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Author
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Topic: Back firing and sluggish
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Svt Tony
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Member # 9959
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posted
 
 
I have a 91 auto lx 5.0 sat for few years so I figure I change some parts before I started using it like
1. Spark plug wires ford racing 9mm
2. Distributor cap n rotor (msd)
3. Install 70mm TB
4. Install BBK cai tru fender
It has cobra intake and cobra/GT40 heads stock bottom end.
Problem: idles ok but under load at certain speed 15-20 mph it back fires and gets really sluggish. No codes no check engine light so what can it be. Did not really run it before so idk i problem was there before (old owner says nope has to be something I did)
What can cause this? Vacuums look ok egr is workin fresh gas in tank and it does it more when car is cold. Once it warms a lido it runs better no back fireing and does better at wot. N e ideas?
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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SLOWFOX
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Member # 11067
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posted
X2 same issue here..
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" A Wolf under sheep's clothing"-svoRICK 2/10/12
Almost everything I asked for.
Posts: 2399 | From: ESSJ | Registered: Jul 2011
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90 7up lx
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Member # 10304
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posted
Do you have fresh gas in it, especially since its been sitting for YEARs, change the plugs also
Posts: 1266 | From: north valley | Registered: Sep 2010
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87 coupe
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Member # 10919
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posted
Did it fix the problem after I left your house or it did it again tony brown I tough we found the problem ?
Posts: 2016 | From: Home | Registered: May 2011
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kerry's 50
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Member # 9266
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posted
I had some of the same symptoms and it ended up being my distributor. Maybe check the timing if you haven't done that yet. Could simple as that. Hopefully you get it running right, soon.
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R.I.P 96 GT
1994 Gt sold
1989 Notch sold
1989 Notch sold
1994 GT/Cobra clone in progress-sold
1988 ssp 306 h/c/i soon to be charged
Posts: 408 | From: East Bay | Registered: Jun 2009
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Svt Tony
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Member # 9959
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posted
quote:
Originally posted by 87 coupe:
Did it fix the problem after I left your house or it did it again tony brown I tough we found the problem ?
Did not run it after you left (since you took the cluster and light switch off oh yeah it was already dark) lol jk im try it today after work or I ll wait till you get here.
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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Svt Tony
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Member # 9959
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posted
quote:
Originally posted by 90 7up lx:
Do you have fresh gas in it, especially since its been sitting for YEARs, change the plugs also
Yup fresh gas and no plugs I have not replaced!!! Im gona do that tonite. But if plugs were bad or some wouldnt it run lime crap all the time? Not just under load!!! This thing idles and revs good. Only at certain speed does the back fire happens.
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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Svt Tony
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Member # 9959
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posted
quote:
Originally posted by kerry's 50:
I had some of the same symptoms and it ended up being my distributor. Maybe check the timing if you haven't done that yet. Could simple as that. Hopefully you get it running right, soon.
Yup The dizzy can be bad!!! Timing is set at 12* so the timing is good. I just dont want to start changing all my ignition and see what happends but I might have to change the dizzy!!
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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S550_Andres
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Member # 11083
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posted
I had a back firing issue at 3k rpms. I replaced timing chain plugs rotor distributor cap wires and the problem was still there. It turned out to be te dizzy module once I replaced that my car ran great
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86 notch coyote swapped
89 convertible 302 hci
85 notch 347 hci
Posts: 2747 | From: 650-408 | Registered: Jul 2011
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kerry's 50
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Member # 9266
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posted
I know. I swapped dizzys when it had the symptoms of my tfi heating up. The dizzy was used but ran fine when i first put it in. Then it took a shit on me all together. I then replaced the tfi. No luck. Then the coil. Still no luck. Then I said f it and i bought a brand new dizzy. Runs like a champ now. But I bought things I didn't need at the time. But at least I don't have to worry about those things for awhile. I hope the problem reveals itself and its an easy fix. Fuel pump can be an issue. Maybe starving for fuel under a heavy load. Maybe not strong enough. Just a thought.
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R.I.P 96 GT
1994 Gt sold
1989 Notch sold
1989 Notch sold
1994 GT/Cobra clone in progress-sold
1988 ssp 306 h/c/i soon to be charged
Posts: 408 | From: East Bay | Registered: Jun 2009
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Svt Tony
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Member # 9959
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posted
Yup m replacing the dizzy today see what happens. Im also replacin the plugs. No lose ends lol
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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SLOWFOX
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Member # 11067
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posted
Plz lmk if it wrkd out for you bro?
