Engine High Idle, Rough Start

[jrichker]

The smog pump has a filter inlet made into the back of it. I I remember correctly, there is a stamped perforated metal cover over it.

 

[jcgafford]

sounds good, i will check it for airflow and replace it if need be. what kind of flow shuld be coming out of it? strong or just a light breeze?

 

[jrichker]

You should feel a good flow at about 1200 RPM. A 3" or 4" long by 1" wide paper streamer should flutter pretty good when attached to a hose directly connected to the smog pump output port

 

[Fox8950]

I'm with 88LX5.0h pretty sure only electrical connections on my aod are for the backup light switch and neutral safety switch pretty sure even TC lockup was non-electical up until aod-e

 

[jcgafford]

You should feel a good flow at about 1200 RPM. A 3" or 4" long by 1" wide paper streamer should flutter pretty good when attached to a hose directly connected to the smog pump output port

no access panel i could find although i did not unbolt it. got under the car and looked and there were a couple of holes in the backside for some sort of access. took the elbow off of it and fired the air compressor thru every opening i could find. lots of nasty dust and crud came out and when i tested it it it was strong and has to be working at normal flow now. good steady stream that would definitely blow paper or whatever around.

 

[1989DropTop]

sounds good, i will check it for airflow and replace it if need be. what kind of flow shuld be coming out of it? strong or just a light breeze?

I have a smog pump if you need one just pay the ride to you

 

[jcgafford]

I have a smog pump if you need one just pay the ride to you

thanks! but it looks like mine was just nasty. seems to be working good now.

 

[jcgafford]

where do these vacuum lines go to? passenger fender access hole shown.

this seems to be pulling vacuum correctly...

only the larger hole in the plug has constant vacuum, is this correct?

 

[jcgafford]

reason for the above post is i don't believe the egr is getting vacuum nor any of the smog valves. i realize code 94 and 44 could explain the smog but i get no egr code and have yet to see the egr diaphragm move properly with the engine running. in fact the egr diaphragm appears to be sucking toward the intake and is slightly popping out hte relief slots in its housing with the engine running. you can feel some sort of air movement on the egr vacuum tube but it is not strong or constant, more like a flutter.

 

[jrichker]

Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pin out
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif



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

EGR System theory and testing

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.

The EVR regulates vacuum to the EGR valve to maintain the correct amount of vacuum. The solenoid coil should measure 20-70 Ohms resistance. The regulator has a vacuum feed on the bottom which draws from the intake manifold. The other vacuum line is regulated vacuum going to the EGR valve. One side of the EVR electrical circuit is +12 volts anytime the ignition switch is in the run position. The other side of the electrical circuit is the ground path and is controlled by the computer. The computer switches the ground on and off to control the regulator solenoid.



EGR test procedure courtesy of cjones

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 or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

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 EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
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 the EVR has failed

EGR test jig

To test the computer and wiring to the computer, you can use a test light across the EVR wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker. If the test light remains on the computer or the wiring is suspect.

To check the EVR to computer wiring, disconnect the EVR connector and connect one end of the Ohmmeter to the dark green wire EVR wiring. Remove the passenger side kick panel and use a 10 MM socket to remove the computer connector from the computer. Set the Ohmmeter to high range and connect the other ohmmeter lead to ground. You should see an infinite open circuit indication or a reading greater than 1 Meg Ohm. If you see less than 200 Ohms, the dark green wire has shorted to ground somewhere.

Late Model Restoration may still have the Ford Racing M-12071-N302 kit with the EGR valve & sensor along with the ACT & ECT sensors for $45. See http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=M12071N302 1&comp=LRS for more details[/b]

 

[jcgafford]

the only thing i don't see is the vacuum reservoir. is it buried in the fender? the rest now makes sense. tab and tad. are they the same as the 89 and up tab and tad in the v8 fords just a different looking part? connection for vacuum and electrical is the same.

i pulled my tab and tad and the code 81 was explained. both were cracked through the bottom and rusted.

 

[jcgafford]

the only thing i don't see is the vacuum reservoir. is it buried in the fender? the rest now makes sense. tab and tad. are they the same as the 89 and up tab and tad in the v8 fords just a different looking part? connection for vacuum and electrical is the same.

i pulled my tab and tad and the code 81 was explained. both were cracked through the bottom and rusted.

switched tab and tad with a used tab and tad at local yard. out of a couple 90 something full size fords with v8's. fit perfectly and looks almost identical except where the mustangs have a round end these have a square end where the filters sit. koeo is now no codes! ran koeo 4 times because i could not believe it. code 11 three times is all that shows!!!!


for anyone looking to replace the tab and tad for less than 20 bucks. the ones out of 1990-91 lincoln or mercury 5.0's work perfect and fit the receiving plate on the back of the strut tower perfectly. hit your junk yards

 

[jrichker]

Congratulations: you have a first - no 44/94 and no cats. I wasn't sure that it could be done. I'll have to add that to my list...

 

[jcgafford]

Congratulations: you have a first - no 44/94 and no cats. I wasn't sure that it could be done. I'll have to add that to my list...

well hold on a minute, its no 81 code for koeo. have not run the koer test yet to check for 94/44.

 

[jcgafford]

koer........ all 11's! all codes are GONE!!! koeo and koer! Thanks jrichker! so it did get rid of 94/44 with no cats. but i have to put cats back on eventually, it is just too stinky without them. i smell like exhaust every time i fire it up.

 

[jcgafford]

found a midpipe with the 4 cats in it from a 93, 50 bucks! picking it up next week.

 

[jrichker]

found a midpipe with the 4 cats in it from a 93, 50 bucks! picking it up next week.

If it's good shape, that's a very good deal.

 

[jcgafford]

If it's good shape, that's a very good deal.

look good, but really no way i know to check the cats for function. 50 bucks is worth the risk to get rid of that stink.

 

[jrichker]

There is at least $50 worth of platinum or palladium in the converters if they haven't been gutted or cut open.

 

[jcgafford]

sounds like top converters are bored out. bottoms are unknown. is it even worth it with those gone?

dead deal, all converters are bored out.