Evan Purple240zt Posted August 22, 2006 Share Posted August 22, 2006 I am helping out a freind with an RB25DET. He has a top feed fuel rail installed. The only way we could make the injectors fit was to stick the pintle down into the intake, and use the actual body of the injector to seal it to the intake, which also is pressed against the injector boss. Actually it fits really well, using the side feed O-rings. He has been having fueling issues, namely stumbles and misfire. I am wondering if it has anything to do with the body of the fuel injector contacting the intake manifold and heating up. These are 550cc venom fuel injectors. It develops a stumbly misfire, its a soft miss, not a hard misfire. You can hear it popping out of the exhaust. It still seems to do it when the motor is cool, but not as bad. Its noticeable under low load, and not under high load as much. Next question is whether or not the injectors were damaged from the heat. He is sending the injectors back to the original seller under warranty, but we are trying to make this situation go away and if this scenario could cause problems. Thanks in advance guys, this has been a real pain to troubleshoot. Evan Quote Link to comment Share on other sites More sharing options...
RennWerksMotorsports-Mike Posted August 22, 2006 Share Posted August 22, 2006 Your description of your installation is bit unclear. I would have to see a close-up picture to help give you some advice. Here is what I can tell you as of now. -as long as the injectors and o-rings are firmly seated and pressed to the manifold, you should be ok. 1.check all the vaccum lines, gaskets, intake piping, and injector bosses (seals) for air leaks ~~~~use a smoke machine, or spray the everywhere with soapy water, or better yet spray all connections with carb cleaner and listen for the engine to smooth out--be careful, this technique can be hazardous-keep a fire extinguisher handy. I have never had a fire doing this, but I know those who have. Just be careful not to spray the exhaust or egr piping. 2. EGR system can cause all kinds of missfire problems, stumbling, hesistation, and lack of power depending on the severity of failure. To test::: connect a vaccum gauge/pump (like a Mityvac from an auto parts store) to the egr vaccum port. Create 20in/hg of vaccum. The Egr should hold vaccum for atleast 30 seconds, if not, replace the egr valve. Reason being in cold temp and under load, especially under turbo boost, a weak egr diaphragm can cause the egr to open at undesired times and create the problems you have mentioned. If these don't solve your problems, hit me back and I will give you more advice and diagnostic procedures. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted August 22, 2006 Author Share Posted August 22, 2006 Thanks for the super fast reply. Basically, the problems started pretty much immediately after installation of the new injectors. That was the ONLY change and we checked everything we could possibly think of. Basically, there are no leaks but I was concerned about the body of the injector contacting the cast manifold and overheating the injector. After doing alot of reading, it seems like Venom injectors are problematic in this exact way.. part throttle and idle misfire. Thanks - Evan Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted August 22, 2006 Share Posted August 22, 2006 I have to ask, did you chech the RB Forum first for an answer? http://forums.hybridz.org/forumdisplay.php?f=85 LARRY Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted August 22, 2006 Author Share Posted August 22, 2006 I did read that thread. I guess I was just wondering if the heat from the intake manifold could damage a fuel injector under normal circumstances when there is metal to metal contact. He is sending the venom's in for warranty service. Who knows whether or not they will actually do anything though. The real question is whether or not to use them again, or just snag onto a set of more reliable units. Thats why I had posted in the general fueling area. Evan Quote Link to comment Share on other sites More sharing options...
Garrett76Zt Posted August 22, 2006 Share Posted August 22, 2006 Long time no see Evan! Quote Link to comment Share on other sites More sharing options...
rags Posted August 22, 2006 Share Posted August 22, 2006 Hi Evan, My manifold and injectors are exactly how you describe. The injector body sits right up against the manifold and I don't have the stumble you describe. But then again I'm not using Venom injectors. Joe Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted August 24, 2006 Author Share Posted August 24, 2006 Rags, that answers the question precisely! What injectors do you have. Quote Link to comment Share on other sites More sharing options...
rags Posted August 24, 2006 Share Posted August 24, 2006 Evan, I'm using 55# Siemens injectors. Joe Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted August 25, 2006 Author Share Posted August 25, 2006 Joe, and others. The injectors came from TLF performance parts on ebay, and he agreed to replace all 6 injectors under warranty. He will likely have them sent somewhere to have them flowed/tested before installation. Evan Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.