Change your plugs yourself and swap around your coil packs. If the code changes, probably the coil pack, $20-$30 part.

 

Wow. Thank you everyone for all your input. I sincerely appreciate it.



Sorry I should have gone into more detail. This Firestone in amazing with me. I've been going there for 3+ years and they always do their absolute best with me any try everything. They put new plugs, a new injector, and a new coil pack on cylinder #3, they said it helped, but it still was misfiring. They weren't comfortable giving it back to me without them being sure it was totally fixed, so they took the coil pack and injector off, and only charged me like 40 for the plug job, and 25$ for the diagnosis. He told me to bring it back the next day and he'd do a compression check. Brought it back yesterday morning, did the compression check, and he didn't give me a number, he just said it had compression, one guy said it was low, then when I called back for something else, the other guy said it had compression, but it leaked out. He said to tell whatever shop I take it to that it had a burnt valve and they would understand.

Run a can of seafoam through the brake booster and throw a can in your gas tank. Or get a couple bottles of techron and run them through your jeep. A fouled up injector can cause a misfire, at least it did for my 4.7

Had half a tank of gas and put a bottle of seafoam in it, seemed to help a little bit but it still misfires.

ya fuel system cleaner cleared my misfire in my 300, carbon build up

$10 can is a good start and helps regardless

Same reply above

How did the Firestone shop come to the conclusion it was a burnt valve in the #3 cylinder? Did they remove the head of the engine or was the burnt valve a "guess"? What was the result of the compression test on each of the cylinders in terms of psi per cylinder? That is important to know to determine the seriousness of the problem. There are standards for psi (pounds per square inch) in the Factory Service manual for a six cylinder 3.7L jeep engine --170-225 psi in each cylinder. How much $ did you spend already at Firestone? How many miles are on the vehicle?

First, do not throw any more money at it yet. If you haven't already, get the answers to the compression question above from the folks that did the work at Firestone. If what the people at Firestone told you is true and they did the work you may need a partially rebuilt engine if it is salvageable. You will not find the answer to your question on internet boards. You will need to go to an engine specialist that can give you a proper diagnosis if in fact the problem is compression on the number 3 cylinder.

If it is engine work that you need it could cost anywhere between $800 and $4,000 - if the engine is blown. It really depends on what an expert finds is causing the loss of compression on the #3 cylinder. What surprises me is why someone charged you a diagnostic fee of any amount without telling you the problems causing the check engine light. Those individuals are irresponsible especially if they did not do a compression test for you or at least offer you the option of a compression test for a modest fee. Another puzzling thing is why would Firestone put any new parts on the vehicle if there is a serious compression problem on cylinder #3?

(Unfortunately, the seller of the vehicle probably knows the problem and the cost to fix it. Unless s/he gave you a guarantee it was an as is sale and now you own the problem. If the seller does know the problem s/he is not going to tell you as it is not in their best interest).

A lot more is described in my first reply. They didn't give me numbers for the cylinders, but I didn't know to ask. They charged like 65 for the plugs, diagnostic, compression test, and trying a new injector and coil pack. The jeep has 119108 miles.

I know I'll have to go to a specialist, but they're all closed here until Tuesday. I was kinda just looking for opinions on if there's anything else to do.

The one who charged me the diagnostic fee without telling me anything was actually the dealer. I took it in, told them I had a misfire on cylinder 3, and wanted to know what it was. He said they charge 85 for a diagnostics. I agreed. They came back and said, "you have a misfire on cylinder 3, we'd have to go more in depth and its 95$ an hour and we don't know how long it will take" I was extremely pissed and talked to the manager and all he would was lower the initial charge by $20 and sent me on my way. That's when I went to Firestone. They tried the parts first because that's what they thought it was initially.

Another thing is after all the work Firestone did, I'm getting some additional codes besides just the one I was getting initially. I'll have to get them written down.

The jeep only misfires at an idle or under 5 mph (that I can notice). Once I get up to speed it "seems" to run fine and I haven't noticed any power loss (although I've never driven it without this problem).

