I have this axe to grind a little but I have to check in if my facts are straight before proceding

In late January my check engine light came on and so I took my Ranger 4l v6 SOHC down to Ford to have a diagnostic performed. My reasoning was that a Ford Tech should provide superior service and I was willing to pay the premium for it... something like 125.00 per hour.. would have to check my invoice. At that point (unlike now - my learning curve has been huge) I knew nothing about the 4l Sohc V6 engine.

Anyhow, I got the diagnostic statement, billing me for 2 hours of time, stating that I had codes 174 and misfire codes on cylinders 1 thru 4. Said "Power balance looks good". So taking this and running everything through google, my interpretation of "power balance looks good" was that he did a compression test at a minimum.

Recommendations were that "its probably a vacuum leak". Even said that he sprayed brake cleaner on the engine and "observed it entering the engine while fuel trim data fluctuated wildly"

So, with this trusted advice in my ear, I have spend the last couple months hunting down the mystery source of this vacuum leak. Spraying carb cleaner, brake cleaner, starter fluid, unlit propane torch and soap water, beer and spleen ventings all over the intake and vacuum componants. Had a backyard mechanic pull the intake and replace O-rings and T/B gasket. Cleaned the MAP sensor. Changed the O2 sensors. Changed TPS (because I broke it fiddling around with it). Clean IAC valve. Check tightness of fasteners. Changed PCV and inspected all hoses and changed some. Bought a code reader and monitored trim data in all stages of performance.

It was an insane bug hunt.

So this last weekend, while waiting for some Nichrome wire intended to be used on a homemade smoke machine (really awesome - should check it out)... like I've become a completely obsessed mad scientist to the utter disgust of my wife, I said "f-it, I am going to check compression for the hell of it. Arrrrrrgg! Raaahr!"

Numbers came back Cyl: 1-100psi, 2-100psi, 3-110psi, 4-150psi, 5-150psi, 6-165psi.

Did the wet compression test to follow and the cylinders on bank 1 came up 20 psi.

So, obviously there is a slight problem with power balance. Or am I defining "power balance" incorrectly? This is the crux of my ire. Does power balance not incorporate a compression test? And this after I get from a Ford Tech after paying 125.00 an hour.

After discussing my results with a mechanic, he thinks the timing chain may have jumped and its a timing issue... or "who f'n knows man"... It's hard to tell without ripping out the engine and.... and at that point, might as well replace the engine, right?... which I am doing. Found a good one for a decent price. Happy about that.

So I can't help but feel a little pissed right now. Am I missing something here? I can't help but think Ford Guy took a real long cigarette break and fudged the diagnostic. I'm real close to making a scene on the shop floor.

 

No, power balance is done with crank(CKP) sensor timing, compression test would be listed on invoice if it was done.
The CKP sensor data is also what sets mis-fire codes, the millisecond timing on crank speed can tell if one or more cylinders are not adding to the crankshafts spin, so misfiring.

On the 4.0l SOHC I would guess worn timing chain tensioner/guide would be the cause of the lower compression on one whole bank.
The valve timing on that bank is not correct, which lowers the compression on all 3 cylinders.
I don't think it "skipped" just running a bit behind pistons/crank

An independent mechanic that understands the electronics but has old school reasoning is often a better choice for some work.
Ford dealerships do have these types of mechanics but younger ones often rely on electronic diagnostic tools too much, it's not really their fault I would blame the teacher.

Like in all professions there are good ones and bad ones, my findings are that there alot more bad independent than dealership mechanics, but you can find bad ones anywhere

 

I feel like new techs are trained to read the machines and swap parts and not showed how to diagnose anything.

 

New ''techs'' are part changers...nothing like a mechanic who will actually be able to locate the cause of symptoms x,y and z. Glady I'm an oll dschool new tech :P

If you're running a misfire, check coil + spark. For compression, as one said already, get the timming chain checked out (chains do not normally use out).

Also, if your engine has ever over-heated, get that head checked out, may be warped and need a shave :P

 

Yep, Ron nailed it. The guide was off the peg and sitting on top of the chain bouncing around. Result was slack chain and timing issues. I just swapped the engine 4 sumthin younger. Thanks for your responses.

 

Thanks for the update

 

How many miles did you have on the engine when the issue started? I'm just curious...

 

About 190, 000 km.