rags Posted June 2, 2009 Share Posted June 2, 2009 Well it's been a very confusing weekend. A few of us, EvilZ, 1TuffZ and myself were all set up for Watkins Glen to do some fast driving, David in his LS1 240, Clive in my LS1 280 and me in my turbo 240. Well my 240 never made it due to some scheduling conflicts but all was well otherwise. Since Clive was driving my car it was understandable that he didn't want to drive the car at 10/10 and said he would just try to lock down a line and be smooth. Fine with me. Between me and Clive there is always some banter about who's car is fast and who's car is a slow piece of crap. We do agree on one thing, my brown LS1 car is slower than his old LS1 car and my turbo car. That being said, when he can into the garage after a few laps and said the car had no power, I took it with a grain of salt. As the day went on, the description became more detailed. Third gear, power on then off then back on again. Losing between 30 and 40mph up the esses. WTF??!!? Now just prior to heading to the Glen we had the car tuned and aligned. The car put down 396hp which I was okay with, so to hear we were losing that much speed as baffling to me. The third gear on again off again power has me guessing a fuel issue. Clive had called the shop that tuned his car and they pointed to the tune. I'm having trouble believing that because of the dyno number above. Instead of just jumping in and bringing the car to another tuner, my intention is to bring the car back to the original tuner to get his diagnosis. I'll post back here after speaking to the original tuner. Joe Pretty funny seeing me pay to have the LS1 car tuned with that signature, huh? Damn LS1Edit!! Quote Link to comment Share on other sites More sharing options...
Bigdeezs Posted June 2, 2009 Share Posted June 2, 2009 with that on/off really sounds like fuel. hook up a fuel pressure guage and go beat on it and see. Quote Link to comment Share on other sites More sharing options...
rags Posted June 3, 2009 Author Share Posted June 3, 2009 Well here is one update. The alternator gave up on the way home! Don't know if that is what was causing the erratic behavior but I guess we will see once it is replaced. Joe Quote Link to comment Share on other sites More sharing options...
Bigdeezs Posted June 3, 2009 Share Posted June 3, 2009 hmmm interesting...another LS1 Z I know of was having issues with the Alt power cable contacting the driver side JCI motor mount attachment and causing the same issue but ony in 1st. Might be worth investigating. Quote Link to comment Share on other sites More sharing options...
blueshark123 Posted June 3, 2009 Share Posted June 3, 2009 Did you guys do any data logging while running it at all? Plotting at least the AF ratio could point to any fuel issues. Quote Link to comment Share on other sites More sharing options...
rags Posted June 3, 2009 Author Share Posted June 3, 2009 Well that would have been the smart thing to do so you know I didn't do it New alt got the car running again but still no power. I'll do some logging to see where it's at. Joe Quote Link to comment Share on other sites More sharing options...
EvilC Posted June 3, 2009 Share Posted June 3, 2009 Hey guys, I will give the first hand "feel" of Joe's car. My first two sessions out, I felt that I was about 30 mph slower just due to me not driving the car like I stole it. In the after noon for about 4 laps I drove it at about 8/10 and qas quick to realize that the car was down on power. I am thinking lean in the mid range about 4k-5200k....I was coming out of turn 11 and can drive all of 4th gear to turn one and never see about 5100 rpm. Sometimes, about 3 times, the car would come alive like someone kicked it in the butt. That was only if I kept my foot in it for periods of almost 15 secs or more. I really didn't want to blow anything up so I backed off. I mean it was getting to the point where stock 5 series bmws were catching my up hill on the track. The fuel pressure is reading 43 psi, which is after the fuel rail (return of fuel is done by the regulator, fuel rail is not a dead end point). I took the fuel filter apart and no junk in there. I am guess next step is to remove injectors and see if they are clogged. I don't think we will find anything because it would have made the car miss not just lack power. Like Joe said, we often play around about who's car is "slower" but for sure this 396 rwhp car is MUCH slower than my 388rwhp car. Maybe I can shoot a vid this week and we all can hear what I am talking about. As far as the alternator dying....ha! I was on my way home from the track and then boom...no power. Had to drive 45 mins from where the car died to get the part and then back to fix it. I was about 2.5 hours from home and luckily my dad came up with tools the night before....brand new alternator from Adavance Auto $170..yay! That just makes up for the lack of gas I used on the track =) Will report back as we figure this one out. Quote Link to comment Share on other sites More sharing options...
