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Roush RPM Spike

  • Thread starter Thread starter mkkrs1
  • Start date Start date Jun 27, 2005

mkkrs1

Member
Dec 2, 2004
49
0
6
indian trail,nc
Jun 27, 2005
#1
  • Jun 27, 2005
  • #1
Have any of you Fox body owners encountered this problem. When I shift gears the rpm spikes up a sticks when driving normal. If I shift around 1800 the rpm will climb to 2200-2400. Need to get fixed before mustang week.



mike 89-718
 
S

SGOODRIC50

Founding Member
Sep 12, 2002
130
0
0
Maine
Jun 27, 2005
#2
  • Jun 27, 2005
  • #2
Yes, I have experienced that problem. It was something on the actual transmission that was causing it. I am not sure exactly what it's called, but if you go to your local autoparts store they can look up everything related to the tranny and find it very easily. Good luck
 

marcus95

Active Member
Jan 26, 2004
2,133
0
46
California
Jun 28, 2005
#3
  • Jun 28, 2005
  • #3
mkkrs1 said:
Have any of you Fox body owners encountered this problem. When I shift gears the rpm spikes up a sticks when driving normal. If I shift around 1800 the rpm will climb to 2200-2400. Need to get fixed before mustang week.



mike 89-718
Click to expand...


Sounds like your IAC ( idle air control ) to me. It's that small cylinder unit bolted to the front of your throttle body. Just a shot in the dark but wrap on that with the end of a screwdriver or something that wont damage the outside and see it that clears it up. How many miles? Occasionally, they need to be replaced. Hopefully Casey from Haney Motorsports will chime in and verify what the probelm is. Sounds like something in that area of idle control.
 

FASN8N

Member
Nov 16, 2004
517
0
17
Atlanta, GA
Jun 28, 2005
#4
  • Jun 28, 2005
  • #4
Could also be a throttle position sensor out of range (TPS). You can check the voltage and it shoud be set as close to 1.0 volt w/o going over. .96, .97. 98 etc.....
 
H

HMSPORT

Banned
Mar 30, 2005
60
0
0
Jun 28, 2005
#5
  • Jun 28, 2005
  • #5
That is what I would say is the problem. Take the IAC valve off and try cleaning it out with some brake clean. They do get gummed up inside after awhile. It also can be a possible TPS voltage/thottle blade set idle adjustment. Sometimes when the TPS volts a low, the processor sees that and activates the IAC. Then you start having a hung up idle. Ford has an adaptor plate that goes between the t.b and the IAC. It has a couple of set screws that allow more or less
airflow (bypassing the IAC). This is a good idle tuning peice especially if you have a big duration cam. I think the p/n is
F2PZ-9F929-A
 

mkkrs1

Member
Dec 2, 2004
49
0
6
indian trail,nc
Jun 28, 2005
#6
  • Jun 28, 2005
  • #6
I have cleaned the IAC but I have not checked the TPS voltage. This is a stock 89 saleen with 93k. Does any one know if you replace the TPS or IAC do they have to be calibrated or is it a remove and replace that simple.
 

FASN8N

Member
Nov 16, 2004
517
0
17
Atlanta, GA
Jun 29, 2005
#7
  • Jun 29, 2005
  • #7
If you remove/replace the TPS it has to be calibrated.
 
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