The seller is a coworker that I've known for 2 years. He's not mechanically inclined at all, and told me point blank it had the check engine light on. He was perfectly fine with me taking it to get diagnosed before I bought (I did, and that's when the dealer told me they were 95% sure it wasn't anything major but they wouldn't know until they spent more time on it at $95 an hour)

 

Run a can of seafoam through the brake booster and throw a can in your gas tank. Or get a couple bottles of techron and run them through your jeep. A fouled up injector can cause a misfire, at least it did for my 4.7

 

ya fuel system cleaner cleared my misfire in my 300, carbon build up

$10 can is a good start and helps regardless

 

How did the Firestone shop come to the conclusion it was a burnt valve in the #3 cylinder? Did they remove the head of the engine or was the burnt valve a "guess"? What was the result of the compression test on each of the cylinders in terms of psi per cylinder? That is important to know to determine the seriousness of the problem. There are standards for psi (pounds per square inch) in the Factory Service manual for a six cylinder 3.7L jeep engine --170-225 psi in each cylinder. How much $ did you spend already at Firestone? How many miles are on the vehicle?

First, do not throw any more money at it yet. If you haven't already, get the answers to the compression question above from the folks that did the work at Firestone. If what the people at Firestone told you is true and they did the work you may need a partially rebuilt engine if it is salvageable. You will not find the answer to your question on internet boards. You will need to go to an engine specialist that can give you a proper diagnosis if in fact the problem is compression on the number 3 cylinder.

If it is engine work that you need it could cost anywhere between $800 and $4,000 - if the engine is blown. It really depends on what an expert finds is causing the loss of compression on the #3 cylinder. What surprises me is why someone charged you a diagnostic fee of any amount without telling you the problems causing the check engine light. Those individuals are irresponsible especially if they did not do a compression test for you or at least offer you the option of a compression test for a modest fee. Another puzzling thing is why would Firestone put any new parts on the vehicle if there is a serious compression problem on cylinder #3?

(Unfortunately, the seller of the vehicle probably knows the problem and the cost to fix it. Unless s/he gave you a guarantee it was an as is sale and now you own the problem. If the seller does know the problem s/he is not going to tell you as it is not in their best interest).

 

P2311 Ignition coil "D" secondary circuit
P2308 Ignition coil "C" secondary circuit
P0303 Cylinder 3 misfire

Those are the three codes I'm getting now. In the beginning it was just the last one.

 

Wow. Okay.

If you take it to the specialist, check out the compression in each cylinder first and foremost. That way you can confirm that the engine is good. At its simplest, a gasoline engine is a big air compressor. You want to make sure it can correctly compress air before spending a lot of time and money on parts. The ONLY reason I am suggesting this is because the folks at Firestone said that you had, didn't have, might have a compression problem. Ugh. (By the way, if the compression is within the specs for your model and year engine, there is no compression problem).

119,xxx miles is not a lot of miles. What I like about the codes that you listed is that there are a lot of them. That suggests that something global is potentially wrong and not necessarily compression cylinder number 3.

It could be the PCM - Powertrain Control Module - which is the computer for your Jeep. The PCM takes inputs from all of your engine and transmission sensors and controls fuel and sparks. In the Factory Service Manual there are six (6) specific electrical tests that need to be done prior to testing the PCM as the potential problem. The person doing the test should have a Factory Service Manual for your vehicle. The tests will check out the coils, wires, and then PCM as a last resort. A PCM is expensive and needs to be programmed to your particular vehicle. Only a Jeep dealer can do that. If it is the PCM, and that needs to be tested and confirmed first, you may be able to purchase it from another Jeep Dealer over the internet and have them pre-program it so that anyone can install it. I like MoparPartsDiscounted myself. Good guys there and 30-40% below walk in Dealer prices. They sell the PCM/ECM for $395.

I hate to say this but you may want to go to a Jeep Dealer. They can do the compression test and the electrical tests. They will charge too much $$ but they will get to the route of the problem fast and if it is the PCM they can replace it right away. Tell them that you are a college student and on a tight budget. Hopefully, they will understand. The Firestone guys are probably really nice but a bit uncertain as to whether you have a compression problem or not. And the "burnt valve" comment without pulling off the engine head and inspecting it undermines their credibility.

Take a look at the thread below. Keep in mind I am not saying that it is the PCM but that is a possibility.

http://www.jeepforum.com/forum/f67/2006-grand-cherokee-3-7l-v6-misfire-2662338/

Keep us updated. Good luck.

