Hi all, first time posting!

I bought a 1988 2.9 ranger. 4x4 w/ stick-shift. It initially drove OK but sounded lean.
It has 210K miles and hadn't had a tuneup in I don't know how long.

I replaced following:
Oil
Oil Filter
Spark-plugs (previous ones were corroded and required patients to remove)
- I did torque the new plugs to book spec
Wires
Distributor + Cap + Rotor
Ignition Coil

I had to remove some vacuum lines for this process and put them back. None of them seemed cracked when I put them back.

A negative wire to ignition coil broke in the tune up process and so I had to re-strip and hook that up again. This broken wire was causing no firing at all.

Now, when I start the truck it idles with an easily audible misfire and doesn't go away after accelerating just gets faster.

I've tried unplugging each plug but I can hear a change for each when unplugging so I assume wires are fine?

I used a timer light on #1 plug after installing new distributor and it seems to run as best it can when "TC" (top center) is inside the circular hole. (Sorry, I don't know the name of it)
I did read somewhere that I should have it at 10 degrees. But we tried the whole range of degrees (at least where it wouldn't stall) and all the degree marks still had the intermittent misfire.

I tried to get the new distributor + rotor as spot on to the old one as I could.

 

Welcome to the forum

Assuming this misfire was not there BEFORE you started.........................

Either firing order on cap is wrong or you have a bad new spark plug or wire

Check firing order seen here: https://www.ford-trucks.com/forums/a...1&d=1204731360

Very very easy to reverse wires on firing order, after you have checked it 4 times check it 2 more times
Follow EACH wire to its spark plug

If all is well
Pull out each spark plug on one side
Compare them side by side, you can tell which one is NOT firing by its color
Then do the other side
Replace Questionable spark plug with an old one, cleaned up of course, lol, then start engine and see if misfire is gone, if so get new spark plug

A new "bad" spark plug is more common than you might think, same for spark plug wires



You do NOT use the "eye" for spark timing, that's was there for a Ford timing Tool which never did work very well, lol
You use the pointer and marks on balancer/pulley
Pointer and "eye" seen here: https://www.librum.us/images/timing1.jpg

You can use steel wool or ?? to clean off the marks, then put some white or yellow colored paint on the marks and wipe wet paint off with a rag, paint will stay in the marks making them easier to see

You need to warm up the engine, shut it off, then unplug the SPOUT Connector near distributor, this takes away computer's spark advance, same as unhooking Vacuum Advance on older distributors to do spark timing.
Loosen distributor nut/bolt
Hookup timing light to #1
Restart engine
Set distributor for spark at 10-12deg Before TDC, USING POINTER(not "eye"), which ever you prefer, most like 12deg BTDC
Tighten distributor
Shut off engine
Plug back in SPOUT connector and restart
Make sure engine is running OK, REV it a few times
Shut off and remove timing light
Go for a drive

 

RonD, thank you so much for this detailed reply! I will get back asap once I have checked all these items. I had known nothing about the SPOUT connector until now.

 

Just an update:

Spark plug wire order
I verified the cap for plug order and followed each cord to each plug over and over lol. In my manual I also found that spark order image which was really helpful (I used this first time too).

Spark plugs
I have not yet removed the plugs to check how they look but this will be next when I get back to it!

Setting base time
I don't know why I didn't notice it right away, but I found the exact same timing instructions you gave under the hood of the truck. I got engine temp to half way mark on dash, and followed steps to the end.
In the end, it still sounds the same.
When the SPOUT connector was removed, it did sound a little smoother.
Another description of the misfires: The truck can sound good and smooth for up to 15 seconds, but then can get as bad as having what sounds like misfires multiple times a second. I see the crankshaft and belts actually slow down during these short stalls <-- All this without touching the truck.
I stepped on the accelerator and it sounded like it stalled and died for 1-2 seconds but then ROARed to life right away.

What I might try next
As you mentioned, I'll check spark plugs.
A friend mentioned I might try putting the old distributor and ignition coil back in. Reason I changed them was mistakenly thinking they were bad when it turned out to be a broken wire.

 

So I checked the spark plugs. All looked alike. I also checked the gap on each one and all seemed to spec.
I hooked up the timing light to each plug wire just to see if it would light up for each and it did flash for each of the 6 plugs (is this an OK way to test for all 6 sparks?)
Each plug seemed to be affected by the intermittent misfire (the light pattern wasn't constant for any of them)

Even though I didn't touch the MAP sensor, I wonder if that could be an issue that by coincidence popped up. I saw a video on a way to test using vacuum pump and volt-meter.

I couldn't find anything to do with the MAP sensor in my Chilton repair book, I was hoping to find the desired voltages for specific pressures.

 

Good site to Bookmark here: Fuel Injection Technical Library

Scroll down and select Manifold Absolute Pressure Sensor (MAP) sensor

You need a meter that shows frequency Hz, to test it

Although I would expect a Code to be generated if MAP Hz was changing without TPS(throttle position sensor) changing
MAP reads intake vacuum so its steady with throttle closed for the most part, then vacuum drops as throttle is opened, computer expects this, the TPS is used like the accelerator pump on a carb, TPS causes computer to squirt in extra fuel instantly so there is no delay in throttle response, because MAP would be to slow, but for the same reason MAP Hz showing vacuum change without TPS change should set a code

 

Got some codes!

