Computer codes

[chuck41]

I`M new here and I need a lot of help, computers and codes are new
to me. Just put a Jasper 2.9 engine in a 1989 Bronco 2 auto 4 wheel
drive, it has P/S, P/B cruise and air. When I started it up it ran very bad
I bought a Haynes book and hooked up a voltmeter to get the codes, I
got no. 22, bad map sensor, I put a new one on and what a difference.
It has good power on the road but I think it has more codes because
the idle is about 1200 rpm and it has a up and down rpm surge. I have
not been able to clear the 22, code or get other codes out, I do just
what the book says to do and get code 77, can you tell me what I`m
doing wrong? Do I need to get a cede reader? Drove it to town, about
7 miles one way, started to pull away from a red light and the brakes
are locked up, what is the biggest problem, bad hose or bad caliper?

ANY AND ALL HELP WILL BE APPRECIATED CHUCK41

 

[RonD]

High and/or surging idle is usually a vacuum leak.

22 can be low vacuum pressure AT the MAP sensor so if you still have a vacuum leak in the intake manifold then you would still have 22.

Fuel injected engines use an IAC(idle air control) valve located on the upper intake, looks like a cylinder/tube, the computer opens and closes this valve to control the idle.
These get dirty and sticky, which can also cause high and surging idle, these can be removed and clean and tested.
When first started a fuel injected engine should rev up to about 1,500rpm, then if cold drop to 1,000rpm, if warmed up 750rpm, that's the computer opening the IAC valve all the way to test it then dropping it down to preset level for engine temp.

Code 77 can come up when you read the codes without a scanner, it is a Test you run with a scanner, not a trouble code per-say.


If one brake is locked up then caliper or collapsed rubber brake line, if 2 or 4 are locked up then Master is probably at fault

 

[chuck41]

I want to thank RonD for the help, I have pluged all the vacuum outlets except the
one for the MAP sensor, nothing has changed. The large butterfly valve in front of the upper intake manifold, is that the idle air control valve? The vacuum reading is 15 inchs
and I still have the 22 code. Is there a list of things that could be causing the 22 code?
I bought an Actron code reader and trying to learn how to use it.
THANKS AGAIN CHUCK41

 

[RonD]

The large valve is the throttle plate, smaller cylinder on the side of the upper intake is the IAC

15 inches is a bit low for Delaware, 3-4,000 feet elevation would get down to 15 inches, I would expect about 17/18 inches under 1,000ft to sea level.
Could just be the pressure gauge reading low.

Are the upper and lower intake bolts tight, these can loosen up creating a vacuum leak.
You can often spray carb cleaner on possible leak points while engine is idling, RPM will change if there is a leak and carb cleaner is sucked in.

Code 22 is pretty straight forward.
Manifold Absolute Pressure sensor is out of self test range
MAP (vacuum) or BARO signal out of range

You can check the connector on the MAP, make sure wires are not frayed.
Since you have a scanner now you can test it with MAP unplugged after reset, see if it sets the 22 code with MAP unplugged the same as plugged in, if MAP is new that would mean a wiring issue, or computer connection issue.

 

[chuck41]

THANKS AGAIN RonD just checked manifold bolts, they were tight, sprayed
intake nothing changed, took off the front of the intake and cleaned the throttle
plate, is the IAC on the right side of the intake? how is it tested? The connector
on the sensor screwed in the right side of the intake manifold is broken and I don`t
know if it has good contact with the sensor. I`ll check the things you said as soon
as I can. THANK YOU CHUCK41

 

[RonD]

IAC is on the upper intake left side.
If you look at these pictures of the 2.9l, it is the long horizontal "tube" in the center of both pics
http://www.therangerstation.com/tech_library/2_9_Page.html

best to remove it and visually inspect it for carbon build up inside.
IAC uses a step motor, it should test at 7-13ohms
Computer opens and close this valve, as a controlled vacuum leak, to set idle speed.
All fuel injected engines use an IAC of some form to control idle.
When engine is first started idle should go high, 1,500+rpms, then come back down to cold or warm idle based on engine coolant temp, that is the computer testing the IAC for function, and it will turn on the CEL if it isn't working.

This is not related to the IAC valve but a good page to bookmark for sensor info and testing:
http://oldfuelinjection.com/?p=10

 

[chuck41]

RonD Testing a map sensor step3, determine what type map sensor I have, how can I
determine what type I have? I bought the one the parts man put on the counter.
Step no.4 if the reference voltage --about 5 volts--is out of specification, what is
the voltage supposed to be? I should have tested it when I bought it.
The IAC has 10.0 OHMS, should it be replaced?
THANK YOU CHUCK 41

 

[RonD]

You have a Ford MAP sensor.
5volts is the correct voltage to be at the MAP sensor, it comes from the PCM(computer)
MAP sensors rarely fail, not never fail, just rarely.
You need a meter that can measure Hz to test what the MAP sensor is sending to the PCM.
Most engines have about 17inches of vacuum in the manifold at sea level when warmed up and idling at about 750rpm
MAP sensor would be sending 111Hz to PCM with above numbers.
Scale is here:
http://oldfuelinjection.com/index.php?p=27


10.0 ohms is within the 7-13 ohm range so motor on IAC is OK.
When started does the engine rev up then come down to steady idle?
if so then IAC Valve is not sticking so it is probably OK as well.

