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.

 

You can try moving the injectors around and recheck to see if it's the injectors or something else.

 

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.

 

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.

 

great suggestion. kinda like maybe a failing or jacked up o2 sensor??? !!!!!!!!!!!

 

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.

 

I usually just log the O2 sensors at idle for this test. It's just to check if they are operating at the same range. If they are off you know something might be leaking. If all is ok then I usually test fuel pressure at WOT to make sure the pump is keeping up.

 

The fuel pressure is suspect in my opinion. I have not checked yet at WOT.

 

if it fuel pressure, than why does it only do it on one side? if its running fine than don't worry about data logging.