Arthur,

Yes, one flash each on pins 8 and 14. I'm starting to think that I have air/vacuum leak that seals up once the engine heats up and things start to expand. Possibly in the air intake after the Mass Air Flow sensor. Or maybe a wore out O2 sensor that isn't faulting yet. What do you think?

Thanks again,

John B

After you get the single flash, wait 2 secs and then hold the button 6 secs..then turn off key for 50 secs , on for 10 and then restart.
That will reset the HFM memory to mean..then drive the car for a couple of days for it to re-adapt see how it then runs ... and then check if any codes come back on 8 and 14.
The big power change at rpms comes from both the variable cam advance and the runner length change as rpms increase..you are aware of that????

__________________
A Dalton

Arthur,

Sounds good. I will give that a try. What pin do I use to reset the HFM? 8 or 14 or do it to both? Also, I guess I'm not sure how the variable cam advance system works. I will do a little research to get up to speed. I'll do the reset of the HFM and post in a few days.

Thanks again,

John B

Do them both..
As I stated on a previous post , 8 is HFM and 14 is EA . You have to reset each module, one at a time.

You may also want to clean the MAF , but I would prefer you do nothing until you follow the steps I mention so we know where you are at from the get-go....
And I am assuming from your post that you have no codes on the DM....................

__________________
A Dalton

Arthur,

I did as you suggested and re-set the EA and the HFM. After driving for a few days I checked for fault codes. There were no faults on the Pin 14 EA. The HFM on Pin 8 returned one code: #9 O2S 1 - Voltage too high, circuit open or voltage implausible. I think I have only one O2 sensor one my car. Do you think this O2 Sensor could be bad?

If so, I've read on some posts that generic O2 sensors or O2 sensors from late-model Mustangs work the same as the OEM but are much cheaper. Any idea if these other units would work on my '93 300E 2.8L?

Thanks again for the replies,

John B

Disconnect sensor under rug on passenger side and monitor the voltage output on green wire as you take the vac line off the fuel pressure regulator for high v.and create a vac leak at engine for low v. reading.
Post what you get.

__________________
A Dalton

Arthur,

Sorry for the delay, I got sidetracked for a while with the repairs. I tested the voltages with the vehicle idling on the O2 Sensor as you suggested, here is what I found:

1.) On the smaller green/blue wire to the O2 Sensor, I had a reading of 12.6 Volts. The reading was the same with the vacuum line connected and disconnected from the fuel regulator. (I'm a novice with the voltage reader, please let me know if these values are incorrect)

2.) There was another larger, separate green wire heading to the O2 Sensor, which I believe is for the O2 heater. The reading on that wire was a constant 0.6 Volts with the vacuum line connected and disconnected.

3.) Just for testing, I drove the vehicle with just the O2 Sensor disconnected and then again with the just the vacuum line disconnected.

4.) With just the O2 Sensor disconnected, I couldn't notice a difference in perform. Still sluggish.

5.) With just the vacuum hose disconnected from the fuel regulator, I still couldn't notice a difference in performance. Still sluggish, but I did notice a small vacuum pressure coming from the disconnected hose.

Now I'm kinda lost with what to do next. Any help would be greatly appreciated.

Thanks again,

John Bjork

Your wire understanding is incorrect.

