Shakey idle and sluggish take off

[ryan445]

Hello.

4 years ago I parked my 87 Ranger. One day while driving to work it start feeling strange driving down the highway. When I got off the high way it stumbled at a stop and almost stalled taking off.
4 years later I replaced the 02 sensor and that seemed to fix that issue. I noticed that while idling, it's shaking a little and you can hear a slight miss in the tone of the engine.

Replaced spark plugs. Notice some were a little fouled from a rich mixture. No difference made. I then replace the air temp sensor on the intake plenum and cleaned the throttle body at the same time. It was pretty fouled up and that seemed to help some but still rough and laggy.

The engine smooths out when you give it gas but it's just lagging more then normal for the 2.9l. no codes on KOER but I get TPS code on KOEO.

Not certain that is the cause of my woes though. Its it not smoking out the exhaust, doesn't smell rich, no coolant in oil or vise versa.

Next on my list is to replace the injectors l, but don't wanna keep throwing parts at it that may not fix it.

Also checked for vacuum leaks, fuel in the regulator vacuum line, cap, rotor and wires don't have many miles on them.

Also to note: old gas was drained from the tank and fresh gas was put in after the sit. Its been through 4 tanks with some seafoam.


Edit: Also to add sometimes, not all the time, if I gun it. It will suddenly loose power at the top end of the power band. You can feel the truck stall and see the rpm drop and pick back up.

 

[rusty ol ranger]

If its throwing a TPS code that would be the first thing id inspect.

Check it for 5v reference voltage, if thats there id replace it.

 

[89longbed]

It’s also pretty easy to check that you get a smooth change in resistance as the butterfly goes from closed to open and vice versa. You’ll just need to determine which 2 of the three pins are that circuit. Spikes or drops in the resistance will mean the computer is getting a bad voltage signal at those points.

 

[rusty ol ranger]

It’s also pretty easy to check that you get a smooth change in resistance as the butterfly goes from closed to open and vice versa. You’ll just need to determine which 2 of the three pins are that circuit. Spikes or drops in the resistance will mean the computer is getting a bad voltage signal at those points.

You also need an analog meter to properly check the sweep of the tps

 

[ryan445]

At rest I am reading .72 volts. Slowly sweeping the throttle to WOT it does increase smoothly and tops out at 4.15v

 

[rusty ol ranger]

At rest I am reading .72 volts. Slowly sweeping the throttle to WOT it does increase smoothly and tops out at 4.15v

Find a ECM pinout and a buddy and make sure the signal is getting to the computer

 

[89longbed]

What is the voltage reading for the 5v reference wire? At WOT the signal wire should be the same, and 4,15v is on the low side for the signal. Once you track down the pins on the ECM plug I would check the three lines for resistance, which shouldn't be there.
Definitely get your TPS code sorted out first, but before replacing the injectors I would try cleaning them out. The cylinders that are not running rich may be doing so because the injectors aren't flowing as they should (and the ECM is running the injectors longer). Sitting four years can cause that sort of problem.

 

[ryan445]

I got 5 volts coming from the computer. And voltage is making back from the TPS.

I re-ran the KOEO test and got the pass code. Messed with the throttle body and wires a bit to see if it would come back and it has stayed away this far.

Still idles crappy. On high idle from cold start is when you hear the miss in the sound of engine.

However, while poking around I may have found my culprit or at least a small contributor. I have a Duralast of ignition coil I threw on it who knows how long ago. When the engine warms up you can hear it clicking with the rhythm of the distributor and I suspect an internal short. All this time tinkering around it though it was the injectors I was hearing. If I remember correctly I threw a duralast TFI in it as well at the same time.

On a note: you mentioned to clean them. I am guessing you mean to take them out and manually clean them. Sorry if that's a dumb question. I've always just thrown a can of cleaner in the gas tank every so often.


EDIT: shortly after posting this I decided to pull the cap to look for carbon tracks even though I know it's not that old and one of the wires to the spark plug separated...... Easily may I add. So also may have compounded this issue.

 

[ryan445]

Well guys...... Looks like I've been lying to myself for the past few weeks.

Cap and rotor are have carbon on them. Let me replace cap, rotor and wires and go from there..... Should have done it with the fouled plugs instead of taking short cuts.