 

Thanks for your input. I'm kinda hoping it's the pcm then, grow hat you described it sounds like itd be cheaper. But I don't want to get my hopes up, because if it was that, should it not have any issues whatsoever with the compression? That's the part that really worries me, them saying the compression just leaked out :-/

I'm lucky enough to have another jeep dealer near me besides the one I went to the first time. I'm really hoping they'll be better and be able to actually tell me what's wrong for just the diagnostic fee. I'm going to try going to them on Tuesday.

 

That is a wake up call. Hopefully you will get some good news soon.

 

The dealer called and said the new coil didn't do anything. Now they have to charge me another 190 for another compression test to be sure. He said he thinks it's either the piston or valve :-(

 

Why don't you go to Autozone and rent the compression test kit and find out what's really going on? Over the years I have become very distrustful of shops in general and would prefer to diagnose and repair as much as possible. I'm not saying you have a bad dealership, but for a $50 refundable deposit, and a couple hours of time you can check the compression yourself.

Even found a video for you.

Whatever the case may be, good luck, hope it works out for you.

 

Sorry bobby, completely missed your reply. I can do little stuff, like starters, brakes, alternators, etc, but I'm not really confident enough to be able to do more serious stuff when it comes to things with the engine. I sincerely appreciate you taking your time to look up that video though, it's much appreciated.

Dealer just called back. He said compression was good. He did say it wasn't perfect, that it had some variance in it, but he did say it was good. He says now he's thinking its either a rocker arm, or something else (I couldn't hear what he said the other thing was he was thinking). So I guess that's a bit of good news. He's charging me another 130 to dig deeper into it to figure out what it is.

 

Wow! did you buy this from a private party or through a different dealership?

It might be worthwhile, before you write them a check, to call around/search for a wrecked low miles engine. I may have missed it, but what motor is this? 3.7, 4.7, Hemi?

Just a quick search of ebay shows you can get a 3.7 from anywhere between $800-$1500 complete. Some have warranty some don't. Bring said engine to a shop, not a dealer and find out what the cost to swap would be.

Not saying anything bad will happen, but I would have the same question you did. What happens if this doesn't fix it?? Not only that, but why is 1 lobe of the cam excessively worn? Once the cam, etc. is replaced, what else might you find? I see that you said it has 119k miles. That's doesn't seem like a lot for it to have that kind of issue, unless it hasn't been well maintained or has been abused.

***Disclaimer, not saying I know it all, but in 20+ years of vehicle ownership I've learned a few things..

 

Wow! did you buy this from a private party or through a different dealership?

It might be worthwhile, before you write them a check, to call around/search for a wrecked low miles engine. I may have missed it, but what motor is this? 3.7, 4.7, Hemi?

Just a quick search of ebay shows you can get a 3.7 from anywhere between $800-$1500 complete. Some have warranty some don't. Bring said engine to a shop, not a dealer and find out what the cost to swap would be.

Not saying anything bad will happen, but I would have the same question you did. What happens if this doesn't fix it?? Not only that, but why is 1 lobe of the cam excessively worn? Once the cam, etc. is replaced, what else might you find? I see that you said it has 119k miles. That's doesn't seem like a lot for it to have that kind of issue, unless it hasn't been well maintained or has been abused.

***Disclaimer, not saying I know it all, but in 20+ years of vehicle ownership I've learned a few things..

I bought it from a private party. Cheapest engine install I could get was ~3100 + taxes which is out of my budget. Idk I asked about the other cam and he said it looked fine....

I still dont have any more updates, its been in the shop ever since and every time I talk to them they say the delivery on the part has been pushed back by a week. I called Chrysler and kinda pitched a fit because this is unacceptable. They supposedly expedited my order and have an eta of the 28th.

I asked the dealer about a loaner (I spend 70$ a day in taxi fair to get to and from work/school, seeing as I like 25 miles away) and he said it was up to his manager. I talked to the manager and he told me the only thing he could do was offer me a "discounted" rate at enterprise of 35 a day. I brought this up with the Chrysler rep and she said she was calling the dealer to try and arrange something. She came back on the line and said they told her they wouldn't do anything with that because "what he does on his own time is on him, thats not up to us" which infuriated me. I could have afforded a taxi for the 5 days you told me it would take, but going on 3 weeks is NOT what i can afford and most definitely NOT my fault.