Bosch Pintle style injectors suck
04-17-2002, 11:29 PM
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Track Day
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Join Date: Jan 2002
Location: St. Augustine, FL
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Bosch Pintle style injectors suck
I have commented in the past about the many problems caused by dirty injectors in the 928. This problem is often diagnosed as being caused my other components in the fuel system. I still have on going periodic partial plugging of the injectors on my 88' 928 S4.
I add injector cleaner and the problem eventually corrects itself as the particle plugging the injector is dissolved by the cleaner. I have even considered purchasing my own injector cleaning system because the problem happens on a regular basis.
I know exactly when an injector has crap in it. Depending on how plugged it is, the idle speed will drop, the engine will idle rough, and it may even start to surge if the injector plugs enough. Also, after driving the car and allowing it to sit for more than 15 minutes, the plugged injector may allow fuel to flood a cylinder and make the car hard to start. After adding a good dose of cleaner the problems disappear in a few hours or days.
After doing further on line research into the subject, I have learned a lot and have a better understanding as to why this is and will continue to be an on going problem in my car. The later model 928's used the early design Bosch pintle design electronic injectors. The early Bosch pintle design are highly subject to partial plugging because the center pintle reduces the orifice opening even with the injector open. Also the short tip in the early model injectors is more susceptible to rapid cooling causing the tips to more easily collecting varnish and carbon. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />
Reference (http://www.babcox.com/editorial/us/us120034.htm)
Having to continually add injector cleaner and living with injectors partially plugging and hanging up is a pain in the ***, even if I clears up within a few days after adding injector cleaner.
Question to the experts.....did Porsche change to a different and improved Bosch injector design in later years? If they did, will they fit into earlier model 928 that use electronic injectors?
John (Hawke) Laurenson <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
80' 928 & 88' 928S4 Gemballa
I add injector cleaner and the problem eventually corrects itself as the particle plugging the injector is dissolved by the cleaner. I have even considered purchasing my own injector cleaning system because the problem happens on a regular basis.
I know exactly when an injector has crap in it. Depending on how plugged it is, the idle speed will drop, the engine will idle rough, and it may even start to surge if the injector plugs enough. Also, after driving the car and allowing it to sit for more than 15 minutes, the plugged injector may allow fuel to flood a cylinder and make the car hard to start. After adding a good dose of cleaner the problems disappear in a few hours or days.
After doing further on line research into the subject, I have learned a lot and have a better understanding as to why this is and will continue to be an on going problem in my car. The later model 928's used the early design Bosch pintle design electronic injectors. The early Bosch pintle design are highly subject to partial plugging because the center pintle reduces the orifice opening even with the injector open. Also the short tip in the early model injectors is more susceptible to rapid cooling causing the tips to more easily collecting varnish and carbon. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />
Reference (http://www.babcox.com/editorial/us/us120034.htm)
Having to continually add injector cleaner and living with injectors partially plugging and hanging up is a pain in the ***, even if I clears up within a few days after adding injector cleaner.
Question to the experts.....did Porsche change to a different and improved Bosch injector design in later years? If they did, will they fit into earlier model 928 that use electronic injectors?
John (Hawke) Laurenson <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />
80' 928 & 88' 928S4 Gemballa
