Cold idle sucks.....engine codes pulled (have researched)

[Rock777]

My car has had a horrible idle when cold for a while now, pretty much dies when I start it cold unless I hold the gas for a few minutes. I recently put on a 76mm maf and it is even worse, even in warmer weather. Once it's warm, it runs smooth. I've changed a zillion sensors and parts so far.. maf sensor, o2 sensors, map sensor, tps, iac, ect sensor, coil, fuel pump, plugs and wires less than a year ago. I just cleaned my iac as well, and checked the tps again. Here are the codes a pulled

33-EGR did not open/ respond during test or if memory code, did not open intermittently ( I have been getting this code for a long time????)
21-Engine Coolant Temperature (ECT) sensor out of range (never got this one, until I replaced the ECT????)
46-AIR Bypass (AIRB) not working - Air Injection
Electronic Ignition - primary circuit failure coil 2 - Ignition Systems ( no idea )
66-Vane Air Flow (VAF) or Mass Air Flow (MAF) signal low (Could this be because of the new 76mm meter)

If you have any input on any one aspect or all of my problems, please feel free to leave me your $.02, cause I have tried everything I have read about and can think of and it will be worth more than $.02 to me

 

[ninety15.0]

do u have your MAF calibrated correctly for the injectors that you have? also give us some information about the mods on your car. do u still have to smog pump or not? b/c that would be your 46 code right there with those stupid check valves on the smog pump. take the EGR sensor off and then remove the solenoid and clean the egr valve thoroughly. check to make sure the diaphram doesnt have any cracks or leaks and then clean the carbon builup out of the valve seat to ensure a tight fit. u can use your mouth and suck on the vacuum nipple to check for proper operation of the EGR valve. then just go over all your connections and make sure everything is tight....check for vac leaks! good luck man

 

[Rock777]

I'll give that all a try as soon as I can, thanks. Yes, the maf is calibrated for 19#ers. Disregard the code 21, I just checked my codes again at operating temperature and they all came up except 21, which would make sense. Anyway, mods on my car are o/r x-pipe, flowmasters w/ dumps, 76mm maf, 190lph fuel pump, 3.73, K&N using stock box (no 90 degree turn before maf). That's about it. It does seem like a vacuum leak, but I am not sure of the best ways to check for leaks, but in the meantime I will definitely check what you said ninety15.0, thanks.

 

[jrichker]

Code 33 - Insufficient EGR flow detected.
Look for vacuum leaks, cracked vacuum lines. Check to see if you have 10” of vacuum at the EGR vacuum connection. Look for electrical signal at the vacuum regulator solenoid valves located on the rear of the passenger side wheel well. Using a test light across the electrical connector, it should flicker as the electrical signal flickers. Remember that the computer does not source any power, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

Code 46 - AIR Bypass (AIRB) not working - Air Injection. The first vacuum controlled valve is not dumping the smog pump output to open air on command. Possible bad valve, broken or missing vacuum lines. Check vacuum lines for leaks, & cracks. Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve

Code 66 MAF below minimum test voltage.
Insufficient or no voltage from MAF. Dirty MAF element, bad MAF, bad MAF wiring, missing power to MAF. Check for missing +12 volts on this circuit. Check the two links for a wiring diagram to help you find the red wire for computer power relay switched +12 volts. Check for 12 volts between the red and black wires on the MAF heater (usually pins A & B). while the connector is plugged into the MAF. This may require the use of a couple of safety pins to probe the MAF connector from the back side of it.

There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables.

The MAF output varies with RPM which causes the airflow to increase or decease. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer.

At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt

Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms.

There should be a minimum of 10K ohms between either pin C or D on the MAF and ground.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

To clean the MAF, remove the MAF element and gently spray it with electrical contact cleaner. You can also use non-flammable brake parts cleaner (same chemical in a bigger can & cheaper too). Let it dry and put it back in.

