P0302 low compression 2011 / 120k - Chevy HHR Network

Go Back  Chevy HHR Network > General Discussion > Problems/Service/Repairs
Reload this Page >

P0302 low compression 2011 / 120k

Problems/Service/Repairs If you have a problem with your HHR, want a tip on repairing or performing a particular service to you HHR here is the place to post!

P0302 low compression 2011 / 120k

Old 01-10-2019, 10:50 PM
  #1  
New Member
Thread Starter
 
Join Date: 11-10-2018
Location: AZ
Posts: 14
P0302 low compression 2011 / 120k

I've been reading around for a couple weeks, and now I just want to make sure I'm going in the right direction, before I spend / waste "the big money" on something I could have easily done myself, or throwing unneeded parts at the wrong problem. I recently drove From Arizona to Mississippi and back for the annual Thanksgiving / Christmas family visit ~1500mi each way. Fresh oil change the day before I left, and about half way back to Arizona, got a CEL. No big deal, but I pulled off the highway and found an Autozone to read the code. P0302, #2 cylinder misfire, computer said new coil packs, but the manager suggested swapping #2 and #1 to see if the problem moved over to the other cylinder. I didn't want to chance taking anything apart 700 miles from home, so they cleared the code, and it didn't come back until a few weeks ago.

Since then, I threw parts at it, with a new set of coil packs, and spark plugs, but the light came back on. I decided, instead of continuing to throw money/ parts at it, and blindly waiting, I should just bite the bullet and order a good scan tool instead. I would up with the $250 "Foxwell NT650", which has already payed for itself, by showing that the ESC /TCS problem I was about to throw ~$500+ parts/labor at, replacing hubs, speed sensors, steering sensor, etc, was just the steering position sensor needing to be re-calibrated, which the tool does. Probably "old-hat" to everyone here, but really cool to me. haha!

Anyway, using the tool, I could see that the p0302 was still showing in the potential code lists, even though the CEL hadn't lit again. In the live data, I was seeing that, at idle, it's having about 2-10 misfires per cycle, and upwards of 150 at highway speeds. I also swapped around the #1 and #2 fuel injectors, to see if that was a problem. Still only misfiring on #2. In the meantime, I was down around a quarter tank, and decided to go fill up with E85, to see if it might help at all, and for about the first 50 miles, it barely misfired at all, then went back to the same pattern.

I realize I'm rambling, just bare with me. haha!

The next logical step I've seen suggested here, was to do a compression check, and I came up with 2 sets of numbers, The first set, doing it by myself, were 200 150 195 200. The second set, after I got my GF to sit in the car a few hours later, while I watched the gauge, was 230 170 230 230. I'm not sure which set is more useful to you guys, but either way, it seems like the #2 cylinder is consistently 50psi lower.

Seems like the next test is a "leak down" but I haven't been able to locate a leak down testing kit, yet. I'll probably just order one, since Autozone doesn't seem to have one in the "loan-a-tool" program.

Any guesses on what the problem might wind up being? I couldn't really get enough information, to continue on down the line, confidently, with what the next repair steps would wind up being, after I can get my hands on a leak down kit. I already spent the cash on the coil packs and spark plugs, not a big deal, they turned out to not be needed yet, but at the current mileage, probably not hurting anything by replacing them either. :)

Not to jump the gun, I'm not going any further, until I get the leak down done, but it seems like somewhere in the near future, it might turn out to be a valve problem, and pulling off the cylinder head is going to be one of the steps, if I'm understanding everything right? That's where I'm getting tons of different, conflicting info, as far as, will need new valves, "relap" old valves, get another head from a junkyard, etc etc, and all the other general, "maybe I should just take this to a mechanic now" big problem stuff.

I appreciate any help.
ledbthand is offline  
Old 01-10-2019, 10:59 PM
  #2  
Moderator
 
RJ_RS_SS_350's Avatar
 
Join Date: 05-01-2014
Location: California
Posts: 3,198
Do the leak down test. Probably worn rings, but you won't know until you do the test .
RJ_RS_SS_350 is online now  
Old 01-10-2019, 11:07 PM
  #3  
Technical Moderator
 
donbrew's Avatar
 
Join Date: 01-23-2009
Location: Fredericksburg, Virginia
Posts: 16,041
Next step[ is a "wet" compression test to foigure out if it is the ring or something else.

