Repair/mechanic tricks and or tips?

[ToadHill]

I know my old work cloths are on their last legs when my wife gives them names. Ex " I see your wearing Stan again" It's my quilted jacket.

 

[mrutkaus]

To find bad spark plug or wire, disconnect plugs one at a time at the coil, drive the vehicle a couple hundred feet, note how badly that disconnected plug affects the running. Stop, reconnect plug wire, disconnect another one, drive another couple hundred feet, etc for all plugs. The plug/wire that, when disconnected, LEAST affects the running is the bad one.

Works after you've done this at idle (sometimes problems only show up under load) and examined them in the dark for sparks.

Mike

 

[patrick_g]

To find bad spark plug or wire, disconnect plugs one at a time at the coil, drive the vehicle a couple hundred feet, note how badly that disconnected plug affects the running. Stop, reconnect plug wire, disconnect another one, drive another couple hundred feet, etc for all plugs. The plug/wire that, when disconnected, LEAST affects the running is the bad one.

Works after you've done this at idle (sometimes problems only show up under load) and examined them in the dark for sparks.

Mike

We used to do something like ths but way easier. We didn't drive the car. Disconnecting and replacing plug wires one at a time will cause an i9dle RPM drop and recovery on all good cylinders. When you disconnect a bad plug or sick cylinder you get little or no idle drop.

Pat

 

[bx23barry]

To find bad spark plug or wire, disconnect plugs one at a time at the coil, drive the vehicle a couple hundred feet, note how badly that disconnected plug affects the running. Stop, reconnect plug wire, disconnect another one, drive another couple hundred feet, etc for all plugs. The plug/wire that, when disconnected, LEAST affects the running is the bad one.

Works after you've done this at idle (sometimes problems only show up under load) and examined them in the dark for sparks.

Mike

Works good on older units but I don't recomend it on newer computer controlled cars/trucks.

 

[Soundguy]

Would work.. but will probably throw a code..

soundguy

 

[patrick_g]

Works good on older units but I don't recomend it on newer computer controlled cars/trucks.

Sorry, I forgot to post the standard antiquarian disclaimer about how aspects of technical topics discussed by this poster are frequently based on ancient data and experience and may NOT be in compliance with concepts incorporated in equipment designed in this century or several of the last decades of the previous.

The level of automotive technology related to internal (infernal?) combustion engines with which I am most personally acquainted (hands-on experience such as valve adjustment, plug gapping, spark advance setting, and such) is the likes of air cooled VW bug engines with traditional old fashioned points, plugs, and condensor. Something simple as 3 each Stromberg 97 carbs on a Chevy 6 or dual Webbers on an MG are the limit of my carburettor modification and adjustment hands-on experience. Sure, I may have changed the intake manifold of a Cummins B5.9 but I don't do tuneups.

Now then, the above disclaimers not withstanding, I think I will have to claim that if a computer controlled vehicle coughs up blood because I disconnect a spark plug wire that it is NOT designed properly. What if a spark plug fouls or a wire goes bad and opens up? Is the computer controlled vehicle irreparably harmed? If so, very bad design.

Someone will have to explain to me the difference in my disconnecting a spark plug wire and the wire going open due to misadventure or whatever. If the vehicle is not irreparably harmed by a wire failing the same should be true for one removed in trouble shooting. How can the car know the difference?

Pat

 

[Soundguy]

I doubt it would know the difference.. Either way.. it will probably store a code.. depends on the age of the computer i guess..

Harmed? I don't think anyone is saying it will be harmed.. just that it will store a code.. etc.

soundguy

 

[bx23barry]

I doubt it would know the difference.. Either way.. it will probably store a code.. depends on the age of the computer i guess..

Harmed? I don't think anyone is saying it will be harmed.. just that it will store a code.. etc.

soundguy

Besides throwing codes and lighting lights, O2 sensors and cats really don't like it. Also the computer will compensate for the "miss" and it really can't be used as a tuning procedure. And although I never seen it, I've had manufacturer reps/instructors claim it can blow coils and in rare cases computers.

 

[Soundguy]

If a spark plug line opend up and blew a PC.. I'd have to agree with Pat that it was a horribly brittle design.. and the eng responsible should be stripped of title, money and anything elso of value and then drug thru town behind a horse...

Seriously though.. I'm sure COP units might hate it.. and I can see possible coil damage in rare cases.. but the PC board.. man that would have to be a bad design with virtually no isolation.. Isolation that has been available for .. uh.. decades at least..

soundguy

 

[Skyco]

I'm under the impression most modern vehicles will store codes already telling you which cylinder has a misfire. I know it for a fact for a 98 Ford Windstar V6 I had. It logged a cylinder 4 misfire that gave me fits finding the cause. When playing with the scanner I could see it clocking up misfires randomly long before it would ever set the CEL (check engine lamp). It would go weeks before the CEL was on.
Took me awhile to find the cause though, the computer wasn't that smart to be able tell me why cylinder 4 was misfiring.
It wasn't fuel, ignition or compression or even valve problems.
The problem was an EGR port to the misfiring cylinder was the only one not clogged by crud, thereby dumping ALL the EGR gas that should have been spread over 6 cylinders to that one cylinder