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp

 

[Rock777]

I cleaned out the IAC real good and flipped it (after I heard that you have to flip the Wells IAC's), cleaned the MAF sensor, cleaned the throttle body real good and wiped it out(didn't wipe out last time, throttle was sticking). I also checked the voltage on the MAF wires and they were all what jrichker said they should be at. Anyway, my car with the IAC flipped was idling around 1200 constantly. I tried readjusting the idle and tps and all that, still didn't affect anything. So I cleaned out my old IAC real good and put it back on. Now it would idle around 800 after warmed up a couple minutes.I tried starting it cold and it would die like it always did, but after it minute it would stay running at about 750, rough, but running. After a couple more minutes of driving it would idle nice at 850, I mean perfect. Well, after driving around a little more, getting the temp up by running through the gears a few times, it idles at about 1200 for about 10 seconds and eventually crawls back down to 900. I just ran the codes again after resetting my computer when I did the idle/tps adjustments and they are 33 and 41. I know 33 has to deal with the egr. How do I test to see if it is 10" of vacuum? My car has been reading 41 for a lont time now and that could have somethin to do with the o/r x-pipe or the 76mm maf, but I don't know. I couldn't find any vacuum leaks anywhere, but they are tough to find so that is not completely ruled out. My biggest concern right now is not the codes or even the slightly high idle for a few seconds before coming back down, but the fact that it dies on a cold start. I have a feeling it is going to keep getting harder to keep running once the winter comes, which is why I am trying to get it figured out now. I am assuming it is related to the EGR, since it keeps spitting this code at me, would this effect the cold start idle? I really do appreciate all of your guys input, this site is very helpful!!

 

[Rock777]

Does the EGR affect the cold idle? I guess I will clean it out, what is the best way and is there a way to test the EGR selenoid?

 

[jrichker]

Here’s an EGR test procedure I copied from cjones. You'll need a vacuum gauge ($17 from AutoZone or other auto parts store) to do the testing.

to check the EGR valve:
bring the engine to normal temp.
connect a vacuum pump to the EGR Valve
apply 5 in 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 RPMs (remember snap the throttle don't hold it there).
did the vacuum gauge show about 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 RPMs.
should read about 5 in vacuum.

I typically use engine vacuum to do the first test. I use the spare vacuum port on the vacuum tree near the windshield wipers.

Code 41(Right O2 sensor) or 91 (Left O2 sensor)- O2 sensor indicates system lean. Look for a vacuum leak or failing O2 sensor.
The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel.

Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter.
The O2 sensor ground is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than .4 volt. Remember lean = less voltage.

" When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than .6 volt. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage."
Charles O. Probst, Ford fuel Injection & Electronic Engine control

The EGR will not affect cold starting unless it is stuck open.
Vacuum leaks will cause the code 41 and make the car hard to start when cold. Again, the vacuum gauge is the best test for vacuum leaks. You should have 16"-19" of vacuum with a stock cam on a cold engine at 650-725 RPM.

 

[Rock777]

I was playing around with the idle problem again trying to find vacuum leaks when I noticed a slight hissing coming from what I thought to be the IAC. I sprayed some carb. cleaner around it to see if the idle went up and it did. I then went to autozone and bought a new IAC and put it on(by the way, it was a Wells but they said they never heard of putting it on backwards, and there were no directions either, so I just put it on just like the stock one since it looks exactly like the stock one) Anyway, at the point I put the new IAC on the engine was warmed up, but it did idle smooth at about 800ish, which is great. While searching for vacuum leaks, I did find one broken line. There is a little cluster with 4 vacuum lines(the cluster holds 5, but there are only 4 lines), one of which goes to the EGR valve. This was not the broken one, but the line (white) right in the middle comes out and was broke off. I know it goes about 6 inches to some valve or something closer to the front of the engine because I saw the rest of the line attached, but I have no idea what this is. If anybody knows what the is, please please let me know. Either way, I am going to have to fix it with a new line, but don't know if this is related to my problems or not. Jrichker, you are a very helpful person, and I appreciate all of your advice!

 

[jrichker]

Only 4 of the vacuum line in the rubber coupling are live. See http://www.veryuseful.com/mustang/tech/engine/images/88Stang5.0Vacuum.gif Or http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg for help