I've searched, read and tried everything......Car Still Runs Rich!!!

[Alex in Houston]

As the title states my car runs rich. At idle, give it gas and black smoke shoots out the back. Tail Pipes and lower back bumper cover are black/sooty after a short drive, hell just let it sit at idle and give it gas, they'll become sooty.

302 (stock forged piston rebuilt a few years back. Less then 1500 miles since rebuild)
TFS stage 1 cam instlled "Straight Up"
AFR 165 with 64cc chambers (New Springs and Manley Valves installed a few years back. Less then 700 miles on them since then)
1.6 Stud Mounted rockers
GT40 Upper/Lower (lower port matched to heads)
MAC 1 3/4" Long Tubes, Custom Catco 3" H-Pipe that feeds into 2.5" Mac Flowtubes/Mufflers/TailPipes
Kirban Adjustable (set at 37 Vac disconnected. Have changed back and forth between stock and Kirban, no change in results)
19# Injectors (have tried several sets, same results. I have the 4 hole version in the car now. Heard the pintle type clog more often. )
AutoLite 3924's gapped at 42
Brand New Set of Bosch 8mm Wires
Stock 70mm Mass Air
A9L computer (Complete Fox Body Harness and Distributor) Timing at 18 (set/checked with SPOUT out)

Car pulls 12-14" of Mercury pretty steadily (TFS cam) and idles rock solid at 900 (3.5" tach on Dash). Drives fine outside of the fact that it has no balls! The car was turbocharged for years prior to this. I grew tird of the maintenance and crowded engine bay with the twins (hence the low miles over the years. Always on jackstands or sitting while I saved to fund something else turbo related.............What a waste of time/money over the years) and sold all turbo related items.

Last time the car was N/A it had TFS TW with an E-cam. This was back in 98 and it ran 12.9 @ 108 on street tires (car is a 95 GT). Had constant issues with the Valve Guides (TrickFlow fixed them 3 times. The second time they converted them from pedestal to stud mount. The Third time they changed the valve guides and I sold them once I got them back. Have no idea if they held up) Bought the AFRs about the same time I got into TurboCharging the thing (hindsight, wish I would of left it N/A. Drove it waaaaayyyy more then I worked on it, LOL)

Anyhow, I know it should be easily as fast as my 06 GTO (my GTO is stock down to the paper filter..............for about 20K more miles :evil1: ) Unfortunately it's not (not even close). I'm sure the issue has to do with the richness but I'm at a loss.
Check Engine light has never come on BUT I ran codes and get 34 (EGR above limit, guess it's not opening) and a 67 (neutral switch in tranny to EEC) Both of those will basically only have an effect on idle and I think the EGR will cancel decel fuel shutoff. Though I get no popping out the exhaust during decel.

I'm going to remove the TFI and have it checked. I do remember a time back in 96-97 when the TFI went bad only on the advance. Had a very helpful/knowledgeable guy at an Autozone run the test. First time I heard of such a thing but a new TFI (bought a Motorcraft, hate AutoZone electrical items, lol ) fixed the problem.

Outside of that, I'm out of ideas and thus the need for this long arse diatribe

 

[jrichker]

Code 34 Or 334 - EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat, replace the EGR valve ($85-$95).

If the blow by test passes, and you have replaced the sensor, then you have electrical ground problems. Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1.5 ohm. Next check the resistance between the black/white wire and the negative battery post. It should be less than 1.5 ohm.

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.

Let’s put on our Inspector Gadget propeller head beanies and think about how this works:
The EGR sensor is a variable resistor with ground on one leg and Vref (5 volts) on the other. Its’ resistance ranges from 4000 to 5500 Ohms measured between Vref & ground, depending on the sensor. The center connection of the variable resistor is the slider that moves in response to the amount of vacuum applied. The slider has some minimum value of resistance greater than 100 ohms so that the computer always sees a voltage present at its’ input. If the value was 0 ohms, there would be no voltage output. Then the computer would not be able to distinguish between a properly functioning sensor and one that had a broken wire or bad connection. The EGR I have in hand reads 700 Ohms between the slider (EPV) and ground (SIG RTN) at rest with no vacuum applied. The EGR valve or sensor may cause the voltage to be above closed limits due to the manufacturing tolerances that cause the EGR sensor to rest at a higher position than it should.

This will affect idle quality by diluting the intake air charge


Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

The computer wants to make sure the A/C is off due to the added load on the engine for the engine running tests. It also checks to see that the transmission is in Neutral and the clutch depressed (5 speed). This prevents the car from being driven while the computer is in test mode. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.


Are you sure that there are no other codes? Has the MAF been checked to be sure that its calibration is a match for the injectors? The stock Ford MAF sensor should have Ford p/n F2VF-12B579-A2A.