 

[chuck41]

RonD When started RPM is up around 1500 or 1600 and as it warms comes down to
1100 or 1200 this is the Bronco 2 tach. in the desh. What is used to clean the IAC.
What is the sensor that is in the manifold a little lower then the IAC and back an inch
or two. THANK YOU FOR ALL THE HELP CHUCK41

 

[kimcrwbr1]

Possibly a throttle body gasket? Pull the throttle body and lightly surface the mounting surface soak it in carb cleaner after you pull the IAC. Then blast it with high pressure water and air. Do not overtighten the TB bolts take it down slow and snug. After a couple warm up cycles snug it down again when cold. Is there slop in the throttle butterfly shaft and does it close to its stop when you let off the peddle?

 

[RonD]

There are 2 sensors on the upper intake.
The TPS(throttle position sensor), it tells the PCM where your foot is on the gas pedal, on the 2.9l this would be just in front of the IAC.
TPS gets 5volts from PCM, is sends back .9volts when throttle is closed, and 4.9volts at wide open throttle, so works much like a light dimmer, as you put your foot down on the gas pedal the computer sees the TPS voltage go up so increases fuel flow at the injectors.
On some models the TPS is adjustable, you need a volt meter and a couple of pins to put into the wires to read voltage while adjusting.


The IAT(intake air temp) or ACT(air charge temp) sensor, this tells the PCM the air temperature of the air passing thru the intake, cooler air(denser) requires more fuel than warmer air, not sure where this sensor is on the 2.9l.
This could be the one near the IAC.

On later model engines the MAP and IAT sensors were eliminated, they were replace by a MAF(mass air flow) sensor.

The IAC valve is not a sensor it is a control valve.
If your idle is changing then IAC is probably OK.
Lots of "How-to's" on cleaning IAC valves, all EFI engines use these, and inside they are pretty much the same, so brand and model don't matter.

Engine idle warm should be 700-800rpm
On some EFI engines there is a minimum idle set screw, like on a carb, it would be located on the throttle plate actuator wheel, where the throttle cable attaches, usually under it.
With engine warm and at idle unplug IAC valve wires, idle should drop down, if it doesn't look for that set screw and use it to lower idle to 600-700 RPM, yes lower than needed.
Shut off engine and disconnect battery's negative cable for 5 minutes, this will reset computer so it will relearn idle control, anytime you change something on a computer controlled engine, you need to reset the computer or the changes you made might not be "seen", so any problem might continue.
Reconnect IAC and start engine.

If you can't get idle RPM down make sure throttle cable is not over tight, there is a "cable mod" that can raise idle when done incorrectly.
You can turn off engine open throttle plate all the way and disconnect throttle cable, that will take it out of play in idle adjustment, also cruise control cable if so equipped.

If idle will not go below 1,000 rpm then I would try an old test for a vacuum leak.
This test was to let engine idle and then place hand over intake to stall the engine.
Engine should be warmed up, plug the PCV valve or its hose and unplug the IAC , now the only air source would be through the throttle plate opening(and a vacuum leak), as you start to cover the opening engine RPM will start to drop and engine should eventually stall out.
Often as the engine gets down to very low rpm you will hear a vacuum leak whistling as more air is being sucked in, the IAC valve is such a "leak" so ignore that one.

 

[chuck41]

RonD & Kimcrwbr1
THANK YOU VERY MUCH, without your help I would be lost. I thank you for your time
and the patience you must have to help someone who doesn`t know a thing
about computers or fuel injection. When I retired cars and trucks used carburetors.
AGAIN THANK YOU CHUCK41

 

[chuck41]

Removed and cleaned IAC, same with throttle body still have 22 code and high
idle. Did the vacuum leak test, pluged the PVC, and disconnected IAC, idle is
1000 RPM, as soon as I put my hand over throttle body inlet the engine stoped.
Checked the voltage at the throttle position sensor, pink wire 5.o volts
green wire closed o.9,,,open 4.6. where is the wire to hook up a tach?
and where is the fuse for the A/C clutch? what is the next thing I should
check? THANKS CHUCK41

 

[RonD]

TPS voltage reads correct.

1,000rpm warm idle isn't, especially with IAC unplugged, is there a set screw for idle?
Is the throttle cable too tight?

I assume you have a Ford TFI ignition, so a single coil, external tach can be hooked to the "-" on the coil.

I believe the power for the A/C comes from the EEC(ECU,PCM) relay(30amp fuse) and runs through the WOT(wide open throttle) relay and then thru the high and low pressure switches before it gets to the compressor.

Engine won't run unless EEC relay is working.
EEC relay, Fuel pump relay and WOT relay are all located together, either on the passenger side fender, under the power box on divers side or in the power box.

Also looks like fuse 7 on the inside fuse panel is used by the A/C switch inside.

 

[chuck41]

RonD there is a screw on the throttle body, I unhooked the IAC and RPM went
from 1300 to 600, let it run a few minutes and shut it down, took off the neg, battery cable for 5 minutes, the throttle cable was also off. Put everything back together, this is a hot restart, RPM at 1000 and slowly falling to a steady 800 RPM. I`m not sure I have
the timing at 10 degrees but it must be close it has good power and the best idle yet.
On a cold start RPM goes to 1400 for about 2 minutes and the total time to get to
800 RPM is about 6 minutes. Are these times to long to get down to 800 RPM? The tach.
in the dash is 400 RPM higher then the test tach. I think I`m getting code 11 but not
sure, haven`t done this enough, I`ll try to do a full scan tomorrow. THANKS CHUCK41