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2020 Touring Onyx XT; 2014 Tribeca
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Discussion Starter #1
So, this has been going on for about 20K or so, have to go back and look, but I have been getting surging and knocking going up one of the highways (hwy 17 from hwy 1 if you know the area). I took it in right after it started and they of course could not reproduce, figures and told me to drive it till I get a CEL, so I started getting a CEL about a month and each time I bring it by, no codes
. So today, I had to get the turbo air inlet replaced (corded by blown power steering) and they gave me their scanner, and I was able to get it to pull misfires on cylinder 2,3, & 4. I returned the scanner and they weren't sure what it could be and would like it for an hour for diags now that they have a code (I think they were P0302, P0303, & P0304).

The LGT has 132K on the clock and I am just hoping that this isn't going to be the start of a pattern since I am out of work and want to upgrade to a Outback or FXT shortly after I find work. Any thoughts would be great.

Other than this, it has been 120K of worry free and amazing driving. Love the LGT so much.
 

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Onyx, 2008 LL Bean 3.0R and 2017 Honda Civic Hatchback Sport Touring
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Start with the basics: Pull the plugs. If you see oil on the plugs then it could be that your valve cover and plug gaskets are leaking and you need to get that fixed to avoid re-fouling the plugs.

Run the engine at night and lightly mist water using a spray bottle over the plug wires. If you see a little blue sparks light show then you know the wires are shorting out and need to be replaced.

If you decide to spring for the plugs and wires, I found NGK works well for both and costs less than what the dealership would use. Search for "bad coil" here as well for other suggestions. I did mine in this order to solve my P0302 code. 1. Plugs 2. Wires 3. Coil - none of which should break the bank. Let us know how it goes.
 

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2020 Touring Onyx XT; 2014 Tribeca
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Discussion Starter #3
Thanks, plugs were replaced at about 110K or so, have to find my paperwork. I am not the best under the hood and need dependability so I take it to the dealership (and they give me a good discount so it is very close in cost to independent shops) and they have done 99% of the work on my car.

There is 132K on it now. Hope I can get this solved and isn't too expensive, being out of work and on unemployment, need it to just work.

And to top it off, the suspension on the wife's FXT is going out as well. Just figures.
 

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Onyx, 2008 LL Bean 3.0R and 2017 Honda Civic Hatchback Sport Touring
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When it rains it pours, right? Two things jump out at me. 1. You say this has been going on for about 20K miles. If subtract 110K from 132K I come up with about 20K. 2. The codes were not stored in between the times you went to the shop for that month. A CEL DTC code will clear itself after several (5?) driving cycles if the problem does not persist. So it seems like the misfire is an intermittent problem which is the hardest type to diagnose. You're unemployed so I guess you are not driving Hwy 17 every day like a commute to work would make you do. Sorry to remind you about your situation, just playing Columbo here (Google it if you are under 40).

Does the car consistently have surging and knocking when driving on similar terrain? Think about what you're doing when it happens. Are you flooring it to go up a steep hill? Feathering the gas to go up a slight rise? Letting off the gas completely to make a bend? Etc. Make notes of the most mundane and minute details to bring to the dealer with you. Something that might seem meaningless to you may spark something in one of the mechanic's memory.

Ask them, or review your receipts to see, what was tried and done so far. Ask about the plugs - were they gapped and torqued properly the first time? Try and determine it there was some outside influence that could have started this problem. Did you start using another gas station? Did you wife drive the car off of a retaining wall? Don't ask me about that one!
 

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2020 Touring Onyx XT; 2014 Tribeca
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Discussion Starter #5
When it rains it pours, right? Two things jump out at me. 1. You say this has been going on for about 20K miles. If subtract 110K from 132K I come up with about 20K. 2. The codes were not stored in between the times you went to the shop for that month. A CEL DTC code will clear itself after several (5?) driving cycles if the problem does not persist. So it seems like the misfire is an intermittent problem which is the hardest type to diagnose. You're unemployed so I guess you are not driving Hwy 17 every day like a commute to work would make you do. Sorry to remind you about your situation, just playing Columbo here (Google it if you are under 40).
Not quite 40 yet, but definitely know Colombo, cool dude ;). The codes weren't being saved between starts, I got the CEL, took it to the dealer then no code, at most 2 cycles on the car. I don't normally drive HWY17 anyway, but enough that it is concerning. Yes intermittent problems are the worst, in my field as well (computer repair).


Does the car consistently have surging and knocking when driving on similar terrain? Think about what you're doing when it happens. Are you flooring it to go up a steep hill? Feathering the gas to go up a slight rise? Letting off the gas completely to make a bend? Etc. Make notes of the most mundane and minute details to bring to the dealer with you. Something that might seem meaningless to you may spark something in one of the mechanic's memory.
The road is not too steep, but it is one of those that is steeper than it appears. And Feathering the gas to keep at the speed limit. I have found that If I put it in 4th and drive up that section, it never happens then. Only in 5th. I have had it happen one other place once, which was on my typical commute road, but only the once and have driven it a few dozen times since.

Ask them, or review your receipts to see, what was tried and done so far. Ask about the plugs - were they gapped and torqued properly the first time? Try and determine it there was some outside influence that could have started this problem. Did you start using another gas station? Did you wife drive the car off of a retaining wall? Don't ask me about that one!
The service writer thinks it could possibly be a bad batch of plugs or something since they were done not that long ago. Just have to find the time to bring it in. No different gas stations than normal. I normally use 3 or 4 (Costco, chevron, 76, shell; depending on where I am when needing filling).

