Custom Harnesses Frequently Asked Questions Page
First things first: Some of potential customers ask "can you do it cheaper?", or "is that your best price?", or "what about a price on a "package" deal".
A: Is no, and let me tell you why. First, you are paying me to do a job that 1) either you can't or won't do, or 2) You don't have the time to research, gather and put together the parts and information and have it run successfully. Not everyone is electrical inclined and this is intensive work, electrically.
my prices are posted on the previous page, and if you ask me that day if the prices are still good, I will honor that price to you within 30 days of contact.
Most people have no idea how much time it consumes to take a harness, strip it down, clean, rearrange and solder connections, tie-ins and connectors together. If it is custom conversion, more time is consumed in adding or deleting connectors, wiring and the time to re-pin the ecm connectors. Not to mention time spent to check all connections for proper location and continuity. Then the time spent to do the paperwork, add amended instructions, if required.
How much time you ask?
A: The standard harnesses, items 101-104, you are looking around 8-10 hours, from start to finish. Added ecm length adds another hour. Items 108 to 113 can take anywhere from 10-15 hours, due to the involved nature of conversion to a different system than what came on the car. Item 114, can vary, but 6 hours is normal. Don't forget your daily life, eating, bathroom breaks, interruptions from friends and family and the other daily duties and you can see where it takes time (by the way, these "interruptions" where not added in the total time)!
So please don't ask me for a "break". Call around, search the web, ask how much others would charge for the similar items. If you figure the average "technician" rate of about $25-30 per hour or more, you can easily figure out how expensive it can get.
And if you tell me "so and so can do it for X amount cheaper", my answer to you will be to let them do it.
Q: What information do you need from me before I order a harness?
A: First I need to know if you are going speed density or mass air flow. TBI harnesses are speed density. Then I will need to know where you plan to mount the ecm and the choice will be between the F-body ecm which mounts in the passenger compartment or the Corvette ecm which can go either in the passenger or engine compartment. TBI ecms mount in the passenger compartment. The final location where you plan to mount your ecm will determine whether or not you need a standard length or extra length harness. Then I will need to know the type of distributor you plan to use so I can configure the est connector. Then if your jurisdiction requires full emission compliance you will need to add for emission control connectors. Other options include adding relay and connector to run a secondary cooling fan and an option to relocate the mat sensor from the plenum to the air cleaner or duct as close to the front inlet as possible to monitor cooler air.
Q: What is my choice between speed density and mass air flow?
A: The choice will be influenced by what type of system you desire to run and your budget. Speed density is less complicated wiring, cheaper and easier to install without the complicated and expensive mass air system. However, it does have its drawbacks, as it is not as forgiving when you decide to change cam or exhaust as it depends on the engine manifold vacuum signal to help determine fuel calibrations. But for a very mild or stock engine with no desires to modify, it is a superb system. Mass air although more complicated and expensive will allow for more moderate changes without upsetting the fuel curve, as it calculates the weight and speed of the air to determine fuel load and is more responsive.
Q: How do I determined if I need a standard or extra length harness?
A: To determine your harness length you will need to know where exactly you plan to mount your ecm. This is determined from measuring from the location of the distributor to where the ecm bulkhead connector will enter the firewall. The easiest way is to take a string or rope and starting from the center point of the distributor, run it along the back of the firewall, and take into account the obstructions you must go around, such as a/c boxes, blower motor etc., taking care to avoid any sharp bends or coming within 4 inches of any exhaust system parts. Where you want to go through the firewall, make sure it is clear of any obstructions and the final location of the ecm will be in a spot where it will not be accidentally kicked. Add another 4-6" to this measurement to add as a safety measure. Double check and make sure you don't cheat yourself in thinking you can "fudge" to get a cheaper harness. You know your vehicle and what is needed to make it a proper installation. The wiring on the passenger side of bulkhead connector is approximately 12" long. From my experience vehicles such as early GM A, B, F bodies and Nova, street rods, small pickups such as the S-10, and small imports such as the Mazda RX7 and the 1968-82 Corvettes can use the standard harness. If you plan to use the Corvette ecm for an under hood installation, you must also state which side of the vehicle you plan to mount the ecm, and this can be on either inner fender well or firewall with space permitting. Standard harness is 36" from distributor to ecm connector, extra length is 72".
Q: What about location of my ecm?
A: The F-body speed density tpi and tbi ecms must mount in the passenger compartment. The Corvette ecm with its water resistant (not waterproof) case can mount in either engine or passenger compartment. If you plan to mount the ecm under a seat or in a center console between the seats you will need the extra length harness.
