96 SS - High RPM (under load) Flutter/Missed
08-02-2018, 08:48 AM
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96 SS - High RPM (under load) Flutter/Missed Hello!
I have a 1996 Camaro SS with 50k miles and decided to do bolt Ims to support a head and a cam. The heads and cane came out from another Camaro that was pushing 412 rwhp with a similar set up. The heads have about 5,000 miles on them. Here are the mods on my car:
-SPL original performance exhaust
-Original suspension level 2 upgrade
-Torsten 3.42 original rear end
- T56 transmission original
-C5 from calipers w/upgraded rotors
-Pace setters 3"/1.75" cerámic coated long tube headers with Y - erase cats and EGR/smog
-BBK Pulley
-Electric HD 55gpm water pump LT1 compatible.
-160 degree thermo stat
-MSD cables and Opti (original coil and ICM)
-MSD Opti
- Rear break stainless lines
- Ported Heads (similar to LE1) - upgrades springs; stock valves; 1.6 full rockers with upgraded studs
- XFI 280 Cam
- Ported intake manifold
- new lifters ls7
- new cromolly rods
- new timing set
- 52mm BBK TB
- 30# injectors (TFS)
-SLP CAI
-Z06 wheels (GM)
-original MAF
- new upstream O2 sensors
-Tune by Solomon
I just finished the car about 2 months I love it but it has a hesitation (mis) underload at high rpm (over 5100 rpm) feels like a rev limiter stumble. It stumbles once and the car keeps pushing normal. I had Opti issues and I end up installing an MSD Opti because my original died and the missed/flutter was there with the original Opti so I know is not the Opti. The car idle solis and drives normal under the 5000-5100 rpm. The flutter/mis feels like I’m hitting the rev limiter for that instance. If I release the clutch around 2500 rpm and step on it it will break the tires and since is not under load at that time the engine climb to 6000-6500 rpm no issues.
the car gave me the p0152 code (bank 2 high voltage) so I check resistance on all cables and change spark plugs on the right side with no luck. I checked my fuel pressure with the regulator vacum house disconnected and it was 44psi. The pcm is telling me the car is running rich but I see no smoke, no string gas smells. Injectors are new. I swapped the o2 sensors and cross the harnesses to rule out the sensors and posible wiring issue and the issue stay on bank #2. The issue seems to me electric in nature so my next steps when I get back is to swap my coil with iCM from another can and the MAF to rule that out. Any other suggestions will be greatly appreciated. Do you guys think the code p0152 can be related to the mis/flutter? One last thing I have looked for exhaust and vacuum leaks and everything seems pretty tight. I checked my vacuum and at idle I have 12 “ of mercury I know that is low but I also know when you can a car your vac drops. I then check my friends 2002 z06 and vacuum was 12-13” of Mercury any thoughts on that as welll?
I have a 1996 Camaro SS with 50k miles and decided to do bolt Ims to support a head and a cam. The heads and cane came out from another Camaro that was pushing 412 rwhp with a similar set up. The heads have about 5,000 miles on them. Here are the mods on my car:
-SPL original performance exhaust
-Original suspension level 2 upgrade
-Torsten 3.42 original rear end
- T56 transmission original
-C5 from calipers w/upgraded rotors
-Pace setters 3"/1.75" cerámic coated long tube headers with Y - erase cats and EGR/smog
-BBK Pulley
-Electric HD 55gpm water pump LT1 compatible.
-160 degree thermo stat
-MSD cables and Opti (original coil and ICM)
-MSD Opti
- Rear break stainless lines
- Ported Heads (similar to LE1) - upgrades springs; stock valves; 1.6 full rockers with upgraded studs
- XFI 280 Cam
- Ported intake manifold
- new lifters ls7
- new cromolly rods
- new timing set
- 52mm BBK TB
- 30# injectors (TFS)
-SLP CAI
-Z06 wheels (GM)
-original MAF
- new upstream O2 sensors
-Tune by Solomon
I just finished the car about 2 months I love it but it has a hesitation (mis) underload at high rpm (over 5100 rpm) feels like a rev limiter stumble. It stumbles once and the car keeps pushing normal. I had Opti issues and I end up installing an MSD Opti because my original died and the missed/flutter was there with the original Opti so I know is not the Opti. The car idle solis and drives normal under the 5000-5100 rpm. The flutter/mis feels like I’m hitting the rev limiter for that instance. If I release the clutch around 2500 rpm and step on it it will break the tires and since is not under load at that time the engine climb to 6000-6500 rpm no issues.
the car gave me the p0152 code (bank 2 high voltage) so I check resistance on all cables and change spark plugs on the right side with no luck. I checked my fuel pressure with the regulator vacum house disconnected and it was 44psi. The pcm is telling me the car is running rich but I see no smoke, no string gas smells. Injectors are new. I swapped the o2 sensors and cross the harnesses to rule out the sensors and posible wiring issue and the issue stay on bank #2. The issue seems to me electric in nature so my next steps when I get back is to swap my coil with iCM from another can and the MAF to rule that out. Any other suggestions will be greatly appreciated. Do you guys think the code p0152 can be related to the mis/flutter? One last thing I have looked for exhaust and vacuum leaks and everything seems pretty tight. I checked my vacuum and at idle I have 12 “ of mercury I know that is low but I also know when you can a car your vac drops. I then check my friends 2002 z06 and vacuum was 12-13” of Mercury any thoughts on that as welll?
