2008 with P0305 code.... aaarrgh.

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L

LCGood

Joined
Oct 1, 2023
Threads
4
Messages
15
Location
NV, USA
Hi All -

Looking for advice. 2008 - 200 series with a P0305 code. I have read multiple sources on interwebs and have completed the following -

Replaced all 8 sparkplugs
Replaced all 8 fuel injectors
Swapped coil packs / replaced #5 coil pack
Side note - also replaced thermostat.

It's been a journey this weekend and after fixing a fuel leak from newly installed injectors. I still have the code. Before I take the girl to the shop...does anyone have any other suggestions?

Thanks
 
A couple questions……miles?, any special history of engine problems?, how did plug 5 look? Do you feel the misfire? If so, is it all the time? Why did you replace the T-stat?
 
Sandroad said:
A couple questions……miles?, any special history of engine problems?, how did plug 5 look? Do you feel the misfire? If so, is it all the time? Why did you replace the T-stat?
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Sorry for the late response, I wanted to verify the mileage...at 261k.
I'm the 3rd owner, purchased from a dealer 10/2022. No service records provided, but previous regular work shown on CarFax. I have not experienced any other engine related issues.
I do feel the misfire, all the time, well when under load. For instance it idles just OK, not normal. When reving or moving the engine roughness really shines (bad thing).

I replaced the the T-stat about year after it was purchased. The code once again popped up. I cleared it and had planning for its replacement. I figured that the original replaced part had failed. Since, this other code had displayed, and I was under the hood, I just took care of it as well.
 
LCGood said:
Sorry for the late response, I wanted to verify the mileage...at 261k.
I'm the 3rd owner, purchased from a dealer 10/2022. No service records provided, but previous regular work shown on CarFax. I have not experienced any other engine related issues.
I do feel the misfire, all the time, well when under load. For instance it idles just OK, not normal. When reving or moving the engine roughness really shines (bad thing).

I replaced the the T-stat about year after it was purchased. The code once again popped up. I cleared it and had planning for its replacement. I figured that the original replaced part had failed. Since, this other code had displayed, and I was under the hood, I just took care of it as well.
Click to expand...
Good to know. I just wondered if the T-stat replacement was in any way related to a possible overheating event. You’ve done the things usually related to misfire like plugs, coils, injectors. That persistent misfire in #5 is worrisome. Others on here have reported a broken valve spring or a leaking head gasket causing misfires. If it was mine, I would use my el-cheapo boroscope to look in cylinder #5 after letting it sit overnight. If I saw coolant, I would have my answer. If not, I would probably take it to someone for further diagnosis that might involve doing a leak-down test or removal of the DS valve cover to check on #5 springs.
 
Sandroad said:
Good to know. I just wondered if the T-stat replacement was in any way related to a possible overheating event. You’ve done the things usually related to misfire like plugs, coils, injectors. That persistent misfire in #5 is worrisome. Others on here have reported a broken valve spring or a leaking head gasket causing misfires. If it was mine, I would use my el-cheapo boroscope to look in cylinder #5 after letting it sit overnight. If I saw coolant, I would have my answer. If not, I would probably take it to someone for further diagnosis that might involve doing a leak-down test or removal of the DS valve cover to check on #5 springs.
Click to expand...
Cleaning the MAF sensor didn't do the trick, still misfiring, code still indicates #5 cylinder.

You mentioned 'seeiing coolant, you would have your answer'. What would that be? I have heard of the 'valley plate leak'. Is that what you would suspect?
 
LCGood said:
Cleaning the MAF sensor didn't do the trick, still misfiring, code still indicates #5 cylinder.

You mentioned 'seeiing coolant, you would have your answer'. What would that be? I have heard of the 'valley plate leak'. Is that what you would suspect?
Click to expand...
Mark the #5 and #1 coils (to keep track of their original location) and then swap them. Does your misfire follow?
 
