madden Posted March 8, 2011 Report Share Posted March 8, 2011 I have a 03 Radix SS with long tubes, 60lb injectors, wide band, boost gauge, and fuel pressure gauge. I've been tuning the truck and had it consistently fueling in the 11.5 to 11.9 afr range and running great. (FYI: I think it has a 2.9" pulley). I have run into a fueling issue that I can not fix with the tune. Some times I am only fueling 13.0 to 13.5 at WOT and at other times it fuels fine. The autometer gauge shows 52 psi under vacuum and jumps to 58 psi at 0 boost but never rises above 58-59 psi. I have the return style fuel system with the vacuum/boost operated fuel pressure regulator. The truck has the inline booster pump from magnacharger and I guess has the stock in tank pump. I bought it with the radix already installed. I just got the fuel pressure gauge working after I ran into this problem. I have searched the forum and found that other 03 boosted trucks are getting higher fuel pressures under boost (like 62 to 64 I believe). I suspect a weak in tank pump or maybe a problem with the fpr as it does not ever get the psi above 59. Please help if you have any ideas. The truck really runs well when its fueling correctly but I'm afraid its going to hurt itself if the lean condition continues. FYI: When it does run lean it is lean all across the RPM range; not just at higher rpms. Quote Link to comment Share on other sites More sharing options...
misterp Posted March 8, 2011 Report Share Posted March 8, 2011 Welcome to the forum Sounds like you've covered the essentials. The clue I would zero-in on is the fact that the fuel pressure never rises; with a boost-referenced FPR you should see fuel pressure rise in direct 1:1 proportion with boost, i.e. when you hit 8psi boost you should be observing 64psi at the fuel rail. I personally do not like the extra Magnusson 'pusher pump' they supply with the '03 kits; it's just one more possible point of failure - I recommend to everyone to just upgrade the intank pump, the Walbro-255 will fuel adequately and you can get the complete kit for $135 from Magnusson and ditch the extra inline pump, and associated wiring. Is the fuel filter clean/new? I would also electricaly tap off the fuel pressure sending unit and log that input as well, so you can see logged fuel pressures in relation to your MAP (boost) readings and verify that your FPR is working correctly. Simple question, you DO have the FPR vacuum line plumbed directly to the manifold, right?! And question of curiosity, what did you do about the factory FPR in the Magnusson fuel inlet elbow? Did you replace it, or did you go with custom fuel rails or ??? Got pics you can share? Mr. P. Quote Link to comment Share on other sites More sharing options...
Krambo Posted March 8, 2011 Report Share Posted March 8, 2011 Are you able to post the tune as well? Are your running the MAF? Quote Link to comment Share on other sites More sharing options...
madden Posted March 9, 2011 Author Report Share Posted March 9, 2011 I'll get some photos up later. I did not install the charger. I bought the truck from a customer of mine and started trouble shooting several issues. I will post the latest tune file (its from a beta version of HP Tuners). I don't think that tuning is the problem as it will fuel really close to my comanded afr when it's working correctly and when it goes lean I can't even force it rich with the VCM controls on the scanner. The truck has a new fuel filter (installed by me at the start of all the trouble shooting). I also replaced some crappy iridium plugs with autolite 103s gapped at .035. FYI: The iridium plugs were causing really bad issues making the truck cut out at wot. The vacuum line is properly connected from the manifold to the regulator. The fuel pressure gauge does indicate that under vacuum it is down to 52 psi and then jumps to 58 at 0 psi........... just does not go above 58/59 even under full boost. I may log the fuel pressure but I can watch the gauge and determine that it just isn't getting up to where it should be. Yes I'm running the MAF and I even tried speed density and it didn't seem to help. I am maxing the maf out at 12000k hz but it was giving me plenty of fuel the other day. Another minor note: the wideband is downstream of a cat so it may be slightly richer than what I'm reading. Looks to be the magnuson fuel rails with the fpr in the elbow as you are describing. I was thinking of swapping the fpr with another stock replacement part and then going on to an upgraded in tank pump if that doesn't fix the issue. I thought I'd leave the pusher pump in place to "help" the in tank unit. I'll try and post a tune file. Thanks for the help guys! Supercharged silverado ss file 2003 mod 032 final.hpt Quote Link to comment Share on other sites More sharing options...