Just about, the road she drives up goes from 400ft to 3000ft in 1.5miles and is not maintained all that well.
 

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2006 OBXT L
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Have the AF or O2 sensors been replaced ever? Since I just changed these on my XT and it's a different motor. Should have changed them 20K ago...I'm at 135K.
 

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2020 Touring Onyx XT; 2014 Tribeca
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Discussion Starter #7
I'm not sure, If it is on the schedule, then it should have been done, I have been religious about the maintenance. Just broke up the 90k and 110k services between them and had timing belt done at 110K.
 

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Lawn ornament XT
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Run the engine at night and lightly mist water using a spray bottle over the plug wires. If you see a little blue sparks light show then you know the wires are shorting out and need to be replaced.

If you decide to spring for the plugs and wires, I found NGK works well for both and costs less than what the dealership would use. Search for "bad coil" here as well for other suggestions. I did mine in this order to solve my P0302 code. 1. Plugs 2. Wires 3. Coil - none of which should break the bank. Let us know how it goes.
An 06 LGT should have the coil-on-plug setup, which is totally different from what you're used to, DavidPeab. The mist test doesn't apply at all.

The c-o-p setup uses primary wires from the ECU all the way to each of four coils, installed directly onto the plugs. There are no secondary wires at all in this arrangement.
 

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Onyx, 2008 LL Bean 3.0R and 2017 Honda Civic Hatchback Sport Touring
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So we've ruled out wires. Could it still be plug related?
Also, what does this tell us?
The road is not too steep, but it is one of those that is steeper than it appears. And Feathering the gas to keep at the speed limit. I have found that If I put it in 4th and drive up that section, it never happens then. Only in 5th.
 

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Lawn ornament XT
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The misfire has been caught on 3 cylinders, I think there's a chance it's happening on all 4 but the test period wasn't long enough to catch it.

Knowing that there's only 22k on the plugs, I think we can rule out ignition.

That leaves air & fuel. Too much air or not enough fuel can do this. I'd probably start looking for air leaks on the intake/intercooler path, or possibly a vacuum leak which could be affecting the fuel pressure regulator. That can be done for free at home.

It is also worth investigating the airflow & o2 sensors as kzr750 notes.

bajanut: Have you got a FreeSSM setup? The $20-40 to get an OBDII plug from ebay connected to a laptop with FreeSSM/RomRaider (free software) would probably go a long way towards narrowing this down before you spend anything on parts.
 

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2020 Touring Onyx XT; 2014 Tribeca
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Discussion Starter #11
I don't. Will take a look around next time I am down there and have time (possibly tomorrow ;)). Have been contemplating something like that, but have been just too broke (bought house at the top of the market in CA = screwed). But will contemplate it more heavily.

I am just hoping that I haven't done any damage to it.
 

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The ECU is pretty good about protecting the engine in misfire conditions- but it typically comes at the expense of power & gas mileage. You don't want to be denying yourself fun or gas money, so...

Go read the FreeSSM thread on this board, figure out how to get a cheap cable, post some data/screenshots and hopefully we can get this narrowed down.
 

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2020 Touring Onyx XT; 2014 Tribeca
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Discussion Starter #13
Thanks. I have noticed a reduced mileage for the last 40-50k as well and asked about it at each service and they find nothing. I was averaging 20-21mpg and now 16-18mpg regardless how I drive.
 

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Car: 2008 Tribeca, 2010 LGT, Sold: 2005 XT Limited
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I think oil from leaking gaskets fouling the plugs is a possibility as well.
 

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2006 OBXT L
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I'm inclined to think the crap oxeginated alcohol infused fuel we have to use in California is harder on the sensors. It's not a cheap to replace both but in my case money well spent. Doing so seems to have cleared what I have been fighting for some time.
 

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Thanks. I have noticed a reduced mileage for the last 40-50k as well and asked about it at each service and they find nothing. I was averaging 20-21mpg and now 16-18mpg regardless how I drive.
That's a long time to put up with an impaired car... A lot of extra fuel!
 

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2020 Touring Onyx XT; 2014 Tribeca
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Discussion Starter #17
ok, more to my saga, had the cel come on this morning, but stayed this time. Drove to the dealership and pulled 2 p0301's misfire on cylinder 1. Have made an appointment with a mechanic that I got was referred to by my wives coworker that has a highly nodded wrx as being trustworthy and does good work and should diag for free, I hope.

this is not fun :(
 

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Lawn ornament XT
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I recently upgraded my car diagnostic cable- the new one was under $13 incl. shipping and works with more software. So never mind the $20-40 I mentioned before- apparently its even cheaper now.

I highly recommend that you obtain one. You'd be able to post detailed engine logs for diagnosis.
 

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Discussion Starter #19
can you post a link to the one you got? I think I might be able to get $13 past the finance officer (aka wife ;))
 

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can you post a link to the one you got? I think I might be able to get $13 past the finance officer (aka wife ;))
http://item.mobileweb.ebay.com/viewitem?itemId=290637412911

That plus free software did the trick. Ignore the software suggested by the ebay seller, its generic and lame. Go read the freessm thread to learn the trick to installing romraider. Not as easy as it could be, but once installed it is outstanding. Really easy to record logs of engine data for later analysis.


Why does the AutoGuide.com App have to suck so badly?
 
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