Engine Rpm Problems Out Of Nowhere

93Notchback93 · Jun 28, 2016

Before i start, i have seen the idle surging checklist. Im not too familiar with the terms used and i just want to know what could have caused this out of nowhere

So i got a 1993 Mustang 5.0 and I've had it for about a month now. I would notice on startup sometimes, the RPM's would jump from 500 to 1500 and then it would die if you don't give it gas. As the RPM's would drop to around 500 the battery guage would slightly drop down too and then back up when the RPM's would hit 1500. While driving the RPM's would be stable at 900 and it would run fine. Yesterday I took it for a spin and coming home it suddenly started surging again while in first gear. As I pulled up to a stop sign i put it in neutral and it kept on surging up and down from 500-1500. As i put it into first gear to leave the stop it dropped really low and the car shut off.. it started back up and while driving home it the RPM's kept jumping up and down wanted to die again if i let off the accelerator.

Why has it started doing this out of nowhere, the car isn't able to drive now since it just dies if i don't give it gas..

AFR 165 Renegade heads
24lb injectors
bbk headers
edelbrock intake manifolds
Comp Cam xtreme

mikestang63 · Jun 28, 2016

If you plan on owning a 25 year old modded Mustang, you really do need to familiarize yourself with the terminology and phrases. First thing to do is run the codes. Then follow the surging idle checklist- it could be a multitude of single or combined issues ranging from a dity IAC, MAF, bad ECT, TPS, or vacuum leak

93Notchback93 · Jun 28, 2016

mikestang63 said:
If you plan on owning a 25 year old modded Mustang, you really do need to familiarize yourself with the terminology and phrases. First thing to do is run the codes. Then follow the surging idle checklist- it could be a multitude of single or combined issues ranging from a dity IAC, MAF, bad ECT, TPS, or vacuum leak

I've bought it just to drive right I'm not no expert with this type of stuff.

Noobz347 · Jun 28, 2016

mikestang63 said:
If you plan on owning a 25 year old modded Mustang, you really do need to familiarize yourself with the terminology and phrases. First thing to do is run the codes. Then follow the surging idle checklist- it could be a multitude of single or combined issues ranging from a dity IAC, MAF, bad ECT, TPS, or vacuum leak

IAC - Idle Air Control Valve (sensor..so to speak)
MAF - Mass Air Flow sensor (sensor)
ECT - Engine Coolant Temperature (sensor)
TPS - Throttle Position Sensor (sensor)
EGT - Exhaust Gas Temperature
AFR - Air Fuel Ratio (also short for Air Flow Research they make us sparkle shineys)

folks... jump in and add others:

We really should make a complete list of all of these somewhere.

Here's a link to the Surging Idle Checklist that Mike is talking about and a whole bunch more:
http://www.stangnet.com/mustang-forums/threads/technical-thread-how-to-index.808661/

93Notchback93 said:
Before i start, i have seen the idle surging checklist. Im not too familiar with the terms used and i just want to know what could have caused this out of nowhere

So i got a 1993 Mustang 5.0 and I've had it for about a month now. I would notice on startup sometimes, the RPM's would jump from 500 to 1500 and then it would die if you don't give it gas. As the RPM's would drop to around 500 the battery guage would slightly drop down too and then back up when the RPM's would hit 1500. While driving the RPM's would be stable at 900 and it would run fine. Yesterday I took it for a spin and coming home it suddenly started surging again while in first gear. As I pulled up to a stop sign i put it in neutral and it kept on surging up and down from 500-1500. As i put it into first gear to leave the stop it dropped really low and the car shut off.. it started back up and while driving home it the RPM's kept jumping up and down wanted to die again if i let off the accelerator.

Why has it started doing this out of nowhere, the car isn't able to drive now since it just dies if i don't give it gas..

AFR 165 Renegade heads
24lb injectors
bbk headers
edelbrock intake manifolds
Comp Cam xtreme

+1 on pulling codes and running the surging idle checklist. If you don't know your way around a car very well, you might want to enlist the help of a buddy. If your buddy helps you run the checklist item by item (instead of making the assumption he knows better) then your problem will be revealed.

Post up your codes once you get them pulled. There is little we can do to help you over the internet without them.

93Notchback93 · Jun 28, 2016

Noobz347 said:
IAC - Idle Air Control Valve (sensor..so to speak)
MAF - Mass Air Flow sensor (sensor)
ECT - Electronic Controlled Transmission
TPS - Throttle Position Sensor (sensor)
EGT - Exhaust Gas Temperature
AFR - Air Fuel Ratio (also short for Air Flow Research they make us sparkle shineys)

folks... jump in and add others:

We really should make a complete list of all of these somewhere.

