horrible idle problem..

ex-ricer98gt · 09-30-2006, 04:57 AM

when i start my car it start off at 1500 then it dies down to around 700 - 800 like its suppose then after a minute or after driven for a couple minutes i go to a stop then it goes down to like 200 and up to 1100 then down to 600 and up to 900 it goes crazy, and its not my IAC cause i changed that last week, also when im driven around 20 - 35 miles per hour and i put my foot lightly on the gas my car bucks so bad it feels like my car is going back and forth only when im going that speed and when i put my foot slightly on the gas, i dont no what it is, im thinking soark plugs, coils, wires, maybe fuel injectors?

cobra1923 · 09-30-2006, 07:36 AM

Load your stock program back on your ECU (From the Diablo) and drive it around to see if it still does it. Then reload the Daiblo tune. The only other thing I can think of is a vacuum leak, spray some WD40 around your vacuum hoses and see if it changes the idle, if so, then it's a leak

bassman97 · 09-30-2006, 08:06 AM

Try disconnecting your battery for 15 min and after you connect, start up the car and let it idle w/o anything on and then let it idle w/ your AC on. Then, go for a test drive doing a lot of low rpm driving. Your idle trim curve may need to be relearned. Also, when checking for a vacuum leak, don't you usually use carb cleaner?

ex-ricer98gt · 09-30-2006, 08:11 AM

ill have to try that when i get home, thanks for the help

stage2roush2002 · 09-30-2006, 12:58 PM

Ok, load your stock progam into your car. Start it and drive for a little bit. Then turn you car off and turn your headlights on. Pop the hood and unplug your battery. (This erases any memory on your ECU) Let it sit for about 10 mins. Leave the headlights on! Plug your battery back in. Turn your headlights off and reload your Diablo Tune. Start it and drive it for a little while. (it might take a day or two) Your ecu will write a new plan for running your engine. This will help the idle.

cobra1923 · 09-30-2006, 01:46 PM

I've always done WD40 but it makes sense, since it could feasibly make it's way into the combustion chamber that it be carb cleaner or starting fluid.

Icefreezen · 09-30-2006, 05:51 PM

Quote:

Originally Posted by cobra1923

I've always done WD40 but it makes sense, since it could feasibly make it's way into the combustion chamber that it be carb cleaner or starting fluid.

WD-40 eats away at hoses.....use carb cleaner

04MustangGT · 10-01-2006, 01:51 AM

Check around your EGR tube. Its on the back of the throttle body. Try to listen for a leak there, you can also check by sticking your finger under it were it connects to it to see if it is sucking in any air. My friends car had a crazy idle just like you explained and that was his problem.

ex-ricer98gt · 10-01-2006, 09:53 PM

ok i loaded my stock tune back, waited a little bit and did everything and it still did it

im guna try using the carb cleaner and check my egr tube tommorw

*Randy Stinchcomb* · 10-02-2006, 06:04 AM

sounds like either a IAC problem or could also be a O2 sensor problem, now I saw that you replaced the IAC but did you use and OEM one or some parts store replacement, it does make a difference.

Shambles · 10-02-2006, 07:24 AM

Quote:

Originally Posted by ex-ricer98gt

when i start my car it start off at 1500 then it dies down to around 700 - 800 like its suppose then after a minute or after driven for a couple minutes i go to a stop then it goes down to like 200 and up to 1100 then down to 600 and up to 900 it goes crazy, and its not my IAC cause i changed that last week, also when im driven around 20 - 35 miles per hour and i put my foot lightly on the gas my car bucks so bad it feels like my car is going back and forth only when im going that speed and when i put my foot slightly on the gas, i dont no what it is, im thinking soark plugs, coils, wires, maybe fuel injectors?

Anything hissing underneath the hood.

Im thinking possible Vaccuum leak. When is the last time you replaced your PCV valve? Use carb cleaner and spray it over the engine bay. Listen for the idle change (it should speed up if im not mistaken). That should help you isolate where exactly your problem is.

Most of the time with vac leaks on these cars its not due to the hoses cracking (which I have done on my own, dont ask), but its due to the barbs that connect the hoses together cracking, producing a small leak. Even a leak that is incredibly small can still do this. I know. Its done it to mine before!

ex-ricer98gt · 10-02-2006, 10:10 AM

used an oem iac bout 2 months ago, and i never changed the pcv ethier, ill try the and see if theres a vacuum leak and if that dont work ill try replacing my pcv

ex-ricer98gt · 10-02-2006, 10:12 AM

you no wat randy now that i tihnk about it my check engine light came on a month ago i forget the code but it was something about my o2 sensors

Shambles · 10-02-2006, 10:27 AM

Quote:

Originally Posted by ex-ricer98gt

you no wat randy now that i tihnk about it my check engine light came on a month ago i forget the code but it was something about my o2 sensors

They might not be heating up to temperature.