Q: I have computer controlled carbureted car. Can I buy just a harness and use my stock ecm?
A: No, will not work my friend. The ecm is not designed for running a fuel injection engine.
Q: I have my harness converted from tbi to tpi, can I use my stock ecm.
A: No, again the difference in fuel injection systems will not allow transferring over ecms to different applications. The tbi systems use either the 1227747 (truck) ecm or 1228746 (car) ecm, the tpi's use three different ecms: 1985 only (1226870), 1986-89 MAF (1227165), although the prom for 1989 eliminates the cold start injector. The speed density uses two different ecms, 1990-92 F-body uses the 1227730, the 1990-91 Corvettes use the under hood ecm 1227727. The proms cannot interchange between the ecm families.
Q: What type of distributor do I need?
A: You will need a computer controlled distributor from a Chevrolet small block V8 from 1981 on up. Now, there is 3 different types of HEI's from 1981 on. The first type is what I called the "common" HEI. This was made from 1981 up to 1987. It has the keyed distributor connector common to all the V8's and uses latches to hold the cap down with the following exception which is type #2: 1985-68 F-body TPI 1986-1991 Corvette, the distributor connector is keyed different from all the other HEI's and the cap is held with 4 screws. Type 3 is the 1987 and later design which is smaller and uses a remote mounted coil, the est connector is also smaller and it also has a two wire connector to the coil. The later design is used in the Chevrolet line through 1993, with the exception of the Corvette. My harnesses come with the common design est connector, unless otherwise specified. See my distributor page for explanation. NOTE: If you are purchasing a harness for an older vehicle with a points-type distributor, you must insure you have a full 12V going to power any HEI system. This must be fed off the ignition switch or a 12V source that is hot with the key in the on and start position. Using the original wire for a older points-ignition system will not supply the full 12V unless the coil is supplied with ballast resistor that reduces the 12V down to the 9-10V needed by the coil, then, you can tap off the wire. BUT--use a meter to insure you indeed are getting a full 12V power supply. Also--- If you are installing a vehicle using a mechanical tach. drive off the distributor, you must purchase a aftermarket distributor that allows use of the est system and retain your tachometer.
Q: What about the Vehicle Speed Sensor adapters?
A: These can be ordered through www.jagsthatrun.com or www.painlesswiring.com . Price is around $90.00. I highly recommend using the VSS as the engine will perform better.
Q: I'm using a MAF system, what is required for speed sensor system?
A: Unless you have a way or means to install a factory VSS that is mounted on the speedometer head, you will need the VSS adapter (see question above). Also you will need the speed sensor buffer that was installed in the Firebirds (1986-89) because they used the electronic speedometer. see previous page. The VSS signal is feed through the adapter and the buffer splits the signal to the ecm, electronic cruise and if equipped, electronic speedometer. Most people will opted for the VSS adapter and buffer set up because it is much easier than trying to fabricate a VSS on the speedometer and my MAF harnesses are set up for this, unless otherwise requested.
Q: I'm converting from MAF ( or TBI) to speed density what will I need to do about the VSS?
A: If your MAF harness was not originally equipped with a electronic VSS connector, you will need to purchase a VSS adapter so the ecm will correctly run the TCC in the OD transmissions. If you are running an older 3 speed transmission, the VSS is highly recommended, as many tpi functions depend on speed sensing for proper operation. If you elect not to use a VSS (if your jurisdiction allows emissions exemption) or just don't want it, and if you are using a OD, you will need to purchase an TCC lock up kit. This is mandatory, or transmission will overheat and failure will occur! Also non-VSS will mean that the VSS error code will have to removed from prom, regardless of transmission type.
FOOTNOTE: IF you want full potential from your TPI, you will need a VSS adapter, this is true even if you run a turbo 350/400 automatic. If you are using a 200/700 OD already equipped with the VSS (there will be an electrical plug with two wires-yellow and purple), you wont need an adapter.
Q: I plan on using cruise control, what do I need to do?
A: You will need the electronic cruise control that is common to a lot of GM vehicles starting in the mid 80's. Go to my electronic cruise control page at http://www.chevythunder.com/fuel%20injection%20electr.%20cruise%20cntrl..htm. This has pictures to show the various parts and some mods to make it work. You will need the VSS adapter for the speed density systems and the addition of a VSS buffer you are running a MAF tpi or a TBI systems. It is possible to use the older cable driven cruise servo, but these parts are getting hard if not impossible to find, and the electronic system is much more reliable.
Q: How easy is it to hook up and run?