So this is my first time owning a vehicle before ODBII and I just found out I could do the jumper wire trick to get some codes!
Before I post codes + descriptions, I thought I could post a little more detail about the truck.

1. This truck has a stickshift with gears: 1, 2, 3, 4, OD, R (I read this truck could have 1 out of 2 types of manual trannys (auto just has 1) but I never found out which of the two I had)
2. In the rear of the intake manifold, the vacuum port has the transmission vacuum line cut and plugged.
   1. I read one should go to brake booster, one to gas diaphragm, one to transmission, and the 4th is plugged normally.
3. Stick shift floor plate looks custom.
4. Found out both catalytic converters had been gutted.
5. Exhaust smell and a little smoke comes from the truck (from under hood + into cab) due prolly to #4

Note: two of the codes are 89 + 86 below, aren't those only for auto trannys? I wonder if this was a auto -> manual swap.

Codes from truck + Fuel Injection Technical Library descriptions
- Key On Engine Off -
89 - Converter clutch solenoid circuit failure
Fuel Injection Technical Library » Two Digit Codes 75-99
86 - 3 � 4 Shift solenoid circuit failure.
Fuel Injection Technical Library » Two Digit Codes 75-99

- Memory -
18 - IDM circuit failure or SPOUT circuit grounded (from when I set base timing)
Fuel Injection Technical Library » 2 Digit Self-test Codes 11-32

- Key On Engine On -
21 - ECT out of self test range 0.3 to 3.7 volts (I did this test without warming the truck up)
Fuel Injection Technical Library » 2 Digit Self-test Codes 11-32
41 - No HEGO switching detected always lean (right side). (Missing catalytic converters)
Fuel Injection Technical Library » Two Digit Codes 33-58
13 - Cannot control RPM during ER Self-Test low RPM check
Fuel Injection Technical Library » 2 Digit Self-test Codes 11-32
74 - Brake On/Off switch not actuated during KOER test (user error). (after starting truck, I waited for first blink of light, then quickly floored accelerator, but I think I missed a step where I push brake..)
Fuel Injection Technical Library » Two Digit Codes 59-74

 

Code 41 Lean

OBD1 doesn't test cat converters, and in 1988 it only the one O2 sensor for both banks on a V6 engine, so not a Cat issue

If engine wasn't warmed up that could be the reason for 41, other wise it could indicate vacuum leak or low fuel pressure
Simple test for vacuum leak
Warm up engine and let it idle, should idle at about 650rpm for manual trans
Unplug the 2 wire connector from IAC Valve
RPMs should drop to 500, barely running, or engine may stall, either is GOOD it means no vacuum leaks
If RPMs do not drop then there is a leak

Yes, codes 86 and 89 are for automatic trans, so maybe someone swapped in a manual trans and didn't change the computer, manual trans computer wouldn't have the software inside to control solenoids so there wouldn't be a test for them either

This is a Ford specific 2 digit code list: https://www.therangerstation.com/tec...gitcodes.shtml

 

Thanks again for all the replies and help RonD!

IAC Test Results
I did the IAC test and when I unplugged the wire harness, the engine got much quieter/lower rpms (which was nice compared to how loud this thing is) and it still had the random misfire. I also tried the propane trick along all the vacuum lines without any change in sound/revs.
So is this issue technically a misfire if the engine seems to miss what seems like up to 1 second of no firing at random times?

One find:
I maybe may have reversed the polarity when installing the new ignition coil..
I found this out because previously the wires were connected without a harness, they were individually crimped into those female sliders; I bought a harness and realized there are supposed to be 2 wires to negative side and 1 on positive. But I had had 2 on pos and 1 on neg..
I was reading through some other forums that this isn't damaging, but that having it reversed can cause a weaker spark.

My manual says I should have 2 Red/Light-Green and 1 Dark-Green/Yellow wire going to it.
The 1 grn/yel and 1 of the rd/grn both came from the chunk of wires going somewhere else, and the 2nd rd/grn went just to that little silver capacitor that's mounted to the coils frame/side which also has 2 other black wires attached to the frame/side.
But issue is, the wires on my harness and on a few others I'm finding online have 2 Yellow/Green and only 1 Red/Light-Green.
Link to a wiring diagram (coil is bottom right) https://www.therangerstation.com/tec...n83to882_9.JPG
The wiring harness: https://www.rockauto.com/en/moreinfo...7608&jsn=12398
EDIT: I see similar years and/or engines make use of the 2 green wires. So I prolly just tie them together for mine and have them go to one wire.

Either way, I tried to wire it up a couple different ways today (trusting it wouldn't ruin the coil, I still have old one too) but it didn't seem to make any difference.

Tomorrow I'll take closer look at wiring and maybe also try looking at distributor.

Question Regarding manual swap
Another change I did to the truck right before the misfiring started was get a new battery and so the truck was left unhooked from power for a couple days.
I was curious if having a computer for an automatic would still be fine to use with a manual transmission (as long as I ignore the trouble codes)

 

SOLVED

I didn't want to mess with swapping distributor till end since it involved removing intake manifold. Plus it was a new distributor!
But I put the old one back in the exact same way and it started up so smoothly! Not a single bad chug and I could even rev it good!
So I may look for the warranty info for the new/bad one.

Thank you again RonD

 

Good work

Thanks for update and THE FIX