92 2.3 miss at idle

[Rangeraddict]

I just bought this truck,
It has a miss at idle but clears up above 1000 RPM

I have done a full tune up, plugs wires, fuel filter, air filter etc.

I cleaned the MAF, checked for vacuum leaks (the line to the evap can from the bottom of the TB and the pcv valve were both unplugged so I fixed those)

Tested the egr valve with vacuum from the FPR line. -runs even worse

Disconnected one injector at a time and they all made a difference.

I'm running out of ideas, any suggestions?

Oh and no codes at all

Thanks, Craig

 

[RonD]

Your fuel injectors are Batch fired not Sequential, so 2 injectors open at one time, pulling connector on each injector might not find the missing cylinder.
Batch fire is the fuel injected version of a carb, well 1 step above a carb , it keeps the intake full of fuel/air mix regardless of which intake valve is open.
So stopping 1 injector leans all the cylinders, so effect would be the same no matter which injector was stopped.
But it would also mean all injectors should be working if effect was the same regardless of which injector was stopped.

A can of Seafoam in the tank can clean up sticky or dirty injectors, I do it once a year on my '94 ranger.

On cold engine I would start it and let it idle, so miss for a minute or two, then shut down and pull 1 spark plug from each cylinder, see which one is "dirty", missing.


The 1992 2.3l should have dual coil packs, you can test coil packs with an OHM meter, but I would just swap them around and see if miss goes away.
The waste spark system works pretty good but does have weak spark on 1 plug out of the 2 that fire, the dual coil setup reverses that so each cylinder gets the stronger spark.
If one coil in one pack has a problem 1 cylinder might only be getting the weak spark so is missing now and then.


Google: autozone test ford coil

If you want to test them.

Testing a coil will show if it is bad, but if it passes it doesn't mean it's 100%, heat can cause a passing coil to fail intermittently.

When RPM is increased so is cylinder heat and compression, this makes it easier for spark plug to ignite fuel/air mix, so a miss can disappear.

You could do a compression test, lower compression will cause misfire at idle.

Are you losing any coolant, small head gasket leak can cause misfire at idle because ignition is fouled by small amount of coolant.

 

[Rangeraddict]

that explains why the injectors didnt make a difference then,

I was able to get my truck in the shop at work (I'm a diesel mechanic)
pulling plugs on every cylinder made a difference so I moved on to testing the coils,
tested per the directions I got roughly .5 -.7 ohms on both sides of each pack,
But when I went to test between the coil wire to the plug tower I got OL on every single one, I did this with a jumper wire with the correct terminal on the connector side to eliminate my fat fingers messing it up lol.
I would think this would cause a no run condition but could possibly be causing weak spark. So I'lll pick up a couple new coils in the morning and see how that goes.

I did have a leak at the T-stat housing but I got that sealed up 2 days ago (what a PITA that was) so far so good on using coolant, It's not pushing coolant nor is it Smoking so I would assume no at this time

If the coils dont fix it then I will get a compression tester and go from there

Thanks, Craig