My car has trouble starting

[RedStang.02]

I have a 2002 mustang gt manual that has trouble starting can you please help?
heres a video pay attention of the rpms

View: https://youtu.be/mjdyrtOFhV8

 

[tsemmett]

That "Service Engine Soon" light means the PCM has detected errors. If you don't have a code reader, most parts stores will read them for free. That may very well point to your problem.

 

[wmburns]

Here's some information on how to trouble shooting IAC/idle.

Troubleshoot IAC idle problems 1996-2004

Troubleshoot IAC idle problems 1996-2004

Back to the basics. Check for blown fuses. Especially fuse F2.2 and F2.8 in the Central Junction Box (CJB 1999-2004 MY). Confirm key on power using a known good ground. 1999-2004 MY fuse panel schedule...

www.stangnet.com

Start with a through review of the battery and charging system. Why is this important? Because if the battery voltage is unstable this will cause the PCM to "forget" the adaptive idle trim values.

Howto perform charging system voltage drop test

Howto perform charging system voltage drop test

To anyone else reading any of my posts I usually include the line: Today's cars simply will not run right without a strong battery and charging system! Cut corners here at your own risk I'm a big believer in starting with the basics. As such I...

www.stangnet.com

In the how to, pay attention to the part about how the TPS is used to form a "ratch" function. As well as how the TPS is used to compute the TP-MODE

To truly trouble shoot this issue an ODB2 scanner could make short work of this problem. Here's some information on an affordable Windows unit.

ForScan ODB2 scanner w ELM327 USB

ForScan ODB2 scanner w ELM327 USB

While working on your car have you ever wanted: to find an ODB2 operational PID value (say fuel pressure or MAF)? How about graph a PID value over time? Or compare multiple PID's over time? Access a bi-directional PCM control such as test a...

www.stangnet.com

Do you want an educated WAG? How about a loose throttle body butterfly. Such that when the motor starts up the motor's vacuum is pulling in the butterfly thus changing it's position. There's a delay as the IAC adjusts the idle.

Bottom line. The throttle position MUST remain stable when the throttle is closed. The voltage of the TPS does not matter. What is important is for the TPS to send the SAME value each time the throttle is closed.

 

[RedStang.02]

That "Service Engine Soon" light means the PCM has detected errors. If you don't have a code reader, most parts stores will read them for free. That may very well point to your problem.

Here's some information on how to trouble shooting IAC/idle.

Troubleshoot IAC idle problems 1996-2004

Troubleshoot IAC idle problems 1996-2004

Back to the basics. Check for blown fuses. Especially fuse F2.2 and F2.8 in the Central Junction Box (CJB 1999-2004 MY). Confirm key on power using a known good ground. 1999-2004 MY fuse panel schedule...

www.stangnet.com

Start with a through review of the battery and charging system. Why is this important? Because if the battery voltage is unstable this will cause the PCM to "forget" the adaptive idle trim values.

Howto perform charging system voltage drop test

Howto perform charging system voltage drop test

To anyone else reading any of my posts I usually include the line: Today's cars simply will not run right without a strong battery and charging system! Cut corners here at your own risk I'm a big believer in starting with the basics. As such I...

www.stangnet.com

In the how to, pay attention to the part about how the TPS is used to form a "ratch" function. As well as how the TPS is used to compute the TP-MODE

To truly trouble shoot this issue an ODB2 scanner could make short work of this problem. Here's some information on an affordable Windows unit.

ForScan ODB2 scanner w ELM327 USB

ForScan ODB2 scanner w ELM327 USB

While working on your car have you ever wanted: to find an ODB2 operational PID value (say fuel pressure or MAF)? How about graph a PID value over time? Or compare multiple PID's over time? Access a bi-directional PCM control such as test a...

www.stangnet.com

Do you want an educated WAG? How about a loose throttle body butterfly. Such that when the motor starts up the motor's vacuum is pulling in the butterfly thus changing it's position. There's a delay as the IAC adjusts the idle.

Bottom line. The throttle position MUST remain stable when the throttle is closed. The voltage of the TPS does not matter. What is important is for the TPS to send the SAME value each time the throttle is closed.

Well I actually tested my car with an obd2 code scanner and a code say "idle air circuit malfunction" I think the number was p0511 what part or what can prevent this starting problem

 

[tsemmett]

The IAC (Idle Air Controller) provides air to the engine at idle (when the throttle body is closed) and definitely makes sense for what you're seeing. Replacing the IAC may solve the problem, but when I've had physical issues with an IAC in the past, I didn't get a code. Ideally, troubleshoot the IAC (use the links wmburns provided above), and find the underlying cause.

 

[RedStang.02]

I tested the fuel pressure and its running normal and can you tell me where is the regulator is and it has a new fuel filter

 

[RedStang.02]

The IAC (Idle Air Controller) provides air to the engine at idle (when the throttle body is closed) and definitely makes sense for what you're seeing. Replacing the IAC may solve the problem, but when I've had physical issues with an IAC in the past, I didn't get a code. Ideally, troubleshoot the IAC (use the links wmburns provided above), and find the underlying cause.

My cars rpms drop when i unplug it what else could it be the car does die after letting off the gas, like getting on the highway after letting off the car dies

 

[RedStang.02]

The IAC (Idle Air Controller) provides air to the engine at idle (when the throttle body is closed) and definitely makes sense for what you're seeing. Replacing the IAC may solve the problem, but when I've had physical issues with an IAC in the past, I didn't get a code. Ideally, troubleshoot the IAC (use the links wmburns provided above), and find the underlying cause.

