NWICC Tech Tips                                                   December 2006



“Service Column Lock”.  This message displayed on the drivers information center (DIC) has plagued some of our members on more than one occasion with their C5’s. As originally designed the steering column lock was an anti-theft feature. Since the ignition switch is in the dash, the C5 is programmed so that if the column lock does not unlock when the engine is started the fuel will be shut off as soon as the car reaches 2 mph. This is to prevent you from driving off with the steering wheel locked. All C5 automatics from 97 thru 2000 and 6 speed cars from 97 thru 04 have this system. GM did not install it in the later automatic trans cars (after 2000), probably due to the number of problems experienced.  It was found that low battery voltage or a power interruption to the body control module (BCM) could prevent the fuel shut off.


There have been several recalls by GM to address this problem. One involved the installation of a relay in the automatics to insure the fuel shutoff. This was the infamous K-harness. The 6 speed cars were to be reprogrammed to insure fuel shut off as well. None of this addressed the problem of the steering column locking up, but it did cover GM’s liability in case of an accident.  The K-harness proved to be unreliable and in some cases would shut off fuel even if the column was not locked. The 6 speed programming proved to be problematic as well. Both could leave you stranded needing a flat bed for towing. Also, GM’s 6 speed reprogramming would remove any custom tuning i.e. Predator, Hypertech, dyno tuned, etc. In some cases, especially after a dead battery, the column lock and BCM could get out of sync and cause the “Service Column Lock” message. This can be cured by pulling fuse #25 in the passenger foot well fuse box and reinserting after 30 seconds.


GM’s latest recall, which is good until 2008, involves removal of the steering column lock plate on both automatic and 6 speed cars so the steering wheel cannot lock up because there’s nothing there to lock.  Problem solved.



                                                                                      See you at the track,

                                                                                                   Bill Porter





NWICC Tech Tips                                                   December 2005



Now that the season is over, the question of how do I store my Vette for the winter months comes up from some of our members.


First you need a car cover. For inside storage any cover made of all cotton will do. There are also covers on the market made of the new miracle fabrics that breathe. Stay away from cheap plastic covers. They cause the paint to sweat and can cause damage and discoloration of your car’s finish. The important thing is that the cover you choose is made of a breathable fabric.


There is no need to remove the wheels and tires or place the car on jack stands. Any flat spots that develop in the four months of storage will “drive out” within the first few miles of driving in the spring. You may want to place the tires on carpet or plywood squares to insulate them from the damp concrete.


The fuel system also needs some attention. Fill the gas tank and add a gasoline stabilizer such as “Stabil”. This will prevent the gas from breaking down and forming gum and varnish which will cause you to have to replace fuel injectors in the spring.


The battery in your Vette is subject to a constant drain due to the computer and microprocessors. Disconnecting it is one solution, but you loose all your radio presets, security codes, seat memory, etc. A better solution is to invest in a battery “float charger”. Float chargers allow the battery to discharge slightly and then kick in to bring the battery up to full charge, unlike a trickle charger which constantly charges and can boil away the water/acid in the battery. Just plug it in, hook it up and forget about it – they’re cheap too.


Finally leave the windows cracked slightly for ventilation. On a monthly basis start the car and let it run long enough to bring the temperature up and move it around some. This prevents the engine and transmission seals from drying out causing leaks.


                                                                                      See you at the track,

                                                                                                   Bill Porter


NWICC Tech Tips                                                                March 2005


One of the most popular and usually the first modifications that C4 and C5 owners make to their Corvettes is an upgrade to the exhaust system. The choices on the market are almost endless. Most owners’ choice is based on appearance and sound quality. There are other factors to consider before spending big bucks on a new system.

Some owners start out by replacing the stock exhaust tips with larger polished stainless tips. This helps with the appearance of the rear of the car and we all know that the pipes exiting the rear of C5’s are way too small to be on a Corvette. Unfortunately this doesn’t do anything for the sound. A Vette should sound like a Vette! What’s needed is a good “cat – back” exhaust system. Cat – back refers to a system that starts at the rear of the catalytic converter and includes exhaust pipes, mufflers, and tail pipes.

Sound quality is in the ear of the beholder. Whether it be a mellow rumble or an all out race sound, the choice is up to the owner. The aftermarket manufactures have a system to please everyone. Before making a choice, try and find another owner who has the system you like on their car. If possible, take a ride with them so you can evaluate the amount of interior resonance with the system. Some sound great on the outside but are difficult to live with inside the car at cruise speeds. Some C4 systems are notorious in this respect.

Tubing size and material is another consideration. “Bigger is better and stainless won’t rust”. Don’t forget to use stainless clamps when installing the new pipes and keep in mind that stainless has a tendency to slip out of alignment if not properly clamped. But nothing looks better than a polished stainless exhaust.

