OBD II Shop April
By Norm Brandes
Lack Of Information Impacts Emissions And Industry
by Norm Brandes
Working on OBD vehicles is like peeling an onion: what begins as a simple task can end up being a monumental challenge. You may never see it coming and have no idea until you are several layers deep. And those tears in your eyes? They’re from profits being lost!
Case in point: what should have been a simple machining task called a valve job on a SOHC V6, 24 valve engine, was anything but simple.
On this particular job, a camshaft drive belt tensioner failed causing valves to come into contact with the pistons. This caused catastrophic damage to not only the valves and pistons but the valve seat inserts and cylinder head as well. Replacing the valve seat inserts went as planned, but when it came time to cut the valve seat profile, I found I had no cutters of a similar contour. So my simple philosophy was to call the seat cutter manufacturer and simply order the appropriate cutter. WRONG!
Not only did I talk to one manufacturer of profile cutters, I talked to three. None of them had the cutter for that cylinder head, but they said they would be happy to make one if I supplied the profile of the existing seats. I asked, "Do you mean that no one has ever asked for a cutter for this cylinder head before?" The reply was, "Yes, we have done a profile for the manufacturer – but it’s considered proprietary."
It seemed the only way to get the cutter made was to use cutters I had on hand to find a portion of the cutter that matched the profile on the seat. This technique works great on new cylinder heads, but when dealing with inserts that have experienced millions of cycles it’s hard to define the width of the angle and the exact degree change.
To add to this challenge, the manufacturer had added a radius, which made a match impossible. It seems that if equipment manufacturers were sincere in trying to help find these angles, they would make a kit available with angles and radiuses that we could use to replicate the existing seat. However, not being one to let little hiccups set me back, I went in search of service information.
My first line of attack was with two respectable information providers: Alldata and Mitchell On-Demand. Not deterred by my inability to locate the information needed there, I defaulted to technical service information hotlines. This, too, netted me a big zero. My next stop in quest of the Holy Grail was the manufacturer. Certainly someone there would have this miniscule piece of information. Armed with age and treachery, I got to the service information manager.
I described to him the brick wall I had hit, and that I only needed a profile or list of contours to duplicate the dimensions of the valve seat. He said that information didn’t exist. When I asked if a replacement seat would be available with the proper contours he said they don’t sell seats for their heads. Seeing that the challenge was mounting, I asked what they would do if a dealer needed to replace any valve seats? His answer? Send the head to a machine shop. "I am a machine shop!" I exploded. "I’m trying to get the information to do just that!"
We suddenly realized we were both on the same team. The obstacle we both faced was, if this information exists, then who can we talk to in order to get it? Somewhere an engineering or manufacturing print is used to certify manufacturing tolerances and in-house repairs exist. The problem was to find the right department head to release this information and explain why I would want it.
To answer that question, we now go to the next layer of the onion. This information comes from the engineering side of the cylinder head development group. Today’s production engines have become so sophisticated that a change in seat shape from the OEM design can reduce airflow as much as 10 percent. If the seats replaced on this engine see that much reduced airflow and the injector is not recalibrated to adjust, we’ll have a rich cylinder. When the O2 sensor reads the richer-than-normal mixture in even one of the six cylinders, it’ll cut back the fuel metering for all the cylinders.
This leaning and richening condition can potentially set off idle stability or misfire codes. The engine’s computer will make more adjustments just to keep it stable, reacting more negatively to small vacuum leaks and potential engine misfires from the other five leaner-running cylinders. These conditions will be difficult for the service tech to identify because they will only show up as tricky P300 codes (random misfire).
It seems that we have gotten to the final layer of our onion – potential emissions problems. This means our path to the solution is the Environmental Protection Agency (EPA). Surely, the EPA will want to come to the rescue of the machine shops, service technicians and their customers, right? Well, not exactly.
EPA listened to my dilemma and agreed that such information was essential. However, their hands were tied until an industry task force had reached consensus on service information. The EPA representative on this task force was Holly Pugliese, who serves on the National Automotive Service Task Force (NASTF), which is composed of the Association of International Automobile Manufacturers (AIAM), the Automotive Service Association (ASA) and various service industry groups. The objective of this task force is to make OEM service and training information available to aftermarket repair shops.
I happened to be available when this group met during Industry Week last fall in Las Vegas. The tension level at this meeting was similar to that of counting chads in Florida. Each side seemed intent on trying to negotiate its position for its own interests.
The manufacturers were trying to make information available that would satisfy both the aftermarket and the pending rule from the EPA and the California Air Resources Board (CARB). The penalty for not achieving this goal could be quite costly for the OEMs. Reps from the auto service industry were trying to make certain they had all service information that was available, and were suspicious that they were not being dealt with fairly by the OEMs.
What struck me about this meeting was the absence of remanufacturers associations. I immediately thought, perhaps they don’t want them here?
Stakes were high, as both sides knew the deal they made would set a precedence for service information for years to come. Adding to the pressure, regulations call for a consensus to be reached by spring or mid-summer of 2003.
At a break in the meeting, I approached the task force chairman and told him what I had run into with my valve seats. I asked him if this type of issue was being addressed by this task force. He thought this service information may have unintentionally slipped through the cracks and said it was a fair request.
I believe automotive machine shops now have an opportunity to present examples of information we need to the task force so they can start addressing our needs, too.
Then I began to think on a larger scale. What about the casting proliferation that has gone rampant among today’s vehicles (see "PERA Core Corner," each month in Engine Builder magazine – Roy Berndt does a nice job addressing many of these questions)? What happens when the same casting is in three or four different configurations? And what if a detonation sensor boss is different from one platform to another, and the wiring harness cannot accommodate the differences? What about one cylinder head application that has the same casting number but one has a high swirl port and one has a low swirl port?
As you can see by the examples above, all of these things can have a dramatic impact on the ability to build, rebuild or remanufacture engines correctly.
The bottom line is that if the aftermarket industry is not provided with this information, emissions compliance may not be possible. And where does that leave the entire automotive aftermarket and remanufacturing industry?