chpspecial Posted March 9, 2011 Report Share Posted March 9, 2011 I'll get some photos up later. I did not install the charger. I bought the truck from a customer of mine and started trouble shooting several issues. I will post the latest tune file (its from a beta version of HP Tuners). I don't think that tuning is the problem as it will fuel really close to my comanded afr when it's working correctly and when it goes lean I can't even force it rich with the VCM controls on the scanner. The truck has a new fuel filter (installed by me at the start of all the trouble shooting). I also replaced some crappy iridium plugs with autolite 103s gapped at .035. FYI: The iridium plugs were causing really bad issues making the truck cut out at wot. The vacuum line is properly connected from the manifold to the regulator. The fuel pressure gauge does indicate that under vacuum it is down to 52 psi and then jumps to 58 at 0 psi........... just does not go above 58/59 even under full boost. I may log the fuel pressure but I can watch the gauge and determine that it just isn't getting up to where it should be. Yes I'm running the MAF and I even tried speed density and it didn't seem to help. I am maxing the maf out at 12000k hz but it was giving me plenty of fuel the other day. Another minor note: the wideband is downstream of a cat so it may be slightly richer than what I'm reading. Looks to be the magnuson fuel rails with the fpr in the elbow as you are describing. I was thinking of swapping the fpr with another stock replacement part and then going on to an upgraded in tank pump if that doesn't fix the issue. I thought I'd leave the pusher pump in place to "help" the in tank unit. I'll try and post a tune file. Thanks for the help guys! This might, might not be your issue... At what RPM are you hitting 12000kHz.... Anytime that you hit past 12000kHz, the PCM is fueling blind with no good know reference point. At this point you will have to just set a rich WOT AFR. I haven't got time to look over your tune, but I am sure someone else will quickly chime in. Also, if you are maxing out you MAF at an early enough RPM, you will be better off with SD, set up MAP sensor. If possible run one of HPT custom O.S. getting an SD truck to run as good as a MAF truck will take some time, its not as easy as just swaping tunes and going from there. Quote Link to comment Share on other sites More sharing options...
madden Posted March 9, 2011 Author Report Share Posted March 9, 2011 This might, might not be your issue... At what RPM are you hitting 12000kHz.... Anytime that you hit past 12000kHz, the PCM is fueling blind with no good know reference point. At this point you will have to just set a rich WOT AFR. I haven't got time to look over your tune, but I am sure someone else will quickly chime in. Also, if you are maxing out you MAF at an early enough RPM, you will be better off with SD, set up MAP sensor. If possible run one of HPT custom O.S. getting an SD truck to run as good as a MAF truck will take some time, its not as easy as just swaping tunes and going from there. I hear you on the sd tuning. (I tuned my 404 is tuned with sd and it runs great but I prefer using the maf if I can make it work.) If the weather is warmer it hovers just below the max hz but when colder outside it maxes. Like I said though, even when I use the vcm controls to command the tuning richer it does not change. I think a few guys on here are maxing out the maf with a radix setup and still fueling ok??? Am I correct? Thanks for the reply Quote Link to comment Share on other sites More sharing options...
