Engine 1986 5.0-GT- Idling/bucking Problems

QuickFox86 · Aug 21, 2021

Hey guys. So I'm having running problems with my '86 GT. Sometimes the car runs great, but sometimes it will have a bad idle and buck really bad when you attempt to drive it. It also sounds like it's backfiring sometimes. I know this is probably an ignition/timing issue, or maybe I have a vacuum leak somewhere. It also might be a TFI module, but I am not sure. Anybody have any suggestions? Thanks.

General karthief · Aug 21, 2021

Many things come to mind as possible causes but rather than poke here or jab this do this checklist step by step,

Help me create the "Surging Idle Checklist"

Updated 26-Oct-2019 to clarify creeping idle RPM increase as the car is being driven. Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of...

forums.stangnet.com

Potomus Pete · Aug 21, 2021

Your on the right website

QuickFox86 · Aug 21, 2021

General karthief said:
Many things come to mind as possible causes but rather than poke here or jab this do this checklist step by step,

Help me create the "Surging Idle Checklist"

Updated 26-Oct-2019 to clarify creeping idle RPM increase as the car is being driven. Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of...

forums.stangnet.com

Ok I'll run through it. Thanks.

General karthief · Aug 21, 2021

QuickFox86 said:
Ok I'll run through it. Thanks.

Walk don't run, you could lose an eye.

Rdub6 · Aug 21, 2021

General karthief said:
Walk don't run, you could lose an eye.

And it’s all fun and games until that happens!

Willybill32 · Aug 28, 2021

QuickFox86 said:
Hey guys. So I'm having running problems with my '86 GT. Sometimes the car runs great, but sometimes it will have a bad idle and buck really bad when you attempt to drive it. It also sounds like it's backfiring sometimes. I know this is probably an ignition/timing issue, or maybe I have a vacuum leak somewhere. It also might be a TFI module, but I am not sure. Anybody have any suggestions? Thanks.

So, is your '86 completely stock? If not, what modifications?

QuickFox86 · Aug 31, 2021

As far as the engine goes I know the speed density system has been replaced with a mass air system, and the EGR has been deleted, as well as aluminum heads, msd box, and a tubular intake manifold off a 1st gen lightning.

Willybill32 · Sep 4, 2021

QuickFox86 said:
As far as the engine goes I know the speed density system has been replaced with a mass air system, and the EGR has been deleted, as well as aluminum heads, msd box, and a tubular intake manifold off a 1st gen lightning.

Do you have an aftermarket cam by any chance? I have an original '86 converted to mass air, plus E303 cam, aluminum heads, roller rockers, 24lb injectors, equal-length headers, etc., as well as deleted smog pump and EGR. At low speeds (under 1,500 RPM) I frequently get bucking, which I'm told is likely the cam. But my idle is great. I did take it to a tuner for some work.

Engine 1986 5.0-GT- Idling/bucking Problems

QuickFox86

Member

General karthief

wonder how much it would cost to ship you a pair

Help me create the "Surging Idle Checklist"

Potomus Pete

I'm still waiting for the fully nude shots

QuickFox86

Member

Help me create the "Surging Idle Checklist"

General karthief

wonder how much it would cost to ship you a pair

Rdub6

So while I wait to figure out my rear end issues

Willybill32

But at least it's tight!

QuickFox86

Member

Willybill32

But at least it's tight!

Similar threads

Engine 1986 5.0-GT- Idling/bucking Problems

Member

wonder how much it would cost to ship you a pair

I'm still waiting for the fully nude shots

Member

wonder how much it would cost to ship you a pair

So while I wait to figure out my rear end issues

But at least it's tight!

Member

But at least it's tight!

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