Then a leakdown; the only thing you need for a leakdown test is a screw in compression gauge.

Has coolant been disappearing? Does the oil look milky? Check under the pressure cap. Autozone should have a kit to test for exhaust gas in the coolant. a bad head gasket is more likely than a burned valve.

You can get a borescope that connects to a smartphone for about $20.

If you need "machine" work on the head it would probably be better to get a new head assembly; there is not much extra metal to be ground off.
donbrew is offline  
Old 01-10-2019, 11:26 PM
  #4  
New Member
Thread Starter
 
Join Date: 11-10-2018
Location: AZ
Posts: 14
EDIT: Never mind, I went ahead and ordered a bore-scope camera, and leak tester on Amazon. Should be here in a couple days.

Coolant doesn't seem to be missing, an no overheating issues either, also the oil looked / smelled / felt like normal, I did the oil changes on my GF's car that same day, and didn't notice any differences in either used oil. I also just changed mine again last weekend, and didn't notice anything funny about it.

Let me make sure I have this right, the wet test is the same procedure as the dry test, just add a little bit of oil to the low cylinder first? Then turn over the engine a couple times, and see if the low value on the #2 cylinder goes higher?

This is the compression tester I borrowed, and have on hand. To do the leak test, listening for air, just make sure the psi on the compressor is set to 65, and the cylinder is at half stroke? I think the guy was thinking I was looking for an A/C leak tester kit.



Last edited by ledbthand; 01-11-2019 at 02:38 AM.
ledbthand is offline  
Old 01-11-2019, 03:33 AM
  #5  
Senior Member
 
Join Date: 08-03-2010
Location: Lake Ronkonkoma, N.Y.
Posts: 1,492
Just curious. What's the mileage and engine size ?
Cat Man HHR is offline  
Old 01-11-2019, 09:29 AM
  #6  
Technical Moderator
 
donbrew's Avatar
 
Join Date: 01-23-2009
Location: Fredericksburg, Virginia
Posts: 16,041
That is the right tester if the adapter screws into the spark plug hole, a $5 mechanic's stethoscope would be helpful. Wet test correct, but more than a few revs 7-8.
donbrew is offline  
Old 01-11-2019, 10:23 AM
  #7  
New Member
Thread Starter
 
Join Date: 11-10-2018
Location: AZ
Posts: 14
Cat Man HHR:
The car has about 120,000
Flex fuel / 2.2 LE8 VVT

Ok donbrew, let me get some coffee down me, and I'll go run that test. I think Harbor Freight had one of those stethoscopes last I checked. That would certainly make things a lot easier to pinpoint.
ledbthand is offline  
Old 01-11-2019, 12:57 PM
  #8  
New Member
Thread Starter
 
Join Date: 11-10-2018
Location: AZ
Posts: 14
The #2 cylinder went from 135 to 165, with about a capful worth of oil down in it. That was cranking it "cold". I didn't hear any air leakage, or any bubbles in the coolant, I'm still gonna run over to HF to grab a stethoscope when they open, just to be sure.
ledbthand is offline  
Old 01-11-2019, 02:57 PM
  #9  
Platinum Member
 
firemangeorge's Avatar
 
Join Date: 12-06-2009
Location: Fairhope, Alabama
Posts: 8,297
What about the other cylinders ? You need to "wet test" those also, so you can compare the results of all cylinders.
As Don stated, a leak down test is next to figure out exactly where the compression loss is.
firemangeorge is offline  
Old 01-11-2019, 03:12 PM
  #10  
Moderator
 
RJ_RS_SS_350's Avatar
 
Join Date: 05-01-2014
Location: California
Posts: 3,198
You've reported dry test results 3 times, with significantly different results each time. There's either something wrong with the test equipment, or operator error.
RJ_RS_SS_350 is online now  

Thread Tools
Search this Thread
Quick Reply: P0302 low compression 2011 / 120k


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands