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ignition problem?

 
CareTaker
New User
Posts: 5
Joined: 04/14
Posted: 04/15/14 12:54 PM

Okay I'm having a slight issue.
1.Car seems to run ok at idle, but does intermittent surging.
2.Car accelerates good under hard acceleration, and seems to be normal under deceleration.
3.After at operating temp under normal acceleration between 2,500-3,000rpm engine starts to stumble. I tried to swap ignition coils today and it seemed to not stumble as hard.
4.Intermittently when I push in the clutch to come to a stop, it dies or has idle surge.
5.spark plugs, cap, and rotor are new, but it had the issue before this.
I'm hoping that someone has had a similar problem in the past and knows an easy fix so I don't have to keep throwing parts at this. If it helps to know, I also have an MSD box wired in as well. Confused  

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wayne712222
User
Posts: 127
Joined: 10/13
Posted: 04/15/14 05:38 PM

are you running a carb???

or

are you running fuel injection????

makes a HUGE difference in what i ask you to check..

if you are running a carb... which one.. holley.. edelbrock.. demon.. summit version of the holley 2010/2011. looks like an autolite 4100 but has holley style vacuum secondary.

so if you are running a carb.. i am going to say that you probably have a  undersized or clogged idle feed restriction..

please post as much info as you can.. i will give you some amazing stuff to help you...

please also perform a voltage drop test...


Voltagedroptesting  

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CareTaker
New User
Posts: 5
Joined: 04/14
Posted: 04/15/14 07:23 PM

It's fuel injected. I don't know if it would have anything to do with it but, one night at work I decided to change out my pcv screen, valve, and hose. We removed the upper intake to do so just to make things easier, and we reused the upper intake gasket because it was fairly new and undamaged. It ran fine, until 2 days later, then it started surging so bad that it would die whenever the car came to a stop. I checked all of the vacuum lines and such and it seemed to stop. The next day I was on I-95 on my way to work and this stumbling issue started and it's been doing it the last couple of weeks. I'll have to get back to you on that voltage drop test. my meter is at work.  

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wayne712222
User
Posts: 127
Joined: 10/13
Posted: 04/15/14 10:50 PM

you need to replace the hose to the MAP sensor on the firewall. it might have failed..

and or the carbon canister under the front of the plenum..

1993 Mustang Vaporcanister Hose

how its hooked up and configured depends on the year...

Ford50efirearofintakeplenum

that's where i would start..

ps.. when you tightened the plenum screws.. did you do them equally.. so it was fully seated on the lower intake before you put a final torque on the bolts.

i have seen the plenum gaskets blow out and cause all kinds of issues..  

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CareTaker
New User
Posts: 5
Joined: 04/14
Posted: 04/16/14 08:27 AM

I'll try the map sensor hose. The charcoal canister has been disconnected for some time now the line going to it collapsed and I capped both sides off. As far as I know the intake was fully seated, but I've been debating on pulling it back off and putting on a new gasket just to eliminate that possibility. I went out to take a quick look and it appears that I have a BAP sensor.... I've never seen a vacuum line hooked to it as long as I've owned the car. There are 2 things I'm going to try 1 I already fixed was a tiny vacuum line that was snapped that goes from the tree to the passenger side for the A/C after the check valve, and the other is a fat vacuum line that may have been disturbed. It goes from where the charcoal canister line starts and goes to some junction between the valve cover, and upper intake manifold. It was looking a bit crusty and cracked when I looked under there.  

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wayne712222
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Posts: 127
Joined: 10/13
Posted: 04/16/14 05:14 PM

thats why i ask what year it is..

some use MAF sensors in the intake duct..

some use MAP sensors up on the firewall.

two different systems.. mostly the same motor.. slightly different piping..

there are even differences between the 5.0L EFI and the  5.0 HO versions..

the EFI motors are batch fired injectors.. left 4 and right 4 cylinders fired ..

the 5.0 HO motors have a different firing order and sequential fuel injection..


again.. depends on the year.. and which engine ..

why did you cap off the carbon canister??? it does not reduce fuel economy.. it may actually increase it.. ???  

have you run a KOEO and a KOER test??? since this is in the 87 to 93 mustangs area..  

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CareTaker
New User
Posts: 5
Joined: 04/14
Posted: 04/16/14 06:12 PM

Sorry, it's a 92 GT 5 speed. Well fixing the one hose and replacing the crusty one seems to have stopped the idle surge so far. The canister was capped off because all of the emissions items no longer exist in my car the canister is there and capped and the EGR is there without a vacuum hose to operate it. The emissions items were removed a while ago, not by myself. I haven't run the test yet, I'll be at work tomorrow and have access to my volt meter then I'll have some results for you.  

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wayne712222
User
Posts: 127
Joined: 10/13
Posted: 04/17/14 06:14 AM

unless the computer was programmed to operate with out the EGR it will probably operate in default mode and back off on fuel economy and power..

my sister drives an 87 town car.. after i put  a bunch of new stuff.. she ended up getting like 29 MPG out of her car.. 5.0 EFI..  but she knows how to roll into and roll out of the throttle.. instead of just mashing it..  

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