98BlacknWhite

About a few weeks ago, I had a check engine light come on with a cylinder 3 misfire. As the only noticeable difference was idle sitting around 1500 instead of around 500 RPMs, I let the issue go.

Two weeks ago, I had my water pump changed due to a major leak, and didn't start driving the Stang until about a week ago. Now, after the car has been driven for a few minutes and gets into operating temperature, it will hesitate heavily at around 3000-3500 RPMs and run very rough above that. If I pull the car over and drop it to neutral, I can rev it all day long with no issues (as long as it remains in neutral).

Current problems I have researched that may be the issue are: plugs/wires/coil packs, MAF in need of a cleaning, TPS, fuel filter/pump, and clogged cats.

I will check my codes again tomorrow to see if any new ones have come up, but am looking for someone with a similar -- if not same -- past problem that has been solved before I start tossing money at this project.

VTX1800N1

Post the exact codes you are getting. Swap the suspect coil with one from another cylinder and see if the misfire follows it. Pull the spark plug from the misfiring cylinder and inspect it as long as you are in there. If the misfire stays on cylinder 3 and the plug looks good, swap the fuel injector next in the same manner and test again. If the misfire remains on 3, it's time to do a compression and/or leak down test. If the misfire follows either the coil or injector, you have found your problem.

Brandonfilipponi@yahoo.com

I literally just fixed this problem. My cylinder 8 was missing I replaced all plugs. And just that coil and I was good to go. But if problem keeps up then it may be injectors. Also make sure everything is clean! Nothing clogged

Brandonfilipponi@yahoo.com

Be popping injectors off rail and make sure they squirt

98BlacknWhite

The only code is still the P0303. I have been busy with work and other life matters, but tomorrow I should have enough time to get at that side of the engine. When the problem first arose, I was able to pop the boot off, and I did not see any dampness. I am hoping it is just an electrical problem at this point.

@Brandonfilipponi@yahoo.com Does your problem exactly mirror mine (with the exception of the cylinders being different)?

In any case, if the problem is plug/wire/coil related, I will want to be changing plugs. I heard copper or titanium is best over platinum. Is there a good reason for this? If so, which between copper and titanium is better? Again, why? Lastly, the plugs are said to be gapped at .52-.56. Many are saying to try a .45, if not all the way to .35. As my stang is modified fairly heavily, I feel the best bet is stick to .45, but was wondering if anyone has tried .35 with a (slightly) better outcome in performance. (Before anyone says every car is different and to test it out for myself, it is a major pain to access plugs 1-4 and I have little time these days for tinkering like I used to.)
P0303 Code - Cylinder #3 Misfire

Read more at: http://www.obd-codes.com/p0303
Copyright © OBD-Codes.comP0
P0303 Code - Cylinder #3 Misfire

Read more at: http://www.obd-codes.com/p0303
Copyright © OBD-Codes.com
P0303 Code - Cylinder #3 Misfire

Read more at: http://www.obd-codes.com/p0303
Copyright © OBD-Codes.com

Lackey'sGT

I was having a similar problem and my car has coils unlike your wires but my boots were cracked. I pulled all the plugs re-gaped them to the .45 and changed my cracked boots and it fixed my problem. Are you not getting any hesitation at low rpms? Sounds like you are already on it though.

My car would miss from 500-2000 then miss again when I got on it around 3500-4000.

98BlacknWhite

I was able to get around to the spark plugs today, but the problems are greater than expected; bear with me.

After having a local mechanic change my plugs the last time (due to other events), I found he put a whole different plug in from the rest in cylinder 3. Furthermore, that spark plug was not gapped at all. I tried an OEM in there, and also checked the pressure. Turns out, there was none! I am planning on taking off the heads, and will check to see if there is a spring not working properly, but I have a feeling if there was no compression whatsoever, would that not mean my rings are not shot (if not worse)? If anything, I could be seeing a costly fix with chunks of the pistons missing.

98BlacknWhite

Alright, so there is a hole in the piston about the size of a dime with a crack from that.

Does anyone have any personal preferences as far as piston products? Chances are, I will have to switch out pistons, rings, rods, and toss a new crankshaft in there. However it comes down to it, I will need a new piston, a new car, or drive without a cylinder.

Brandonfilipponi@yahoo.com

All depends on what you want. If you got some money tucked away I would redo it all, because think. Who wants to buy a car they need to put a whole bunch into. Unless they want a project.

TomKat

change the fuel filter too if you haven't lately, those are very over looked.. just read the piston thing... check out summit racing good options of what brands you could run..