Guys, For the last few months I have been living with and trying to solve injector problems on a different vehicle, not my GTS. I think some of things I have learned, the hard way. This information may be helpful.
The vehicle involved is my 1988-Porsche 928 S4. In many ways it is much like the GTS, never really caught on with general public, but it is one of the finest touring machines ever made. In fact I like it so much, I own two a 1980 and 1988 ; both bought new and held on to. Back to my point. They both sat in storage for nearly 7 years. I did nothing to prepare them; ie: like drain the gas or put them up on blocks. I know stupid.........:>) The problems I am now living with in trying to bring these machines back to life is a magnification of what happens when allowing any vehicle sit for months over the winter when being used. Obviously with the cars, the tires are shot. They develop flat spots so bad that have a flatspot memory no amount of driving will ever make them round. New tires solved that problem. But, the real problem is the fuel system. Gasoline has waxes, impurities, and additive that separate out when allowed to sit. They will coat everything inside the system when any vehicle is allowed to sit without use. I have probably used a couple gallons of fuel additives over the last 5,000 miles trying, not very successfully to clean up my 928 fuel system up. The injectors sometimes work and sometimes don't as pieces of coating crap breaks loose from inside the system. One day the car will start fine, the next day I need to crank the hell out of it because it is flooded from an injector getting crap in it and hanging up. I just replaced all the injectors...that worked well for about an week and now the problem is starting all over again. I'm getting ready to drop the tank and clean it by hand and install another new fuel filter. The tank is plastic so rust is not the problem. I may have to replace all the fuel lines before I am through. My point is old gasoline can play hell with any fuel system, including the one in a GTS. Sitting over a single winter won't cause the degree of problems I am experiencing from my own neglect on the 928's, but sure isn't good for the bike. The injector openings on the GTS are probably a fraction of the opening on the Bosch injector for the 928. The GTS injectors are probably even more susceptible to partial plugging that will cause engine surging and other problems. I had some interesting discussion on the topic of additives on the 928 list as I asked for help. One I found of particular interest. It was from a guy that worked for a gasoline additive manufacturer. In his dissertation on the topic he pointed out things I did not realize. 1. Most additives don't work. 2. There two basic types of additives, aromatic(solvent) and detergent. Based on extensive testing he only recommends aromatic. It dissolves the build up where detergent have a tendency to break it up. Below are some of his comments on the topic....... My point in bringing all of this up is to make the GTS owners that are experiencing some surging aware that the problem may be more easily addressed with proper storage and adding a can of the proper additive in the spring to clean up the injectors and fuel system. GOOD LUCK Hawke COMMENTS FROM AN EXPERT ----------------------------------------------------------------- I work in the petrochemical industry and have been involved in exhaustive tests of just about every additive under the sun. For varnish and carbon build-up. I recommend a SOLVENT based fuel cleaner containing any of the following: isobuytanol, methanol, Methyl Ethyl Ketone. read the back of the bottles of the additives you're shopping for. I am biased in the fact of recommending Justice Brothers Injector cleaner as I represent that company. As our product range is not widely available in retail outlets, you may not be able to find it in your area. I will share with you though that Ford manufactures an excellent top engine cleaner called "Carburetor Tune-up" (don't worry about the carb. part on the label, it's an excellent product). This product is not available at every Ford establishment but it is out there. It's a liquid that you add to your fuel system. Do not mistake this for the other ford injector cleaners or their pressurized fuel service. At about $4.00 a can, it performs very well (next to ours of course!). Mitsubishi also has an excellent Fuel injector cleaner that is manufactired for them. Read the labels on the back of Redline, techron, BG, etc. They are detergent based cleaners and we have found they do not perform nearly as well as a solvent based cleaner in our testing. These products are based upon petroleum aromatics, Tolulene, benzene, trimethylchloride, polyetheramine. I recommend you don't bother with stuff you find at Pep Boys as we have not yet tested a product that perfomed very well. One trick that is done is to use a vacuum line to "suck" SMALL amounts of cleaner in to remove carbon build-up on valves. Works great, smells awful! If you're not convinced, burn a small amount of gas in a bowl. when it's done burning, you'll see the carbon and varnish left. Pour ANY of the detergent stuff (techron, redline, etc.) in the bowl and see what it does. Try the same test with any solvent based cleaner I recommended. You can see for yourself the difference in the way each works! I would not worry too much about putting a petrochemical solvent in the fuel system. Gasoline in the US contains about 29% aromatics - petrochemical solvents (toluene, etc) used for octane boosting (among other things, as I recall). Gasoline in the land of Porsche contains even 10% more aromatics than the gas we use. And a racer's trick, that has been in use forever, is to mix even more Toluene in the gas to raise the octane. The same does NOT apply for alcohol - this can wreak havoc on older "rubber" parts not designed for it. However, since gas in many states has contained ethanol for many years now, most of the newer parts are designed to tolerate it. (Technology marches on...) "Automobile manufacturers upgraded fuel system elastomers ay different times. Elastomers in pre-1975 vehicles may be sensitive to oxygenated and high-aromatic gasolines, including alcohols. Elastomers in 1975 10 1980 vehicles were upgraded, but not to the same extent as in later models" (Changes in Gasoline II, Downstream Alternatives, Bremen, 1998). The problem that was found with alcohol based oxygenates was in a problem called phase seperation. When alcohols were used as an oxygenate (i.e. ethanol) they would seperate from the gasoline given extended storage time in gas storage containers. Phase seperation of alcohols (water) can cause corrosion problems in transfer pipelines but is not a big factor in your car. Unless you are storing your vehicle for extended periods. Here's a test you can try. Get some o-rings and soak them in for example our IC/15 fuel injection cleaner ( Moss). In our testing, we dozens of various o-ring and seals soaking them in straight additive for nearly 15 days. We found no disintegration, degredation, or hardening of any of the rubber. Not true for some origional vacuum line off a mid-70's TR6 I had, Were we found moderate swelling. Try the same test with an additive that contains benzene, yikes! the alcohol complaints you hear are typically carryover's from older mechanics that dealt with the more obsolete rubber compounds. Sort of like my dad telling me to using the engine to assist in braking. You needed to do that when cars were equipped with 8" drum brakes all around. I know I'd rather replace pads than a worn engine from the increased loading. As far as sucking in the cleaner through a vacuum line. We use an I.V. bottle to regulate a small flow of cleaner into the intake of the vehicle. What you could use is just a small vacuum line from the intake to do the same thing. When i say a small amount, I actuallly mean to suck it in slowly. Liquids, as we are well aware, are not compressable and intake manifolds are designed for gases, not liquids. If you try to draw in too much, you may stall the vehicle. Worse, there is a remote possiblity of hydrostaticly locking a cylinder ($$$). Just be careful and slowly draw in a small amount, you'll be fine. Oh, by the way, I would not recommed the Justice Brothers stuff in plastic bottles. Only use the stuff in metal cans like IC/15. The stuff in the bottles just don't work as well as they are a different formula. They were made for quick lubes and service stations. Just being honest! -----------------------------------------------------------------
