DJ23GSX
20+ Year Contributor
- 773
- 6
- Feb 22, 2004
-
W. Springfield,
Massachusetts
I believe i'm having some sort of fuel delivery issue. I just got my keydiver stage 3 chip and eprom ecu last week and was hoping that would take care of it. It didn't. The chip is compensating for my 2g maf and the 680's with bfp@38psi. I had to add about +18% at idle to get the low trim to 100. After driving the car for a couple of days with the safc set at 0 (except at 1k) the mid and high fuel trims were up in the mid 120's. Jeff suggested to add fuel pressure till the trims evened out. Right now I'm at roughly 45psi bfp and for some reason the high fuel trim was up around 134 now. Totally backwards right? 
Even on my old Non-eprom ecu my fuel trims were always out of wack. I was adding roughly +17-20% on the safc to get them close to 100 on the 2g maf and 680's so I don't think the eprom chip is to blame.
I'm also having knock issues at 6-7k rpm that I can't tune out no matter how much fuel I add or take out. Not sure if these are related or if its phantom knock as I am able to lean out the safc about -5% up to 6k with 0 knock. I dropped my base timing to 3ish* and the knock did drop a little bit at 6-7k. Does that confirm if its real or phantom knock??
All this is at 18psi on a s16g with a fmic, 2g maf, 680's, rewired 255lph, safc, afpr and 93 octane. There's more mods but those should be the important ones for now.
So far i've:
1. Boost leaked tested the car and only have one tiny leak. I am able to pressurize to 25psi and it takes a good couple of minutes to bleed down to 0.
2. Thought maybe the fuel pump (255lph) was leaking at the o-ring in the tank so I cut off the bell on the sending unit and attached the pump to the sending unit with fuel line and hose clamps. One thing I noticed after this was the pump was a lot quieter. I was also able to lean out the safc at idle by a few %. Didn't help the trims or top end knock though. When I pulled out the pump I noticed that the top of it by the o-ring seal and electrical connector was soaked and the rest of the pump was dry. I though for sure that was a sign the seal was leaking. After doing the fuel line/clamp mod I made a few runs and when I got home pulled the pump out again only to see the top of it soaked again while the rest of the pump was dry. I don't know whats going on here so any suggestions would be helpful.
3. New OEM o2 and knock sensors about 1k miles ago. Retorqued the knock sensor a half dozen times and didn't see a difference. Also filled the hole with jb weld and again no change.
4. Ran some fuel injector cleaner. It made no difference.
5. Teflon taped every port including the adjustment rod on my afpr. Didn't help either.
6. I started logging o2 volts and got some wacky readings. At 45psi bfp and +14% at 6-7k on the safc the leaner my o2 volts were reading and they got very jumpy at wot. I have a log if anyone would like to see it. At 42psi bfp and safc at 0 at 6-7k the o2's were consistent at wot (.76v's with no knock till 6k). My idc's are barely reaching 70% even with the safc set to +14% at 6-7k.
I'm stumped and need some advice on where else to start looking. The car pulls decent at 18psi till 6k then timing gets yanked and it falls on its face. I don't see why I can't run 18psi with my mods on 93 octane pump gas.
Even on my old Non-eprom ecu my fuel trims were always out of wack. I was adding roughly +17-20% on the safc to get them close to 100 on the 2g maf and 680's so I don't think the eprom chip is to blame. I'm also having knock issues at 6-7k rpm that I can't tune out no matter how much fuel I add or take out. Not sure if these are related or if its phantom knock as I am able to lean out the safc about -5% up to 6k with 0 knock. I dropped my base timing to 3ish* and the knock did drop a little bit at 6-7k. Does that confirm if its real or phantom knock??
All this is at 18psi on a s16g with a fmic, 2g maf, 680's, rewired 255lph, safc, afpr and 93 octane. There's more mods but those should be the important ones for now.
So far i've:
1. Boost leaked tested the car and only have one tiny leak. I am able to pressurize to 25psi and it takes a good couple of minutes to bleed down to 0.
2. Thought maybe the fuel pump (255lph) was leaking at the o-ring in the tank so I cut off the bell on the sending unit and attached the pump to the sending unit with fuel line and hose clamps. One thing I noticed after this was the pump was a lot quieter. I was also able to lean out the safc at idle by a few %. Didn't help the trims or top end knock though. When I pulled out the pump I noticed that the top of it by the o-ring seal and electrical connector was soaked and the rest of the pump was dry. I though for sure that was a sign the seal was leaking. After doing the fuel line/clamp mod I made a few runs and when I got home pulled the pump out again only to see the top of it soaked again while the rest of the pump was dry. I don't know whats going on here so any suggestions would be helpful.
3. New OEM o2 and knock sensors about 1k miles ago. Retorqued the knock sensor a half dozen times and didn't see a difference. Also filled the hole with jb weld and again no change.
4. Ran some fuel injector cleaner. It made no difference.
5. Teflon taped every port including the adjustment rod on my afpr. Didn't help either.
6. I started logging o2 volts and got some wacky readings. At 45psi bfp and +14% at 6-7k on the safc the leaner my o2 volts were reading and they got very jumpy at wot. I have a log if anyone would like to see it. At 42psi bfp and safc at 0 at 6-7k the o2's were consistent at wot (.76v's with no knock till 6k). My idc's are barely reaching 70% even with the safc set to +14% at 6-7k.
I'm stumped and need some advice on where else to start looking. The car pulls decent at 18psi till 6k then timing gets yanked and it falls on its face. I don't see why I can't run 18psi with my mods on 93 octane pump gas.
