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No throttle response when floored, "Popping" sound?

  • Thread starter Thread starter ryangruhn
  • Start date Start date Oct 3, 2011

ryangruhn

Member
Oct 5, 2000
53
0
6
Oct 3, 2011
#1
  • Oct 3, 2011
  • #1
So I just got my mustang back on the road from being stored for about 2 years. My throttle seems to be acting up. When I floor it I get a popping sound which sounds like it's coming from the cold air intake. Then, if I hold the gas pedal down to the floor I get no throttle response and it bucks all over the place.

When idling it runs fine.

Thoughts?
 

Onefine88

Previously 89SSC18
10 Year Member
Aug 3, 2006
1,422
796
154
Oct 3, 2011
#2
  • Oct 3, 2011
  • #2
Sounds fuel related. Could be old two year old gas. Or lack of fuel pressure due to a bad pump or clogged fuel filter.
 

ID89GT

10 Year Member
May 26, 2008
1,659
18
49
Spokane Valley, WA
Oct 3, 2011
#3
  • Oct 3, 2011
  • #3
I would dump the gas tank, clean it out really good then run fresh gas through it. I would probably replace the fuel filter too just for good measure, plus its extremely easy to do anyway.
 

ryangruhn

Member
Oct 5, 2000
53
0
6
Oct 3, 2011
#4
  • Oct 3, 2011
  • #4
I put 93 in it and the fuel additive. Fuel filter is next.

Any other ideas?
 

jrichker

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Dublin GA
Oct 3, 2011
#5
  • Oct 3, 2011
  • #5
Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.





If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Or for a nicer scanner see http://www.midwayautosupply.com/p-7208-equus-digital-ford-code-reader-3145.aspx– It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
 

ryangruhn

Member
Oct 5, 2000
53
0
6
Oct 3, 2011
#6
  • Oct 3, 2011
  • #6
Would everyone concur that the popping sound is a backfire? Would that mean that it's running lean when I hit the throttle?
 
B

BYRDPE

Founding Member
Nov 4, 1998
1,556
0
37
Memphis,Tn.
Oct 4, 2011
#7
  • Oct 4, 2011
  • #7
yep...highly probable it's a lean condition.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
17,937
224
Massachusetts
Oct 4, 2011
#8
  • Oct 4, 2011
  • #8
I agree...lean condition.

Pull the codes as to a hit as to why this might be. But you might want to siphon out the old gas, fill with fresh gas and change the fuel filter as well. Gas has a life of about 6 months in a tank. (but i say that when i started my own car fine on 7 year old gas)
 

Onefine88

Previously 89SSC18
10 Year Member
Aug 3, 2006
1,422
796
154
Oct 4, 2011
#9
  • Oct 4, 2011
  • #9
89SSC18 said:
Sounds fuel related. Could be old two year old gas. Or lack of fuel pressure due to a bad pump or clogged fuel filter.
Click to expand...

This= lean.
If you put a fuel pressure guage on it, you'll more than likely see 10-15psi at idle.

I've been there.
 

ryangruhn

Member
Oct 5, 2000
53
0
6
Oct 4, 2011
#10
  • Oct 4, 2011
  • #10
Fuel filter replaced and it's still doing it.

It's very smooth as long as I don't depress the gas pedal more than 1/4 of the way. As soon as I take it past that it seems like no fuel is getting to the engine.

Thoughts?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,252
17,937
224
Massachusetts
Oct 4, 2011
#11
  • Oct 4, 2011
  • #11
Hook a fuel pressure gauge up to the schraeder valve and confirm 39psi vac off.

Next up...run the codes. See if anything major is stored
 

Kdubslugga

Active Member
Jun 7, 2003
1,515
3
38
Akron, OH
Oct 7, 2011
#12
  • Oct 7, 2011
  • #12
You need to check fuel pressure. Your symptoms sound as if your running out of gas. Not saying you are but this is how my car acts when Im really low on fuel.
 

baddbradd

New Member
Sep 13, 2010
14
0
2
Sylvan Springs, Al
Oct 7, 2011
#13
  • Oct 7, 2011
  • #13
i just went thru this myself----tps sensor. may need checked or adjusted
 
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