Tuning Problems
07-05-2003, 11:53 AM
#1
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Tuning Problems
I have a 97 Z-28 with a Corvette 4-bolt block, bored .030 over, Lunati stroker crank, Lunati rods, SRP flat top pistons, AFR 195 LT4 heads, LT4 intake, CompCams 1.6 Pro Magnum rockers, Crane hydraulic roller lifters, Comp Cam 503 cam, Meziere water pump, Holley 58mm throttle body, Holley adjustable fuel pressure regulator, Ford SVO 30# injectors, Del-Trans 4L60E tranny with Pro-Torque 2400 stall convertor, Moser 12 bolt rear with 3.73 gears, blah blah blah. Anyway I have a tune sent to me from PCMSFORLESS and I am having trouble. The car seems to be running fine, it feels strong, very seldom do I get misfire codes, but my best times on at the ¼ mile is 13.03. I thought I have done everything correctly with the setup and thought I should be in the low 12s at least with this. I have been running on M/T ET Streets so traction isn’t the problem. I am thinking it may be a fuel problem. At normal cruise I am around 36psi and at WOT I’m around 40.5. I have OBDII scantool software and don’t really know where to start looks on my scans for the problem. If someone could maybe point me in the right direction for things to look for. I know this question is vague but all input is greatly appreciated. Thanks!
07-05-2003, 02:17 PM
#2
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put down some data you are seeing.
Have you had this engine Dynoed? Have it been wideband 02 tested?
Just from my experience, there are so many more factors that affect 1/4 mi time that must be considered. I would start with what the dyno says and go from there. You may in fact have fueling issues, but the track will not tell you that, a wideband will.
Have you had this engine Dynoed? Have it been wideband 02 tested?
Just from my experience, there are so many more factors that affect 1/4 mi time that must be considered. I would start with what the dyno says and go from there. You may in fact have fueling issues, but the track will not tell you that, a wideband will.
07-05-2003, 04:37 PM
#3
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I haven't had it on the dyno yet. After spending close to $18k on this project I am pretty much broke for a little bit. I have LT1_Edit and this OBDII scanner software so I figure I could get some info and maybe make some changes until I can afford some dyno time. Anyway I just grabbed some data from the scantool software and don't really know what I should be looking for but here is some of the data I am seeing:
LOAD_PCT: 98.8 %
SHRTFT1: 0.0 %
LONGFT1: 25.0 %
SHRTFT2: 0.0 %
LONGFT2: 25.0%
MAP: 28.1 inHg
RPM: 5704
VSS: 110
SPARKADV: 32.0 degree
IAT: 102 F
MAF: 32.833 #/min
TP: 100.0 %
02S11 SHRTFT11: .850 0.0
02S12 SHRTFT12: .895 N/A
02S21 SHRTFT21: .885 0.0
02S22 SHRTFT22: .330 N/A
Here is another reading at 30% throttle
LOAD_PCT: 13.7 %
SHRTFT1: 0.0 %
LONGFT1: 25.0 %
SHRTFT2: 0.0 %
LONGFT2: 17.2%
MAP: 12.4 inHg
RPM: 2591
VSS: 75
SPARKADV: 29.0 degree
IAT: 100 F
MAF: 9.344 #/min
TP: 30.2 %
02S11 SHRTFT11: .835 0.0
02S12 SHRTFT12: .280 N/A
02S21 SHRTFT21: .840 0.0
02S22 SHRTFT22: .880 N/A
Once again any input would be greatly appreciated. Thanks!
LOAD_PCT: 98.8 %
SHRTFT1: 0.0 %
LONGFT1: 25.0 %
SHRTFT2: 0.0 %
LONGFT2: 25.0%
MAP: 28.1 inHg
RPM: 5704
VSS: 110
SPARKADV: 32.0 degree
IAT: 102 F
MAF: 32.833 #/min
TP: 100.0 %
02S11 SHRTFT11: .850 0.0
02S12 SHRTFT12: .895 N/A
02S21 SHRTFT21: .885 0.0
02S22 SHRTFT22: .330 N/A
Here is another reading at 30% throttle
LOAD_PCT: 13.7 %
SHRTFT1: 0.0 %
LONGFT1: 25.0 %
SHRTFT2: 0.0 %
LONGFT2: 17.2%
MAP: 12.4 inHg
RPM: 2591
VSS: 75
SPARKADV: 29.0 degree
IAT: 100 F
MAF: 9.344 #/min
TP: 30.2 %
02S11 SHRTFT11: .835 0.0
02S12 SHRTFT12: .280 N/A
02S21 SHRTFT21: .840 0.0
02S22 SHRTFT22: .880 N/A
Once again any input would be greatly appreciated. Thanks!
