Borescope recommendations Mazda 6 content

I brought home a manual Mazda6 wagon yesterday where the car runs but has little power. It seemed to struggle driving up the trailer and around my driveway. My understanding is the rear precat was replaced recently, but probably not the front. I would like to get a look at the precats and thought I might be able to do this looking through the O2 sensor holes. It probably wouldn't hurt to have a look in the cylinders as well. It is my understanding that when the precats go the EGR can suck the cat material up and send it through the engine.

Any recommendations on a borescope that would work well for this type of work? The threads I was able to find on the subject were many years old, so I was hoping to get an updated perspective.

Exhaust pulses will suck the cat material into the exhaust valves just fine. Exhaust isn't a smooth flow, it's a rocky rough pulsing motion that can move debris in both directions, especially if a cat is clogged causing a major flow restriction.

Two things you can do. First, since you're planning on removing the upstream O2 anyway, is see if it runs better with the O2 out. Second, is plug in a scan tool and look at the fuel trims for bank1 and bank2. If the fuel trims are wildly different, like -30 combined for one bank and +20 for the other... you either have a restricted cat or a cam that jumped time.

Skinny sub-$20 unit from Amazon that plugs into your smart phone.

The Harbor Freight borescope is actually amazingly good. The screen resolution is ridiculous.

Make sure the scope end is small enough to fit into the O2 sensor bung, much less the spark plug holes.

Most cheap units I've found are to big to fit in the smaller plug holes but I did buy a Titan unit that even fits in my 10mm plug holes on my motorcycles and I could read the numbers stamped on the piston. :)

NickD wrote: The Harbor Freight borescope is actually amazingly good. The screen resolution is ridiculous.

There are two on Harbor Freights site. Any idea which you are referring to? http://www.harborfreight.com/high-resolution-digital-inspection-camera-with-recorder-60695.html http://www.harborfreight.com/digital-inspection-camera-62359.html

The first can record and save. The second cannot. Which you want depends on how you want to use it.

Knurled wrote: Two things you can do. First, since you're planning on removing the upstream O2 anyway, is see if it runs better with the O2 out. Second, is plug in a scan tool and look at the fuel trims for bank1 and bank2. If the fuel trims are wildly different, like -30 combined for one bank and +20 for the other... you either have a restricted cat or a cam that jumped time.

I have a USB borescope on order from eBay. I bought one with the smallest diameter head I saw (5.5mm)

Below is a graph from driving the car up the driveway. The long term trims flip depending on if I am accererating or on overrun/idling. I'm also not sure what to make of the high and steady O2S12 yet. I should probably mention that the battery was dead, so the history for fuel trims may have been wiped out. This was just from the car idling a while before driving it up and down the driveway.

The car doesn't run super smooth and has a light knocking sound that to me sounds like it is coming from the bottom end, but I could be wrong.

The car currently has no codes stored, but again that could be a result of dead battery and little driving.

I believe these 3.0L use a timing chain, so I am assuming it is very unlikely the cam jumped a tooth.

I know this sounds dumb, but have you checked the oil? They sound funny when low on oil, might be mistaken for a knock. Also check the PCV hose, rear top center of the intake - it tends to collapse and crack, then you have a vacuum leak. Replace the PCV valve at the same time, mine was burning oil due to the valve.

Can't help on the rest of it - good luck.

Something in the PCV system was replaced. I think it was a hose, but I would have to check the receipts again.

According to receipts, the bank 1 precat was just replaced. I would have guessed the swing to negative bank 1 fuel trims would indicate low flow through that side, but then I don't know why it would be positive under idle and overrun.

In case anyone is curious, here are some pictures from the 5.5mm Android/PC scope on eBay. Still haven't figured out what is wrong with the car.

Front cat has some damage, but I don't think this would cause the almost no power condition.

I don't know what this is in the back cat, but again there appears to be plenty of flow area left. It kind of looks like welding wire, but I don't know how one would get the pool of wire. This is supposed to be a new cat.

Here is a piston.

The mirror that came with the camera is near worthless.

Anyone know if the larger diameter cameras give better image quality?

I just ordered the 5 dollar ebay version.

Thanks for this thread.

Oh, and those cats really don't look very healthy.