misfire #3

year 2000 and just had the head gaskets replace. I i had the heads sent out and checked over. After fix i had misfire #3. Now new plugs new wires new coil and new injector. Van still runs alittle rough and have misfire #3 show up after running van and stopping for awhile. Van runs down road great just when you stop it will stumble and miss. Any ideas because monday i will take it back in to shop. Also could a valve cause the sensor to read misfire?
Thanks i don't know what else to do.

Do a compression test on cylinder 3.

Okay i'll have shop do test. Can you explain what kind of result i might get from the compression test? Does it give you accurate infomation as to why you have a miss? Or does it let you know where to look next? The motor also is a Jasper remanufactured engine and has 55,000 miles 4 1/2 years so no warranty. And still headgasket went bad??? Jasper let me down. I'm going to take it on longer drive to see if it works it self out. Thanks

The misfire could be caused by a bad valve, a cracked compression ring, fouled/ arcing plug, bad wire, bad coil, stuck open/closed injector, etc.

To test compression, you remove the plug from that cylinder, insert the guage, crank it over a few times, check reading, repeat test like 2x more. (this is done with the fuse for the injector harness unplugged) Repeat test for all cylinders and the lowest reading of the 6 cylinders should be within like 10% of the highest or something like that.

If you do have a weak cylinder, put a tablespoon full of oil in the plug hole and repeat the test for that cylinder, if compression increases you have bad rings, if not suspect head gasket or valve leakage.

Have you ran some seafoam through the top end?

I was getting a cylinder 6 misfire, I changed #6 plug for #2, installed a replacement wire, and found I had a bad ALT SENSE fuse (#30) in the underhood fusebox, it has never returned.....

Thanks for reply and on my longer drive i added seafoam to a full tank of gas. I went around a 100 miles and still have small shaking or stumble with no check engine light. The van runs perfect going down the road. Only while idling do i feel the shake. And at idle if i rev up alittle is smooths out. This only started after head gasket change. I know the shop will take another look but they seam to not be able to figure it out. Shop put new plugs and wires on for free but this didn't work. Today they put new injector in and still no luck. Wish me luck because we didn't talk about money on that and i have van without paying. I checked #30 fuse and was good. Tomorrow i think i'll clean maf and push on all air lines, who knows maybe that will help. Thanks again for reply and ideas.

Mine was rough untill I seafomed thru a vac line and blew a BUNCH of carbon out, is much smoother, I also cleaned MAF, but not much change there (240k on the clock.)

Do you rev up engine as you use seafoam or just let idle. Thanks

Depends upon how fast you are feeding the seafoam in. The faster you feed it in, the faster you need to have the engine run so as to not hydrolock the motor. Most people will put 1/2 in the tank, fill the tank. Hold the other 1/2 near a manifold vacume source (I put a piece of hose over the vac supply for the transmission vac modulator, being yours is a 2000 you may not have the vac modulator, but the port will be very near the air filter side of the manifold with a rubber cap if no vac modulator. Use the rubber hose to pull the seafoam in slowly at idle and a little faster when revved, it is BEST to do this with the engine warmed up. The last little bit of seafoam should be used to stall the engine, let it sit for 10 min or so, then the fun of trying to restart it begins, you will have lots of pretty white smoke as the carbon burns off and I did mine in the snow, I had lots of black debris in the snow under the tailpipe, I also had some white smoke comming from under the van behind the engine (found an exhaust leak near the manifold- actually the doughnut from manifold to the pipe is bad, might explain the low mileage!!!!) Good luck!

I ran out of time today. Brakes on my car needed attention. So i will want to let the vacuum line pull the seafoam out, not pour it in? No check engine light today so maybe it's getting better. I read the bottle and it says you can put in the oil or the gas. Would putting some in oil help anything? And do you just leave in oil intill you change it?
Thanks again, if i firgure this out i'll let you know.

I dont recommend doing it in the oil, it could wash the oil off your cylinder walls or out of the bearings, that could be bad, Not to say it hasnt been done without ill effect (I have done it once, but it didnt help). Changing the oil regularly and with good quality oil will help clean it up. I use it regularly in gas and in the intake with no permanant damage (sometimes you can foul up plugs or plug an EGR with carbon).

I took in today and he sprayed maf sensor with cleaner and not much changed. He spent about 1 1/2 hours hooked up to computer driving and checking and couldn't find anything out of range. So i took him with me for about six blocks ran great, then stopped and started chugging alittle. I don't think he belived me about not running correctly. Now after me and him in van he knows what i'm talking about. I'm dropping off tomorrow for a strut bearing repair and i'll let him keep for a few hours to see what he finds now that he know what the shake i feel is.

