check engine light on?

What code 12 means is unable to control RPM during test likely cause Idle air by-pass see diagram lets rerun the codes though to confirm

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

Thanks for the info. I have another and will change out. Will check for power first.

iv re-timed it with out the spout connector and it ran ok. i then found a spout connector and pluged it in. it idles smoother but has a missfire. the engine will not rev over 2500 with the spout, and 3000 without the spout, iv scaned for codes and pulled a code 18 c.what can cause all this?

start with a compression test to verify the motor is good.

check fuel pressure as well.

check the cat converter as well. it may be clogged.

Roy

i have no cat converter i did a compression test and got 140 psi lowest to 155 psi highest i have not checked the fuel psi. i scanned the truck (KOEO) and pulled codes:
14 c
18 c
34 c
41 c
48 c
87 c
88 c
96 c

truck still runs and drives. i had a cracked manifold but i replaced it. still has these codes

Engine Performance problem
1990 Ford Ranger 4 cyl Two Wheel Drive Manual

In this 2.3L the check engine light is off at idle but goes on with higher rpm, then off again as rpm falls. Vacuum reads steady 21 lbs. What are the usual suspects?

Just rpm or vehicle speed? could be an EGR problem, honestly too many things to guess, need to read the codes, check in "freeze frame/failure records since the light doesnt stay on

You wrote:
Just rpm or vehicle speed? could be an EGR problem, honestly too many things to guess, need to read the codes, check in "freeze frame/failure records since the light doesnt stay on

Both rpm & speed, but I don't recall any pattern with speed & gear shifts.

What exactly do I replace if it's an EGR problem?

What do I need to read the codes on this vehicle?

Thanks...

You need and OBD-1 scanner. There are several pieces to the EGR system, once again , it would be a a wild guess

[quote:51b8f8dfc8="2CarPro Jack"]You need and OBD-1 scanner. There are several pieces to the EGR system, once again , it would be a a wild guess[/quote:51b8f8dfc8]

Where are the diagnostic self-test connectors located on this vehicle to connect the scanner?

What individual pieces makeup the EGR system in this vehicle?

Lets not get ahead of ourselves, you will need to check thecodes first. Imnot saying it is EGR, lets see what the comp says first.The connector is located on the right front fender apron, will say EEC test on the cap

90 Ranger 2.3

The CEL comes on cold start, runs fine idles good comes down as it is supposed to after warmed up usually around 10 miles the light goes out and it imediatly starts spuutering on accerlation not so bad in 1-2-3 gear gets really bad in 4-OD Actron code reader says first code is 87 (Fuel pump relay circut failure) Is it the fuel pump or the Relay? I t also states code 98 ( Hard Fault Present) 88 (Loss of dual Plug inpute control) HELP Please

Sounds like the computer located on the passenger side in front of the door panel. Try disconnecting the ground from the battery for a couple of minutes to reset it. If you replace it, every digit must be exact or it won't run right. Have the coil packs checked as well.

Engine Performance problem
1990 Ford Ranger 4 cyl Four Wheel Drive Manual
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To make a long story short my Ford ranger started to miss or stall just once in a while acting like a fuel problem or ignition problem.
I'v had two independant shops look at it with test equipment and both said that so many problem codes come up they don't know where to start.

When this first started I would see the Check Engine Light come on momentarily out of the corner of my eye and the engine would stumble slightly by the time I looked the light was out and everything would be fine for a few days or even a few weeks before it would happen again.

Then the light would come on more often once the engine got up to operating temperature accompanied by the Tach going crazy as the light was on and the engine stumbling, by that I mean I would loose power and the engine would act like it was running out of gas or I had an ignition problem.

This went on for several weeks and more often then I took it to a local Ford Dealer who changed both coils, the spark-plug wires, ECM or Engine Control Module, and the DIS Modual. Still the problem persist and now the light stays on all the time, runs very rough at idle, bearly goes down the road over 40mph. and the Tachometer is dead, as in will not register at all. During this process I noticed the Tach reading much lower than the engine actual RPM and as time went on it would respond less and less until now where it does not move at any RPM! The dealer had this truck for 29 days, and eventually gave it back and told me and said it was unrepairable, by that I can only assume they don't know what else to do either. I'm stumped.......

i have the same issue with my ranger its a 94 v6 4.0. the spark plgs were white when i changed them telling me it is running lean. ive replaced the plugs, wires, air filter, fuel filter, pcv valve, ignition coil pack at 1 friends suggestion, crank sensor at anothers suggestion which ended up being rotted anyway. problem still exists. im now being told to swap out the 02 sensors and if that doesnt work try the fuel pump, not sure what the heck the fuel pump has to do with the tach though. also if you cycle the ignition switch once it happens everything goes back to normal for a while. could be fine for a minute or a week but it always acts up again. i also read something about the intake manifold needing to be retorqued due to loosening bolts and the ground strap needing to be relocated from the firewall to the block??? anyone with ideas or actual usable knowledge would instantly become my favorite person in the world!

What trouble code are you getting from the computer?

Make: Ford
Model: Ranger
Year: 2001
Mileage: 90,000
Engine Size: 2.5 4cyl

Is there a way you can turn a check engin light off manually to see if it comes on again?

you can pul the neg cable off for about a half an hour then plug it back in

thanks , jim

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