A: Once it is installed in the desired location, all you need to do is hook up the sensors, the proper ecm and connect to the battery 12 hot (on starter), ignition on power (under dash at fuse box or starter switch) and connect the grounds to the firewall securely. A 12 page instruction booklet is included as a guide and all the connections are labeled for fast, foolproof hookup. As close to a plug and play system as you can get. A basic schematic is supplied that corresponds to your particular set up.
Q: How do you test your harnesses?
A: I have three separate tests I do. First is the continuity check to determine that all the connections are corresponded properly to the proper functions. If there is any mistakes, this is where I catch them and make the corrections. The second step involves power test, where I hook up all the power, ground and ecm connections on a test bench with noid lights, test lamp for fuel pump check and diagnostic run. I hook up a distributor and then simulate a "start" test to insure the ignition circuit is triggering the fuel pump and injector circuits. With a voltmeter, I check the 5V sensor output power from the cts, mat, tps and map where applicable. The third step involves hookup to a laptop with Diacom and installing all the sensors to the circuits. With it in this test, I can insure that the ecm is receiving the sensor and inputs such as a/c on, park-neutral input, VSS and others appropriate to your harness. I do all these tests to insure that when your harness is shipped to you and is properly installed, it will function as a factory system.
Q: Why should I purchase one of your harness?
A: If you are on a budget, this is an viable option. If you are not wholly concerned that not all the wiring colors match, but do want a harness that will fill your needs, customized to fit your vehicle, this will do. My harnesses are carefully selected, stripped down, modified and all connections are soldered and shrinked wrapped to protect it. All connectors are tested for brittleness and replaced if necessary. And I bench test every harness.
Q: Do the "other guys" test their harnesses?
A: They may or may not. They do use brand new parts and that's their advantage. They buy all their parts in bulk, and have a huge overhead to contend with. They also carry a better warranty, but they can afford to "eat" a bad harness or two along the way due to their volume and take a loss. But, their harnesses are more expensive and you are at their mercy on ecm location. And ordering a "custom" harness will cost you easily $400-600. On the other hand, I do this to help the average working guy (like me) who wants the advantage of fuel injection and because I can save them a few dollars, don't mind buying a used, converted harness that's easy to install. I can't afford to sell a bad harness, that's time and labor to repair, not to mention trying to build a reputation.
Q: Do you have a warranty?
A: One full year from date of purchase, covering my workmanship on soldered connections.
If there is a problem, you will need to ship the item back to me, then I will ship it back, with your shipping costs refunded.
Does not cover abuse, misuse, misapplication, improper installation, or any damages caused by such improper procedures that are beyond control of the supplier. Also does not cover labor cost for removal and installation and any other incidental charges.
Q: How long will it take to get my harness?
A: Once I receive your payment, I will notify you within 24 hours. From this time it takes normally 10-14 days when I ship it out. Sometimes, when work load is light, I can get it out under 7 days, but don't count on it. I do have a regular job and family obligations that still come first. If there is going to be a delay, I will contact you.
Q: Can you do high performance chips?
A: Sorry, I cant do high performance chips.
Q: Do you have a number where I can contact you?
A: Sorry, I don't give out my number. Although I value you as a potential customer, time constraints do not allow me to spend time on the phone.
Q: I just bought a TPI on a auction, what do I need to complete this set up besides a harness?
A: It depends on how complete the set up you bought is. Visit my website from the very beginning and make notes from all the pictures of parts you will need starting at the mechanical link.
Q: What sensors do I need to complete my installation
A: Again, visit my website starting at the electrical link.
Q: Do you sell just the instructions to convert a harness over my choice?
A: Sorry, Time does not allow me to "individualize" instructions for repining a harness to convert over. This information is available in the local library in most large metropolitan areas. Plus, If you glean my site carefully enough, you can probably figure it out.
Q: I have a LT1 engine and 4L60E or 4L80. Can I use one of your harnesses and ecm?
A: Sorry, My harness and ecm(s) will not work on the late model engines such as the LT1. The ecm for these engines control the shifting on the transmissions through activation of solenoids. NOTE: Chevrolet Performance Parts sells a kit that will allow you to the 4L60 transmission. This kit was made to install in older carbureted vehicles, but probably will work for a tpi system.
Q: I don't need emission controls for my harness, what do I need to do to keep check engine light from coming on?
A: If your jurisdiction allows for emission exemptions, I can deprogram the egr error code for the prom.
Q: I have bought a ecm and stock prom and car still wont start, what do I need to do?
A: If you can get the fuel pump to run during a test mode and you are getting spark, the fuse to the injectors are good but still wont make a "noid" light flash and the ecm is from a Camaro, Corvette, or Firebird, the factory VATS program is keeping it from running. I do offer a service to deprogram VATS.