Stock 93 Explorer runs as if it has a vacuum leak but

[Turdle]

Just a hunch.
Some ECM's will develop leaking fuel pump control capacitors. You might take the ecm out, remove the cover and take a look at the circuit board.

 

[ddenton749]

Just a hunch.
Some ECM's will develop leaking fuel pump control capacitors. You might take the ecm out, remove the cover and take a look at the circuit board.

Please explain the fuel pump capacitor issue further. Isn't the fuel pump simply on/off via the relay?

 

[ddenton749]

you sure your 02's are working and are not aftermarket crapola from tinbucktooland?

I am not 100% sure if the O2 sensors are working correctly. There are no codes that reference O2 sensors.

 

[Turdle]

The ecm commands on-off cycles of the fuel pump. Relays just accomplish this.

It's not uncommon to find bad capacitors on the ecm combined with fuel control issues.

 

[ddenton749]

The codes I got:

Several regarding the fuel pump voltage but I had unplugged the fuel pump relay.

The others were 157, 158, and 159 referencing the MAF voltage.

 

[ddenton749]

The ecm commands on-off cycles of the fuel pump. Relays just accomplish this.

It's not uncommon to find bad capacitors on the ecm combined with fuel control issues.

I understand that the ECM controls the fuel pump. The way I understand it is: Key on fuel pump primes for 2 seconds then shuts off. Engine start fuel pump is on. Fuel pressure is managed by the fuel pressure regulator.

It appears to be working this way.

It the fuel pump circuit was bad in the ECM would the pump run at all?

 

[Turdle]

post 85 here

93 explorer sport starting issues

post 10 here

MAF sensor troubles.

It pretty easy to crack the ecm open and have a look. Take a picture for us to look it over with you.

 

[RustyMacintosh]

Just some ideas when googling those codes--just some ideas

https://www.ford-trucks.com/forums/895078-1993-ford-ranger-maf-problem.html

https://www.f150forum.com/f10/code-157-a-112437/

 

[Centaurious]

If you are getting codes 157, 158, and 159 you need to test the MAF Sensor and inspect all the MAF wiring for damaged insulation. Inspect the throttle tube for cracks and damaged rubber ends if yours is plastic.

 

[ddenton749]

The ecm commands on-off cycles of the fuel pump. Relays just accomplish this.

It's not uncommon to find bad capacitors on the ecm combined with fuel control issues.

If you are getting codes 157, 158, and 159 you need to test the MAF Sensor and inspect all the MAF wiring for damaged insulation. Inspect the throttle tube for cracks and damaged rubber ends if yours is plastic.

I am going to replace the ECT sensor first, then try the MAF. I will inspect the wiring as well.

 

[ddenton749]

**UPDATE... FIXED***

It turned out to be the Mass Air Flow Sensor. I bought a new complete unit and presto! Problem solved. It is running better than ever now.

Replaced:
Air tube from the MAF to the throttle body. It was torn at the accordion.
Fuel Injectors. They had at least 300K miles on them.
Plugs and wires.
Engine Coolant Temperature Sensor. I broke it while unplugging it. It was original.
Mass Air Flow Sensor. It too was original.

Maybe a moderator can add "FIXED" to the title of the thread?

 

[410Fortune]

So glad you got it fixed!

 

[ddenton749]

Status Update... Not Fixed!

Moderator please remove the "Fixed" from the title.

 

[ddenton749]

So...

The repair lasted four days. The Explorer ran perfectly up to yesterday. This morning it sputtered a little when cold but ran fine after it warmed up for a few minutes.

Then seven miles into my eight mile commute it began to die. It lost all power; stepping on the gas did nothing. I pulled off to the side and it idled fine. I started back on my way and it began to cut out again. This time I lost all electrical power briefly, enough to clear the radio presets, but the power came back on and i was able to get the car off the road. I checked my battery connections and they were tight.

I started the car again and it was running rough, much like it was before I replaced the MAF. I disconnected the MAF and it ran better (not great but driveable). I drove the last mile to work.

I am at a loss. Could there be a short somewhere?

 

[410Fortune]

check fuel pressure?

 

[ddenton749]

check fuel pressure?

Fuel pressure, while not tested, appears to be good. The Explorer runs reasonably well with the MAF disconnected.

 

[ddenton749]

This is a new MAF purchased from Rock Auto. It lasted four days. The symptoms are similar with one major difference: With this new MAF the engine will die when the RPM's increase over 1,500-2,000 or under load. During the original problem the engine would idle terribly and then tend to clear up at higher RPM's. This MAF problem has slightly different symptoms.

I back-probed the MAF last night. The results at the pins:

Alternator voltage: 14.4 to 14.8 v
system ground: near zero (I believe)
signal voltage: 5.6 v
signal return: 0.18 to 0.28 v and highly variable at idle. With increase in throttle it went up to 0.7 v. (I was looking for 0.09 to 0.1 at idle and increase to 0.4) The engine would die at higher RPM's.

It runs reasonably well with the MAF disconnected. I can get back and forth to work with no major problems.

I am working under the assumption that I got a defective MAF and I will initiate a return/replacement with Rock Auto.

In the mean time, does anyone believe my alternator voltage is too high. The alternator is a junk yard alternator that I installed several years ago. Is it possible that high alternator voltage can fry the MAF?

 

[410Fortune]

5.6V on the sensor signal return feed is pretty high and 14.8V is also pretty high
I usually see more like 14.4V from alternator and 4.9-5.2V on the SSR 5V power feed from the PCM
You maybe onto something
Or it could be your meter?

 

[kmack]

FWIW...
Might want to look at an OEM MAF sensor. Don't know why, but it seems all after-market sensors these days are crap 50% of the time, even straight out of a new box! This across all makes: Ford, GM, Chrysler, etc. Even the OEM's have their problems, but much less than with aftermarket.

These days, if it's an electrical sensor, I won't buy anything but OEM.

 

[410Fortune]

What Kmack said is truth