Question about 1986 Ford Mustang

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Sputters at cruising speed (86 5.0 mustang)

I have replaced all sensors, egr valve, injectors, fuel filter, spark plugs and wires, fuel pressure regulator, cap and rotor, cleaned ten pin connectors, no vacuum leaks. I just don't know what else it could be, please HELP!

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  • Sambam12 Mar 06, 2009

    My '86 V6 3.8L does the same thing. I've had 3 mechanics say they "fixed" it, put new catalytic converters on, new filters, hoses, erg valve, etc. It will idle no problem, start down the road, sometimes 2 blocks, sometimes 10 blocks, then just sputters and dies!! I really don't want to get rid of it, but it seems nobody can fix it. HELP!

  • Sambam12 Mar 29, 2009

    Great idea, however, this started just after I got a new gas tank & fuel pump. Possible that it wasn't installed properly?

  • mike loshbough
    mike loshbough May 11, 2010

    how about throttle position sensor?

  • Anonymous Mar 15, 2014

    sometimes runs smooth, others it spits an sputs , changed filter , plugs wires egr pressure sensor



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  • 453 Answers

Check fuel pressure. Could be fuel pump witch is in the tank and replace the TFI module located under the distributor.

Posted on Mar 24, 2009


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When I am accelerating the car sputters and dies some time if you can keep it idling about 1 rpm it might not die but it still sputters. if at a stop light it will sputter and quite. The car restarts.

Sound like it needs a tune up, replace spark plugs check high tension cables , make sure there is a good spark to the plugs, clean or replace air filter, replace fuel filter , check fuel pressure and flow. check fuel injectors for leaks.

May 05, 2015 | 2000 Daewoo Lanos

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2002 Sable sedan choke/missing/sputtering intermittent

The PO 316 is still misfires om first 1000 revolutions
so the shop did a poor job for you on resolveing the
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Jan 17, 2013 | 2002 Mercury Sable

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I have a 2001 mazda 626 and when im driving it skips sometimes

Engine stops unexpectedly at beginning of acceleration or during acceleration
Engine stops unexpectedly while cruising
Engine speed fluctuates during acceleration or while cruising
Engine misses during acceleration or cruising
Vehicle bucks or jerks during acceleration, while cruising, or upon deceleration
Momentary pause at the beginning of acceleration or during acceleration
Momentary minor irregularity in engine output

Possible Causes
Air leakage from intake-air system parts
Improper operation of idle air control valve
Crankshaft sensor circuit malfunction
Camshaft sensor circuit malfunction
Spark leakage from ignition coil
PCV valve malfunction
Restriction in exhaust system
Open or short circuit in fuel pump and related harness
Improper fuel pressure
Fuel leakage from injector
Improper A/C system operation
Purge solenoid valve malfunction
EGR valve malfunction
EGR solenoid malfunction
Low engine compression
Vacuum leakage
Fuel pump control relay and resistor
Poor fuel quality
Air filter restriction
Electrical connector disconnection
No battery power supply to ECU or poor ground
Fuel pump mechanical malfunction
Clogged injector

Diagnostic Procedure

1. Verify vacuum hose connections, check the air filter, check for leakage or restriction of the intake-air system, ensure proper sealing of intake manifold and components attached (e.g. EGR, IAC), examine ignition components, fuel quality, and electrical connections. Are all items okay?

Yes - Go to next step
No - Service as required.
2. Check for stored OBD-II error codes. Are there any stored codes?

Yes - Go to appropriate DTC test
No - Go to next step
3. Is engine overheating?

Yes - Go to Symptom #10 for "engine overheats"
No - Go to next step
4. Connect an OBD-II scan tool capable of logging sensor output and drive the vehicle. Are engine speed (RPM), mass-airflow (MAF), throttle position (TP), and vehicle speed (VSS) PIDs within specifications?

Yes - Go to next step
No - Inspect crankshaft position sensor (RPM) circuit, mass airflow sensor (MAF) circuit, throttle position sensor (TP) circuit, and vehicle speed sensor (VSS) circuit.
5. Visually inspect the crankshaft position sensor and the teeth on the crankshaft pulley. Are these components okay?

Yes - Go to next step
No - Service as required
6. Measure the gap between the crankshaft position sensor and the teeth of the crankshaft pulley (specification: 0.5-1.5mm). Is the gap within specification?

Yes - Go to next step
No - Adjust crankshaft position sensor
7. Check spark plug condition. Are spark plugs wet, grayish white, or covered with carbon soot?

Yes - If wet or sooty, check for leaky fuel injector
No - Install spark plugs on original cylinders then go to next step
8. Remove PCV valve and shake PCV valve. Does the valve rattle?

Yes - Go to next step
No - Replace PCV valve
9. Verify that the throttle lever is resting on the throttle valve stop screw and/or throttle valve orifice plug. Are there any faults present?

Yes - adjust as necessary
No - Go to next step
10. Is there an exhaust restriction?

Yes - Inspect exhaust system
No - Go to next step
11. Check fuel pressure between fuel filter and fuel rail. Connect a jumper wire between the F/P terminal at the engine bay DLC connector and ground. Is the fuel line pressure within specification (280-330kPa or 41-48psi) with the ignition switch on?

Yes - Go to next step
No - If there is no or low pressure, check the fuel pump circuit, control relay and resistor, fuel pump relief valve as well as for fuel leakage inside the fuel pressure regulator and for a restricted main fuel line. If the fuel pressure is too high, check the fuel pressure regulator, the fuel pump control relay and resistor, and for a clogged fuel return line
12. Does fuel pressure increase when the accelerator is depressed?

Yes - Go to next step
No - Examine the fuel pressure regulator control (PRC) solenoid
13. Skip to the next step if the symptom occurs with or without the A/C running. If symptom occurs only with A/C operation, connect a pressure gauge to the A/C line and measure both low and high side pressures. Are the pressures within specifications?

Yes - Go to next step
No - Check the refrigerant charging amount, A/C pressure switch operation, condenser fan operation, and the A/C relay
14. Skip to the next step if the symptom occurs with or without cruise control operation. If symptom occurs only during cruise control operation, inspect the cruise control system. Is cruise control system operating properly?

Yes - Go to next step
No - Repair cruise control system
15. Is the evaporative emissions purge control system okay?

Yes - Go to next step
No - Check if purge control solenoid sticks open mechanically. Inspect the evaporative emissions control system.
16. Visually inspect the camshaft pulley, is the camshaft pulley okay?

Yes - Go to next step
No - Replace camshaft pulley
17. With the engine idling, disconnect the vacuum hose from the EGR valve and plug it. Is the engine condition improved?

Yes - Check for a stuck EGR solenoid vacuum valve, vent valve, and solenoid valve connector terminals
No - Check if the EGR valve moves smoothly. If yes, go to next step. If no, replace the EGR valve
18. Is the air-bypass valve actuator okay?

Yes - Go to next step
No - Replace air-bypass valve actuator
19. Check engine compression with a cylinder compression test tool. Is the engine compression within specifications?

Yes - Verify valve timing and transmission operation
No - Check for cause
20. Verify test results

Apr 25, 2012 | 2001 Mazda 626

1 Answer

My '01 impala 3.4 v-6 flat spots when COLD, at around 20mph. the idle is ruff with random misfires. acceleration is overall poor. when HOT, most symptoms go away leaving only some slight acceleration...

depending on mileage, but possible tune-up could fix it. if already done then check ignition coil pack and ignition wires also spark plugs, check vacuum hoses for leaks or porous, last injectors clogged - use some techron fuel injector cleaner (wal-mart has them). Also get the throttle body and iac valve cleaned by throttle cleaner . Also this other possibilities are to be checked and confirmed.:---- Engine running rough or misfiring can be cause by the following:

1.Defective spark plugs
2.Inadequate spark/coil, defective spark plug wire.
3. Lack of compression
4.False air leakage.
5. Faulty fuel injectors.
6. Insufficient fuel pressure.
7. Contaminated fuel.
8. EGR valve that is leaking.
9. Oxygen sensors.
10. Throttle position sensor.
11. Manifold absolute pressure sensor
12.Mass Airflow Sensor
13.Idle air control valve

--------- This should help.Keep updated.Thanks.Helpmech.

Mar 27, 2011 | 2001 Chevrolet Impala

1 Answer

I have replaced egr valve and mass flow air sensor and egr sylinoid and have replaced catylatic converters. Truck still sputters. I have put new plugs, wires, and distributer cap and button. Truck fells...

I recommend you test your fuel pressure to see if it fluctuates any.If it were to be any of the other sensors you would have a check engine light that would come on.The only system that doesn't have any sensors would be your fuel system unless it has a fuel pressure sensor and you would have a light for that also.I would take a look at your fuel pump and filter.Also have your injectors balance tested this will tell you if you have any bad injectors or pressure regulator.

Mar 13, 2011 | Ford F-150 Cars & Trucks

1 Answer

Engine sputters when accelerating to speed limit and fails to hold it . also loses power climbing hills

Check your EGR valve, IAC valve, fuel pressure regulator, fuel pump, fuel filter, spark plugs and spark plug wires

Jan 02, 2010 | 1993 Ford Escort 4 Door

2 Answers

Starts fine, but then bogs out when accelerating, practicaly have to give it no gas and creep up to speed.Doesn't want to go up hills. Just replaced the cpi, fuel filter and fuel pump 3 months ago. Also...

Check the fuel pressure regulator and the EGR valve, I would check the fuel pressure regulator first and go from there. Good luck and keep me posted. Not sure what the pressure should be but thinking it's 62 to 65 PSI upon start up and should drop 5 PSI when engine running, check the vacuum line to the regulator.

Dec 09, 2009 | 1993 Chevrolet S-10 Blazer

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1998 astro sputtering when taking off and while at driving speed

loose vacuum line, check for same, also check the map sensor and the measure the fuel pressure, make sure its at spec

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1999 Ford Taurus mechanical problem

your problem appears to be the idle control motor located on the air intake manifold it is a small motor that goes bad quite often. Other items that can cause this is a bad /clogged air filter or a tune up (spark plugs and wires), or clogged fuel injectors. to clean the injectors you can buy a container of fuel system cleaner and pour it into the gas tank and as you drive it cleans the system.

Once the fuel system is cleaned via a tankful of cleaner & gas then the idle controller motor would be next on the list to be replaced.

Good Luck !
Rich Lilja

Dec 03, 2008 | 1999 Ford Taurus

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