Check engine light

change out the penlum gasket and now the check engine light came back on and the codes are 301 and 302 miss fire on the bank 1 and 2. not sure what it is now. mechanic is lost. need help here.

Your mechanic knows the make. model and year of your vehicle, type transmission and engine size and the history of the problem and he can’t figure it out. What exactly are you expecting from us when we don’t have any of that information.

My dog is sick, what’s wrong with him?

P0301 and P0302 indicate a consistent miss in cylinders #1 and #2. If this car/truck has a distributor and spark plug wires, look for misplaced cables; damaged cable wires: or cable boot not completely engaged to the spark plugs. Since this is the 2.8 liter V6 it is possible that the 1&2 spark plug cables have been interchanged.

Post back with more information for more specific suggestions.

@Researcher where does it say the engine type and size?

Perhaps I need a new prescription . . .

Well, bank 1 and bank 2 refer to the two exhaust banks. The OP must have either a v6 or a v8, as the inline engines usually only have one exhaust bank.

OP: A misfire means the ECM is monitoring the speed of the crankshaft and the crank isn’t being accelerated as much as it should be due to those spark plugs firing. So the problem is either that the spark isn’t consistently firing, or firing at the wrong time, or the fuel/air mixture or compression is out of whack for those firings.


I believe you’re overthinking it

P0301 means misfire cylinder 1
P0302 means misfire cylinder 2

OP said P0301 means misfire bank 1
OP said P0302 means misfire bank 2

Unfortunately OP is not quite correct. Sometimes cylinder 2 is on the same bank as cyinder 1. It really depends on the engine manufacturer

I may be mistaken, but I believe the Jeep 4.0 straight six has a bank 1 and bank 2. I believe bank 1 is the front 3 cylinders . . .

None of this answers how researcher knows the OP has a 2.8 V6. The only thing I can think of is that this is a continuation of a previous post that somehow was shown as a new post.

yes it is from a previou post. it is a 2001 ford taurus, v6 u engine. replaced the engine with a used engine 130k miles. the check engine has been on since the change. the mechanic has changed the 02 sensor upstream, the spark plugs, wires and pack and the penlium gasket. it got rid of the code 174, but is now coming up the codes 301 and 302. he has checked the compression and it is at 120.

sorry for the confusion

check to make sure all of the ground straps are in place

Compression test will not say for certain if you have bad headgasket. Ala wet plugs.

In today’s computerized world, engine swaps are usually a nightmare…The installed engines wiring and sensors must match the original EXACTLY or the ECM will be throwing codes forever…

Sorry @DB4890 and @oldtimer11, I was just “shooting the moon” with wild supposition.

I guess if this were my car the first thing I’d do is a vacuum system check, checking hose and each vacuum controlled device for leaks. Use a vacuum pump/guage test gadget to do this. It isn’t a likely cause, but a vacuum leak could cause a misfire symptom, and this is a fairly quick test to do, maybe takes an hour. And with a used engine installed, since there are so many things that could go wrong during the installation, it’s good to know the vacuum system is working correctly at least in any event. And I’d probably check the fuel pressure at the rail. Again, probably not a problem, but just to get some baseline data in hand.

For misfires, sometimes mechanics will swap things between two cylinders, like swapping the spark plugs for example, and see if the problem moves with whatever was swapped. In other words if the code says there’s a misfire in cylinder 1, and you swap the spark plugs between cylinder 1 and 3, and after that the code says there’s a misfire in cylilnder 3, that’s pretty good evidence you’ve got a bad spark plug. Depending on how the engine is configured, you might be able to swap the plugs, wires, coils (if there is a separate coil/plug), injectors, etc. But be aware that just b/c the code says there’s a problem w/cyl 1, that isn’t necessarily the case. It could be the problem was actually on the firing of the cylinder in the order prior to cyl no. 1, and it the ECM doesn’t see it as the crank slowing down until the following firing (for no 1).

A timing problem could cause this too. Have you checked the ignition timing w/a timing light? What about the crank sensor? Have you tried another one? Might be worth a shot. A valve timing problem might cause this symptom too, but less likely. Is there any chance the valve timing wasn’t set correctly when the timing belt/chain was installed?

As mentioned above, when you swap engines, there’s always a risk you have incompatible software in the ECM for the engine you are using. If you have the ECM that matched the used engine, you might try swapping that in. And sometimes the only way to figure this kind of problem out is with real time engine analysis equipment, usually done with the manufacturer’s scan and diagnostic tool. Best of luck.



120psi compression is pretty low, actually