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" A Wolf under sheep's clothing"-svoRICK 2/10/12
Almost everything I asked for.
Posts: 2399 | From: ESSJ | Registered: Jul 2011
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Svt Tony
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Member # 9959
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posted
Replaced dizz(used but good workin condition)y but still doing the same thing!!! Im replace the plugs just for the hell of it!!! If not im put it back to stock.
Stock wires,plugs,air intake,TB and all see what happends!!!
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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50DADDY
CAFords OG
Member # 3076
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posted
1-3-7-2-6-5-4-8.Counter clockwise.
Timing @ 10-14 degrees advanced with spout connector out.
Posts: 4827 | From: Suckramento | Registered: Jul 2003
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87 coupe
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Member # 10919
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posted
Did u change the fuel filter sometimes it could be the smallest shit ever on my coupe when it sat for ever it use to run good only in high rpms but when it was at a stop sounded like shit and ran like shit at low rpms
Posts: 2016 | From: Home | Registered: May 2011
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Svt Tony
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Member # 9959
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posted
Ok so updating this post
I replace dizzy nothing
I replaced spark plugs nothing
I replaced egr valve nothing
Firing order correct
Replaced cap n rotor msd nothing
Replaced fuel filter nothing
Replaced coil nothing
Replaced icv nothing
Replaced tps nothing
Timing is set @ 12*
So car still does the same shit freakin back fires and runs like shit sluggish fuck im getting so fn pist!!!
Funny shit tho as soon as the car gets warm or it has been runnin for a lido it freakin runs fine!!! Wtf can it be which sensor?
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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Stang66
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Member # 10504
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posted
fuel pressure regulator?
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1966 Ford Mustang
1990 Notchback
1975 Pontiac Trans Am 400ci
Posts: 754 | From: Stockton | Registered: Dec 2010
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Svt Tony
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Member # 9959
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posted
I been reading a lido more about this common problem on line. I forgot to mention on my original post that my 91 lx has a freaking exhaust leak. IDK if its a bad headder or at the union with the h pipe? but is there. Can this be why it back fires? and when the metal heats up n expands it gets better? some guys on diff forums seem to think so. so im changing the headders/gasket and also installing a x pipe. we will see if it gets fix.
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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SLOWFOX
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Member # 11067
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posted
Maf?
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" A Wolf under sheep's clothing"-svoRICK 2/10/12
Almost everything I asked for.
Posts: 2399 | From: ESSJ | Registered: Jul 2011
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Svt Tony
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Member # 9959
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posted
quote:
Originally posted by SLOWFOX:
Maf?
Cleaned!!! Not teplaced!!!
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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BAD ASS 5.HO
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Member # 10947
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posted
quote:
Originally posted by Stang66:
fuel pressure regulator?
Good point, iff i whas u i would just change the maff, injectors and regulator. just my O2 but think ur injectors are dirty and ur not getting enough flow.
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98 boosted/stroked cobra
98 rio red cobra
Posts: 991 | From: modesto | Registered: May 2011
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nitrous_bob
CAFords OG
Member # 77
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posted
none of the mechanicals broke from sitting (other than vac lines)
go back to basics
check your plug wires...burned ? on all the way ? firing order correct ? wires cross firing where they are touching each other ?
check vac...if it gets better when it warms up...something is sealing IMO
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5.0 OG since 1990
Posts: 1402 | From: st clair shores MI | Registered: Nov 2000
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Svt Tony
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Member # 9959
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posted
quote:
Originally posted by nitrous_bob:
none of the mechanicals broke from sitting (other than vac lines)
go back to basics
check your plug wires...burned ? on all the way ? firing order correct ? wires cross firing where they are touching each other ?
check vac...if it gets better when it warms up...something is sealing IMO
Yeah I ve been messing with the timing and it seems the 12* is where she likes it the best ( it back fires once in a while) but shes doin much better she even passed smog today lol!!! Im just gona drive her more often and see if it gets better or the prob disapears. Thanx for the input tho everyone!!!
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" u wanna play u gatta pay "
Posts: 1579 | From: 209 | Registered: Apr 2010
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