07-06-2003, 03:00 PM
#4
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If you don't have a bigger-than-stock fuel pump, you may be on the edge of its ability to supply your engine's needs.
Your O2 sensor values look a bit low, especially that the .330 and .280 values (VERY lean for WOT). Looks to me like you don't have enough fuel.
You should be able to get a decent 255lph pump for less than $150.
Your O2 sensor values look a bit low, especially that the .330 and .280 values (VERY lean for WOT). Looks to me like you don't have enough fuel.
You should be able to get a decent 255lph pump for less than $150.
07-06-2003, 03:14 PM
#5
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I was thinking of getting an Aeromotive fuel pump. I don't have the money right now. Those two numbers on the O2 sensors that are reading low, are they the rear two sensors? The rear two sensors have been replaced with O2 simulators.
07-06-2003, 11:31 PM
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Just by looking at your combo...
What headers are you running?
What did you set fuel pressure at (should be 39-43psi with the vacuum line off)?
What was your 60'?
What kind of mph are you trapping?
What are your shift points?
All of that extra stereo stuff probably doesn't help either.
I wouldn't suspect a fuel problem yet.
I would spend the $100 and get some baseline pulls somewhere on a dyno and log your a/f ratio. After spending $18k you have to have an extra hundred somehwere.
The O2 voltage is fine, kind of worthless to help in figuring your problem out but fine.
What headers are you running?
What did you set fuel pressure at (should be 39-43psi with the vacuum line off)?
What was your 60'?
What kind of mph are you trapping?
What are your shift points?
All of that extra stereo stuff probably doesn't help either.
I wouldn't suspect a fuel problem yet.
I would spend the $100 and get some baseline pulls somewhere on a dyno and log your a/f ratio. After spending $18k you have to have an extra hundred somehwere.
The O2 voltage is fine, kind of worthless to help in figuring your problem out but fine.
07-07-2003, 01:46 AM
#7
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my shift points are set at 5750 RPMS. These were originally set at 5900 but I told Brian I was hitting a rev limiter, which I forgot was in my MSD. That has been fixed but I didn't change the shift points back to their original points (5900 from PCM4Less programming).
I am running SLP shorty 1 3/4" coated headers. My fuel pressure is reading 40.5-41 at WOT when driving. I forget what it was when I set it with the vacuum line off (not driving).
R/T .617
60' 1.962
330 5.456
1/8 8.364
MPH 83.89
1000 10.902
1/4 13.036
MPH 106.04
I am running SLP shorty 1 3/4" coated headers. My fuel pressure is reading 40.5-41 at WOT when driving. I forget what it was when I set it with the vacuum line off (not driving).
R/T .617
60' 1.962
330 5.456
1/8 8.364
MPH 83.89
1000 10.902
1/4 13.036
MPH 106.04
07-07-2003, 06:17 PM
#8
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CC 305 cam in a 383? Seems kind of small for that displacement. But I'm sure others would know better than I would.
60ft time seems pretty slow. I would think you should be solidly in the 1.7's with a marginal suspension? My buddies hotcam/longtube car does it with a stock suspension.
There is some ET and mph there.
What torque converter is in the car?
Longtubes might be worth a couple mph.
Other than that stuff that would help pull every little bit out of your car, the only other thing I could tell you is to get it on a dyno so we could see the hp/torque graph and wideband data.
60ft time seems pretty slow. I would think you should be solidly in the 1.7's with a marginal suspension? My buddies hotcam/longtube car does it with a stock suspension.
There is some ET and mph there.
What torque converter is in the car?
Longtubes might be worth a couple mph.
Other than that stuff that would help pull every little bit out of your car, the only other thing I could tell you is to get it on a dyno so we could see the hp/torque graph and wideband data.
07-07-2003, 06:32 PM
#9
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No, not the 305, it's the 503.
http://www.compcams.com/catalog/086_087.html
CompCams recommended this cam for me over the 306. The said it would be better suited for an N/A vehicle that will be driven a lot.
I am using a Pro-Torque 2400 stall converter. Even though this seems low it was also recommended for a car driven a lot.
http://www.compcams.com/catalog/086_087.html
CompCams recommended this cam for me over the 306. The said it would be better suited for an N/A vehicle that will be driven a lot.
I am using a Pro-Torque 2400 stall converter. Even though this seems low it was also recommended for a car driven a lot.
