Hi,
I just bought a 92 ranger with only 50K miles. Only 5K miles in the last 10 years. It starts great and runs fine but it has a slight missfire under acceleration and cruise up hill. Idle is smooth in the exhaust, no puffing or odd smell. It is also getting about 5 mpg less than it should around town and seems to get lower MPG on the highway than it does in town. It does NOT have a check engine light or any codes. It doesnt seem to matter if the engine is cold or hot, the missfire is just the same. Here is what I have done:

New autolite platinum plugs
New O2 sensor
Cleaned EGR valve
Checked PCV valve
Compression fine
Used several cans of injector cleaner
Ran Sea Foam into intake to clean engine (has helped many engines).
Checked for intake system leaks
Checked Mass airflow for dirt.
New exhaust system including cat.
New timing belt installed correctly.
Thermostat works OK (not stuck open or closed)

Still it has a missfire under acceleration and low MPG and even seems low on power a little. However, under WOT acceleration, it does not seem to missfire.

One odd observation is if you unplug the coil for the intake side plugs, the engine will start and run fine. If you unplug the coil for the exhaust side plugs it will not start. Does this engine detect a coil failure and not allow it to start?

It does have a slight exhaust leak where the exhaust pipe connects to the manifold, can this cause a problem?

I dont trust garages to do anything but parts swap and charge a fortune for not fixing anything so any help you can give would be appreciated.

Dave

 

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Check your connections and wiring plug ins that runn through the fire wall. In particular the ones involving the leads to the coils. They are known to have issues with them. Are you the guy from the windy city that owns a turbo Pantera

 

Also check out the thermo stat there were problems there also missassembly and core sand sticking them. Poor heat and poor economy are the result.

 

I have done as some people suggested. The wiring connector is good and clean and well seated. I know the thermostat is working correctly. The truck quickly warms up and has good heat inside. The temp gauge hovers right around the "N" in Normal.

A couple of other things I have noticed. In Neutral it hesitatates real bad if you press throttle very fast when at idle. It is a little better when the engine is warmed up really good but the mis is still there. The Mis feels like lean-misfire and not total cylinder cutout.

I pulled the 4 exhaust plugs and 1,2, and 4 look fine. 3 looked ok for color but appeared to be firing to the side like the spark was getting blown sideways.

I got a check engine light the other day briefly but the only code that was stored was 218 which is not listed in the OBD-1 code list.

Can anyone tell me what the symptom of a bad MAF is??

Can anyone tell me about how the dual coils work? One for start, one for run? If I unplug the exhaust coil the engine will not start. If I unplug the intake coil while the engine is running it slows way down.

I am getting really annoyed and am about ready to pull the engine rebuild it and replace every EFI part on the truck.

Any help is appreciated.

Dave

 

Both plugs should be firing all the time. If I rember correctly pulling either side the engine should run. Your throttle position sensor might be causing the hesitation. I would check the fuel system pressure and also see if it hold after shuting off the engine to see if an injector is leaking. You might swap #3 plug around to see if it is firing properly in other cylinders. Exhaust leaks in smaller engines can cause power losses you wouldnt notice in a V8.
I work on Panteras woundering if you know Chris from the motor city.

 

EFI hesitation == MAF or fuel pressure issues. Miss while accel == plugs/wires or fuel problem.
The plugs do not fire all the time. Search this site for a description of the dual plug engines. The second plugs are phased in and out as desired by the ECM programming.

Check the temp sensors, ECT, ACT both. If they are broken, it will 'think' the engine is all warmed up when that is not the case, or will think that the air coming into the intake is balmy when not.

Plug wires can allow for smooth idle, but can buck like you are towing a trailer that is not happy... Run the engine at night, with the hood open and watch the show, or test for ohms 12-14K ohms per foot, iffen my grey cells are functional. If too HIGH, then the sparkie will not want to go out where it should, and will take a shortcut.

tom

 

Hello! I have the exact same issues with my '94 Ranger. Glad to see I'm not the only one that these things happen to... Idles great, then there's a slight hesitation accelerating from idle when at a stand-still, but it runs fine. As I accelerate or go uphill, it losses power and feels like a mis of some sort. I've changed the fuel filter and wires and replaced several rotted vaccuum hoses and such, with no real change. Haven't done plugs yet, but suspect (or at least hope) it'll make some difference. Have you come up with the fix yet?


Thanks! Lorne

 

I have been trying to get with the guy that used to be the chief engineer for the 2.3 engine to ask him about your issues. I remember there was an issue with both plugs firing and the wiring harness. Myself I used to work with the group near the end of its production. If you have one of the 2.5 stroked 2.3 engines I designed the cast aluminum pan they use.

 

I have some new developments in the missfire problem. Even though the plugs looked fine, I changed them anyway since it looked like the were firing on the side of the electrode. The engine had Autolite AP764 Platinum plugs. I replaced them with standard plugs. Although not completely what I would call running correctly, it runs much better. Has better power all around, small mis at idle is gone and most of the misfire under accelerations is gone but I can still detect a small amount.

The big question is, Does this engine not like Platinum plugs??? Anyone ever had experience with Platinum plugs?

I will continue to look for more problems as the weather gets warmer. Right now, no heat in the garage.

Dave

 

I was experimenting with mine last night and decided to try running with individual spark plugs disconnected. I thought it interesting that on the exhaust side, I was able to run with both cylinders 2 and 3 disconnected at the same time and was unable to detect any difference in performance. Runs smooth at idle and has the same slight mis on accel. Disconnecting 1 or 4 individually made a big difference, even at idle. Plugs looked old, but OK and were not fouled. Guess we'll try new plugs tonight and see what happens.


Lorne

 

I was looking at the wiring diagram for the 2.3. It appears that there are 2 cylinders per each half of the coil. Does anyone know if cylinders 2 and 3 are on the same side of the coil? If so, it might point to the coil pack or wire coming from the computer. That being the case, someone on the thread made mention of the intake and exhaust plugs firing at the same time. I wonder if a wire could be run from the input of one coil pack to the same input on the other coil pack to see if the actual wiring is at fault?

Thanks, Lorne

 

Here is what I found out. Both plugs opperate at all times. One side is the lead plug which originaly was platinum the trailing plug was a standard plug. The plug wire or coil has some sort of marker to denote this. Good news a service bullitin stated platinum can be used on both sides. He also said regular plugs of the proper heat range will also work. You might check the coils themselves with a multimeter.

 

my 92 ranger is doing the exact same thing

 

My 96 ranger had similar problems but gave a OBD-II camshaft position sensor code. I changed the sensor twice and it made no difference. I could see on my scanner that the timing was all screwed up. It stayed at 27 as a default and then as you accelerated the knock sensor would start pulling it back.

I finally gave up and took it to the dealer. They relocated the negative battery cable per the Ford service website and it was fine. All they did was unhook it from the fram and bolt it to the intake manifold. It looks a little silly now but it fixed the problem. A ground strap from engine to frame would probably accomplish the same.