspected areas. You will be able to pin it down.
You stated that you don’t have a lot of experience yet as a tech but from what I can see from your postings so far, you will make an excellent tech.
Thanks. No I have not pulled out the injector to check to see if it’s actually doing it’s job. When I replaced the upper and lower intake gaskets I pulled, cleaned and replaced the o-rings on the injectors. There is always a possibility that I put it back in the same spot. I’m going to drive it for a few days as it is and see what happens. I could always find a donor sho engine and swap it in.