High RPM breakup
09-06-2005, 11:13 PM
#1
High RPM breakup Hey guys I have a problem that I never really noticed untill after I put the blower on my car. It seems like an ignition problem to me, but I don't know what to do.
Some details from after the blower install, and while tuning:
Opti had 35,xxx on it
Crane HI-6
Crane LX92 coil
new Taylor wires
new NGK TR6 plugs (checked the tips, all tight)
stock MAF (screen still in it)
LPE/Accel 58mm TB
Here is a dyno graph from then:
http://performin.homeip.net/images/hosting/joshdyno.bmp
Since I thought it was the Opti going south, I replaced a few items:
NEW GM opti (from a dealership)
New (again) TR6 plugs (checked the tips, all tight)
New (used) engine wiring harness (changed for other reasons)
New Bosch O2 sensors
Edelbrock 58mm TB.
The car is still acting EXACTLY like it was before.
BUT
A shop here in town recently had this exact problem with a heads/cam 97SS. Our dyno graphs looked almost exactly alike after 4500 rpm.
Some things about that car:
New opti
stock ignition
tried new coil, and ignition module
added Delteq-NO CHANGE
traced all the engine grounds-all checked out good.
Have any of you experienced this? What else should be checked?
Any and all help is greatly appreciated!!!!
Thanks,
Some details from after the blower install, and while tuning:
Opti had 35,xxx on it
Crane HI-6
Crane LX92 coil
new Taylor wires
new NGK TR6 plugs (checked the tips, all tight)
stock MAF (screen still in it)
LPE/Accel 58mm TB
Here is a dyno graph from then:
http://performin.homeip.net/images/hosting/joshdyno.bmp
Since I thought it was the Opti going south, I replaced a few items:
NEW GM opti (from a dealership)
New (again) TR6 plugs (checked the tips, all tight)
New (used) engine wiring harness (changed for other reasons)
New Bosch O2 sensors
Edelbrock 58mm TB.
The car is still acting EXACTLY like it was before.
BUT
A shop here in town recently had this exact problem with a heads/cam 97SS. Our dyno graphs looked almost exactly alike after 4500 rpm.
Some things about that car:
New opti
stock ignition
tried new coil, and ignition module
added Delteq-NO CHANGE
traced all the engine grounds-all checked out good.
Have any of you experienced this? What else should be checked?
Any and all help is greatly appreciated!!!!
Thanks,
09-07-2005, 09:52 AM
#2
i just got my car tuned and i have the exact same problem except i have stock ignition so im about to buy new coil, and msd box, possibly opti but check your fuel pump because they put a gauge on mine and thats going also so not sure what else it could be
oh yeah what about injectors?
just trying to help out
mark
oh yeah what about injectors?
just trying to help out
mark
09-07-2005, 11:36 AM
#3
Originally Posted by lt1 97 formula
i just got my car tuned and i have the exact same problem except i have stock ignition so im about to buy new coil, and msd box, possibly opti but check your fuel pump because they put a gauge on mine and thats going also so not sure what else it could be
oh yeah what about injectors?
just trying to help out
mark
oh yeah what about injectors?
just trying to help out
mark
The fuel pump is good-holds pressure throughout the run. The injectors are new 42# Motorsports. There is a lot left in both the pump and the injectors, so it doesn't look like they are the problem.
09-07-2005, 01:04 PM
#5
Well I am having the same issue with my 383 n/a motor. I fixed a charging issues and now running 14.2 volts and anything above 5k rpms the car breaks up.
Looking at your sheet, you go from 12's to pig rich 10's as you move up in the rpm band. I would tend to think that the spark is being interupted or snuffed out..... cus when you dont get spark to happen, you dont get combustion hence your fuel is being unburned..... there for pig rich.... I am replacing my opti for the short term and then going to a coil per cyl setup.
Looking at your sheet, you go from 12's to pig rich 10's as you move up in the rpm band. I would tend to think that the spark is being interupted or snuffed out..... cus when you dont get spark to happen, you dont get combustion hence your fuel is being unburned..... there for pig rich.... I am replacing my opti for the short term and then going to a coil per cyl setup.
09-07-2005, 01:33 PM
#7
Originally Posted by 98pontiacfirehawk
Have you check the opti jumper harness, I had the same problem, ended up being the harness gummed up with green crap.
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09-07-2005, 01:35 PM
#8
Originally Posted by BlackScreaminMachine
Well I am having the same issue with my 383 n/a motor. I fixed a charging issues and now running 14.2 volts and anything above 5k rpms the car breaks up.
Looking at your sheet, you go from 12's to pig rich 10's as you move up in the rpm band. I would tend to think that the spark is being interupted or snuffed out..... cus when you dont get spark to happen, you dont get combustion hence your fuel is being unburned..... there for pig rich.... I am replacing my opti for the short term and then going to a coil per cyl setup.
Looking at your sheet, you go from 12's to pig rich 10's as you move up in the rpm band. I would tend to think that the spark is being interupted or snuffed out..... cus when you dont get spark to happen, you dont get combustion hence your fuel is being unburned..... there for pig rich.... I am replacing my opti for the short term and then going to a coil per cyl setup.
