Crank then dies unless I give it throttle
- Thread starter $h0neyG
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08GT500
5 Year Member
Hi,
Just to double check, this is not a later model Pony with drive by wire, correct?
Any EEC codes? May be present in the absence of a CEL, recommend checking.
This is isolated to an idle issue, the engine otherwise runs & drives normally & doesn’t bog out under varying throttle levels & will stay running at idle by manually holding the throttle open?
Typical issues:
1) IACV idle air bypass valve faulty or gasket behind is leaking.Verify function/seal.
2) Throttle position sensor voltage setting is out of range. Adjust if necessary.
3) Chech for any vacuum lines that may be loose, damaged or landed incorrectly. New gasket used under throttle body on debris-free surfaces torqued to specification to ensure no T.B./Intake vacuum leaks present.
Feel free to post any questions and/or findings.
Good luck!
-John
Just to double check, this is not a later model Pony with drive by wire, correct?
Any EEC codes? May be present in the absence of a CEL, recommend checking.
This is isolated to an idle issue, the engine otherwise runs & drives normally & doesn’t bog out under varying throttle levels & will stay running at idle by manually holding the throttle open?
Typical issues:
1) IACV idle air bypass valve faulty or gasket behind is leaking.Verify function/seal.
2) Throttle position sensor voltage setting is out of range. Adjust if necessary.
3) Chech for any vacuum lines that may be loose, damaged or landed incorrectly. New gasket used under throttle body on debris-free surfaces torqued to specification to ensure no T.B./Intake vacuum leaks present.
Feel free to post any questions and/or findings.
Good luck!
-John
wmburns
SN Certified Technician
I give up. What model year Mustang are we dealing with?
Troubleshoot IAC idle problems 1996-2004
www.stangnet.com
In additional to above there are other "possibilities".
Is the design of the IAC value (black vented or not) the same as the original? Why is this important? Because it won't work correctly if the PCM is calibrated to one style of IAC and a different IAC design is used. The black vented IAC will allow some air in during certain stages of operation. Where as the non vented version is only open when the PCM tells it to.
Do you have an ODB2 scanner that is capable of monitoring operational PID's? Because if you did it would be helpful to know what the IAC duty percentage is. This would give a way to confirm IF the PCM even has control of the IAC valve.
Here's some information on a very affordable ($30) USB dongle that will support ForScan on a Windows PC.
ForScan ODB2 scanner w ELM327 USB
www.stangnet.com
Troubleshoot IAC idle problems 1996-2004
Troubleshoot IAC idle problems 1996-2004
Back to the basics. Check for blown fuses. Especially fuse F2.2 and F2.8 in the Central Junction Box (CJB 1999-2004 MY). Confirm key on power using a known good ground. 1999-2004 MY fuse panel schedule...
www.stangnet.com
In additional to above there are other "possibilities".
- Does your IAC valve work at all? If you place a test light across the IAC terminals does the test light vary as the throttle is moved?
- design of the TB. There are a number of small bleeder holes in the throttle butterfly valve that allows some bleed air through. Does the replacement TB have the same design?
Is the design of the IAC value (black vented or not) the same as the original? Why is this important? Because it won't work correctly if the PCM is calibrated to one style of IAC and a different IAC design is used. The black vented IAC will allow some air in during certain stages of operation. Where as the non vented version is only open when the PCM tells it to.
Do you have an ODB2 scanner that is capable of monitoring operational PID's? Because if you did it would be helpful to know what the IAC duty percentage is. This would give a way to confirm IF the PCM even has control of the IAC valve.
Here's some information on a very affordable ($30) USB dongle that will support ForScan on a Windows PC.
ForScan ODB2 scanner w ELM327 USB
ForScan ODB2 scanner w ELM327 USB
While working on your car have you ever wanted: to find an ODB2 operational PID value (say fuel pressure or MAF)? How about graph a PID value over time? Or compare multiple PID's over time? Access a bi-directional PCM control such as test a...
www.stangnet.com
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