LCGood said:
It's been a journey this weekend and after fixing a fuel leak from newly installed injectors. I still have the code. Before I take the girl to the shop...does anyone have any other suggestions?
Click to expand...
Not sure what may have happened with the injectors, but an injector might be part of the issue. Did the code come before or after the injector install? Sounds like you had some trouble there which is suspect. I'd also swap the #5 coil with another hole just to eliminate that possibility.
 
LCGood said:
Cleaning the MAF sensor didn't do the trick, still misfiring, code still indicates #5 cylinder.

You mentioned 'seeiing coolant, you would have your answer'. What would that be? I have heard of the 'valley plate leak'. Is that what you would suspect?
Click to expand...
From your first post, it looks like you’ve already swapped coils on #5 to eliminate a bad coil.

If you remove the spark plug to use a boroscope inside cylinder 5 after sitting all night and see coolant in the cylinder, you have a bad head gasket.

A valley plate coolant leak is not relevant to misfire; that leak is under the intake plenum so it’s not your problem.
 
auggafj80 said:
Following. Any resolution to the misfire? I have a misfire on #2. Swapped coils, new plugs. Still persists on 2. 2008 LC. 331k. Haven’t taken it to my guy yet.
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After taking it to a mechanic, I found out the head gasket had failed. So, of the 2 options given to me, neither is good. I have decided to replace the motor with a remanufactured one. It was suggested to look for a used motor with fewer miles, maybe a newer version. However, given the price differences and that this is a long-term vehicle for me, I thought a remanufactured engine would be a better investment. Our household has a 'repair' philosophy. I would much rather pay a one-time amount than take on a new payment. I bought this one with 240k miles (3rd owner), and I have only put on an additional 20k in the four years I have had it. I'm fortunate to work from home. The longest one-time trip would have been completing the White Rim Trail, which was a blast. I bought the LC to go off-roading/camping. It has not disappointed me. So getting her fixed up and ready for the next trip is my reasoning for the new engine.
 
LCGood said:
After taking it to a mechanic, I found out the head gasket had failed. So, of the 2 options given to me, neither is good. I have decided to replace the motor with a remanufactured one. It was suggested to look for a used motor with fewer miles, maybe a newer version. However, given the price differences and that this is a long-term vehicle for me, I thought a remanufactured engine would be a better investment. Our household has a 'repair' philosophy. I would much rather pay a one-time amount than take on a new payment. I bought this one with 240k miles (3rd owner), and I have only put on an additional 20k in the four years I have had it. I'm fortunate to work from home. The longest one-time trip would have been completing the White Rim Trail, which was a blast. I bought the LC to go off-roading/camping. It has not disappointed me. So getting her fixed up and ready for the next trip is my reasoning for the new engine.
Click to expand...
How much is this manufactured engine…? Is it a short block or heads also?
 
LCGood said:
After taking it to a mechanic, I found out the head gasket had failed. So, of the 2 options given to me, neither is good. I have decided to replace the motor with a remanufactured one. It was suggested to look for a used motor with fewer miles, maybe a newer version. However, given the price differences and that this is a long-term vehicle for me, I thought a remanufactured engine would be a better investment. Our household has a 'repair' philosophy. I would much rather pay a one-time amount than take on a new payment. I bought this one with 240k miles (3rd owner), and I have only put on an additional 20k in the four years I have had it. I'm fortunate to work from home. The longest one-time trip would have been completing the White Rim Trail, which was a blast. I bought the LC to go off-roading/camping. It has not disappointed me. So getting her fixed up and ready for the next trip is my reasoning for the new engine.
Click to expand...
That sucks on the head gasket. We seem similar, fix it mentality and work from home (mostly). We just got a tundra for the wife so also don’t need another payment at this time.

I have to check the fuel injector next. If that’s not it most likely head gasket as well. Can I ask why not go new head gasket route? Did you overheat? I haven’t had an overheat (I don’t think!)
 
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