Here's a link to the Surging Idle Checklist that Mike is talking about and a whole bunch more:
http://www.stangnet.com/mustang-forums/threads/technical-thread-how-to-index.808661/

+1 on pulling codes and running the surging idle checklist. If you don't know your way around a car very well, you might want to enlist the help of a buddy. If your buddy helps you run the checklist item by item (instead of making the assumption he knows better) then your problem will be revealed.

Post up your codes once you get them pulled. There is little we can do to help you over the internet without them.

Should I start by just cleaning the sensors first

Noobz347 · Jun 28, 2016

93Notchback93 said:
Should I start by just cleaning the sensors first

You should start by pulling codes. You'll find instructions in that link to the Technical Index that I posted above.

93Notchback93 · Jun 28, 2016

Noobz347 said:
You should start by pulling codes. You'll find instructions in that link to the Technical Index that I posted above.

https://m.summitracing.com/parts/ino-3145
Would that be suitable to pull the codes?

JD1964 · Jun 28, 2016

93Notchback93 said:
https://m.summitracing.com/parts/ino-3145
Would that be suitable to pull the codes?

That would work for pulling codes. I have one too but haven't used it yet.

93Notchback93 · Jun 28, 2016

John Dirks Jr said:
That would work for pulling codes. I have one too but haven't used it yet.

It's just plug in and they should show right? I think that would be the easiest way for me

JD1964 · Jun 28, 2016

93Notchback93 said:
It's just plug in and they should show right? I think that would be the easiest way for me

I have not used mine yet so not sure on the procedure

Noobz347 · Jun 29, 2016

Mike pointed out to me that ECT in relation to our vehicles is:

ECT - Engine Coolant Temperature (sensor)

Sorry for the mis-type.

Thanks @mikestang63

Noobz347 · Jun 29, 2016

93Notchback93 said:
https://m.summitracing.com/parts/ino-3145
Would that be suitable to pull the codes?

Perfect. It's the only code reader that you will ever need for a Fox body.

MikeH686 · Jun 29, 2016

How did I get tagged in this?

Then I look on the thread and you tagged @mikestang63

93Notchback93 · Jun 30, 2016

So the car was idling fine and when I wiggled the tps wire it just died right away..
Tested this 2 times and both times it just idle low and died almost instantly.

jrichker · Jul 1, 2016

93Notchback93 said:
So the car was idling fine and when I wiggled the tps wire it just died right away..
Tested this 2 times and both times it just idle low and died almost instantly.

Dump the codes first to find what part of the TPS circuit died. There is a power, a ground and a signal. Each one of them has a separate repair strategy . The code dump will help you figure out which one is the source of the problem.

Swapping the sensor is a costly way to find the problem - price is from $36-$52. For that much money, you can strain your brain and fingers to find out what is really wrong.

Check the TPS connectors for loose contacts
Check the TPS wiring for broken wires
If you don't find either one, replace the TPS

Shelden · Dec 28, 2016

Might seem somewhat random (I'm Shelden the new kid on the block as of ten minutes ago) but been having issues with performance and idling , did some research that led me to inspect the Coolant Temp Sensor, lil guy was just hangin there sensor is broke in half so just the metal end is in the head, not sure how that happened.... but what would be the best approach at taking the metal piece out...? it doesnt look like there's room enough for extensiona or pliars, curious to yalls input before I started taking things apart to get to it lol

General karthief · Dec 28, 2016

Shelden said:
Might seem somewhat random (I'm Shelden the new kid on the block as of ten minutes ago) but been having issues with performance and idling , did some research that led me to inspect the Coolant Temp Sensor, lil guy was just hangin there sensor is broke in half so just the metal end is in the head, not sure how that happened.... but what would be the best approach at taking the metal piece out...? it doesnt look like there's room enough for extensiona or pliars, curious to yalls input before I started taking things apart to get to it lol

send a pic

Shelden · Dec 28, 2016

karthief said:
send a pic

Shelden · Dec 28, 2016

Thats standing at the front bumper looking straight down at it

General karthief · Dec 28, 2016

you should be able to get a socket on that, I don't know what size, likely metric

Engine Rpm Problems Out Of Nowhere

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there is enough sticking out to grab on to

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there is enough sticking out to grab on to

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Mine is only two inches though.

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wonder how much it would cost to ship you a pair

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wonder how much it would cost to ship you a pair

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