1986, 2.3L--runs RICH and rough idle

[Dan B.]

Working on the "new to me" 1986 Ranger. I'll try to cover all the bases to minimize possibilities.

It's a 4 plug 2.3L (EFI), five speed with a LOT of new parts that were installed when I got it. The front cover and valve cover have been off.

The problem....idle is rough and it belches black smoke....almost like it "identifies" as a diesel. It flooded itself so bad that it would not start (with the MSD plugs). I removed them and installed new Champion plugs (were in the cab with lots of other stuff) and gapped at .044". Below is a picture of the spark plugs after five minutes of run time.

New Fuel tank (unsure about the pump). Fuel level is very low and not sure how old it is. Going to get new high test and dry gas today and add it in.

New MSD coil, wires, cap, rotor, plugs. New injectors.

New IAC and EGR.

Compression test shows 120# at each cylinder.

Timing is set at 10BTDC. HOWEVER...I did not pull the cover to check all the timing marks to make sure they are all in sync.

Checked the firing order to make sure they had it proper...it was.

I unplugged the MAP sensor (truck was off). Restarted and the idle did not seem to change pitch. However when I plugged it back in (while already running) the idle did smooth out and black smoke went away for about 15 seconds. Then it came right back....ugh. Got a new MAP sensor and nothing changed.

There is a vac line (metal elbow) from the BOTTOM of the throttle body that has a section of rubber line on it and is plugged. I'm sure it is supposed to go somewhere but I'm not sure where. I pulled the capped rubber line off the elbow while running and the idle speeds up substantially (as expected).

The plan...for tonight I will add new fuel, clean the plugs and check the vac line from the MAP to the T-body for obstruction.

What else can I do to trouble shoot this bugger. Thanks.

 

[Daniel Black]

If I remember correctly there's a smaller hose from the IAC valve that goes to the back of the throttle body and a smaller one points forward that goes to the valve cover like a vent. I'd check the fuel pressure regulator. It may be bad and dumping fuel in.

 

[tomw]

If you are blowing black smoke, it is most likely too rich. That can be from leaky injectors, bum fuel pressure regulator, or a computer that's very mistaken. The MAP can cause idle surge and loping. It can also cause a no-start.
I would check fuel pressure, engine off, key ON, key being cycled a few times to build pressure. Start the engine, and check pressure. It should steady up around 40psi, more or less. Pull the vacuum line from the regulator and the pressure should shoot up. You should not get any fuel from the vacuum port on the pressure regulator. If you take a whiff of the vacuum line before starting, and smell fuel, it is likely the regulator diaphragm has a leak. Pressure will be incorrect if that is the case, and you need to replace the regulator.
The PCV system routes from the canister on the drivers side of the block, under the intake, forward through the hose, through the embedded PCV valve, around and up, backwards towards the under side of the intake manifold, where it connects and feeds in any crankcase ventilation gases. The canister has a maze to hopefully catch oil droplets and let them flow back to the pan, which can get clogged after a lot of miles of poor engine maintenance. The PCV valve connects two lengths of hose, and is often overlooked. The PCV system gets fresh air from the engine air intake, after the filter, but before the throttle body, which is fed into the oil filler on the top of the cam cover. Doubtful that is plugged.
tom

 

[Dan B.]

I need to provide some updates.

The MAP sensor...I took apart the vacuum lines that were bundled together inside of the wire loom covering. The line providing vac to the MAP was melted and there were several small holes in it. Cut out the bad section and spliced it with a section of very tight rubber line. That fixed the surging and black smoke. Now the idle is smooth but very fast.

Next I found the oil separator canister did not have a PCV valve inline. There is a vacuum line from the bottom of the throttle body that was plugged. Turns out this port is supposed to hooked to the other end of the PCV. So I got that routing fixed and in working order. After that I reset the timing and the idle is slightly better but still fast.

I also sprayed carb cleaner around the throttle body and vac ports near it. The engine speed did increase. So there is a leak near that that needs addressed. No whistling but there has to be a leak there somewhere.

Tonight I was going to explore the vac leak near the TB and try the TPS to see what it reads.

 

[Dan B.]

The last vacuum leak has been located. I trickled carb cleaner around the vac ports on the top of the intake manifold. No change in idle. So I want gangster and blasted everything around the throttle body. This got a response! Some more spraying and investigating led me to the EGR. The passenger side of the EGR mounting flange was wrapped in black tape. Not electrical tape but something similar but MUCH stickier. I pulled it off (with pliers!) then the whistle started. A shot of carb cleaner confirmed. Turns out the bottom bolt was too long and bottomed out in the hole so they tried to tape it! The gasket was also torn and reused. so I cut a temp gasket from heavy card stock, put a thin bead of high temp sealer around the hole and reinstalled everything. I also washered up the bottom bolt to make it tighten. The idle is now kosher! The timing needs reset again...currently setting at 20 BTDC.

Exhaust parts also showed up over the weekend. Picked up a new EGR gasket today. I'll get those installed tonight, then reset the timing. All should be good now!