S 4 has a slight hesataion or miss after SC install & is there an EGR Valve
07-05-2007, 10:58 PM
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Burning Brakes
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S 4 has a slight hesataion or miss after SC install & is there an EGR Valve
After installing the Murf SC system (Loving it by the way) I have a very slight miss or hesation problem. I am not saying this was caused by the SC it is just something that has crept up. I have installed new plugs, plug wires, had the MAF reworked, New O2 when I installed the X pipe, I just did the TB/WP and the cap's and rotors look like new. When the SC was installed we un did the fuel lines at the fire wall and installed a Vortec FMU, We disturbed the fuel line and I am thinking we knocked some dirt loose. Car does not miss at all that I can tell when I give it pedel just when I am crusing at a steady speed.
I have the problem only when I am driving at a steady speed and it is a slight seat of the paints feel. It happens when I am driving around town in any gear when I am holding it at 2-5K rpm like when your in 2nd pulling at 3k rpm going from light to light. I pulled the injectors today and will be sending them out tomorrow to be reworked and balenced. With 20 year old injectors and only 80K miles it won't hurt to have them cleaned and balenced anyways. I am about running out of things to check, has anybody had this type of problem? Like I said this did not happen becuase of the SC install it is just a weak link that has now come up
Cliff 87 S4 Murf # 44
I have the problem only when I am driving at a steady speed and it is a slight seat of the paints feel. It happens when I am driving around town in any gear when I am holding it at 2-5K rpm like when your in 2nd pulling at 3k rpm going from light to light. I pulled the injectors today and will be sending them out tomorrow to be reworked and balenced. With 20 year old injectors and only 80K miles it won't hurt to have them cleaned and balenced anyways. I am about running out of things to check, has anybody had this type of problem? Like I said this did not happen becuase of the SC install it is just a weak link that has now come up
Cliff 87 S4 Murf # 44
Last edited by Cliff Ruckstuhl; 07-06-2007 at 12:14 AM.
07-05-2007, 11:39 PM
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No EGR valve.
Try explaining that to the dude doing the visual emissions check...
Try explaining that to the dude doing the visual emissions check...
07-06-2007, 10:10 PM
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Cliff,
I have not had this issue, but the injectors are probably overdue for a cleaning anyway. My old 19# injectors were pretty far off at 51000 miles. You are now pushing yours a bit harder than stock, so it could cause a bit of an issue.........
Have you ever been under the intake to check the TPS, isv, knock sensors, breather and vacuum lines?
Also, are you sure the MAF boot is totally sealed off, tight to both the throttle body and MAF? That is another good place to look while the fuel rails are off and access is good.
Jim
I have not had this issue, but the injectors are probably overdue for a cleaning anyway. My old 19# injectors were pretty far off at 51000 miles. You are now pushing yours a bit harder than stock, so it could cause a bit of an issue.........
Have you ever been under the intake to check the TPS, isv, knock sensors, breather and vacuum lines?
Also, are you sure the MAF boot is totally sealed off, tight to both the throttle body and MAF? That is another good place to look while the fuel rails are off and access is good.
Jim
07-07-2007, 07:28 PM
#7
Could be TPS, but it would have had similar symptoms before the Murph SC....
The symptoms along with the fact that you've just had your intake and assorted items off, indicate to me intake or vacuum leakage....
Pressurize your intake with the inner-tube or rubber glove trick and check it out.....
Best,
The symptoms along with the fact that you've just had your intake and assorted items off, indicate to me intake or vacuum leakage....
Pressurize your intake with the inner-tube or rubber glove trick and check it out.....
Best,
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07-16-2007, 04:31 PM
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Burning Brakes
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I am back from vaction and had a chance to install the fuel injectors. I had sent them out to be cleaned and balenced. Miss is allot better and almost gone, I am going to drive it some and see how it works. It is possible that this was there before the Murf SC and I am now driving it differently. Since adding the SC I do allot more of the 2-3-2 shifting and I am not sure if I did allot of that before. I am sure the MAF boot is down tight.
I have the Vortec SC so the intake never came off and where would my TPS be on my set up with the Murf SC??
Cliff 87 S 4 Murf # 44
I have the Vortec SC so the intake never came off and where would my TPS be on my set up with the Murf SC??
Cliff 87 S 4 Murf # 44
07-17-2007, 02:12 AM
#9
My bad Cliff, I just assumed the intake was off.....
The TPS is under the intake mounted to the side of the throttle body shaft.....
You can check its function easy enough with a meter though.....
Pull the LH computer plug and check the idle contact for continuity between pins 2 and 5 with the throttle closed, then you should lose continuity when you barely open the throttle......
Then check the full load contact at pins 3 and 5..... You should have no continuity between these until the throttle is 2/3's open....
I'd still investigate for intake or vacuum leakage, by pressurizing the intake and see if it holds.....
One simple method is to take a rubber glove with a little hole cut in one finger, then take a 4" hose clamp and put it on top of the MAF and blow in it..... It should inflate the glove and hold air pressure without leaking away quickly...
Best,
Greg
The TPS is under the intake mounted to the side of the throttle body shaft.....
You can check its function easy enough with a meter though.....
Pull the LH computer plug and check the idle contact for continuity between pins 2 and 5 with the throttle closed, then you should lose continuity when you barely open the throttle......
Then check the full load contact at pins 3 and 5..... You should have no continuity between these until the throttle is 2/3's open....
I'd still investigate for intake or vacuum leakage, by pressurizing the intake and see if it holds.....
One simple method is to take a rubber glove with a little hole cut in one finger, then take a 4" hose clamp and put it on top of the MAF and blow in it..... It should inflate the glove and hold air pressure without leaking away quickly...
Best,
Greg
