idle problem

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mustangjoe02

Member

Apr 29, 2011

84

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Aug 31, 2011

#1

• Aug 31, 2011

• #1

installed lt headers and now the idle is bouncing up and down and seems like it wants to die. feels like it has a small miss too. someone help

 

D

Deleted member 38176

Aug 31, 2011

#2

• Aug 31, 2011

• #2

I had a similar problem after installing my LT's. I cleaned my MAF and IAC along with installing a new tune and it went away. I'd suggest cleaning the MAF/IAC first since its easy and cheap.

Also, I damaged one of my 02 sensors while installing the LT's. A damaged sensor could cause similar problems.

 

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mustangjoe02

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Apr 29, 2011

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Aug 31, 2011

#3

• Aug 31, 2011

• #3

where did you get your tune from? and you did replace your o2 sensor?

 

wmburns

SN Certified Technician

Aug 14, 2009

5,892

514

204

Houston Texas

Aug 31, 2011

#4

• Aug 31, 2011

• #4

+1 on clean the MAF.

Cleaning the black vented IAC isn't likely to fix the problem.

Are there any other DTC codes?

Replace the PCV valve. Check for vacuum leaks especially around the valve covers, EVAP system, and PCV vacuum lines, PCV grommet, oil dip stick, oil cap. In short, anyplace un-metered air can enter.

Are there any exhaust leaks?

Note, a low idle can also result when cylinders are not pulling their weight (power balance). Confirm that the ignition system is in good repair.

Another possible cause for a surging idle is not enough vacuum to keep the black vented IAC vent value closed. Seems more likely after an aggressive cam upgrade (or anything that reduces vacuum).

More information on how to trouble shoot idle problems.

Is your mustang stumbling, dieing at idle or idling rough? - Page 14 - Ford Mustang Forums

 

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mustangjoe02

Member

Apr 29, 2011

84

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Aug 31, 2011

#5

• Aug 31, 2011

• #5

no codes. i feel like its the o2 sensors or spark plugs or somethin to do with the tune.

 

D

Deleted member 38176

Aug 31, 2011

#6

• Aug 31, 2011

• #6

mustangjoe02 said:

where did you get your tune from? and you did replace your o2 sensor?

Click to expand...

I had a custom tune written by BAMA and yes, I replaced my O2.

 

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mustangjoe02

Member

Apr 29, 2011

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Aug 31, 2011

#7

• Aug 31, 2011

• #7

I got tuning from them as well. What did you tell them to put in your tune?

 

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mustangjoe02

Member

Apr 29, 2011

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Sep 10, 2011

#8

• Sep 10, 2011

• #8

Ok so after cleaning maf, iac, egr and retune, nothing happened. Still barely surrges at idle. Like 750-800. Then when pulling to a stop of after revving the engine at a standstill the idle drops to 550 then returns to 750 and surges. Maybe spark plugs or fuel filter?? Should I run a can of seafoam in it or is that stuff junk? It just started after the lt headers install. Can't find an exhaust leak either. What's a better way of finding a leak than just listening through a tube at all the connections??

 

D

Deleted member 38176

Sep 11, 2011

#9

• Sep 11, 2011

• #9

Wow that sounds EXACTY like my surging problem after the LT install.

What kind of octane tune are you running? Did you specify that you had long tubes and an O/R exhaust when ordering your tune? Do you notice any idling surge after the engine is warmed up? The front O2's are a lot farther downstream with LT's than previous so it might take a little longer for them to warm up.

I called them and spoke to BAMA in person. We discussed all of my mods, including the O/R longtube exhaust, and they sent me the tune a few days later.

 

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mustangjoe02

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Apr 29, 2011

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Sep 11, 2011

#10

• Sep 11, 2011

• #10

The surge is there all the time and the drop only comes after revving or stopping. I just replaced both o2s and got a retune. I'm not sure if they actually know my mods. I put them in online and got a tune the got the next tune after talking to them through email. Ill give them a call tomorrow so I can speak to them directly and maybe see if they want me to datalog it

 

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mustangjoe02

Member

Apr 29, 2011

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Sep 11, 2011

#11

• Sep 11, 2011

• #11

Oh ya and I run 91 octane

 

nyuk98gt

15 Year Member

Oct 10, 2000

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Chesterfield, MO

Sep 12, 2011

#12

• Sep 12, 2011

• #12

mustangjoe02:

Call up your tuner and ask him about increasing the O2 sensor delay and, perhaps, the heater duty cycle. The O2 sensors are seeing colder gas due to the larger diameter piping. This is a well-known issues with LT's. Increasing the heater duty cycle keeps the sensors warmer (and working 'in the zone') and the longer delay helps the computer adapt to the new geometry. (The existing delay values may not be big enough with respect to the stock learning range.) With these one or two changes, the engine will idle very nicely.

HTH,

Chris

 

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mustangjoe02

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Apr 29, 2011

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Sep 13, 2011

#13

• Sep 13, 2011

• #13

Thanks. I just got done datalogging my car so I'm going to send that in to bama and hopefully the tune is perfect now.