MAF troubleshooting & diagnosis:
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 element is secured by 2 screws & has 1 wiring connector. To clean the element, remove it from the MAF housing and spray it down with electronic parts cleaner or non-inflammable brake parts cleaner (same stuff in a bigger can and cheaper too).

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) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

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

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

Computer,. actuator & sensor wiring
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

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

Vacuum routing
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

 

[Alex in Houston]

No other codes and it's the correct MAM as it's the stock meter (have several with that part number).

 

[jrichker]

Get out your voltmeter and measure the MAF voltage as you idle.

If that checks out OK, then do a cylinder balance test to look for stuck injectors.

Cylinder balance test:
Warm the car's engine up to normal operating temperature. Use a
jumper wire or paper clip to put the computer into test mode. Start
the engine and let it go through the normal diagnostic tests, then
quickly press the throttle to the floor. The engine RPM should exceed
2500 RPM's for a brief second. The engine RPM's will increase to about
1450-1600 RPM and hold steady. The engine will shut off power to each
injector, one at a time. When it has sequenced through all 8 injectors,
it will flash 9 for everything OK, or the number of the failing cylinder
such as 2 for cylinder #2. Quickly pressing the throttle again up to
2500 RPM’s will cause the test to re-run with smaller qualifying figures.
Do it a third time, and if the same cylinder shows up, the cylinder is
weak and isn’t putting out power like it should. See the Chilton’s Shop
manual for the complete test procedure

Here's the link to dump the computer codes with only a jumper wire
or paper clip and the check engine light, or test light or voltmeter.
I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

For those who are intimidated by all the wires & connections,
see http://www.actron.com/product_detail.php?pid=16153 for what a
typical hand scanner looks like. Normal retail price is about $30 or so
at Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes
or beeps.. Cost is $33.

Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder
balance test. Low compression on one of these cylinders rules out the
injectors as being the most likely cause of the problem. Look at cylinders
that fail the cylinder balance test but have good compression. These
cylinders either have a bad injector, bad spark plug or spark plug wire.
Move the wire and then the spark plug to another cylinder and run the
cylinder balance test again. If it follows the moved wire or spark plug,
you have found the problem. If the same cylinder fails the test again,
the injector is bad. If different cylinders fail the cylinder balance test,
you have ignition problems or wiring problems in the 10 pin black &
white electrical connectors located by the EGR.

How to do a compression test:
Only use a compression tester with a screw in adapter for the spark
plug hole. The other type leaks too much to get an accurate reading.
Your local auto parts store may have a compression tester to rent.
If you do mechanic work on your own car on a regular basis, it would
be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the
throttle wide open, crank the engine until it the gage reading stops
increasing. On a cold engine, it will be hard to tell what's good &
what's not. Some of the recent posts have numbers ranging from
140-170 psi. If the compression is low, squirt some oil in the cylinder
and do it again – if it comes up, the rings are worn. There should be
no more than 10% difference between cylinders. Use a blow down
leak test (puts compressed air inside cylinders) on cylinders that
have more than 10% difference.

See the link to my site for details on how to build your own blow
down type compression tester.

 

[Alex in Houston]

Decided to run a compression test as a way to rule some things out. Motor warm, all plugs out (with burns on my hands to prove it) and throttle wide open :

1---155
2---151
3---165
4---135 (squirt of oil = 155 ---ring not sealing well)
5---155
6---160
7---150
8---150

Plugs from Drive side had the most soot on them for some reason. Seems strange since cylinders 5-8 have the highest compression across the board. It's also the same side for the tail pipe that smokes the heaviest.

Plugs laid out in order (1-4 then 5-8) from left to right

Plugs from drive side

Plugs from passenger side

Outside of 4 being a bit low on compression (and it's plug looked no worst then the rest. No oil on it or anything) I can't say the motor is the culprit of the richness.
Tried a New BAP, changed the TFI to a known working MotorCraft one and went over every ground in the car. Still can't pin point the problem. :rant:

 

[Alex in Houston]

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.

Just did test on the MAF (using my ever handy and always accurate Fluke 77). All resistance numbers are in order BUT the voltage at idle is 1.1 to 1.36 (idle at 900 engine warm) . What's up with that? If your numbers above are correct (.6 at idle) why is this thing so out of range?

 

[jrichker]

Just did test on the MAF (using my ever handy and always accurate Fluke 77). All resistance numbers are in order BUT the voltage at idle is 1.1 to 1.36 (idle at 900 engine warm) . What's up with that? If your numbers above are correct (.6 at idle) why is this thing so out of range?

The increased MAF output voltage would cause a rich mixture, so it is the likely source of your problem.