My best guess for this is a leaking intake valve.

I got the strut fixed and thats the good news. I may be loosing coolant again. MY wife had the heater get cool and the temp gauage started jumping around. When the garage looked it was low on coolant. After looking at engine no sign of leaking anywhere. So he thinks it was maybe a air bubble. I don't i wish the engine would blow or something so i can tell him to fix it. Or he can pay me off and i'll go away and not fix this junking van ever again. I'm starting to look around at the ford dealers and see what i like. Let you know how the van ends up.

If it using a tiny bit of coolant then my next best guess is leaking head/head gasket.

If it using a tiny bit of coolant then my next best guess is leaking head/head gasket.That would be bad because just had that done. Had heads over and shop and checked and cleaned and sanded or planed or ground or grind the bottom to make flat. Whatever they called it. Also paid to have new lifters and pushrods and new headbolts put in.

Okay pressure test today and no problems. Put on new radiator cap lets see how it goes. Also my misfire three has gone away but still have a miss or shake to motor. I was told by a few other people that i should just drive it intill the problem becomes more clear. Otherwise i can start changing those sensors and hope i find the bad one first not last. So far i've gotten free plugs and wires and thermostat and injector and mass airlow cleaned. But i did pay $5 dollars for the cap today. I'll call that even:p

Well i don't know if the seafoam did anything but my wife filled up van and it seems to be running better. Very little shake at idle. When i figure this out i'll let every know. That way it may help someone els.

Did you seafoam the intake or in the gas tank?

Just the gas tank so far. Today the garage checked the plug on #3 and found a small line or crack in the porcelain. While on the rack they did a compression test on apparently only three cyclinders and thought the tester was bad because the readings were under 100psi. He had a new one sent over and still the readings were around 90-70-110. I wouldn't think if the numbers that low the engine would run so good going down the road. He drove me around town and it wasn't shaking hardly at all. He's going to call the shop that checked and cleaned the heads and see what they have to say about the work. Now if the rings are the problem would the van be burning oil or smoking or something. It really does run great if the idle shake stays away.

Went over today and he called the machine shop and they claim everything was checked and all was good. I see no reason to lie about the work. So they said maybe i have some piston or rings going bad. The problem now is if i have shop tear engine down to see who is at fault, the machine shop or my shop i would get the work done for free. But if i have a ring problem or whatever i would be out a bunch more money on a van i don't want to fix again. So i'll take the weak engine that runs and drive good now and hope for the best.

I have taken an engine with stuck rings and ran some seafoam down the intake to help clean the top end loosening the rings in the process...... just a thought.

lesterl could to tell me the best way to get it in the intake. There's the big hose in back or the pcv in front. It would be worth a six dollar try. Thanks

You could use the brake booster line, on my van I used the Trans modulator line, it took in plenty of seafoam, but I couldnt get enough in to stall it, just ran 3/4 of can and shut it down, let it sit for about 10 min, then started it back up (took some cranking) ended up with plenty of black crud in the snow under the tail pipe.

Hey Lesterl, seafoam in the intake may have done some good. Did it today after work but i didn't get much smoke after start up. Only let sit about 5min like can said. Maybe 10 min like you suggested would have been better. Either way it is most defintly running smoother at idle. Come to a stop sign and it doesn't bog down and don't get that misfire feel. The only problem i had was i wanted to do it some more with the little i had left and used a different port, my 3.4 has a vacuum plugged in the upper right intake. When i did the motor spit the seafoam in my face and eyes. Someday i'll learn to use my goggles that sit right out in the open, easy to grab. Thanks again my van is really running good again.

Yeah, I changed the fuel filter on my sister'nlaws 99 taurus and when I was still under I couldnt resist the urge to blow thru it. Mistake I built up pressure inside the filter and when my lips let off it blew gas all over me!!!! Later, I seafoamed my intake 3 times recently, and ran some good injector cleaner thru the tank. Mine has an intermittent stumble at Idle I have yet to diagnose (waiting on some $ for a scanner) but it is minor. The throttle is much snappier and I also replaced an exhaust doughnut and it is getting better MPG.

I read somewhere that a fuel pressure regulator can cause poor idle because a spring gets weak and lets to much fuel through. Going down the road it would be okay because it would let more fuel through like normal. Any thoughs on this would be great.

Put a fuel pressure guage on it.