There are two plugs for the 02 sensor...one is a single wire plug and the other is a 3 wire plug.
They are right next to one another..under rug
The single wire one has a green wire coming from the engine [ ECU] and it plugs into the single wire connector.. THAT connectors wire is the signal wire coming from the Sensor and that is the wire you want to monitor.[ not the green one]
The 3 wire plug contains the heater circuit and the ground wire. Leave those plugged in.
You unplug the single wire connectors green wire so that the 02 sensor sig can not report back to the ECU.
Now, normal running coolant temp and engine @ idle, you take the vac hose off the FP regulator, that causes the fuel pressure to increase and when it does , more gas gets thru the injectors and causes a RICH condition...so, YOU are MANUALLY making the engine run RICH by increasing the Fuel Pressure beyond spec, and you should see the 02 sensors V increase to about .9v ...meaning it is RESPONDING/RECOGNIZING the rich condition you have created. [ You must plug the vac hose you took off the FP reg for this test so you do not have a lean input thru that open hose at the same time].
Now, note the 02 V for this test and then put that hose back on Reg.... this time, pull off another/different vac hose and create a vac LEAK... the 02 should now respond and show a lean condition by reading a low V [ like .2v]
So, what you are doing is basically manually changing the rich/lean condition of the engine and seeing if the 02 picks up on your changes..if it does , it is working..if it doesn't, it's not....you are just using the engine as a lean/rich generator of sorts..and b/c you have unplugged the green wire going back to the ECU, the ECU can not correct the imbalanced air/fuel mixture that you are creating b/c it sees NO 02 SIGNAL.
This is just a simple 02 sensor test, where YOU are manually controlling/changing the air/fuel mixture and watching the sensors reaction to your inputs.
When you do the lean test, you can actually put your thumb on/off the vac hose you are using to make the engine lean out and as you open/close that hose end , you can see the 02 sig jump up/down with those inputs..verifying the sensors speed for change.
Pretty simple trick...

Get it ????

__________________
A Dalton

Arthur,

Thanks for the response. I attempted the voltage reading as you suggested, but I was unable read a change in the O2 Sensor voltage with the fuel regulator hose unhooked. I did however see a significant change when I would press the accelerator. At idle, the reading on the O2 Sensor was 0.06 volts. As soon I hit the gas, the reading shot up to roughly 0.80 volts at 2000 RPM. The voltage from the O2 Sensor varied up and down as I throttled up the engine up and down. Once the engine came back to idle, the O2 Sensor reading slowly leveled back to 0.06 volts after about 20 seconds. Does this mean the O2 Sensor is working? Its strange if the O2 Sensor is working, then why does the car seem unaffected when disconnected?

Thanks again,

John Bjork

<<

I assume this .06v is a typo?????

__________________
A Dalton

I just read through your ordeal and have an idea. When did this problem first occur? All of a sudden or ? After some other repairs? It sounds like your valve timing may be off. I've seen it a couple of times on the 104 engine b/c it is not the easiest engine to time properly. If you have a late cam it will be very sluggish but will pick up power in the higher revs. Since it would be a basic mechanical problem you won't have any fault codes pointing directly at the problem. O2 sensor codes, adaptation codes, and random logic chain codes could be caused by the late cam due to the engine dynamics with the late cam will not give the expected responses that a properly timed engnie will. The best check would be to pull off the valve cover and confirm valve timing. If you have acces to a compression tester, check the compression first. I'd expect the cranking compression would be low if the valve timing is off. If compression is low, then pull the valve cover and check the cam timing.

Arthur,

Like I said, I'm kind've a novice with the volt meter. With the dial set to 20V, the reading at idle was between 0.04 volts to 0.06 volts, with the average being about 0.06 volts . As the RPM's increased, the voltage steadily rolled up to between 0.75 to 0.85 volts, with the average being about 0.80 volts.

If I am correctly reading the volts, what does a reading of 0.06 volts mean? Is my engine starving for fuel at idle?

Thanks again,

John Bjork

duxthe1,

Thanks for the suggestion, I've considered having the compression checked. I just haven't pulled the trigger yet for the cost. I'd like to exhaust all my ability first, then hire someone. I may be close to that point, heh. I bought the vehicle with somewhat sluggish performance, so I'm not sure how it began. I'm trying to rule out vacuum leaks and O2 Sensors before I crack open the head.

Thanks again,

John Bjork

OK

Your sensor is not putting out a decent signal at low rpm...so, we have either a bad heater circuit or a bad sensor.
The heater input should be 12 v....thatwould be the two same colored wires [ probably white] on the 3 wire connector.
Check for V and then unplug the connector and check the sensor for heater OHMS. probably open circiuit on heater, allowing the sensor to go open loop at low rpm ..meaning a new sensor is in order.

__________________
A Dalton

If valve timing were off , I would expect to see a Cam Position Sensor/ Crank Position sensor relationship code...HFM/SFI are Sequential Injected via cam sensor timing.

__________________
A Dalton