One of three things is the likely problem source:

1.) MAF sensor is the wrong part number to match a A9L or A9P computer.
The 70 MM Ford MAF's that are A9P or A9L compatible are:
1995-94 Mustang 5.0 F2VF-12B579-A2A,
1995-94 Mustang 3.8L F2VF-12B579-A2A,
1994-92 Crown Victoria 4.6L F2VF-12B579-A2A,
1995-94 Mustang, Mustang Cobra 5.0L F2VF-12B579-A2A,
1994-92 Town Car 4.6L F2VF-12B579-A2A,
1994-92 Grand Marquis 4.6L F2VF-12B579-A2A,

2.) The MAF sensor is bad. See the above list for the correct sensor part number.

3.) The MAF housing has been modified from its stock configuration.

 

[BigHairyMonkey]

not a help at all but, my name Alex and i live in houston, just thought that was wierd

 

[BigHairyMonkey]

might be stupid but have you checked to see if your 02's are still alive, that could richen things abit

 

[Alex in Houston]

02's are new and switching just fine at idle and part throttle. They go full rich and no longer switch during WOT.

Oh Yeah, if you look at my join date, you'll see I've been using the Alex in Houston moniker since the forum switch from BBS to UBB/PHP

 

[Alex in Houston]

The increased MAF output voltage would cause a rich mixture, so it is the likely source of your problem.

I really have tried to find some light on this voltage range you posted. No matter what meter I have tried, none seem to run at/around .6 at idle. I'm going to have to probe a few other Ford vehicles and see what they put out. I can even remember back (1998 or so) I had an Air Adjuster! thingamajig and the voltage on that never read that low at idle (and the car ran great back then). I know none of the meters I've tried this past weekend (see below) have ran (allowed my car to hold an idle) at less then .987 or so. If possible, could you link me to the source of this info? I'd really like to read more on it.

One of three things is the likely problem source:

1.) MAF sensor is the wrong part number to match a A9L or A9P computer.
The 70 MM Ford MAF's that are A9P or A9L compatible are:
1994-92 Crown Victoria 4.6L F2VF-12B579-A2A,
1994-92 Town Car 4.6L F2VF-12B579-A2A,
2.) The MAF sensor is bad. See the above list for the correct sensor part number.
3.) The MAF housing has been modified from its stock configuration.

Got a hold of a few totally stock unaltered MAF's. One from a 93 Mark8 and one from a 94 Crown Vic. I for the life of me, could not find a meter with the a2a part number. Plenty of AA, AB but no A2A. The CrownVic one I got is an A1A.
The electronics are the original ones for the meter (never have been removed/replaced) with the post in the middle of the meter. The Crown Vic is 70mm and the Mark8 is 80mm. No real difference in the driveability with either, but both were an improvement.
The torque and power is OK from 1k-3800 RPM, but not great. I say "ok" because it's not the way the car used to feel but much better then a few weeks back. Definitely NOT what this combo should feel like. The real issues start as I get over 3800 RPM. It feels like the engine is suffocating. It will still build up RPM, but just at a much slower rate. The higher the RPM, the more it struggles I guess you could say. I tried rolling along in 1st gear at 5-10mph and matting the pedal. It was torquey and pulled OK, but it can't even spin the tires. Before I could melt the tires in 2nd gear at 25mph.
So basically what I'm saying is, the combo is way down on power...especially at higher RPM's. Now for the strange part. At lower RPM, idle and cruising the car seems to run PERFECT. It doesn't die, doesn't backfire, plugs look great etc. With the way it behaves at light throttle, you'd think everything is fine. It's just as docile and a pleasure to drive as a bone stock car.
Timing is at 17, FP is at 38 Vac off, etc. I've checked the plug wires and they're fine. Replaced the TFI with a MotorCraft one. Checked TPS voltage (.87 closed 4.81 WOT) . The 02's, fuel pump, vacuum level (no leaks) and all that are fine. I need to put in a new steering shaft, so while I'm under there I plan to check out the NDS wire to see why I keep getting a code 67. I can't run KOER test and that is the only thing I can see to be causing that issue.

 

[jrichker]

The source for tha MAF data is:

Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.

It's about $25 from Borders.com see http://www.amazon.com/ . Select boo...4 characters (F2VF) are the most significant.

 

[Alex in Houston]

The source for tha MAF data is:

Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst It is very good, and I found it to be very helpful.

The Probst book, I can get that from someone I know.

I personally checked mine and at approximately 800 RPM, I get .79-.80.

Yeah and my car is set to idle at 950-1000 (with TFS Stage 1 cam) and I get around .9, so I don't think my voltages are off

The part number on the MAF sensor on my car is F2VF-12579-A1A. From the posts for vristang, I am told that the first 4 characters (F2VF) are the most significant.

Exactly the number I have for the A1A.
I really need to get this KOER issue figured out as the more I search/learn, the more I feel that the issue lies somewhere other then the MAM.
Thank You Jrichker, you have been very helpful and I truely appreciate it.