Injector duty cycle % too high on a few injectors
#1
Injector duty cycle % too high on a few injectors
Hi all,
It's been a long road for me with my SC project. I'm definitely nearing the end.
Car is still running good but I've been doing some datalogging. I noticed that as soon as I hit around 6lbs of boost a couple of my injectors bank 1 and 3 (sometimes 7) hit way over 100% duty cycle; the other 5 are all around 68-70%. I'm wondering if this means that my injectors are going bad. These RC440cc injectors came with the kit and are easily over 10yrs old. I need to find out what's up before I push this car a lot more. Do you think I need new injectors? Has anyone experienced something like this before? Thanks for the help.
It's been a long road for me with my SC project. I'm definitely nearing the end.
Car is still running good but I've been doing some datalogging. I noticed that as soon as I hit around 6lbs of boost a couple of my injectors bank 1 and 3 (sometimes 7) hit way over 100% duty cycle; the other 5 are all around 68-70%. I'm wondering if this means that my injectors are going bad. These RC440cc injectors came with the kit and are easily over 10yrs old. I need to find out what's up before I push this car a lot more. Do you think I need new injectors? Has anyone experienced something like this before? Thanks for the help.
#3
I think I may have found the problem.
Stock 251cc injectors are high impodence (saturated) type and have an ohm/resistance rating of around 15 - 15.5. My RC 440cc injectors I think are suppose to have an ohm reading of 12.5 when new. Mine are around 16.5 - 16.9. Not sure if this is the problem but after research I found that if an injector's resistance is too high it would be fine under normal load conditions but would start to fail under increased load (which is happening to me - issues at higher boost levels).
However, I did read online that typical saturated type injectors ohm ratings range from 13 - 16. So can ~.7 ohm over cause issues? I'm not sure. I'm going to call RC Engineering today to find out more. I may just need new injectors. As noted earlier, they are over 12yrs old.
I'll keep you posted.
Stock 251cc injectors are high impodence (saturated) type and have an ohm/resistance rating of around 15 - 15.5. My RC 440cc injectors I think are suppose to have an ohm reading of 12.5 when new. Mine are around 16.5 - 16.9. Not sure if this is the problem but after research I found that if an injector's resistance is too high it would be fine under normal load conditions but would start to fail under increased load (which is happening to me - issues at higher boost levels).
However, I did read online that typical saturated type injectors ohm ratings range from 13 - 16. So can ~.7 ohm over cause issues? I'm not sure. I'm going to call RC Engineering today to find out more. I may just need new injectors. As noted earlier, they are over 12yrs old.
I'll keep you posted.
#4
I doubt your problem is injectors since it is all happening on one side. I would check for leaks around the manifolds (intake and exhaust) on bank 1. Check all the vacuum lines, injector seals, pcv gasket etc on that side as well. ***P.s. I've seen a lot of lean conditions like that due to cracks in lower injector seals*** If you can do a smoke test. Pepboys usually charges about $30 to do it. I would also compare O2 readings on both banks. If it is a leak your bank 1 O2 readings should be leaner.
Last edited by SweetS160; 12-27-15 at 09:25 AM.
#6
I hear you both and will do a smoke test. BUT, I fail to see how a weak or failing O2 can affect my injector duty cycle when I'm at WOT. The O2's have ZERO input anywhere during WOT. From the things I've read O2's only have a say in how your car runs during closed loop only which is not during WOT. My duty cycle gets jacked up only when I'm in open loop.
#7
I hear you both and will do a smoke test. BUT, I fail to see how a weak or failing O2 can affect my injector duty cycle when I'm at WOT. The O2's have ZERO input anywhere during WOT. From the things I've read O2's only have a say in how your car runs during closed loop only which is not during WOT. My duty cycle gets jacked up only when I'm in open loop.
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