SRX cold start misfire

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kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

SRX cold start misfire

Post by kevm14 » Fri Dec 30, 2016 9:05 am

I am in Windsor. I had to move the SRX this morning, and since everything was ice I decided to warm it up and drive it around the block. When I started it, it was idling with a bit of a miss. This is actually something it has been doing occasionally since we got it, but only when cold and like backing out of the garage. Never at any other time.

Well when it was idling a little rough this morning I decided to give it some revs in park just to see. The miss stayed. Then the check engine light started flashing, which I've never seen. Jamie may have mentioned this once before many months ago but I didn't have enough details and it was so intermittent that I dismissed it.

I got out and there was a definite miss from the exhaust. Then probably no more than 30 seconds, it smoothed out and eventually the check engine light went off. I drove it around the block and there were no issues. I don't have my scan tool with me but I would bet a sum of money that it is a coil pack, which is fairly normal at 110k on these (and many other vehicles). It has 8 coils. I will scan when I get home. I really should do spark plugs while I am at it since I think they are original. It is probably due for them. Coils are about $50/ea and spark plugs are $5/ea for OEM double platinum. I would only replace the offending coil, not all 8.

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Fri Dec 30, 2016 9:06 am

I am just going to order 8 plugs and a coil pack to have on hand. Eventually it will need one, and it probably needs one now. I just hope the code isn't P0300 (multiple/random).

The car is also due for trans fluid service, coolant and maybe diffs and transfer case if I am really ambitious.

It also needs a TPMS sensor but I don't think I need to make a thread on that. The sensor is around $35, plus a tire shop mount/balance.

8 OEM plugs, a coil and a TPMS sensor comes to $128 shipped. Not bad considering many tire shops charge like $100 just for a TPMS sensor.

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Fri Dec 30, 2016 3:43 pm

Scanned it. No codes. Sigh. I will do the plugs soon and then I guess wait for something to present in a way that I can diagnose it.

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Sat Jan 14, 2017 12:46 pm

kevm14 wrote:It also needs a TPMS sensor but I don't think I need to make a thread on that. The sensor is around $35, plus a tire shop mount/balance.
Fixed. Reprogrammed sensor using the same method as my CTS-V and it is reading fine - no more light.

Maybe I could do the plugs this weekend.

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Sun Jan 15, 2017 2:17 pm

kevm14 wrote:Scanned it. No codes. Sigh. I will do the plugs soon and then I guess wait for something to present in a way that I can diagnose it.
Just did the plugs. That plugs that were in it were the same AC Delco that I bought from RockAuto. The old plugs looked fine, all the same, but also a little worn on the center electrode. Just about what I was hoping for - ready to be done, but nothing looked broken. I don't know that this will solve that misfire thing and I have yet to road test the car. I will follow up.

Total time was around 3 hours. Someone a little less careful and a little more paid by flat rate would probably do it in half the time. Everything is done from the top as you would expect for DOHC. Apparently the first run of the first gen SRX used a coil assembly/rail that had to be replaced as an entire bank of 4. Somewhere possibly in the 2006 time frame they switched to individually replaceable coils which mine has.

The driver's side was easier and I did that first. Since this vehicle came to me with no engine cover, that was one less step to perform. Basic steps:
- Remove rubber coil cover, which just snaps in on two studs
- Remove a coil retaining bolt which was a T-30 head I think
- Pull coil out
- Remove spark plug

That sounds easy but there were a few clearance-related hiccups, which is where the extra time comes from. List of clearance issues:
- Coil wires generally just long enough to lift the coil out of the head but maybe 3 of them required disconnecting the harness first
- One required that I temporarily relocate an A/C line bracket on the driver's side shock mount
- Passenger side required that I bend two metal tabs holding some wires way up out of the way so I could actually remove the coil. This is what took the longest (FSM said zero about this and online research didn't do much, either) until I realized I would just bend them up and bend them back

I also used some dielectric grease on the coil boot and also a dab of anti-seize on the plug threads. There is an interesting side note about that. I've heard conflicting reports on that and I think I have gotten to the bottom of it (for all cars). These are aluminum heads so the plugs don't take much torque (11 lb-ft) and I also worry about the steel plug getting stuck in the aluminum head and taking the threads with it. All but 1 plug required an 18" cheater bar on my ratchet to break loose and you can bet I was really nervous the first couple times until I just got used to it.

Anyway, the deal with anti-seize is that you don't want any to get on the plug electrode because it is conductive and will short out the plug. If the plug is totally shorted, it will never fire and you'll have a misfire until the plug is pulled and cleaned. So I just used a small amount on the threads and I think that will work fine. I think I did the same thing on my CTS-V.

Pics next.

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Sun Jan 15, 2017 2:28 pm

Driver's side, pics at the start before I did anything.
WP_20170115_10_40_58_Pro.jpg
WP_20170115_10_41_06_Pro.jpg
Rubber coil cover off, exposing the coils.
WP_20170115_10_46_28_Pro.jpg
First coil removed.
WP_20170115_11_06_28_Pro.jpg
WP_20170115_11_06_47_Pro.jpg
Clearance issues on the passenger side.
WP_20170115_12_55_58_Pro.jpg
WP_20170115_12_56_05_Pro.jpg
My solution. Inelegant certainly. Not exactly sure how else to do it - that plastic thing houses more wires and I don't know how to remove it.
WP_20170115_13_50_03_Pro.jpg

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Sun Jan 15, 2017 5:58 pm

Road tested. Runs great - smooth. It is amazing how much more gets done under 3,000 rpm on this vs the truck. This has another 100 lbs on the truck though you'd never know by driving them. It drives really nicely. The 6-speed automatic also has something to do with it.

The satisfaction was somewhat diminished by the freshly burnt out left headlight...

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Mon Jan 16, 2017 11:56 am

Another fun fact relevant to this thread: spark plug replacement on the 3.6L V6 is atrocious. How atrocious? You have to remove the upper intake manifold. Combine that with how many problems those engines can have (namely timing chain stretch) and this is definitely one of those cases to opt for the Northstar on this vehicle (the other big one is power - the V6 in this vehicle is anemic).

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Sun Feb 05, 2017 3:32 pm

No issues reported. Probably too early to call this fixed but nonetheless this is the right direction.

kevm14
Posts: 13936
Joined: Wed Oct 23, 2013 10:28 pm

Re: SRX cold start misfire

Post by kevm14 » Tue Sep 26, 2017 10:21 am

So 10,000 miles later, apparently the misfire is back. And worse. Jamie called at lunch. I do have a spare coil on hand. And my Tech 2 comes tomorrow. Curious what the codes are.

Fortunately I have an STS for her to use if necessary.

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