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Obd II Shop : The Sensitivity Of Obd-IISystems Will Present Significant Change For Shops
Any machining which changes air, fuel or exhaust will be detected by OBD-II
By Norm Brandes
For nearly 30 years, engine rebuilders were sheltered from the dramatic changes sweeping through the automotive industry. While other shop owners and technicians scrambled to relearn almost everything they knew because of computers, engine rebuilding remained essentially the same.
Now, machine shops, custom and production engine rebuilders are faced with relearning virtually everything they know. In many cases they will be required to make major changes in how they work. It is no exaggeration to say that within a few years, engine rebuilders with weak management and/or technical skills are doomed to fail.
Rebuilders who aren’t prepared will be blind-sided by change. But rebuilders who prepare for change should see a substantial increase in business volume and profit because their products, services and knowledge will be in greater demand than it has ever been. Those who are keeping pace with change will be the successful survivors.
This column, which will appear quarterly, will give you the tools you need to survive and grow into the 21st century. What are my qualifications to write this column? For 19 years, I’ve owned and operated Westech Automotive, an independent repair shop and engine rebuilding business located in Silver Lake, WI, a small town midway between Chicago and Milwaukee, about 25 miles west of Lake Michigan. This area is still mostly rural, but suburbia is close and growing fast.
Despite our rural location, years ago I made a commitment that Westech would stay on the leading edge of technology and would always be able to do even the most sophisticated diagnosis and repair problems. We’ve fulfilled that commitment, going so far as to add a dedicated chassis dyno bay, complete with the latest diagnostic equipment.
Because of our capabilities, we’ve served as the "beta site" (test center) for several diagnostic equipment manufacturers. We’ve also assisted manufacturers of various emission control components, including catalytic converters, to obtain EPA and CARB (California Air Resource Board) certification for their products.
On the rebuilding side, we are a small, job shop that performs general work and custom/performance modifications for our own customers, plus other local shops. For years, we’ve scrambled to stay current with new technology in our vehicle service work. Now, we see new technology making an impact on our machine shop and its rebuilding work.
Why are rebuilders now facing major changes? For years, computer control systems were used to control spark timing and fuel to optimize performance and power while reducing emissions. Because the computer had the ability to report problems with the various spark, fuel and emission control devices, they were called on-board diagnostic (OBD) systems. Starting in the mid-1990s, the systems were upgraded to OBD-II, second generation systems.
OBD monitored control system performance. OBD-II monitors control system and engine performance, both overall and down to individual cylinder performance with a nearly unbelievable degree of precision. Every new car and light truck uses OBD-II technology. Even more sophisticated OBD-III systems are presently being developed.
With OBD-II, literally every drop of fuel and virtually every molecule of air entering an engine is precisely measured and accounted for. Spark timing is adjusted to each cylinder and the combustion inside each cylinder is more precise and better understood than ever before.
The exhaust stream is continually monitored both before and after the catalytic converter. The smallest change in exhaust gas content triggers immediate changes in fuel metering and spark timing so the exhaust always meets emission standards. OBD-II stores not only "hard codes" (permanent faults due to a problem with a sensor or other component), but also, to some degree, intermittent faults which are short-term "out of spec" conditions.
The sensitivity of OBD-II alone is enough to cause major changes in engine rebuilding. Any machining operation that results in even a slight change in air, fuel or exhaust movement from OE specifications will be detected by OBD-II. The system will set a code and the machine shop may face an expensive comeback because the customer will say, "The engine didn’t do that before you worked on it."
Even if you restore everything to OE specs, an error by the installer or technician setting up the rebuilt engine could cause serious problems, setting the stage for ugly finger pointing over who is to blame.
One situation I know of, which has "lawsuit" written all over it, involves a rebuilder in Michigan who does custom work on Dodge engines. He accepted an out-of-state order for a modified Dodge engine to be installed in a 1993 Ram pickup truck. The work was done, the job was paid for, and the engine was shipped to the local shop the owner specified, because, as he said, "I trust the technician; he has a lot of experience and is good with Dodges."
The "experienced" technician installed the engine and set it up, but never took any readings with a DRB (the scan tool used by Chrysler) because he didn’t have a DRB. The engine was installed, but it ran poorly.
The technician blamed the rebuilder for the problems. The truck owner took the pickup to a Dodge dealer who said the problems were the result of the modifications made to the engine. (In my experience, dealerships automatically condemn any non-OEM change to any engine).
However, the dealership found that the electrical grounds were not properly installed and the basic setup specifications were set too lean. These are installer, not rebuilder, problems. But before everything was sorted out, the too-lean engine backfired and blew a head gasket.
There may have been another installer problem, but it will probably never be proven. I discussed this specific case with Chrysler engineers. They said in their "test to destruction" procedure for this model engine, they could never get the engine running lean enough to blow a head gasket unless there also was a cooling system problem. The engineers speculated that this particular engine was reinstalled and initially run without enough coolant, maybe even without any coolant in the block.
The pickup truck owner returned the engine to the rebuilder and wanted his money back. The rebuilder said the problems were not his fault. The "trusted technician" said the rebuilder was to blame. The dealership says both the rebuilder and the technician were at fault.
