Cylinder Misfire

[ShafferNY]

Ever since we bought our '06 Liberty we've been having problems with it. First it was throwing a cylinder five misfire, and then a cylinder three misfire.

It's an incredibly long story that I'd rather not reiterate here.

Can a defective BCM cause the check engine light to come on by throwing a P0303?

The last Jeep dealer it was taken too claimed the Bosch Platinum spark plugs I put in may have been causing the code, or it could have been a defective BCM. The replace both and claim it's been fixed.

I'm not convinced.

 

[belvedere]

Personally, I'd be a little skeptical, too, but I hope they got it fixed for you this time.

 

[adamkrz]

Mine went to the dealer last month with p0300 - p0306 codes - I knew it wasn't the plugs or coil packs, These 2 codes would come and go for about 2 years but within the last 4 months they stayed on.

Anyway they determined it was internal and ended up changing the intake valves ( all 6 ) as per the TSB instructions.

3 weeks so-far and no engine light yet ( knocking on wood ).. My KJ is a 2004 with 57k.

 

[ShafferNY]

I haven't been able to determine if they actually performed the TSB you're speaking of or whether they just replaced the cylinder head gaskets.

The first time it went into the shop I didn't get a straight answer from the salesman I bought it from(Chevy dealership). The Jeep dealer they took it too would not even talk to me as I wasn't "the customer who presented the vehicle".

I was told they took the cylinder head(left) to a machine shop for inspection and everything checked out.

 

[JeepJeepster]

Those plugs are junk. Best to replace them, I like double platinum autolites.

I do not think a bad BCM would cause a cylinder misfire. A bad PCM very well can though.

 

[belvedere]

When we bought our '06 Sport, it had nearly new Bosch Platinums. They are not what I would have installed, but I have to admit, they seem to work fine.

 

[Dave]

Darn-it.........I thought that they had that thing fixed.

Dave

 

[tjkj2002]

Bosch platinums would not cause a misfire unless they where worn or had a cracked in them and that can happen to any plug no matter who makes it.A bad BCM has nothing to do with the firing of the plugs,that's the PCM's job.

Common misfire faults for top loaded plugs........

1-Bad coil/s
2-torn boot on end of coil/plug wire(bad wires)
3-leaking valve cover o-rings/leaking plug tube seals
4-corrosion
5-bad coil driver in PCM
6-bad plugs(worn,cracked,or fouled)
7-coil/wire not properly seated on plug

 

[mikes07kj]

These is going to sound lame but how do you know if you have these codes? Is it something by turning the key on and off?

 

[offrovering]

These is going to sound lame but how do you know if you have these codes? Is it something by turning the key on and off?

your check engine light will illuminate

 

[sprsonic]

take it to the dealer and recommend they look into tsb 09-007-06, i had performed this bulletin on close to 50 kj's and not a single one came back for any of the po300-306 misfires. and i've seen more problems with platinum spark plugs on jeeps than you can shake a stick at, just use the recommended ngk coppers, and they are cheap too. if you were under warranty and close to me i'd take care of it for you. good luck, sounds like you have a crappy dealer.

 

[ShafferNY]

I ran Bosch Platinums in my Taurus for 50,000+. Never a problem.

Now, I'm not saything the 3.7L is the same engine or that they wouldn't cause problems. I know some engines are finicky like that. I just find it hard to believe.

After we got it back from the garage once the engine work was done we drove it for three weeks without a problem. Then all of a sudden on a trip out of town, the darn check engine light came back on.

Since I was right next to the Jeep dealer who had done all the work the first time, I took it right there. After all, they knew the history of the vehicle.

They pulled the code; P0303. Then proceded with all the usual stuff; test the injector on that cylinder; swap coils and plugs to different cylinders to see if the code jumped; and nothing. Still throwing P0303.

Finally they admitted they didn't know what was wrong with it. The leakdown test was less than 2%, so the mechanical condition of the engine was good.

I took it back to the place I bought it from and they took it to a different Jeep dealer. This other Jeep dealer claims it was the platinum spark plugs and BCM. Neither of which make sense to me.

I'm confident the check engine light is going to come back on, it's just a matter of when.

BTW, I've got over a year and 12,000 on the Bosch Platinums in my '03 Liberty without a single problem. Go figure.

 

[k99jk99j]

Finally they admitted they didn't know what was wrong with it. The leakdown test was less than 2%, so the mechanical condition of the engine was good.

At that time nothing was mechanically wrong! the valve not rotating (according to the tsb) is an intermittant problem! thats why their is revised valve locks according to the tsb, this ensures valve rotation like it is suppose to!

second change the plugs out for the oem ngk's. why would you give them an excuse to blame the problem on you?

did you mention the tsb and the tsb# to both jeep dealers? and what is the misfire count per minute?

we all know you need the tsb!

 

[ShafferNY]

Well. First off all. If it's a Jeep dealer, I would hope they looked for a TSB. Especially since the customer has had this thing in multiple times. If not, they're not worth their salt.

And as for the plugs. Cost $20, not covered under any warranty, could have potentially saved me this headache, and the vehicle had 33640kmi on it anyway.

BTW, when I pulled out the plugs that were in it, they were NGK. They were also shot. You could have driven a truck through the gap.

 

[JeepJeepster]

Just wanted to correct myself.. the bosch plugs are not junk. For some reason I thought it said bocsh+4.. my bad.

 

[k99jk99j]

Well. First off all. If it's a Jeep dealer, I would hope they looked for a TSB. Especially since the customer has had this thing in multiple times. If not, they're not worth their salt.

well there you go, you can not assume they know about the tsb (especially if it is a low volume dealer!)

you are going to have to be assertive in a firm but calm way and ask them specifically about the tsb and tell them you want this problem covered under the tsb! i gave you a copy of the tsb in the previous thread on this subject! so copy that and go into the dealer with it! mike

 

[adamkrz]

When I took mine in I mentioned the TSB, They didn't want to see it, They did all the tests and found more cylinder misfire's than I had and changed the intake valves and lapped the seats on the heads.

The dealer who did all the work is a very high volume dealership here in CT.

 

[sprsonic]

the right dealership makes all the difference, some dealers have alot of turnover, as for the dealer i work for has the same guys for several years and see what happens with the cars they work on frequently. and making repairs fixed right first visit and customer satisfaction higher. definately do some reserch on your choise of dealer.

 

[sprsonic]

When I took mine in I mentioned the TSB, They didn't want to see it, They did all the tests and found more cylinder misfire's than I had and changed the intake valves and lapped the seats on the heads.

The dealer who did all the work is a very high volume dealership here in CT.

i dont know why any dealer would turn this tsb down, the valve replacement on these is a money maker. any of you guys have a problem with your vehicles under warranty or not and your close to toledo ohio, pm me and lets get it done

 

[sprsonic]

I ran Bosch Platinums in my Taurus for 50,000+. Never a problem.

BTW, I've got over a year and 12,000 on the Bosch Platinums in my '03 Liberty without a single problem. Go figure.

i'm not bashing platinum by any means, i just would not use them in my vehicles. i had actually removed the factory platinums from mt srt-8 jeep to install ngk coppers. imo they are just a waste of money