Idle Problems.. new thread for problems

The only thing i can think of is that you might have a bad mass air meter. That is one of the main things that effect idle quality....especially when combined with a CAI that might be effecting the flow across the filaments.

Not trying to be rude but looks like your problems have lasted a while.........ever thought of dropping it off at a mechanic to look at? Are 100% sure you checked the vacuum lines good? I know I thought I did and my idle problems came back. I rechecked and I had missed a bad line. replaced it and its all better.

MAN I HAVE THE EXACT SOME PROBLEM, I JUST ORDERED A AIR TEMP. SENSOR I HOPE THAT WORKS.

i didn't noticed if anyone already asked but have you tried swapping ecu's to see if that helps?

yup. just another shot at something ya know. anything is better than nothing.

i had purchased an empty shell theft recovery as my third stang and swapped everything over from my second one which was wrecked badly enough to be totaled out. everything was good except it was rich and sorta sputtery. i tried everything to fix it including changing all sensors including cleaning the mass air. then times got tight so i sold it to an acquaintance. the dude unplugged the mass air and plugged it back in and voila'! i was so pissed because i just unbolted it without unplugging it to clean it and i lost a perfectly good car for dirt cheap. anywho, sometimes its the simple things to look at.

do you have the correct vacuum line going from the egr solenoid to the egr? if the wrong vacuum line is hooked to the egr it will keep the egr open all the time causing the car to idle kinda rough like its got a cam in it, or it may be that the egr solenoid is clogged, on the passenger side near the firewall the solenoid is the one on top, and it has a round cap on it that you can pop off, once the cap is off you will see a tube sticking up with a hole in it, anyways if that hole is blocked it will cause constant vacuum to the egr also causing the egr to be in the open position all the time.
I just found that out yesterday because i stuck my finger on my solenoid clogging the hole and my idle dropped slightly and started to lope.
May not be your problem but its just a thought.

dcurtis said:

do you have the correct vacuum line going from the egr solenoid to the egr? if the wrong vacuum line is hooked to the egr it will keep the egr open all the time causing the car to idle kinda rough like its got a cam in it, or it may be that the egr solenoid is clogged, on the passenger side near the firewall the solenoid is the one on top, and it has a round cap on it that you can pop off, once the cap is off you will see a tube sticking up with a hole in it, anyways if that hole is blocked it will cause constant vacuum to the egr also causing the egr to be in the open position all the time.
I just found that out yesterday because i stuck my finger on my solenoid clogging the hole and my idle dropped slightly and started to lope.
May not be your problem but its just a thought.

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vacuum lines are almost as fun as electrical issues anyday.

dcurtis said:

do you have the correct vacuum line going from the egr solenoid to the egr? if the wrong vacuum line is hooked to the egr it will keep the egr open all the time causing the car to idle kinda rough like its got a cam in it, or it may be that the egr solenoid is clogged, on the passenger side near the firewall the solenoid is the one on top, and it has a round cap on it that you can pop off, once the cap is off you will see a tube sticking up with a hole in it, anyways if that hole is blocked it will cause constant vacuum to the egr also causing the egr to be in the open position all the time.
I just found that out yesterday because i stuck my finger on my solenoid clogging the hole and my idle dropped slightly and started to lope.
May not be your problem but its just a thought.

Click to expand...

Excellent input. That's one of the things that I like about the forum approach. Other people's insight and experience can help with the process.

Some basic theory to clarify how things work is in order…

The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption. The primary result of EGR usage is a reduction in NOx emissions.

The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EVR is located on the back of the passenger side shock strut tower. The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR valve and the passages in the heads and intake manifold route exhaust gas to the EGR spacer (throttle body spacer). The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.





Troubleshooting:
There should be no vacuum at the EGR valve when at idle. If there is, the EVR (electronic vacuum regulator) mounted on the backside of the passenger side wheelwell is suspect. Check the vacuum line plumbing to make sure the previous owner didn’t cross the vacuum lines.

Diagram courtesy of Tmoss & Stang&2birds. (the diagram says 88 GT, but the EGR part is the same for 86-93 Mustangs)


The EGR sensor is basically a variable resistor, like the volume control on a radio. One end is 5 volt VREF power from the computer (red/orange wire). One end is computer signal ground (black/white), and the middle wire (brown/lt green) is the signal output from the EGR sensor. It is designed to always have some small voltage output from it anytime the ignition switch is the Run position. That way the computer knows the sensor & the wiring is OK. No voltage on computer pin 27 (brown/lt green wire) and the computer thinks the sensor is bad or the wire is broken and sets code 31. The voltage output can range from approximately .6-.85 volt.


EGR test procedure courtesy of cjones

to check the EGR valve:
bring the engine to normal temp.
connect a vacuum pump to the EGR Valve
apply 5in vacuum to the valve.
if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.
if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.
if engine stumbled, connect vacuum gauge to the hose coming off of the EGR Valve
snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
did the vacuum gauge show about 2-5 in vacuum?

if not, check for manifold vacuum at the EGR vacuum valve.
if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500 RPM.
should read about 2-5 in vacuum

Just judging from what you said about the car idling like it has a cam in it I would definatly verify that the egr is geting correct vacuum and functioning properly-also jrichker you are the man, if not for you my car would still be running like crap.

savegoodautonfg said:

I'm gonna get a vacuum gauge and check for vacuum..

jrither you said "if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500 RPM.
should read about 2-5 in vacuum"

SO your talking about where the vacuum hose connects to the egr valve?

what are some other places i can look for vacuum on the car?

also a good vacuum gauge just to read or pump?

also thanks for the input guys.

anything helps.. keep it coming.

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When testing the EGR, insert a plastic Tee in the line between the EGR valve and the EGR regulator.

savegoodautonfg said:

What do you mean?

The plastic vacuum tree with 4 vacuum hoses coming out. I only have one vacuum hose that goes onto the egr valve??

Honestly i dont even know what a EGR regulator is..

I know i have the EGR Valve and the EGR Position Sensor that the plug goes into the bottom of?

Click to expand...

I guess that you didn't bother to read the post with the explanation of how the EGR works.