C5 owners might also want to consider installing an X-pipe with their new system. An X-pipe is a type of crossover that evens out the exhaust pluses, increases flow and helps to eliminate that “rattle” you hear with some systems at idle and cruise speeds.

Performance wise you can’t go wrong. No matter what style, be it straight thru or baffled, targa style or mufflers; aftermarket looks better, sounds better, flows better, and produces more horsepower than stock GM.


                                                                                      See you at the track,

                                                                                                   Bill Porter





NWICC Tech Tips                                                              May 2003



Some of our members have recently had questions concerning wheel and tire upgrades on their C4 Corvettes. Should you go from 16” to 17 or even 18” wheels? What size tires will fit? Do you have to use adapters or spacers? Will the wheels clear the brake calipers? What about fender clearance? Will the tires stick outside the body? Considering the number of combinations available there is no simple answer to these questions. 

First of all Corvette went to larger wheel and tire sizes for one reason and that was to put more rubber on the road…… more rubber - better traction and handling. All C4’s use the same size bolt pattern so different years can be interchanged with some limitations. 1984 thru 87 Corvettes came with 16” wheels, 1988’s had both 16 and 17” and 1989 thru 96 were all 17”. The difference is in the wheel offset. 1988 thru 96 wheels, all interchange with no problem. If you put 1988 thru 96 wheels on an earlier model Vette they will fit, but the tires will sit inside the fender by about an inch instead of being flush with the fender edge. Also brake clearance may be a problem. There are adapters / spacers available to correct this problem however they can be a problem within itself. Each adapter has 5 lug nuts, so what you end up with is 20 additional lug nuts to worry about loosening up.

If you decide to go with 17” wheels on an 84 thru 87, the best bet is to go with an aftermarket reproduction wheel. These are available with the correct offset and in a variety of styles including ZR-1 and Z06 styles in polished and chrome. Tire size should be the same as what originally came on that wheel. Hope this answers some of your questions.


                                                                                    See you at the track,

                                                                                                   Bill Porter


NWICC Tech Tips                                                             February 2003



Although we’re still in the middle of winter and our Corvettes are, or should be, under wraps in the garage, this might be a good time to look at one of the problems many of us experienced last summer. Overheating or cars running too hot was a major concern of many of our members. The first thing to consider is the condition of the cooling system. Is the system clean? Has it been flushed and refilled with a 50/50 mix of antifreeze and water?  Do not run straight antifreeze or just water!

Next take a look at the radiator and check for debris, dirt, leaves etc. in this area. Corvettes are like vacuum cleaners, anything you drive over in the road is likely to be sucked up in the radiator. One of our members, who I won’t name, couldn’t figure out why his car started to run hot until he discovered a sheet of notebook paper plastered against the radiator.

Corvettes come from the factory with 195 degree thermostats. This causes the car to run 210 – 220 degrees and even hotter with the A/C on. This was done to decrease exhaust emissions, but the cost is less power. You might want to consider changing out the thermostat for one rated 160 degrees for summer or 180 degrees if you drive your Vette during the winter. Also, C4 and C5 Corvettes have electric cooling fans that are programmed to come on at about 228 degrees. Reprogramming the computer so these fans come on around 185 and off at 175 degrees in combination with the thermostat change will produce a cooler running engine and an increase in power. 84-93 C4s can be reprogrammed by installing a custom PROM (Chip); 94-96 C4s, and C5s require use of a Power programmer.  Stay cool.


                                                                                      See you at the track,

                                                                                                      Bill Porter






NWICC Tech Tips                                                              January 2001





Ok…you’ve installed a high performance chip, changed the thermostat to 160 degrees, and installed a low restriction and better sounding exhaust system from the catalytic converter back to those shiny polished stainless tips………..What next?

While the Vette’s down for the winter, how about doing some improvements to the intake side of the engine?

Installing a K&N air filter is the first place to start.

Next, how about ram air. There are several systems on the market; one is a reverse flow system that takes cool intake air from the radiator cavity rather than hot air from under the hood, and another takes cool air from under the front end just forward of the radiator. Both systems work, but be careful with the latter if going through deep water…. but who does that anyway. The least you should do is replace the stock air cleaner lid with a low restriction cutout unit. You can do the modification yourself or they are available pre-cut in stock black or chrome from several aftermarket sources.

While you are at it, you should relocate the MAT sensor to the back side of the air filter housing just ahead of the MAF sensor. This is especially important on L98 engines because the stock location under the plenum is prone to reading hot intake air rather than cool air from your new intake system, which will give you a richer mixture. LT1 engines can also benefit from this change.

Next, take a look at your MAF sensor; there are two screens on the front and rear of the sensor to prevent debris and curious fingers from contacting the internal components. Some racers remove both screens to increase air flow through the sensor. For a street car, remove only the rear screen, this can easily be done with a pair of needle nose pliers, but be careful, MAF sensors are expensive.

                                                                                      See you at the track,

                                                                                                     Bill Porter