# 2006 Mustang GT - P0302 with hard misfire **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** mustang, ford\ **Created:** [September 12, 2024, 2:54am UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188 "2024-09-12T02:54:42Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Phildo](https://avatars.discourse-cdn.com/v4/letter/p/ecb155/32.png) [@Phildo](https://community.cartalk.com/u/Phildo)\ **Post date:** [September 12, 2024, 2:54am UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/1 "2024-09-12T02:54:42Z")
Originally had two misfiring cylinders (no 2 and no 7). Swapped out all coil packs and car ran fantastic for 3-4 days with no codes thrown. P0302 came back even worse than before with hard misfire (blinking check engine). Have since: 1- Swapped spark plug and code remains in cylinder 2. 2- Swapped injectors and code remains in cylinder 2. 3- Swapped new coil packs just to be sure. 4- Changed the fuel filter as it was due. Anyone have any ideas? I’m stumped at this point. Maybe the cats or a camshaft position sensor? It runs great for the first 30 seconds then I start getting blinking check engine light. Power is still there but I hear the occasional pop out of the exhaust and it runs slightly rough. ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [September 12, 2024, 3:25am UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/2 "2024-09-12T03:25:32Z")
With a “stubborn” P0302 you can forget cats and cam or crank position sensors for a while. I don’t know how difficult it is to check the compression on this engine configuration, but it would be a best first step. I also don’t know easy it is on this configuration to get to the fuel injectors, but step #2 would be to swap the #2 fuel injector with another to see if the misfire follows the injector. Mis-“fire” is a bit of a misnomer. It should be called “mis-combustion” - as in the air/fuel mixture didn’t explode. That can be from lack of spark (the “fire”), or fuel (injector problem), or air (unlikely if confined to one cylinder), or compression. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [September 12, 2024, 3:39am UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/3 "2024-09-12T03:39:27Z")
OK, you have a 2006, that 7 years ago in 2017 you had clutch issues, that is normally a high mileage issue, but I have yet to see how many miles are on this thing… How many miles are on the engine/vehicle??? ---
**Author:** ![Phildo](https://avatars.discourse-cdn.com/v4/letter/p/ecb155/32.png) [@Phildo](https://community.cartalk.com/u/Phildo)\ **Post date:** [September 12, 2024, 3:54am UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/4 "2024-09-12T03:54:35Z")
Ah, 150k. I really only drive it to and from work these days which ends up being like 5k miles a year. I think it had 130k back in 2017. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [September 12, 2024, 3:58am UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/5 "2024-09-12T03:58:37Z")
OK thanks, I second cigroller, do a dry/wet compression test on all the cylinders (correctly), you may have internal engine failure… ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [September 12, 2024, 11:20am UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/6 "2024-09-12T11:20:19Z")
Clearly the engine has an internal mechanical problem that no amount of parts swapping will fix. The OP has done this and proved it is not an ignition or injector problem. A compression test isn’t hard to do on these engines. Pull the fuel pump relay and you can crank the engine from the starter relay by jumping across the terminals… both are in the underhood fuse box. If cylinder #2 reads low, and I’m sure it will, pull the valve cover over #2. Look for broken rocker arms, broken valve springs or if one of the 3 valves is stuck open. Hopefully it is a broken spring or rocker and that the rocker hasn’t torn up the cam. If you can’t find a reason that cylinder is dead, time either dig deeper into the engine, or search for a used replacement. ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [September 12, 2024, 3:39pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/7 "2024-09-12T15:39:13Z")
A 260hp 4.6 ohc is different than a pushrod 302 for head replacement. A bare head does not include cams and you have to work on timing chain as well. Is what it is. I guess you can’t fight progress. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [September 12, 2024, 3:57pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/8 "2024-09-12T15:57:13Z")
It is a 300 hp 3 valve OHC V8, not a 260 hp 2 valve. Just a clarification but it doesn’t make the job any easier. ---
**Author:** ![Phildo](https://avatars.discourse-cdn.com/v4/letter/p/ecb155/32.png) [@Phildo](https://community.cartalk.com/u/Phildo)\ **Post date:** [September 12, 2024, 4:20pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/9 "2024-09-12T16:20:43Z")
I kinda thought that was where this was all headed but needed to hear it from someone else, I think. I’m probably just going to trade it in and get another car instead of futzing around with it. Only reason I haven’t is because I have a less than five mile commute to work. Seemed like a waste as long as this one worked reliably. ---
**Author:** ![ledhed75](https://avatars.discourse-cdn.com/v4/letter/l/f6c823/32.png) [@ledhed75](https://community.cartalk.com/u/ledhed75)\ **Post date:** [September 12, 2024, 4:54pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/10 "2024-09-12T16:54:18Z")
Bear in mind… if you try to sell it with a Check Engine light, it’s going to lower what some would be willing to pay. Like the old mechanic said, you’re going to pay me now or pay me more later. ---
**Author:** ![Phildo](https://avatars.discourse-cdn.com/v4/letter/p/ecb155/32.png) [@Phildo](https://community.cartalk.com/u/Phildo)\ **Post date:** [September 12, 2024, 5:28pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/11 "2024-09-12T17:28:50Z")
I would trade this thing in and get what I get. Ive gotten 19 years out of this so she doesn’t owe me anything. Don’t think I could consciously sell this thing to some HS kid when it has engine problems. ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [September 12, 2024, 6:20pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/12 "2024-09-12T18:20:34Z")
The good news is that car prices are dropping. Unless you want a very popular model, don’t expect to pay MSRP for a new car. ---
**Author:** ![asemaster](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@asemaster](https://community.cartalk.com/u/asemaster)\ **Post date:** [September 12, 2024, 7:40pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/13 "2024-09-12T19:40:30Z")
You haven’t yet verified that the PCM is trying to fire the injector. See if the O-Reillys or Autozone near you will loan you a noid light. ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [September 12, 2024, 7:47pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/14 "2024-09-12T19:47:18Z")
It’s not making 300hp with a dead cyl. It’s only making 262hp. Or 7/8. Sorry. I was off 2 hp ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [September 12, 2024, 8:31pm UTC](https://community.cartalk.com/t/2006-mustang-gt-p0302-with-hard-misfire/196188/15 "2024-09-12T20:31:38Z")
> [@Phildo](#): > > thought that was where this was all headed but needed to hear it from someone else It seems like you’ve done all the simple tests for the problem, so I expect the folks above are right, there’s an internal engine problem. An engine compression test definitely makes sense at this point. There’s one puzzle remaining though, why did the symptoms get remarkably better for 3-4 days, then got worse again? If the compression test shows a problem, it’s possibly a simple problem, like a valve is sticking. If it shows there’s not a compression problem, make sure the battery and alternator are working to spec, and that the engine compartment ground connections are in good shape, especially for the cylinder head and battery. The electrical path between the pcm and the coils and injectors for that cylinder should be checked with an ohm meter, line by line, for broken or “iffy” connections too. If you have access to a lab o’scope, comparing the ignition and injector waveforms between the faulty cylinder and one that seems to be working might provide an important clue. That’s probably where I’d start were I diy’ering the job. . If you feel lucky you could just try the common methods to unstick a stuck valve, chemical treatments, etc.