2.3L ('83-'97) Codes

[John501]

I have a 1990 ranger 2.3 5 speed. It runs completely fine, the only issue is my tack doesn't work right anymore, and the truck idles at about 900-1000 and I get 20mpg. I pulled codes, and I had to jump the single pin to the negative battery. I got the following codes

11 o passed

18c erratic idm input

33 c egr opening not detected

88 c loss of dual plug
To be completely honest I don't know exactly how to go through and out what exactly is causing these problems, I'm use to obd2 systems that pamper you. Some help getting the old boys happy again would be appreciated.

 

[RonD]

1989-1994 Ranger 2.3l engines used a separate spark module, called the ICM(ignition control module)

The ICM is connected directly to crank sensor and the Coil Packs, and runs the spark system autonomously
It also sends out a timing pulse(PIP) and a diagnostic(IDM) signal to the Computer so it can time fuel injectors and check ICM functions

In the OBD2 systems the spark module was inside the computer, so not separate

The ICMs were a known issue on these years
Its located on the front of lower intake just behind the fan to keep it cooler, spark modules generate a lot of heat
Which is why OBD2 computers were moved to the engine bay

Anyway I would pull out the ICM and check its wires, they can get frayed(31 years old), it also needs a good ground via bolts that hold it to intake, these can get rusted
Auto parts stores can test these ICMs but.................they can test OK when cold, and become intermittent when hot, so you can't test if an ICM is "good", you can only test if it is "bad"
That's for the 18 and 88 codes


33 is an EGR code that means the EGR sensor is not detecting the movement of EGR valve when computer opens the EGR solenoid and sends vacuum to the EGR valve
Find the EGR valve
It will have a vacuum hose attached
You can follow that vacuum hose back to the EGR solenoid, it will have 2 vacuum hoses
Follow the other vacuum hose back to the engine's vacuum manifold, it may be via a "T" in another vacuum hose
Check that these vacuum hoses are in good condition, no breaks

If possible get a longer vacuum hose that fits EGR valve port, put it on EGR valve
Start engine, let it idle
Apply Vacuum to the other end of the longer hose, i.e. suck on it, no there shouldn't be any exhaust coming out, lol
Engine should start to stumble if EGR valve is opening, and will even stall if enough exhaust comes in
If so, that's good, it means EGR valve is not stuck closed or blocked
If no change in engine RPMs, then EGR valve will need to come off to be inspected

If RPMs did drop, EGR Valve is working, then you will need to remove the EGR solenoid and test it
Its just a 12volt solenoid, no polarity, so if you apply 12v and ground to the 2 contacts it should "click" open, 9volt battery works as well
Repeat a few times
You can also put a hose on either port of the EGR solenoid and blow thru the hose, air should not go thru it unless power is applied, so its closed with no 12v/gnd and open with 12v/gnd

The EGR sensor that detects the movement might be at fault, but..........................that's usually code 34 or 35, EGR sensor fault

 

[John501]

1989-1994 Ranger 2.3l engines used a separate spark module, called the ICM(ignition control module)

The ICM is connected directly to crank sensor and the Coil Packs, and runs the spark system autonomously
It also sends out a timing pulse(PIP) and a diagnostic(IDM) signal to the Computer so it can time fuel injectors and check ICM functions

In the OBD2 systems the spark module was inside the computer, so not separate

The ICMs were a known issue on these years
Its located on the front of lower intake just behind the fan to keep it cooler, spark modules generate a lot of heat
Which is why OBD2 computers were moved to the engine bay

Anyway I would pull out the ICM and check its wires, they can get frayed(31 years old), it also needs a good ground via bolts that hold it to intake, these can get rusted
Auto parts stores can test these ICMs but.................they can test OK when cold, and become intermittent when hot, so you can't test if an ICM is "good", you can only test if it is "bad"
That's for the 18 and 88 codes


33 is an EGR code that means the EGR sensor is not detecting the movement of EGR valve when computer opens the EGR solenoid and sends vacuum to the EGR valve
Find the EGR valve
It will have a vacuum hose attached
You can follow that vacuum hose back to the EGR solenoid, it will have 2 vacuum hoses
Follow the other vacuum hose back to the engine's vacuum manifold, it may be via a "T" in another vacuum hose
Check that these vacuum hoses are in good condition, no breaks

If possible get a longer vacuum hose that fits EGR valve port, put it on EGR valve
Start engine, let it idle
Apply Vacuum to the other end of the longer hose, i.e. suck on it, no there shouldn't be any exhaust coming out, lol
Engine should start to stumble if EGR valve is opening, and will even stall if enough exhaust comes in
If so, that's good, it means EGR valve is not stuck closed or blocked
If no change in engine RPMs, then EGR valve will need to come off to be inspected

If RPMs did drop, EGR Valve is working, then you will need to remove the EGR solenoid and test it
Its just a 12volt solenoid, no polarity, so if you apply 12v and ground to the 2 contacts it should "click" open, 9volt battery works as well
Repeat a few times
You can also put a hose on either port of the EGR solenoid and blow thru the hose, air should not go thru it unless power is applied, so its closed with no 12v/gnd and open with 12v/gnd

The EGR sensor that detects the movement might be at fault, but..........................that's usually code 34 or 35, EGR sensor fault

Thanks for the write up RonD, you are a ranger expert. I called it today because of weather but once it's clear I'll get going on working with the egr, and ignition box. I installed a new tach and It doesn't read right either. I saw a old tread, that mentioned if one coil pack was not working then the rpm would read half, which based on the tacks reading it is half of what it should be. So there is definitely a problem if that is true.