09-07-2005, 01:42 PM
#9
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I am having a similar problem and it has been going on for the last two years. I still have not figured it out. My car has been on the dyno numerous times and the tuner kept telling me to replace things and bring it back and each time it did the same thing and he just looked at it puzzled. Mine breaks up or kind of surges after about 5000 rpms.
I have replaced Opti, plugs, wires, coil, and checked all the grounds. The tuner did insist that it was ignition related and did not have anything to do with fuel. I am very frustrated at this point. I am thinking about taking it to another local shop to see if they can't help me pinpoint the problem. Let us know if you get it figured out. Good luck!
Brian
I have replaced Opti, plugs, wires, coil, and checked all the grounds. The tuner did insist that it was ignition related and did not have anything to do with fuel. I am very frustrated at this point. I am thinking about taking it to another local shop to see if they can't help me pinpoint the problem. Let us know if you get it figured out. Good luck!
Brian
09-07-2005, 02:02 PM
#10
Originally Posted by INSTG8R
I am having a similar problem and it has been going on for the last two years. I still have not figured it out. My car has been on the dyno numerous times and the tuner kept telling me to replace things and bring it back and each time it did the same thing and he just looked at it puzzled. Mine breaks up or kind of surges after about 5000 rpms.
I have replaced Opti, plugs, wires, coil, and checked all the grounds. The tuner did insist that it was ignition related and did not have anything to do with fuel. I am very frustrated at this point. I am thinking about taking it to another local shop to see if they can't help me pinpoint the problem. Let us know if you get it figured out. Good luck!
Brian
I have replaced Opti, plugs, wires, coil, and checked all the grounds. The tuner did insist that it was ignition related and did not have anything to do with fuel. I am very frustrated at this point. I am thinking about taking it to another local shop to see if they can't help me pinpoint the problem. Let us know if you get it figured out. Good luck!
Brian
09-07-2005, 03:23 PM
#11
Originally Posted by 98pontiacfirehawk
Have you check the opti jumper harness, I had the same problem, ended up being the harness gummed up with green crap.
09-08-2005, 11:05 AM
#13
Originally Posted by BlackScreaminMachine
I also got a new connector that goes to the opti spark. It was 88$ but since its been mentioned sooooo many times, i am going to do it as a precautionary reason.
09-08-2005, 05:01 PM
#14
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Yeah, the one that goes into the opti. You can not clean it as I know of .I changed the opti,wires,plugs aswell it ended up being the jumper harness.It may be your problem it may not, but sounds just like the problem I had.
09-09-2005, 10:32 PM
#17
Ponyhtr I was having very similar problems are you are...on my car the only mod I had was a magnaflow exhuast and I was breaking up really bad at 4500k+. I replaced the coil with the msd one and that didnt work. So I got datamaster and a cable and found out the PCM was putting 11 degrees of timing at pretty much anything over 4k. I assumed it was doing this because of the exhaust so I got the LT4 knock moduel and problem solved, not it is not retarding any timing at all. I could show you some screen shots from datamaster of the before and after results if you wanted.
I dk if you have any exhaust work or a noiser valve train but it you do I would try the LT4 KM its only $30-40. Takes like 5 minutes to do
I dk if you have any exhaust work or a noiser valve train but it you do I would try the LT4 KM its only $30-40. Takes like 5 minutes to do
09-10-2005, 07:14 AM
#18
Originally Posted by z28_theantirice
Ponyhtr I was having very similar problems are you are...on my car the only mod I had was a magnaflow exhuast and I was breaking up really bad at 4500k+. I replaced the coil with the msd one and that didnt work. So I got datamaster and a cable and found out the PCM was putting 11 degrees of timing at pretty much anything over 4k. I assumed it was doing this because of the exhaust so I got the LT4 knock moduel and problem solved, not it is not retarding any timing at all. I could show you some screen shots from datamaster of the before and after results if you wanted.
I dk if you have any exhaust work or a noiser valve train but it you do I would try the LT4 KM its only $30-40. Takes like 5 minutes to do
I dk if you have any exhaust work or a noiser valve train but it you do I would try the LT4 KM its only $30-40. Takes like 5 minutes to do
I've done scans of it on the dyno, it's not pulling any timing at all...it's at the desired 17-18 degrees at WOT.
Mitch-
I haven't had a chance to work on the car yet...hopefully I will this weekend.
09-11-2005, 10:23 AM
#19
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I'd do all of the simple things; check for exhaust leaks, make sure all of your connections are tight(especially on f.i.-specifically going into your throttle body), check fuel filter, plug wires etc. I've also found that if your roller rockers are not set properly tight they can cause a break or erratic looking dyno graph. Just some things to look at that I've run across.
03-12-2006, 09:32 AM
#20
Well guys, I found my problem! It was the vacuum line going from the intake to the fuel pressure regulator! It had been pinched at one time, and had a hole in it. Replaced it, and wala! Went to the track yesterday, and had 0 problems! Ran a new best also, times in sig!!
Just wanted to let those that had subscribed to this thread what I found!
Just wanted to let those that had subscribed to this thread what I found!