rags Posted June 3, 2009 Author Share Posted June 3, 2009 What really has me puzzled is the kick after keeping your foot in it. Valet mode should never do that. Opps, did I say that? I had to do something to keep the blue paint off the car!:lol::lol: OUCH!!!!! Quote Link to comment Share on other sites More sharing options...
blueshark123 Posted June 3, 2009 Share Posted June 3, 2009 Hey guys, I will give the first hand "feel" of Joe's car. My first two sessions out, I felt that I was about 30 mph slower just due to me not driving the car like I stole it. In the after noon for about 4 laps I drove it at about 8/10 and qas quick to realize that the car was down on power. I am thinking lean in the mid range about 4k-5200k....I was coming out of turn 11 and can drive all of 4th gear to turn one and never see about 5100 rpm. Sometimes, about 3 times, the car would come alive like someone kicked it in the butt. That was only if I kept my foot in it for periods of almost 15 secs or more. I really didn't want to blow anything up so I backed off. I mean it was getting to the point where stock 5 series bmws were catching my up hill on the track. The fuel pressure is reading 43 psi, which is after the fuel rail (return of fuel is done by the regulator, fuel rail is not a dead end point). I took the fuel filter apart and no junk in there. I am guess next step is to remove injectors and see if they are clogged. I don't think we will find anything because it would have made the car miss not just lack power. Like Joe said, we often play around about who's car is "slower" but for sure this 396 rwhp car is MUCH slower than my 388rwhp car. Maybe I can shoot a vid this week and we all can hear what I am talking about. As far as the alternator dying....ha! I was on my way home from the track and then boom...no power. Had to drive 45 mins from where the car died to get the part and then back to fix it. I was about 2.5 hours from home and luckily my dad came up with tools the night before....brand new alternator from Adavance Auto $170..yay! That just makes up for the lack of gas I used on the track =) Will report back as we figure this one out. Sucks to hear man. Was this car ever running properly before the dyno tune? If so what was changed? Quote Link to comment Share on other sites More sharing options...
Bigdeezs Posted June 3, 2009 Share Posted June 3, 2009 43psi after the fuel rail?...did you check at the fuel rail? It should be 58-62 there. I originally had a fuel pressure issue with mine. It turned out my pump wasnt getting enough voltage because of the 280Z fuel pump wire. It read about 12 volts at the fuel pump at idle (shoulda been 14.5). I ran a new wire and that solved my issue. Quote Link to comment Share on other sites More sharing options...
blueshark123 Posted June 3, 2009 Share Posted June 3, 2009 43psi after the fuel rail?...did you check at the fuel rail? It should be 58-62 there. I originally had a fuel pressure issue with mine. It turned out my pump wasnt getting enough voltage because of the 280Z fuel pump wire. It read about 12 volts at the fuel pump at idle (shoulda been 14.5). I ran a new wire and that solved my issue. Yeah but then he would have been seeing this problem on the dyno. Sounds like it might be a fuel pickup problem. This happened on a friend's car (not a 240z) when he was on a dyno all was fine but when he got on it on the street it would break up and feel slow. It turned out that the pickup was made wrong and when the car would accelerate the fuel would go to the back of the tank and starve the pickup; something that wont happen on the dyno. Quote Link to comment Share on other sites More sharing options...
EvilC Posted June 3, 2009 Share Posted June 3, 2009 Pic of engine bay, see location of F/R: Will have to check the voltage at the pump, wonder if that was the cause od the first one failing on Dale. We assumed it died cause of "crap" that may be at the bottom of the tank. Also will check the FP at the rail and while driving. Rags will do some data logging and see what he is getting. Quote Link to comment Share on other sites More sharing options...
Bigdeezs Posted June 3, 2009 Share Posted June 3, 2009 Yeah but then he would have been seeing this problem on the dyno. Sounds like it might be a fuel pickup problem. This happened on a friend's car (not a 240z) when he was on a dyno all was fine but when he got on it on the street it would break up and feel slow. It turned out that the pickup was made wrong and when the car would accelerate the fuel would go to the back of the tank and starve the pickup; something that wont happen on the dyno. True...unless something happened since being on the dyno. But yeah another buddy of mine had that same problem with his 260...keeping the tank at least 1/2 full kept that under control tho. My 75 280Z tank has the internal baffling and I havent experienced that issue. Will have to check the voltage at the pump, wonder if that was the cause od the first one failing on Dale. We assumed it died cause of "crap" that may be at the bottom of the tank. Also will check the FP at the rail and while driving. Rags will do some data logging and see what he is getting. Looks like your FPR has a vacuum line hooked up to it. I'm not sure who your tuner is but if he didnt account for it that could be part of the problem. 98+ LS1s dont have a return or use any vacuum adjustment. The tune in these computers would likely have issue with that setup unless the tuner knew that and adjusted for it. To my knowledge only the 97 vette had a return style system. Also 43psi is about what LT1s run...its possible that was adjusted for in the tune but then the lower pressure changes what your injectors would be capable of putting out, effectively going from 26lb/hr to something lower. Anyhow I would focus on making sure FP is correct...just make sure you know what its supposed to be for your setup as it may have been adjusted for in the tune. Quote Link to comment Share on other sites More sharing options...