 

[RonD]

The 1989-1994 2.3l also has a "Coil inhibitor" circuit on the ICM
It shuts off the intake side(drivers side) coil and spark plugs when starting the engine
To give the exhaust side coil and spark plugs full available voltage when starter motor is active
As soon as RPMs are above 400 the intake side coil will start to work

Never heard of this circuit causing an issue, but................certainly could
This 2.3l engine ran fine on 4 sparks plugs with distributor from 1974 to 1988

 

[John501]

Alright sadly more issues. Driving home today every bumb in the road, and I mean EVERY bump my ranger would spudder, the rpm guage would rear right and my check engine would turn off. Then a few seconds later it would half the rpm spudder and the light came back on. It's never done this, and I'm starting to think 100% the icm is junk and maybe more. Since it's issues just seem to get worse, for now I'm parking and going back to my "retired" high mileage explorer. Any input on this issue RonD? Or anyone else. When I checked wiring it looked fine.

 

[RonD]

Yes, reads like a loose connection somewhere in engine bay

You can start with battery grounds to engine and body
Should be larger cable to starter motor bolt or engine block
Then smaller wire to inner fender/rad support
Also a ground strap from engine to firewall, usually back of head to firewall

Then check Power distribution point on Starter Relay post on inner fender, follow battery positive cable, it goes to that post
ALL 12volt power comes thru that post, remove, clean all wire ends on that post

Then start pulling out relays in the engine fuse box, inspect contacts
PCM/EEC relay powers the computer and ICM so swap it out with another similar relay

One thing that can work in narrowing down an electrical issue is to have engine idling and start moving wiring around a bit to see if you can cause a stall or glitch in engine operation

 

[John501]

Yes, reads like a loose connection somewhere in engine bay

You can start with battery grounds to engine and body
Should be larger cable to starter motor bolt or engine block
Then smaller wire to inner fender/rad support
Also a ground strap from engine to firewall, usually back of head to firewall

Then check Power distribution point on Starter Relay post on inner fender, follow battery positive cable, it goes to that post
ALL 12volt power comes thru that post, remove, clean all wire ends on that post

Then start pulling out relays in the engine fuse box, inspect contacts
PCM/EEC relay powers the computer and ICM so swap it out with another similar relay

One thing that can work in narrowing down an electrical issue is to have engine idling and start moving wiring around a bit to see if you can cause a stall or glitch in engine operation

Once my college finals are over I'm going to go through the wiring clean everything, and add some more grounds. I wanted to ask if a really bad battery can cause this issue. The current battery has leaked acid out since I got the truck and has definitely corroded the terminals. Could that be all of the problem or just a part?

 

[RonD]

Just part

The alternator provides ALL vehicle power when engine is running, battery is only used to start engine or when engine is off
A car Battery's maximum voltage is 12.8 maybe 13.0 when brand new
Alternator's put out a minimum of 13.5volts, but usually just under 14volts
Thats how the alternator keeps the battery charged, it runs at a slightly higher voltage to voltage flows TO the battery when engine is running, assuming alternator is working

So IF.........it is an electrical issue it wouldn't be battery specific because battery is not being used at that time

 

[John501]

Okay, I looked at all of the wiring for the icm, I couldn't find anything wrong. So I got a new one, put it on cleaned the back of the plate put on electric grease, and added 3 new grounds to the 3 of the bolts for the icm. I then cleaned and greased it's connectors and pins. I checked both coil pack plugs they are good. I checked all the grounds and positives on the starter relay, cleaned them and tightened them up. I then started the truck and nothing changed, I left running and aggressively shaked all the wiring I could find. Nothing changed so I turned the truck off and swapped the 30a fuel relay with the ecc relay. Still didn't change a thing. I'm really not sure where to go from here.

 

[RonD]

Refresh us on the symptoms

I remember engine would cut out or die after hitting a bump?

 

[John501]

Refresh us on the symptoms

I remember engine would cut out or die after hitting a bump?

Alright so I still have the same codes 11c, 18c and 33c, 88c and adding a code 30. The rpm guage still reads half the real value. After the new icm and 3 more grounds it only cuts out on really big bumps, I had to hit the rail road crossing at 25 to make it cut out, when it does I definitely notice a fuel smell from the exhaust. The truck runs okay, but for the 2.3 my mpg sucks, and it back fires a lot. The only issue I saw with the icm was that I can only get 1 bolt holding it to the intake, since 2 snapped off in there holes. That is why I went crazy and added in 3 big new ground cables to the bolts since they could still screw into the backplate between the icm and intake.

 

[John501]

I will also add, when it cuts out if I hit a large bump the engine light turns off

 

[RonD]

Just the engine light, or are there other lights on that stay on?

CEL bulb gets 12v from cluster, the computer grounds that bulb to turn it on
So loss of either would turn it off

 

[John501]

Just the engine light, or are there other lights on that stay on?

CEL bulb gets 12v from cluster, the computer grounds that bulb to turn it on
So loss of either would turn it off

Just the engine light

 

[RonD]

Then best guess is the computer is turning it off because it reboots(looses 12v) or looses ground