No start, codes for no o2 activity and random misfires all cyl.

nickb2

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#1
Make
Mazda
Model
CX-7
Year
2007
Miles
211000
Engine
2.3l turbo
Just a heads up for this problem I got from another garage.

Lady came to us via towing, no start.

Check signal connector to starter for key to start signal, has signal, plug it back in, car starts up, but notice when I pull my hand out, there is oil all over my hand.

Next, try to bring car into my bay, won't keep an idle, basically runs like shyte and check engine is lit.

Check codes, 3 of them are for o2 sensor, 5 misfire codes, all cyl and random. Notice a brand new o2 sensor in there, try to keep car alive to see activity on scanner but notice a huge whistling sound coming from intake area. Spray some intake cleaner around intake area, can't pinpoint exact area but call for an intake gasket anyway as when sprayed, idle smooths out.

Once the intake was removed. No small feat on this type of engine, find a huge gash in the PCV vac hose underneath and tucked behind the GDI injection system.

Hence, found the source of ALL of this lady's problems. The no start was oil on starter signal connector, coming from the gash in the PCV vac hose which also was causing the o2 codes and of course, the misfires.

Called for a new PCV hose, they had one in stock. In fact many.

So, for those who fall on this type of problem, look there first. You still need to pull intake to get to the hose. But plz don't do like the other garage and just throw a useless o2 sensor at this type of problem.
 
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#2
WOW, that is the most weird convoluted story I have heard for a while. Congats on the diagnosis and repair.
 

billr

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#3
I went through similar with that Ford Escort that plagued me a few years back. I got led astray because it had also been shredding timing belts, so I suspected/inspected for all kinds of grim thing, like bent valves or VVT gone bad. All the operating problems turned out to be a cracked PCV hose (a large diameter one on this engine, as I recall) buried way on the back side of the engine. The "shredding belt"... now that was a real PITA to fix!
 

nickb2

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#4
Well, I got her buttoned up today, took some pictures of it. Test drove it, ran great. Yeah, great enough to give back keys. But. Still have o2 codes as follows.

Heater circuit high, and low and still no activity.

Problem is, client already got that diagnosed at another garage and the brand new o2 in there is obviously not the problem.

Client just wanted a car that would start and keep running without stalling every where.

So, I offered for to come back anytime, but first I wanted for her to go back to the shop in question to see if they would back their work.

The circuit for that o2 was not diagnosed first, just a part chucked at it in hopes of fixing the codes.

What hit me where the fuel trims. They were @ o%, both long term and short term. But it was getting close to 12pm, time we close on sat, (which BTW is our last one for the spring rush of summer tires):D

So I washed the engine, told her to report back in a few days of driving to put in on the hoist to make sure all oil leaks are now plugged up, but I suspect the turbo of leaking externally and internally seeing the soot on the valves and runners and in the inter cooler. It may show up in the pics I took.

I also cleaned and tightened the starter signal connection at starter, put in a new PCV valve with that new vac hose, as there is no way a mans hands can swap that out once the intake is in there. So with out further ado, here are those pics. Tight fit. Just getting the EGR tube off was mind boggling.


IMG_20180526_092224.jpg IMG_20180526_092908.jpg IMG_20180526_093032.jpg
 
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nickb2

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#5
In these two snap shots I zoomed in, you can see the glistening chunks of soot/carbon on intake valves. When she comes back, I proposed to do a GDI combustion chamber pressure cleaner.

For now, she is pissed off at the other shop for missing all this. I hate knocking other shops, but I saw what they charged her, and they did nothing but put in a new o2 sensor which by no means fixed nada, gilch etc. Old freeze frames where still in there, codes active and that means they gave her the keys knowing full well that check engine light was still on and NOT fixed, but still charged her. She told me she just got stuck, had to go to another shop cuz she was to far away from us for a reasonable towing charge.

Car would buck, stall and finally just would not even turn over anymore so she got it towed to us where she is used to coming. That shop has no CAA affiliation and no nationwide banner of any sort. I think she will be shyte out of luck getting reimbursed on this one, even if I took pictures galore. I even kept recorded freeze frames with recording of events in real time where you see the "new" o2 not responding, and documented anything I could off of my autel scanner such as these pictures and such.

I hate this, cuz you can tell she is a sweet single mom trying to make ends meet.

Second snap zoomed in, you can see the white connector to start, you will notice the whole harness is still slick with fresh oil. That was still after first wash off with clean rag. Nuts what oil on a simple exposed connector will do. I don't know why manufacturers don't make a more secure starter signal connection. Screenshot (216).png Screenshot (217).png
 
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nickb2

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#6
At Jack, I was mistaken in first post saying it was source of ALL problems, the o2 problem is still there, but car now runs light years better than before. O2 as written above still active, but that is just a harness issue I will address if she gets no satifaction from initial shop that gave her back her keys saying it was ":fixed:"

The trims are even a steady zero, which you hardly ever see, even on a pristine car. Probably more oil on or in another connector, this thing was a mess, especially the underneath of the engine where the turbo is simply discharging oil at an alarming rate. I suspect the o2 connectors are ridden with oil, I just had enough time to power wash it off in time to give back her keys so she could spend time with the kids, our two client loaner cars were out on loan.

Next time I see her, she has promised me coffee and doughnuts and mostly what I like of all, that nice smile. You know, single mom kind. ;)

She is advised that she will need a new turbo, but for now, she can get the kids to school without having to pay another god damn tow guy!:eek:
 
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#8
de nombreux TSB, car il s'agit d'un GDI, suggèrent d'afficher tous les codes.
Je regarderais le capteur d'o2 - le marché des pièces de rechange est souvent de la merde et la résistance du réchauffeur est problématique. Je voudrais l'OEM