07-07-2003, 08:17 PM
#10
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That stall speed sounds too low for your combination. When I bought my Vigilante, Precision Industries recommended a 2600 stall for my stock LT1. Yours has to have a higher torque peak than mine so your stall would need to be higher, 2800 or so....??? Just guessing about your combo, don't know where it peaks.
07-07-2003, 08:22 PM
#11
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Ahh...sorry. 
I'm sure there might be some more mph in the tuning though. A mail order tune isn't dead nuts on.
I think you have to realize that you may have skimped a little on some parts (namely the cam and converter) and that it isn't fair to compare your car to everyone else's on this site that has a similiar combo.
What kind of weather did you run the 13.03@106 in?
Not sure what else we can tell you regarding the actual tune on the car without dyno info. But you're right, there should definitely be more in it.
I'm sure there might be some more mph in the tuning though. A mail order tune isn't dead nuts on.
I think you have to realize that you may have skimped a little on some parts (namely the cam and converter) and that it isn't fair to compare your car to everyone else's on this site that has a similiar combo.
What kind of weather did you run the 13.03@106 in?
Not sure what else we can tell you regarding the actual tune on the car without dyno info. But you're right, there should definitely be more in it.
07-07-2003, 08:40 PM
#12
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Well I wouldn't say I skimped on some parts. I think of that as meaning I should of spent the extra money to get a better quality item I was told not to use the 306 because I have emissions in my state and I would never pass. I recently realized since I am OBDII they just plug in and check for codes and don't run a sniffer. So I could of went with the 306 and not worried about it. As far as the converter Pro-Torque is a good company and it is a $750 converter. But I think you meant I should of went with a higher stall and even CompCams recommended at 2000 which is on their catalog with that setup. Anyway, I am probably going to have to get the 306 and maybe atleast a 2800 in the future.
I think I am meeting with Bryan from PCMforLESS on Wed. to hit a dyno. Thanks for the info.
I was told not to use the 306 because I have emissions in my state and I would never pass. I recently realized since I am OBDII they just plug in and check for codes and don't run a sniffer. So I could of went with the 306 and not worried about it. As far as the converter Pro-Torque is a good company and it is a $750 converter. But I think you meant I should of went with a higher stall and even CompCams recommended at 2000 which is on their catalog with that setup. Anyway, I am probably going to have to get the 306 and maybe atleast a 2800 in the future. I think I am meeting with Bryan from PCMforLESS on Wed. to hit a dyno. Thanks for the info.
07-07-2003, 09:10 PM
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Originally posted by OrionSPL
Well I wouldn't say I skimped on some parts. I think of that as meaning I should of spent the extra money to get a better quality item I was told not to use the 306 because I have emissions in my state and I would never pass. I recently realized since I am OBDII they just plug in and check for codes and don't run a sniffer. So I could of went with the 306 and not worried about it. As far as the converter Pro-Torque is a good company and it is a $750 converter. But I think you meant I should of went with a higher stall and even CompCams recommended at 2000 which is on their catalog with that setup. Anyway, I am probably going to have to get the 306 and maybe atleast a 2800 in the future.
I think I am meeting with Bryan from PCMforLESS on Wed. to hit a dyno. Thanks for the info.
Well I wouldn't say I skimped on some parts. I think of that as meaning I should of spent the extra money to get a better quality item
I was told not to use the 306 because I have emissions in my state and I would never pass. I recently realized since I am OBDII they just plug in and check for codes and don't run a sniffer. So I could of went with the 306 and not worried about it. As far as the converter Pro-Torque is a good company and it is a $750 converter. But I think you meant I should of went with a higher stall and even CompCams recommended at 2000 which is on their catalog with that setup. Anyway, I am probably going to have to get the 306 and maybe atleast a 2800 in the future. I think I am meeting with Bryan from PCMforLESS on Wed. to hit a dyno. Thanks for the info.
I think you'll be happier after the dyno tune. Let us know what happens.
07-10-2003, 08:00 PM
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Well the dyno confirmed that I wasted $20K. I got a 360max hp 360max torque going in and came out with 359 max power and 378 max torque. They said the only thing they could see was maybe the headers are not sufficient for my setup. I think I am going to go with a set of long tubes. I am using the SLP shorties and they said they were probably too restrictive. I am also thinking of another cam. Anyone have any recommendations? Every road seems like a dead end with this POS.
I got a 360max hp 360max torque going in and came out with 359 max power and 378 max torque. They said the only thing they could see was maybe the headers are not sufficient for my setup. I think I am going to go with a set of long tubes. I am using the SLP shorties and they said they were probably too restrictive. I am also thinking of another cam. Anyone have any recommendations? Every road seems like a dead end with this POS.