Monday, July 08, 2013

Monday, July 01, 2013

Replacing A Bad Computer On Your Car

Cleaning EGR Passages with a Speedo Cable

I found Scotty's video about EGR Passages to be entertaining and as usual catering to the "fix it" crowd of the "It's simple and easy and quick" with the mentality that auto repair is easy and cheap.

 I gave up on using Speedo Cables for EGR Passage cleaning after my first couple attempts, DECADES ago. They just don't work for this, they're far to Wimpy. Ya might as well chuck-up a string of yarn in your drill for this use. I don't exactly know how this myth of Speedo Cable in a Drill for EGR Passage clean-up started, but it persists none the less.

You see, EGR passages that are plugged with Carbon Deposits is normal over time and mileage, but these deposits are ROCK HARD, unless the Engine is an oil-burner, then they are a bit gooshy. Think about the basic chemistry of combustion, our fuel of choice is a HydroCarbon and Carbon is one of the elements that is left-over, nothing is perfect.

I have had to use hammer and chisel on a few, and a regular drill bit in a drill can speed things up. I do have a unique parking brake cable that I salvaged and conscripted to EGR Passage cleaning for the "easy" ones that are gooshy. It has a steel ring or band that is crimped onto it from the factory. I cut the cable about a foot long and left the end away from the crimp about 6 inches long. MUCH MUCH better than a wimp wet noodle Speedo Cable.

I never sprung for one of these Snake Bits
 because my time tested methods served me well.












The deposits usually condense on the "cold" side.  The part between the EGR and Intake.
Most of the time I can reach through a wide open Throttle with some custom-made  90 and 45 degree "poke and scrape" tools that I made, of course I have the EGR Valve off also.

A few notes about detecting plugged passages...
Just yank the EGR Valve off and start the engine!  On a MAP based system the engine will scream at about 3 grand (don't worry, it's safe) if the passage between the EGR and Intake is open, AND you'll be able to feel if the OTHER passage is flowing, the Exhaust port to the EGR.
Many of today's cars though are MAF based, you'll want to duct tape over the Intake port before starting (so it will start and run) and be ready to hold the throttle whilst you take off that duct tape to check for STRONG vacuum on that port.

There are a few other ways to check for proper EGR flow using a vacuum gauge and/or Scanner, but I'll get into that another time as I'm mainly wanting to comment about this particular video.

And his comment about soaking the EGR Stem with a penetrant?  Don't trust it!  I have NEVER EVER had a successful "repair" doing so.  They ALWAYS came back STALLING and SPUTTERING at idle and off-throttle because the dang thing stuck AGAIN!
I will say this though, IF the EGR is stuck open because a chunk of HARD CARBON booger is trapping the valve open at the Pintle, you are probably safe to clear it and re-use the Valve.
BUT, if the Valve stuck open because of the STEM being sticky or binding, DON'T BE FOOLED, it will stick again and continue your grief.

Also, I was impressed that he used at the end, the On Board diagnostic system to detect and confirm the repair.  However, an important part was left out!  OBD Regulations state that the System can only clear the MIL (Malfunction Indicator Lamp, ie Check Engine light) after at least TWO CONSECUTIVE trips that run the same failure test within 10% of the load and rpm wherein the failure occurred.  It IS a good way to confirm a repair, but it takes TIME.  The car must cool down and also be driven multiple times, not something Scotty mentioned.  Far better to use proper diagnostic and repair techniques from the get-go.

Best Regards,

Mike.