Replace the PCV with a Motorcraft PCV (trust me on this), check for vaccuum leaks, and THEN, after all that, check the O2 sensors. Easiest way to do that is to switch the O2 sensors from one side to the other (Obviously disconnect them and switch them, dont just switch the harnesses between them). If one throws a code, go under the car, switch them back. See if the code comes up on the other side. If its an O2, thats where its going to display itself.

The other way to test is to see how the car performs if you put it into open loop (WOT). If it seems to perform fine in open loop, it could very well be a O2 sensor.

The other thing I can think of is possibly bad gas. When is the last time you changed your fuel filter? If you cant remember its probably due.

Here is your process of elimination:

REPLACE PCV VALVE FIRST!! (Cheapest thing to do)
Check for vaccuum leaks by using carb cleaner
Switch O2's from one side of the midpipe to the other (you only need to switch the front two, dont worry about the rear two) and check for any CEL's going off
Put car into WOT and see what happens (keep stock tune on there!)
Then I would look into possible issues w/ your fuel system.

*Randy Stinchcomb* · 10-02-2006, 10:27 AM

Quote:

Originally Posted by ex-ricer98gt

you no wat randy now that i tihnk about it my check engine light came on a month ago i forget the code but it was something about my o2 sensors

well, there's a start. how many miles on them?

Shambles · 10-02-2006, 10:28 AM

Quote:

Originally Posted by Randy Stinchcomb

well, there's a start. how many miles on them?

Psst...I posted first...and my post is better :P and gives a better logical deduction of problems.

*Randy Stinchcomb* · 10-02-2006, 10:29 AM

Quote:

Originally Posted by Shambles

Psst...I posted first...and my post is better :P and gives a better logical deduction of problems.

ex-ricer98gt · 10-03-2006, 02:17 PM

shambles, i replaced the pcv valve and checked for vacuum leaks witht eh carb cleaner, everythin was good, i then switched the o2 sensors! then 2 codes come on, p0430 and p1131, 0430 is o2 sensor not working right and 1131 means im runnin lean i think i duno i googled it and thats what came up. what should i do now? i think i might have to change my o2 sensors, and randy my car has about 95k miles on it

Shambles · 10-03-2006, 03:28 PM

which O2 is 0430...

Give randy a post in his parts section. Just replace that O2 and that will be a step in the right direction.

ex-ricer98gt · 10-03-2006, 03:51 PM

passenger side o2 sensor

Shambles · 10-03-2006, 09:51 PM

Theres what you need to replace!

ex-ricer98gt · 10-04-2006, 05:24 AM

goin to auto zone after work to pick 1 up there like 60-70 bucks and about 1 or 2hr labor shouldnt be bad at all ill knock it out in 2 hrs

ex-ricer98gt · 10-04-2006, 05:25 AM

thanks for the help!

*Randy Stinchcomb* · 10-04-2006, 06:50 AM

Quote:

Originally Posted by ex-ricer98gt

goin to auto zone after work to pick 1 up there like 60-70 bucks and about 1 or 2hr labor shouldnt be bad at all ill knock it out in 2 hrs

Nooooo, Don't do-it

get genuine Ford!! parts store electronic stuff does not work well on Fords and Ford O2's are only $69.00 each + shipping and we have plenty.

Do Not Buy Sensitive Electronic Parts for Fords at parts stores!!

Ford designs a part to work wthin certian parameters, say A to D and the aftermarket opens up these parameters, say from A to G to work on other brands of cars, thats why ther parts are cheaper(sometimes) then OEM stuff.

09-30-2006, 04:57 AM	#1 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	horrible idle problem.. when i start my car it start off at 1500 then it dies down to around 700 - 800 like its suppose then after a minute or after driven for a couple minutes i go to a stop then it goes down to like 200 and up to 1100 then down to 600 and up to 900 it goes crazy, and its not my IAC cause i changed that last week, also when im driven around 20 - 35 miles per hour and i put my foot lightly on the gas my car bucks so bad it feels like my car is going back and forth only when im going that speed and when i put my foot slightly on the gas, i dont no what it is, im thinking soark plugs, coils, wires, maybe fuel injectors? __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams

09-30-2006, 07:36 AM	#2 (permalink)
cobra1923 Senior Member Join Date: Nov 2004 Location: Baltimore Posts: 581	Load your stock program back on your ECU (From the Diablo) and drive it around to see if it still does it. Then reload the Daiblo tune. The only other thing I can think of is a vacuum leak, spray some WD40 around your vacuum hoses and see if it changes the idle, if so, then it's a leak __________________ 2003 10th Anniversary Cobra Convertible All Stock and staying that way... well maybe some pipes since it's so quiet..ahhhh! it's a sickness 1995 mustang GT vert - all black (almost back together)

09-30-2006, 08:11 AM	#4 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	ill have to try that when i get home, thanks for the help __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams

09-30-2006, 01:46 PM	#6 (permalink)
cobra1923 Senior Member Join Date: Nov 2004 Location: Baltimore Posts: 581	I've always done WD40 but it makes sense, since it could feasibly make it's way into the combustion chamber that it be carb cleaner or starting fluid. __________________ 2003 10th Anniversary Cobra Convertible All Stock and staying that way... well maybe some pipes since it's so quiet..ahhhh! it's a sickness 1995 mustang GT vert - all black (almost back together)

10-01-2006, 01:51 AM	#8 (permalink)
04MustangGT Senior Member Join Date: Dec 2005 Posts: 354	Check around your EGR tube. Its on the back of the throttle body. Try to listen for a leak there, you can also check by sticking your finger under it were it connects to it to see if it is sucking in any air. My friends car had a crazy idle just like you explained and that was his problem. __________________ 04 GT 5 spd Modifications: SLP Catback Exhaust SLP catted X-Pipe SLP Headers Pro 5.0 Shifter H&R Sport Springs Raptor Shift light, 17x9 & 18x10 Black Bullitts http://s26.photobucket.com/albums/c103/04MustangGT/ Soon To Come:4.10 Gears

09-30-2006, 08:06 AM	#3 (permalink)
bassman97 blank Join Date: Jun 2006 Location: North Jersey Posts: 1,485	Try disconnecting your battery for 15 min and after you connect, start up the car and let it idle w/o anything on and then let it idle w/ your AC on. Then, go for a test drive doing a lot of low rpm driving. Your idle trim curve may need to be relearned. Also, when checking for a vacuum leak, don't you usually use carb cleaner?

09-30-2006, 12:58 PM	#5 (permalink)
stage2roush2002 Roush #6147 Join Date: Mar 2006 Location: Dallas, Tx Posts: 476	Ok, load your stock progam into your car. Start it and drive for a little bit. Then turn you car off and turn your headlights on. Pop the hood and unplug your battery. (This erases any memory on your ECU) Let it sit for about 10 mins. Leave the headlights on! Plug your battery back in. Turn your headlights off and reload your Diablo Tune. Start it and drive it for a little while. (it might take a day or two) Your ecu will write a new plan for running your engine. This will help the idle.

10-01-2006, 09:53 PM	#9 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	ok i loaded my stock tune back, waited a little bit and did everything and it still did it im guna try using the carb cleaner and check my egr tube tommorw __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams

10-02-2006, 06:04 AM	#10 (permalink)
Randy Stinchcomb Super Moderator Join Date: Aug 2005 Location: Randallstown, Md Posts: 2,734	sounds like either a IAC problem or could also be a O2 sensor problem, now I saw that you replaced the IAC but did you use and OEM one or some parts store replacement, it does make a difference. __________________ Randy Stinchcomb contact info: Liberty Ford of Baltimore 410-655-2000 parts ext 5618 like to fish visit us at www.sportfisherman.com need fishing tackle www.binnacletackle.com

10-02-2006, 10:10 AM	#12 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	used an oem iac bout 2 months ago, and i never changed the pcv ethier, ill try the and see if theres a vacuum leak and if that dont work ill try replacing my pcv __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams

10-02-2006, 10:12 AM	#13 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	you no wat randy now that i tihnk about it my check engine light came on a month ago i forget the code but it was something about my o2 sensors __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams

10-03-2006, 02:17 PM	#18 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	shambles, i replaced the pcv valve and checked for vacuum leaks witht eh carb cleaner, everythin was good, i then switched the o2 sensors! then 2 codes come on, p0430 and p1131, 0430 is o2 sensor not working right and 1131 means im runnin lean i think i duno i googled it and thats what came up. what should i do now? i think i might have to change my o2 sensors, and randy my car has about 95k miles on it __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams

10-03-2006, 03:28 PM	#19 (permalink)
Shambles The Baninator! Join Date: Mar 2005 Location: Springfield, PA Posts: 2,652	which O2 is 0430... Give randy a post in his parts section. Just replace that O2 and that will be a step in the right direction. __________________ Chris "Shambles" Chamblee

10-03-2006, 03:51 PM	#20 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	passenger side o2 sensor __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams

10-03-2006, 09:51 PM	#21 (permalink)
Shambles The Baninator! Join Date: Mar 2005 Location: Springfield, PA Posts: 2,652	Theres what you need to replace! __________________ Chris "Shambles" Chamblee

10-04-2006, 05:24 AM	#22 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	goin to auto zone after work to pick 1 up there like 60-70 bucks and about 1 or 2hr labor shouldnt be bad at all ill knock it out in 2 hrs __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams

10-04-2006, 05:25 AM	#23 (permalink)
ex-ricer98gt Senior Member Join Date: May 2006 Posts: 194	thanks for the help! __________________ mods now: flownmaster 40's, mac long tubes, mac prochamber, Motive 4.10's, diablosport tune, k&n fipk waiting to be installed: pi intake and cams