'92 - Does a AFM failure always throw a code? (1 Viewer)

[MDarius]

Getting lots of hesitation while driving. I'm thinking multiple choice
1. MAF
2. Bad fuel
3. Fuel filter
4. Fuel injectors
5. Fuel Pump
6. Distributor

No check engine light and I don't think it's burned out. Did I miss anything?

 

[jonheld]

What maintenance have you done to try to remedy the issue?
The 3FE has an AFM not a MAF. Check for stored codes.
You could try resetting the ECU by pulling the 15 amp EFI MAIN fuse for 10 minutes.

 

[OffRoadScott]

Best way to check your MAF is with a volt meter and check it per the FSM testing procedures. The resistance will vary due to ambient temperatures and the FSM states those variances.

Also, I would check the O2 sensors as well, they can cause issues like you are explaining. Resistance on those should be 5.5-6 ohms, I do not recall the pins but FSM can tell you this.

The FSM is downloadable via a link here on MUD.

 

[MDarius]

What maintenance have you done to try to remedy the issue?
The 3FE has an AFM not a MAF. Check for stored codes.
You could try resetting the ECU by pulling the 15 amp EFI MAIN fuse for 10 minutes.

None yet. It started before we left town for 4 days in a different vehicle. I said, "It's probably not a big deal to fix, but we'll need to take care of it when we get back." Immediately when we get back, at 10pm, and after 8 hours of driving, my daughter hops in the cruiser to see her boyfriend and calls me, "It's barely driving. Should I come home or keep going?" It's raining.

Yes. Please keep going. And don't ever call me again.

We'll pick it up today from boyfriend's house and I'll have a look.

 

[jonheld]

Start with the basics. Plugs, cap, rotor, wires.
Make sure it's nothing silly like the hand brake dragging.

 

[MDarius]

Start with the basics. Plugs, cap, rotor, wires.
Make sure it's nothing silly like the hand brake dragging.

Thanks! Always a good reminder. I drove behind her bringing it home. It does fine until the engine warms up, then lags and blows dark, fuel rich smoke out the exhaust. We talked about it, and she just wants to take it to a mechanic rather than wait to diagnose and fix it in the driveway. We've got another thunder storm today and she just needs to drive it.

So, we dropped it off and will pay someone else to learn about our car. It's an option. I guess.

 

[jonheld]

It does fine until the engine war.a up, then lags and blows dark, fuel rich smoke out the exhaust.

O2 sensors
Coolant temp sensor
Those would be the first places I would look.

 

[inkpot]

Start with the very basic test. Does your Check Engine light come on briefly when you first turn the key to RUN?

 

[Mixelplix]

On my 3fe the rearmost (No 6) sparkplug wire is very tight. I embarrassingly drove it for several years with the plug wire not connected.

 

[MDarius]

Update: We've been through the tuneup, the distributor was arcing and that was a problem. Now the mechanic is replacing the IAC and the housing it connects to is cracked. I don't have the rig here so I can't take a picture, but does anyone have one of those housings, or have a connection that can help me out?