Misfiring Aerostar
Thread Starter
|
Junior User
Joined: Jan 2008
Posts: 59
Likes: 0
From: USA - New Mexico
Misfiring Aerostar
My '92 4.0L AWD (195K) Aerostar has been starting rough when cold. Now it 's starting to misfire sometimes under load. After driving several hundred miles today it tried to stall at a stop sign. It did throw a check engine code today a little while before it misfired, but I don't have an easy way to check codes. Is this a spark plug issue or is there something else I should be looking for? Thanks for your help!
Post Fiend
Joined: Oct 2005
Posts: 5,242
Likes: 0
From: Kiev, Ukraine
well, '92 4.0 is OBD-I so you have to pull blink-codes (https://www.ford-trucks.com/forums/7...procedure.html). Okay, I think you have other issue. Does van missfires under load ore at idle only? Starts rought when cold only, yep? seems to me you have two problems. One is really ignition related. Usually it is bad spark plug, bad wire ore bad distributor cap. It is not OBD-II vehicle with cranckshaft speed sensor, so you will not get missfire codes and the only way to check all spark plugs and wires one by one.
Rought cold start and intermediate stalling is IAC issue. Just clean it (i used carb cleaner, but TB cleaner is recomended).
Rought cold start and intermediate stalling is IAC issue. Just clean it (i used carb cleaner, but TB cleaner is recomended).
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
most auto parts stores will read codes for free plus some parts sales BS.
call ahead and ask.
how many miles/years on plugs and wires?
as our top Aero mechanic and forum head machinist in Europe advises, please read the codes and post to the forum, otherwise just a bunch of expensive parts throwing guesses.
another code reading thread
http://fordfuelinjection.com/?p=13
call ahead and ask.
how many miles/years on plugs and wires?
as our top Aero mechanic and forum head machinist in Europe advises, please read the codes and post to the forum, otherwise just a bunch of expensive parts throwing guesses.
another code reading thread
http://fordfuelinjection.com/?p=13
Thread Starter
|
Junior User
Joined: Jan 2008
Posts: 59
Likes: 0
From: USA - New Mexico
I have a digital dashboard, so it's not giving a check engine flash code. I have a code reader but don't have it with me so check will have to wait. Where would I find the IAC?
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
http://fordfuelinjection.com/?p=13
If you are a lost soul that does not have a working engine light, or did not install a light into your dash don�t fret. You can still get the codes. You still need that wire to ground out the STI. Now you will need one of the following tools; digital volt meter, analog volt meter, test light, or you can hook up any other 12 volt light that does not draw more than 0.5 watts max.
1. Turn key to OFF.
2. Get a length of wire that can connect the STI to the negative battery terminal or body ground.
3. Ground the Self-Test Input.
4. Attach one side of the test device to the Self-Test Output (STO).
5. Attach the other lead to the positive side of the battery.
a) If you are using a digital voltmeter you�ll want to use the continuity setting.
b) If you are using an analog voltmeter you�ll be counting the meter make sweeps.
c) If you are using a cheep light you�ll count like the rest of us.
6. Get some paper and a pen.
7. Get comfortable in the drivers seat.
8. Try to keep your self from getting distracted from here on.
9. Turn key to RUN.
10. You will hear some relays engage and the fuel pumps prime the system. This is the EEC beginning the test.
11. When the fuel pumps stop be ready to count!
IAC
http://fordfuelinjection.com/index.php?p=39
location on Ford 4.0L OHV eng.
https://www.ford-trucks.com/forums/1...rol-valve.html
If you are a lost soul that does not have a working engine light, or did not install a light into your dash don�t fret. You can still get the codes. You still need that wire to ground out the STI. Now you will need one of the following tools; digital volt meter, analog volt meter, test light, or you can hook up any other 12 volt light that does not draw more than 0.5 watts max.
1. Turn key to OFF.
2. Get a length of wire that can connect the STI to the negative battery terminal or body ground.
3. Ground the Self-Test Input.
4. Attach one side of the test device to the Self-Test Output (STO).
5. Attach the other lead to the positive side of the battery.
a) If you are using a digital voltmeter you�ll want to use the continuity setting.
b) If you are using an analog voltmeter you�ll be counting the meter make sweeps.
c) If you are using a cheep light you�ll count like the rest of us.
6. Get some paper and a pen.
7. Get comfortable in the drivers seat.
8. Try to keep your self from getting distracted from here on.
9. Turn key to RUN.
10. You will hear some relays engage and the fuel pumps prime the system. This is the EEC beginning the test.
11. When the fuel pumps stop be ready to count!
IAC
http://fordfuelinjection.com/index.php?p=39
location on Ford 4.0L OHV eng.
https://www.ford-trucks.com/forums/1...rol-valve.html
Post Fiend
Joined: Oct 2005
Posts: 5,242
Likes: 0
From: Kiev, Ukraine
Look! you will not get missfire codes. It iS OBD-I and the only way if to do "manual search"...... So pull out all 6 hidden plugs and look at them. Missfiring spark plug is of other color.... )))
Lead Driver
Joined: Sep 2003
Posts: 7,018
Likes: 210
From: SoCal
Sounds like your check engine light is working, so you can use that to count the codes after running the self-test as 96 described.
Unfortunately, after you successfully run the test and gets some codes out, they will not give you something as direct as "ECT sensor failed, please replace". You usually get codes like a rich/lean condition not met, which could mean any number of things have gone bad.
I would start with the simplest things first. See if there is a loose vacuum line at the tree located on the rear of the driver's side of the intake manifold. If that's OK, I'm suspecting the HEGO sensor, based on the symptoms you described. But again, there is no direct test for that, since most of the tests use the sensor to perform the tests.