blueshark123 Posted June 3, 2009 Share Posted June 3, 2009 Looks like your FPR has a vacuum line hooked up to it. I'm not sure who your tuner is but if he didnt account for it that could be part of the problem. 98+ LS1s dont have a return or use any vacuum adjustment. The tune in these computers would likely have issue with that setup unless the tuner knew that and adjusted for it. To my knowledge only the 97 vette had a return style system. Also 43psi is about what LT1s run...its possible that was adjusted for in the tune but then the lower pressure changes what your injectors would be capable of putting out, effectively going from 26lb/hr to something lower. Anyhow I would focus on making sure FP is correct...just make sure you know what its supposed to be for your setup as it may have been adjusted for in the tune. That's true but most aftermarket FPRs increase fuel pressure 1:1 for every lb of boost seen. This motor is NA and shouldnt see this happening. Either way this would have been picked up on the dyno. I wonder why there even is a vac source connected to the FPR? Im not sure what brand it is either Quote Link to comment Share on other sites More sharing options...
rags Posted June 3, 2009 Author Share Posted June 3, 2009 43psi after the fuel rail?...did you check at the fuel rail? It should be 58-62 there. 43, 58, 62 doesn't mean a thing if the tune was done at that FP. Now if the pressure changed after the tune was done then there will be problems. As of right now we are just grasping at straws. What I have to do is find out from the tuner what base FP he used and then check FP under load. Until I do that we don't have a baseline to work off of. A vacuum source is doing the same thing to FP as is done with boost. It is adjusting for the difference in pressure seen at the tip of the injector. Look at it this way, if the engine is running under vacuum, the tip of the injector is being sucked on which will pull fuel from the injector. The reason a FPR does the 1:1 thing under boost is to compensate for the pressure the tip of the injector sees under boost. As for the FPR being after the rail, the rail will see all the pressure that the pump can supply. The regulator just bleeds off anything higher than it is set for. Joe Quote Link to comment Share on other sites More sharing options...
Bigdeezs Posted June 3, 2009 Share Posted June 3, 2009 That's true but most aftermarket FPRs increase fuel pressure 1:1 for every lb of boost seen. This motor is NA and shouldnt see this happening. Either way this would have been picked up on the dyno. I wonder why there even is a vac source connected to the FPR? Im not sure what brand it is either On an NA car they also increase FP at WOT when vacuum becomes 0. 43, 58, 62 doesn't mean a thing if the tune was done at that FP. Now if the pressure changed after the tune was done then there will be problems. As of right now we are just grasping at straws. What I have to do is find out from the tuner what base FP he used and then check FP under load. Until I do that we don't have a baseline to work off of. Joe yup:icon14: Quote Link to comment Share on other sites More sharing options...
rags Posted June 3, 2009 Author Share Posted June 3, 2009 On an NA car they also increase FP at WOT when vacuum becomes 0. They don't really increase FP. The FP will just go to what is initially set without vacuum. Actually, I always set FP with the vacuum line disconnected. Quote Link to comment Share on other sites More sharing options...
Bigdeezs Posted June 3, 2009 Share Posted June 3, 2009 They don't really increase FP. The FP will just go to what is initially set without vacuum. Actually, I always set FP with the vacuum line disconnected. ok fine...they reduce fuel pressure in vacuum conditions Quote Link to comment Share on other sites More sharing options...
blueshark123 Posted June 3, 2009 Share Posted June 3, 2009 Rags you're right. Just do some datalogging and see what's up. I got to check this car out sometime. I wanted to see it at Glens but unfortunately I couldn't take off of work. Quote Link to comment Share on other sites More sharing options...
EvilC Posted June 3, 2009 Share Posted June 3, 2009 I thought it was just the big 18 inch wheels slowing it down! =P Seriously though it is a fuel issue and will get it solved soon. FP needs to be check during engine load, tank drained to make sure no crap is in it and finding out from tuner FP he tuned at. Sucks that it is raining today.....weekend is almost here anyway. Quote Link to comment Share on other sites More sharing options...
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