Ford Mustang Forums banner

1 - 20 of 30 Posts

·
Registered
Joined
·
168 Posts
Discussion Starter #1
Cold start, idles great.. stock 5.0 long block, 6psi Paxton SN2000, base line timing at 6 degrees.
The car, cold starts and idles great, once it gets warmed up the idle starts to climb, like a high idle setting on a carburetor.
I set the TPS voltage long ago at 0.96, haven't touched it since.
Has A9L PCM, and no trouble codes.
Is this normal because of blower?
Car runs well, the way it's set up, just the quirky high idle, at operating temp.
Thanks for the help everyone!
 

·
Registered
Joined
·
4,321 Posts
How high is high?
 

·
Registered
Joined
·
168 Posts
Discussion Starter #4
Still have stock RPM Gauge, almost hits about 1500 rpm, I changed IAC, motor probably 2004-05.
 

·
Registered
Joined
·
23,245 Posts
Cold start, idles great.. stock 5.0 long block, 6psi Paxton SN2000, base line timing at 6 degrees.
The car, cold starts and idles great, once it gets warmed up the idle starts to climb, like a high idle setting on a carburetor.
I set the TPS voltage long ago at 0.96, haven't touched it since.
Has A9L PCM, and no trouble codes.
Is this normal because of blower?
Car runs well, the way it's set up, just the quirky high idle, at operating temp.
Thanks for the help everyone!

to state you have High idle you must see DESIRED idle speed

otherwise you will have no idea, desired idle changes all the time

if you perform an engine running self test, the ecm will tell you if it has control of idle

but that rpm suggests you have jacked with throttle stop, in an effort to cure a rolling, surging idle at cold starts

Also, if the idle is going up, suggests there is NOTHING wrong with the IAC
 

·
Registered
Joined
·
168 Posts
Discussion Starter #7
No blow off valve just an FMU, on the fuel side. If I shut it off at operating temp. and start it back up, the idle will run low speed again, and start increasing.
I can try to run a KOER test, my scanner's been acting up, but will try it tomorrow.
 

·
Registered
Joined
·
23,245 Posts
when you restart, you go back into OL, until timer is complete, then back into CL.
 

·
Registered
Joined
·
4,321 Posts
to state you have High idle you must see DESIRED idle speed

otherwise you will have no idea, desired idle changes all the time
What would drive DESIRED idle speed to 1500rpm based on ECT?


but that rpm suggests you have jacked with throttle stop, in an effort to cure a rolling, surging idle at cold starts
Wouldn't jacking the throttle stop too far open also cause a high cold idle, too? I would think if there's too much air flow for the desired idle speed when the engine is at operating temperature, there would also be too much air flow when ECT is low. Does the stock idle strategy give the ECU a better ability to lower idle RPM when ECTs are low?
 

·
Registered
Joined
·
23,245 Posts
What would drive DESIRED idle speed to 1500rpm based on ECT?



Wouldn't jacking the throttle stop too far open also cause a high cold idle, too? I would think if there's too much air flow for the desired idle speed when the engine is at operating temperature, there would also be too much air flow when ECT is low. Does the stock idle strategy give the ECU a better ability to lower idle RPM when ECTs are low?

if only if it was that easy

to explain, would cut into my beer time

if you are truly interested

download and install a free trial of binary editor, load up a GUFB/a9l

then go through all the idle related PIDs

then download the GUFB and go to the idle strategy section, and start reading

if you want a one on one tutoring, $500/hour
 

·
Registered
Joined
·
23,245 Posts
if that were to happen, rpm lockout would close the IAC and reduce timing quite drastically

not a tps issue
 

·
Registered
Joined
·
2,098 Posts
Isn’t the real difference between OL and CL the use of the O2 sensors?
Could this be an issue with the O2 sensors causing increased timing advance?
 

·
Registered
Joined
·
1,197 Posts
I was logging with my quarter horse once when my idle went up to approx 1500. The TPS voltage at start up was .92v and when the idle went up it was 1.09v. I was able to get under hood and verify the throttle blade was closed. On the next start up the EEC zero's out the 1.09 and it idled almost normal. I replaced the TPS and it solved my problem.

My min speed for closed loop RPM control is 18 mph.
 

·
Registered
Joined
·
23,245 Posts
must look at desired rpm

must look at desired rpm.....
 

·
Registered
Joined
·
168 Posts
Discussion Starter #16
Finally got a working code reader, the simple Ford OBD 1 Inova.
I just did a KOEO, test, and I did get a Code 23 for TPS signal out of range.
And a Code 33, for EGR. I did recently install an EGR delete, and capped the connector. No other trouble codes.
Should I try, adjusting TPS, for a lower voltage, to get idle lower after warm up, and CL? Is that possible?
Appreciate all the replys , everyone!
 

·
Registered
Joined
·
23,245 Posts
you did not post engine running codes

what is the TPS voltage at closed throttle?
 

·
Registered
Joined
·
168 Posts
Discussion Starter #18
Could not get any KOER codes at all.
Reader was functioning, but no codes appeared. I am wondering if it's because I have trouble codes on the KOEO test.
I have 1.4 volts on TPS, at idle, and 4.5 at WOT.
The stop screw on throttle body, looks like its halfway in.
 

·
Registered
Joined
·
23,245 Posts
your tps is above 1.15volt limit

what did you do?

stock tps and stock tb would have to seriously whacked

have you jacked with the throttle stop?
 
1 - 20 of 30 Posts
Top