08-02-2018, 01:55 PM
#5
OP
FWIW I replaced what I thought was a failing AC Delco opti with a new MSD. Problem persisted. Basically high rpm stumble where car fell flat on its face. I don't want to list the LONG line of parts replaced because "my brand new MSD Opti must be good"....it was not. Put on Delphi I had purchased new and all resolved
If you got the MSD opti in the last 2 years....they have a horrible record
Just my $.02
FWIW I replaced what I thought was a failing AC Delco opti with a new MSD. Problem persisted. Basically high rpm stumble where car fell flat on its face. I don't want to list the LONG line of parts replaced because "my brand new MSD Opti must be good"....it was not. Put on Delphi I had purchased new and all resolved
If you got the MSD opti in the last 2 years....they have a horrible record
Just my $.02
08-02-2018, 02:28 PM
#6
TECH Regular
Do you have any way to datalog the car? That would be a great thing to do... Also, as ****** and others on here have seen - a new opti, especially if its an MSD, doesn't mean jack. The code you have says that the PCM is pulling fuel from that bank because it sees it as rich, which may make it misfire.If your injector inspection doesn't show anything obvious, I'd swap the injectors over side-to-side and see if that makes the code jump sides. If not, I'd really start giving the MSD opti the stinkeye
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08-02-2018, 03:05 PM
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08-02-2018, 03:09 PM
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FWIW I replaced what I thought was a failing AC Delco opti with a new MSD. Problem persisted. Basically high rpm stumble where car fell flat on its face. I don't want to list the LONG line of parts replaced because "my brand new MSD Opti must be good"....it was not. Put on Delphi I had purchased new and all resolved
If you got the MSD opti in the last 2 years....they have a horrible record
Just my $.02
FWIW I replaced what I thought was a failing AC Delco opti with a new MSD. Problem persisted. Basically high rpm stumble where car fell flat on its face. I don't want to list the LONG line of parts replaced because "my brand new MSD Opti must be good"....it was not. Put on Delphi I had purchased new and all resolved
If you got the MSD opti in the last 2 years....they have a horrible record
Just my $.02
08-02-2018, 03:13 PM
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Do you have any way to datalog the car? That would be a great thing to do... Also, as ****** and others on here have seen - a new opti, especially if its an MSD, doesn't mean jack. The code you have says that the PCM is pulling fuel from that bank because it sees it as rich, which may make it misfire.If your injector inspection doesn't show anything obvious, I'd swap the injectors over side-to-side and see if that makes the code jump sides. If not, I'd really start giving the MSD opti the stinkeye
08-02-2018, 03:48 PM
#12
Weak valve springs do show up in higher rpm feeling like the car will "nose over", stumble, misfire "symptom"
Your issue may not be valve spring related...just passing on my experience with the Comp Bee Hives
Only way to find a original AC Delco Opti is junkyard. Delphi seem to be extinct now.
Occasionally rockauto has "reman" AC Delco...I have no experience with them but if I had to get a Opti today that is what I would get simply by default as best possible option.
08-02-2018, 09:10 PM
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08-03-2018, 01:00 PM
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08-03-2018, 01:05 PM
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As an update... I have a friend that has a 97SS and I’m getting his MAF, Coil and ICM module probably Monday and I will attempt to rule the injectors, coil and MAF. i have some old logging I did but I’m in the process of getting the software. I will give you an update of my findings... if all that fails we will have to look at Opti or Valve springs... I hope I don’t have to do a LS swap on this car... I like the LS engine but I love the sound of my LT! Stay tune and than you for your input
08-08-2018, 12:35 AM
#20
TECH Resident
Get the car on a dyno, get a scope....logging scope like a pico would be best....put a current clamp on the primary of the ignition coil, you'll then need a sync pulse to id the cylinders of the primary current pulses you'll be looking at....can be a secondary ignition signal or even the opti low res signal.
Run it up to 6000rpm. You should be able to log the current ramps and give you a direction as to if the problem is primary or secondary ignition given how the current ramps look. Might not be in the ignition at all....but given the MSD Opti track record...
You can also do some secondary ignition logging with the right probes as well.
Run it up to 6000rpm. You should be able to log the current ramps and give you a direction as to if the problem is primary or secondary ignition given how the current ramps look. Might not be in the ignition at all....but given the MSD Opti track record...
You can also do some secondary ignition logging with the right probes as well.