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Engine Rev Engine To About 3k And It Bogs Down

  • Thread starter Thread starter Southport2014
  • Start date Start date Mar 11, 2016
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Southport2014

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#1
  • Mar 11, 2016
  • #1
I have a 87 fox body gt. Minor mods explorer intake and idk about heads. H pipe short tube headers and flowmaster out rear. I just replaced fuel pump because car would just crank and no start. It starts fine now no problem. Only thing is now it wont rev past about 3200 rpm and bogs down and acts like its going to die when i push the pedal down. Any suggestiond ?
 

Jace_78

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Mar 10, 2016
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Mar 11, 2016
#2
  • Mar 11, 2016
  • #2
Timing? How old are plugs rotor wires?
 
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Southport2014

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Mar 11, 2016
#3
  • Mar 11, 2016
  • #3
Forgot to mention i replaced fuel filter as well. And i have no clue about plugs and wires. Ive had the car since october and my dad had it about 4 years before that. I do not know ifnhe put plugs or new wires on it. When he had it it drove fine. I bought it off him changed dash harness and interior over winter and it set for 5 months. I got it out last sunday started fine and irevved up fine . It always idled a little fun due to the iac i belive. But anyways i had it out sunday took it to gas station and everything went great. Went to leave and car would not start. Just cranked. Towed it home and then changed the fuel pump snd filter and now she starts. But now she will not rev up past 3200 rpm and will bog like crazy and back fire.
 

Jace_78

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Mar 10, 2016
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#4
  • Mar 11, 2016
  • #4
Mine lost power above 3k and would not Rev above 4k when I bought it. .. fuel filter and plugs, rotor, cap and wires was my fix. Always first thing I do when I buy a car, since you got it off your dad I'd ask of he ever did, may be a good place to start. ..
 

Jace_78

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Mar 11, 2016
#5
  • Mar 11, 2016
  • #5
Oh and check the timing, doubtful if it ran fine before but something simple to check
 
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Southport2014

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#6
  • Mar 11, 2016
  • #6
Alright ill talk to him. Just doesnt make much snce why this is happening now.
 

Jace_78

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Mar 10, 2016
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#7
  • Mar 11, 2016
  • #7
I'm assuming fuel isn't the issue anymore, backfiring sounds more ignition, if you can pull a plug and check color/saturation
 
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Southport2014

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#8
  • Mar 11, 2016
  • #8
Any plug ? And i feel like the exhuast smells a little funny. I think it may be how my father in law sprayed i believe starting fluid in the intake where the intakr tupe hooks up. Like itll idel pretty much fine but once ur at around 3k its a pos
 

jrichker

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#9
  • Mar 11, 2016
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Does the problem occur only on a warm engine?

The TFI module mounted on the distributor is one of the culprits for a high speed miss on a warm engine. If the problem does not occur when the engine is cold, the TFI module is definitely suspect. You may need a special socket to remove the TFI module, but most auto parts stores will have one for $5-$7.

Be sure to use plenty of the heat sink grease on the new TFI and clean the old grease off the distributor.



See Automotive Tools Specialty | Auto Mechanic & Technician Diagnostic, Testing Equipment | Thexton


diagram courtesy of Tmoss & Stang&2Birds
 

madspeed

Colonel Mustard
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Mar 11, 2016
#10
  • Mar 11, 2016
  • #10
codes??
 
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Southport2014

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#11
  • Mar 12, 2016
  • #11
Acts this way when cold or hot. Its weord because it never did anything like this until fuel pump went bad .
 
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Southport2014

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#12
  • Mar 12, 2016
  • #12
I dont have a obd1
 

madspeed

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#13
  • Mar 12, 2016
  • #13
copied from @jrichker can also be viewed from the sticky posted at the top of the fox tech section....


Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

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.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

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.

View attachment 548885

View attachment 548886

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.

View attachment 548887 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 ablack/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 theanswers 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.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10




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 www.midwayautosupply.com/Equus-Digital-Ford-Code-Reader/dp/B000EW0KHW 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 $22-$36.

 

Jace_78

Member
Mar 10, 2016
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Mar 12, 2016
#14
  • Mar 12, 2016
  • #14
Pull any plug, tfi is another possibility but see what your plus look like
 
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Southport2014

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Jan 28, 2014
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Mar 13, 2016
#15
  • Mar 13, 2016
  • #15
Unistalled the autozone airtex fuel pump and returned. I think its not working right or not enough lph. What size walbro should i get
 

stykthyn

I want to measure mine. It doesn't look that tall.
15 Year Member
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Mar 13, 2016
#16
  • Mar 13, 2016
  • #16
155 for a stockish engine.
 
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Southport2014

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Jan 28, 2014
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Mar 13, 2016
#17
  • Mar 13, 2016
  • #17
Will it hurt if i go any larger since there is a return? I do want to upgrade more eventually. Also do you think that the autozone fuel pump was not large enough as well. It stated like 90lph
 

stykthyn

I want to measure mine. It doesn't look that tall.
15 Year Member
Jul 6, 2006
5,232
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gainesville
Mar 13, 2016
#18
  • Mar 13, 2016
  • #18
The stock pump is a 90. 155 will be more than enough for a decent hci. Unless you are planning boost or big cubes you will be fine with that.
 
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Southport2014

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Jan 28, 2014
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Mar 13, 2016
#19
  • Mar 13, 2016
  • #19
I was gonna do boost eventually not any time soon though. So i beleive i will do 155 then can u dorect me to a good one also does the stock replacement st autozone seem to be to low ? Thats why i couldnt get any hogher rpm ?
 

stykthyn

I want to measure mine. It doesn't look that tall.
15 Year Member
Jul 6, 2006
5,232
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gainesville
Mar 13, 2016
#20
  • Mar 13, 2016
  • #20
Without seeing fp numbers I can't even speculate.
 
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