misterp Posted March 9, 2011 Report Share Posted March 9, 2011 (edited) ... The vacuum line is properly connected from the manifold to the regulator. The fuel pressure gauge does indicate that under vacuum it is down to 52 psi and then jumps to 58 at 0 psi........... just does not go above 58/59 even under full boost... That is your fuel rail line pressure problem, the little factory in-line FPR (in the inlet elbow) is 'capping' the pressure at 58-psi (like it's supposed to); you need to remove that from your fuel rail. Wait a minute - where is your FPR plumbed??? Is it in the pressurized fuel supply line, prior to the fuel rail? or in the return line? Pic please?? Your plumbing with an external FPR should be: 1. tank pump to fuel rail 2. fuel rail to injectors 3. excess fuel from fuel rail to FPR 4. FRP to return line, back to tank. Ideally, running an external FPR is the IDEAL solution because you can go into your injector pulsewidth table and use the same value in the whole table; with a factory-style return system you have to 'scale' the injector pulsewidth table. This is better discussed in depth on the tuning forums, both EFILive and HPTuners... So either get rid of the external FPR and run the Radix fuel rails as Magnusson intended, OR plumb custom fuel rails to "do the job right" - "right" in this case will not be "better", you can workaround the factory Magnusson fuel rail setup in the tune and still have a workable fueling strategy. Mr. P. Edited March 9, 2011 by Mr. P. (see edit history) Quote Link to comment Share on other sites More sharing options...
madden Posted March 9, 2011 Author Report Share Posted March 9, 2011 That is your fuel rail line pressure problem, the little factory in-line FPR (in the inlet elbow) is 'capping' the pressure at 58-psi (like it's supposed to); you need to remove that from your fuel rail. Wait a minute - where is your FPR plumbed??? Is it in the pressurized fuel supply line, prior to the fuel rail? or in the return line? Pic please?? Your plumbing with an external FPR should be: 1. tank pump to fuel rail 2. fuel rail to injectors 3. excess fuel from fuel rail to FPR 4. FRP to return line, back to tank. Ideally, running an external FPR is the IDEAL solution because you can go into your injector pulsewidth table and use the same value in the whole table; with a factory-style return system you have to 'scale' the injector pulsewidth table. This is better discussed in depth on the tuning forums, both EFILive and HPTuners... So either get rid of the external FPR and run the Radix fuel rails as Magnusson intended, OR plumb custom fuel rails to "do the job right" - "right" in this case will not be "better", you can workaround the factory Magnusson fuel rail setup in the tune and still have a workable fueling strategy. Mr. P. I thought that the fuel system was plumbed exactly as magnusson intended by looking at it.... ?? Here's some pictures: http://i869.photobucket.com/albums/ab257/madtunesracing/IMG_20110309_110730.jpg http://i869.photobucket.com/albums/ab257/madtunesracing/IMG_20110309_110743-1.jpg http://i869.photobucket.com/albums/ab257/madtunesracing/IMG_20110309_110716.jpg How is this setup? Quote Link to comment Share on other sites More sharing options...
Krambo Posted March 9, 2011 Report Share Posted March 9, 2011 (edited) The vac line you have going to your FPR is incorrect. You need that line to see both boost AND vac. There are 2 little brass plugs on the drivers side manifold (near the firewall side of the manifold) of which both SHOULD see both boost and vac. Remove one of these plugs (1/8NPT) install a small hose barb fitting (available in Home Depot where the fridge ice maker kits are sold) and connect the FPR port with the appropriate sized tubing. Your FP should then see low 60's when in boost and low 50's at idle. Let us know your results! EDIT: Some more thought... What 60# injectors are you running. The picture shows a stock injector plug and stock height rails. Are you using the honed out 42#'rs? Just struck me as suspicious. Another improvement you can do is to create another fuel line X-over to help balance out one fuel rail to the other. Simple fittings and a 10 inch -6an fuel hose are all you need. Edited March 9, 2011 by Krambo (see edit history) Quote Link to comment Share on other sites More sharing options...
misterp Posted March 9, 2011 Report Share Posted March 9, 2011 The upper vacuum port on the J-tube (you are using now) is supposed to go to the bottom nipple of the EVAP purge solenoid. Doublecheck all the fundamental vacuum plumbing - download the Radix install manual (free download from Magnusson's site) and read those instructions, make sure all the kit's vacuum lines are routed correctly. Just so you and I are on good terms (!) I am not busting on you at all; every used truck that I've seen sold with a forced induction kit was not done correctly and required re-doing. My point being, don't assume anything on your truck, take the Magnusson instruction booklet and walk all the way through it again to make sure the original owner did everything correctly, no amount of "software" tuning will ever correct for "hardware" issues! The pics were VERY helpful, don't be afraid to post more. We'll get that rig down into the mid-12's soon! I did not see your external FPR?? Mr. P. Quote Link to comment Share on other sites More sharing options...