Unfortunately, after you successfully run the test and gets some codes out, they will not give you something as direct as "ECT sensor failed, please replace". You usually get codes like a rich/lean condition not met, which could mean any number of things have gone bad.
I would start with the simplest things first. See if there is a loose vacuum line at the tree located on the rear of the driver's side of the intake manifold. If that's OK, I'm suspecting the HEGO sensor, based on the symptoms you described. But again, there is no direct test for that, since most of the tests use the sensor to perform the tests.
Trending Topics
Thread Starter
|
Junior User
Joined: Jan 2008
Posts: 59
Likes: 0
From: USA - New Mexico
Checked all of the wires and plugs -- one of the boots had a huge tear in it. Replaced it and all the plugs which fixed the misfiring issue. Cleaned the IAC which was full of carbon but that didn't make a difference in idle problem. Was finally able to get the codes: 172 and 121. Now the exhaust has started leaking at the connection to the flex pipe and above the front sway bar.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
http://fordfuelinjection.com/?p=45
121 Closed throttle TPS voltage higher or lower than expected
possible TPS failing, causing idle problems
171 Fuel system at adaptive limit, HEGO unable to switch (right side)
O2 sensor may have failed or failed wiring, will cause poor cruise fuel mileage.
clear codes and see if they repeat. disconnect battery to clear codes, also clears KAM of adaptive learned engine control from any failed components such as plugs, plug wires and sensors.
if code repeats check suspect sensor
http://fordfuelinjection.com/index.php?p=30
http://fordfuelinjection.com/index.php?p=31
121 Closed throttle TPS voltage higher or lower than expected
possible TPS failing, causing idle problems
171 Fuel system at adaptive limit, HEGO unable to switch (right side)
O2 sensor may have failed or failed wiring, will cause poor cruise fuel mileage.
clear codes and see if they repeat. disconnect battery to clear codes, also clears KAM of adaptive learned engine control from any failed components such as plugs, plug wires and sensors.
if code repeats check suspect sensor
http://fordfuelinjection.com/index.php?p=30
http://fordfuelinjection.com/index.php?p=31
Thread Starter
|
Junior User
Joined: Jan 2008
Posts: 59
Likes: 0
From: USA - New Mexico
I rest the codes when I replaced the plugs and wires and cleaned the IAC. The check engine light only comes on at highway speed after you have made a stop. I am getting about 15mpg highway cruising. Should I try to work on the TPS or O2 sensor first? Where are they and how hard are they to access?
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
is the check engine light continous or only flashing while driving?
doesn't tell us what code or codes you have now
no use wasting hard earned money on a working part
O2 and TPS sensors are replace only items, they wear out over time. may be defective wiring/connector to them.
O2 sensor is mounted on exhaust pipe threaded connector in front of catalytic converter under passenger side.
TPS is Under hood, center, upper engine area, front of intake manifold, mounted on driver side of throttle valve assembly
from Ford Svc CD
DTC 23/121 indicates that the Throttle Position (TP) sensor's rotational setting may be out of Self-Test range.
Possible causes:
-- Binding throttle linkage.
-- TP sensor may not be seated properly (tightened down).
-- Damaged TP sensor.
-- Damaged Powertrain Control Module (PCM).
l Visually inspect carburetor/throttle body and throttle linkage for binding or sticking.
l Verify the throttle linkage is at mechanical/closed throttle. Check for: binding throttle linkage, speed control linkage, vacuum line/electrical harness interference, etc.
---------------------
when was the throttle body interior and plate cleaned last. gummy deposits can cause throttle sticking
doesn't tell us what code or codes you have now
no use wasting hard earned money on a working part
O2 and TPS sensors are replace only items, they wear out over time. may be defective wiring/connector to them.
O2 sensor is mounted on exhaust pipe threaded connector in front of catalytic converter under passenger side.
TPS is Under hood, center, upper engine area, front of intake manifold, mounted on driver side of throttle valve assembly
from Ford Svc CD
DTC 23/121 indicates that the Throttle Position (TP) sensor's rotational setting may be out of Self-Test range.
Possible causes:
-- Binding throttle linkage.
-- TP sensor may not be seated properly (tightened down).
-- Damaged TP sensor.
-- Damaged Powertrain Control Module (PCM).
l Visually inspect carburetor/throttle body and throttle linkage for binding or sticking.
l Verify the throttle linkage is at mechanical/closed throttle. Check for: binding throttle linkage, speed control linkage, vacuum line/electrical harness interference, etc.
---------------------
when was the throttle body interior and plate cleaned last. gummy deposits can cause throttle sticking
Elder User
Joined: Dec 2006
Posts: 830
Likes: 0
From: Kitchener,Ontario,Canada
172 is engine o2 sensor indicates system lean, which is why you are burning too much gas. You need to find out source of air leak, vacuum lines PCV etc. This could also affect idle somewhat.
121, closed throttle voltage too high or too low.
Closed throttle should be at 1V or slightly less mine reads about 0.8v. If not observe voltage reading while smoothly operating throttle pedal with analogue voltmeter, (KOEO) Voltage should vary smoothly with throttle operation. If needle is jumpy or sticky, replace TPS. Make sure pedal operation is not obstructed or limited.
121, closed throttle voltage too high or too low.
Closed throttle should be at 1V or slightly less mine reads about 0.8v. If not observe voltage reading while smoothly operating throttle pedal with analogue voltmeter, (KOEO) Voltage should vary smoothly with throttle operation. If needle is jumpy or sticky, replace TPS. Make sure pedal operation is not obstructed or limited.
Thread
Thread Starter
Forum
Replies
Last Post
broncofanoc
1968-Present E-Series Van/Cutaway/Chassis
1
Jan 1, 2017 11:21 PM