Here's some information on how to trouble shooting IAC/idle.

Troubleshoot IAC idle problems 1996-2004

Troubleshoot IAC idle problems 1996-2004

Back to the basics. Check for blown fuses. Especially fuse F2.2 and F2.8 in the Central Junction Box (CJB 1999-2004 MY). Confirm key on power using a known good ground. 1999-2004 MY fuse panel schedule...

www.stangnet.com

Start with a through review of the battery and charging system. Why is this important? Because if the battery voltage is unstable this will cause the PCM to "forget" the adaptive idle trim values.

Howto perform charging system voltage drop test

Howto perform charging system voltage drop test

To anyone else reading any of my posts I usually include the line: Today's cars simply will not run right without a strong battery and charging system! Cut corners here at your own risk I'm a big believer in starting with the basics. As such I...

www.stangnet.com

In the how to, pay attention to the part about how the TPS is used to form a "ratch" function. As well as how the TPS is used to compute the TP-MODE

To truly trouble shoot this issue an ODB2 scanner could make short work of this problem. Here's some information on an affordable Windows unit.

ForScan ODB2 scanner w ELM327 USB

ForScan ODB2 scanner w ELM327 USB

While working on your car have you ever wanted: to find an ODB2 operational PID value (say fuel pressure or MAF)? How about graph a PID value over time? Or compare multiple PID's over time? Access a bi-directional PCM control such as test a...

www.stangnet.com

Do you want an educated WAG? How about a loose throttle body butterfly. Such that when the motor starts up the motor's vacuum is pulling in the butterfly thus changing it's position. There's a delay as the IAC adjusts the idle.

Bottom line. The throttle position MUST remain stable when the throttle is closed. The voltage of the TPS does not matter. What is important is for the TPS to send the SAME value each time the throttle is closed.

if it helps any my car is straight piped and one was the codes said i was too lean but i figured its cause of the straight pipe

 

[RedStang.02]

im thinking that iac code was from me unplugging it earlier before

 

[tsemmett]

You unplugged it before shooting that video? That could explain the PID for idle air.

A lean condition suggests you're getting more air than the PCM expects. I'd inspect your intake tubing/throttle body; my car does all sorts of odd things when the intake tubing comes apart (cheap CAI someone put on it before me likes to come loose right after the MAF every few months, I hate it but am too cheap to replace it ). I'd start at the MAF and work your way back. Make sure everything is tight and connected. Check the throttle body; it could actually be a loose blade as wmburns mentioned. Listen/look for vacuum leaks. That sort of thing. If it checks out, it could be worth cleaning the MAF and IAC (use the correct solvents).

From there, it's likely to require a scanner and some data logging to see what's really going on. You may have a bad sensor, or an electrical issue, but it's silly to go throwing parts at something like that. I've been there and wasted time/money in the process.

 

[Shuttleman83]

First try vac lines - usually try to eliminate those first - then it could be the idle is too low set with screw on TB, could be faltering sticking IAC, could be too little few (try priming 3 times before start), could be bad maf, could be the battery / computer just needs reset for 30 min, bad or leaking down fuel injectors, bad fuel pump, bad fuel filter, could be bad gas - try iso heet red bottle. Hell, even o2's.

 

[RedStang.02]

Priming does stop it from dropping but i check the codes and there are no misfiring or maf codes and i checked the fuel pump and it read 38, is there any other symptoms that could result in the rpms going wonky like that

 

[RedStang.02]

Sometimes the car doesn't start at all

 

[wmburns]

if it helps any my car is straight piped and one was the codes said i was too lean but i figured its cause of the straight pipe

Straight pipes won't CAUSE a lean DTC. IMO it's more likely there really is a vacuum leak.

Sometimes the car doesn't start at all

Here's some more information.

1996+ Crank with no start check list

1997 mustang wont ignite

Hello lets start with I have a 97 mustang gt v8 standard I had new engine transmission ect put all new well last month i shut the car off and had no power at all bought a new battery and alternator got all power back but it wont ignite brought to mechnic for a month all sensors codes ect are fine

www.allfordmustangs.com

Trouble shooting a modern car is a data driven process. Data in the form of test results either from visual inspection, ODB2 data, or checks with testing devices. But in general, I always recommend to start with the BASICS and work your way up. Don't guess. Test! Replace parts when the evidence points to a bad part.

For example. You stated that you measured fuel pressure. What was the fuel pressure BEFORE cranking? IF key cycling improves starting that usually means there fuel pressure leak down occurring. I could also see a case that IF the fuel pressure dropped at start up and then came back up it could cause your symptom. Again. Having data changes the thought process.

Regarding your question about the fuel pressure regulator. The 1999-2004 model year uses a return-less fuel system and does not use a regulator. Instead it uses a Fuel rail pressure sensor (FRPS) located on the fuel rail. There a fuel pump driver module (FPDM) that varies the voltage duty cycle to the fuel pump to control fuel pressure in an acceptable range.

Note. regarding if it's possible this is an O2 sensor problem. IMO I don't believe so. Why? Because the O2 sensors are only used during closed loop operation. At initial startup the engine would still be in open loop. The PCM operating mode can easily be answered with an ODB2 scanner.

 

[Shuttleman83]

Another thing to try - vapor purge valve, solenoid, and or charcoal canister. Try removing the gas cap for 3-5 minutes after the car is off then trying it.