madden Posted March 9, 2011 Author Report Share Posted March 9, 2011 The upper vacuum port on the J-tube (you are using now) is supposed to go to the bottom nipple of the EVAP purge solenoid. Doublecheck all the fundamental vacuum plumbing - download the Radix install manual (free download from Magnusson's site) and read those instructions, make sure all the kit's vacuum lines are routed correctly. Just so you and I are on good terms (!) I am not busting on you at all; every used truck that I've seen sold with a forced induction kit was not done correctly and required re-doing. My point being, don't assume anything on your truck, take the Magnusson instruction booklet and walk all the way through it again to make sure the original owner did everything correctly, no amount of "software" tuning will ever correct for "hardware" issues! The pics were VERY helpful, don't be afraid to post more. We'll get that rig down into the mid-12's soon! I did not see your external FPR?? Mr. P. Thanks Krambo and Mr. P Mr. P: I'm not offended by anything you have said I didn't build this truck but I'm going to get it right! (and I prefer to have all of the experienced help that I can get so I don't intend to make you mad either ;) FYI: I've tuned around 400 lsx cars/trucks but have limited experience with boosted applications. Any help is greatly appreciated. As for the external fpr... I didn't think that I had one other than the stock style that is mounted in the fuel rail (in the photo). I'll look at this tonight in detail and try to get the vacuum/boost lines sorted out and then see what results that I can get. From researching old threads, I had found that 03 trucks fuel correctly when set up correctly. I remember reading about an 03 that Zippy was working on and it seems like the fpr was hooked up improperly on his as well and once he got it corrected it fueled great. Hopefully I can fix this without replacing the intank pump. (Although I'm sure it would be better to swap it anyway) Oh and the injectors are deatsch werks : http://cgi.ebay.com/ebaymotors/Chevrolet-Silverado-4-8L-5-3L-6-0L-60lb-Injectors-Chevy-_W0QQcmdZViewItemQQhashZitem2551b5462aQQitemZ160284624426QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories They are a plug and play flow matched set. The 42lb injectors were tapping out at 127% duty cycle (although they may have worked ok if the fpr had been hooked up correctly). Quote Link to comment Share on other sites More sharing options...
misterp Posted March 9, 2011 Report Share Posted March 9, 2011 Awesome - I'm very confident you'll get it to run great. Search for a thread Krambo wrote about tuning for the Radix, there's some good experience documented there. Mr. P. Quote Link to comment Share on other sites More sharing options...
madden Posted March 9, 2011 Author Report Share Posted March 9, 2011 Awesome - I'm very confident you'll get it to run great. Search for a thread Krambo wrote about tuning for the Radix, there's some good experience documented there. Mr. P. I plugged the port on the passenger side of the manifold and tapped into one of the two fittings on the drivers side to plumb the fpr. It immediately hits low 60 psi when I brake boost the truck. I launched from a dead stop and it was spinning all 4 leaving the line. I'll do some extensive testing and datalogging asap and I'll post the results. I imagine I'll have quite a bit of tuning to correct now that it's building the correct fuel pressure. Thanks again. I'll also take another picture (and post it) to show a proper hook up of the fpr which fixed the pressure problem. That will help others in the future. Quote Link to comment Share on other sites More sharing options...
misterp Posted March 10, 2011 Report Share Posted March 10, 2011 ... I launched from a dead stop and it was spinning all 4 leaving the line... WOO-HOOO! Quote Link to comment Share on other sites More sharing options...
ss454327 Posted March 10, 2011 Report Share Posted March 10, 2011 WOO-HOOO! This is great news to hear. I rode in this truck shortly after Jason bought it and it didn't feel much stronger than my high 13 second SSS. He put a ton of hours into making this thing run right and I'm glad to see the fruits of his labor coming together. It's a beautiful and very clean SSS and I hope to be there for the maiden voyage down the 1320! 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.