Sadly, there won’t be any winners in this situation. The only question is how bad will each person be hurt. This installation example highlights a number of the changes and challenges you can expect to impact your engine rebuilding business due to OBD-II.
From now on, you better know the service history of the engine before you start any work, including: What problems did the owner report before the engine was pulled? Were there trouble codes stored before the engine was pulled? What, if anything, was done to clear the codes? After the repair attempt, did the same codes return, or were new codes set? Without this information, you are going into a job blind and that is simply asking for trouble.
At Westech, we now have "death certificates," "autopsy reports" and "birth certificates" for our engine work. It is a lot more paperwork, but we know the job we don’t do the paperwork on is the job that will come back to take a big bite out of our profits and reputation.
The death certificate is the documented history of the engine, listing all complaints and attempts to solve those complaints. If we can’t get this history, we may refuse the job; or the repair order, which the vehicle owner must sign, states we are not responsible for any problems not directly related to the work we do.
The autopsy is a detailed summary of our measurements and findings as we disassemble and inspect the engine. We try to record everything. If we are removing the engine, and it still runs, the vehicle goes on the engine analyzer to give us a base set of readings which are recorded.
The birth certificate shown on page 30 is a detailed report of all measurements and findings as we reassemble the engine. If we do all the work, including pulling and reinstalling the engine, which is what we prefer to do, the birth certificate also includes a complete summary of the engine diagnostics when the installation is complete and the engine is run for the first time in the car.
Good enough isn’t good enough
Every rebuilder has faced the situation of a customer whose budget can’t stretch to cover a complete repair. In the past, many rebuilders would try to do a "good enough" job to repair the engine at a cost the customer could afford. But cutting corners won’t cut it any more.
If you don’t restore the engine to OE specifications, you run the risk of setting codes. The engine may fail an emission test, raising questions about your work. And if the engine starts setting codes, seeing the "service engine soon" light will quickly make your customer forget that you tried to save him money.
You can’t do that anymore
Some long standing rebuilder practices can’t be done on OBD-II engines. For example, "cleaning up" intake and exhaust ports by smoothing the surfaces and removing minor obstructions is a long standing practice whenever working on heads. Try that on some OBD-II engines and you’ll be in trouble.
Today’s intake passages and injector placement are designed to produce a very specific "mixture motion" (the precise movement of the air-fuel mixture inside the cylinder immediately before combustion). Achieving the desired mixture motion requires turbulence in the air stream. If you change the turbulence by "cleaning up" the intake ports, you’ll upset the mixture motion and probably decrease performance and increase emissions. After you’ve caused a "mixture motion" problem, the only thing you can do is replace the heads with OE units.
Even on the exhaust side, where common sense says the smoothest possible flow is good, you may see obstructions designed to cause turbulence in the exhaust stream. This turbulence is necessary so the oxygen sensor can accurately monitor exhaust gas oxygen levels. If you clean up the exhaust port and change the designed turbulence, the oxygen sensor can’t take accurate readings. You will almost certainly upset engine performance and set trouble codes that can’t be cleared until the heads are replaced.
You’ll do it differently
Is there any rebuilding job more basic than cutting valves? Chuck the valve stem into a holder, set the cutting angle, and push the value into a cutting wheel. Wait until you try to cut a "flex valve" used on some new engines. The stem on these valves actually flexes under pressure.
Push a flex valve into a cutting wheel and it tries to move away. You’ll have to stay current on new techniques to handle new components or you’ll wind up losing money on jobs and adding a bunch of new curse words to your "frustration vocabulary."
Knee bone is connected...
Without detailed knowledge of the various quirks on today’s engines, you may either cause additional problems or be unable to solve an existing problem because you don’t know two "separate" systems are actually related.
For example, on some new engines, oil pressure controls camshaft advance. And camshaft advance changes spark timing. So changes in oil pressure ultimately change spark timing. If your rebuilding work changes the OE specified relationship between rpm and oil pressure, you’ve permanently reset spark advance which can trigger codes and cause performance problems.
I don’t want your work
Would you ever turn down work for someone who has been a good customer and has a good credit record? You probably will in the future. If the shop/installer hasn’t stayed up-to-date on new technology and isn’t qualified to do OBD-II service, you’ll be better off not doing their work.
If a rebuilt engine immediately sets new codes, who is at fault? The rebuilder, the installer or both could be to blame. If you’ve upgraded your skills to handle tomorrow’s engines, you don’t want to work for someone who hasn’t kept pace, too.
On the other hand, it makes good sense to start forging strong relationships with good service shops in your area. You want to be their preferred rebuilder because you can have more confidence in their abilities. But to make the relationship work, you must make sure your standards match theirs.
It’s easy to get pessimistic about the future of rebuilding, especially for the smaller job shop. But if you are willing to make the commitment to learn and meet the challenges, tomorrow’s work could be the most rewarding jobs you’ve ever done.
I’ve made this commitment. I hope you do, too, because there is still a good future for small rebuilders who can meet tomorrow’s rebuilding demands. In future columns, we’ll discuss more of the specifics of how to fulfill that commitment.