95 GT Bucking when cold on takeoff

Discussion in '94-95 5.0 - Specific' started by dirtracer115, Feb 7, 2020.

  1. dirtracer115

    dirtracer115 New Member

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    Shorty Headers
    Offroad H pipe
    GT40 heads
    CAI
    75mm TB
    EGR Delete
    Smog pump delete

    The previous owner put the GT40 heads on the car when changing the head gaskets from when i believe the owner before him blew one using nitrous(the line is still in the car). That is what I'm betting on anyways

    So ever since i bought the car it hasn't ran great. It runs rich all of the time, I'm getting about 10 mpg with the factory 3.06 gears. The real problem tho is that until it gets some heat in it if i try to pull off nice and easy the engine cuts out and bucks several times. it sounds like i get backfires out of the axle dumps when this happens as well as the smell of fuel which leads me to believe i am intermittently losing ignition at low rpm with load until the car is warmed up. To avoid this i must pull off at a decent rpm(2.5-3k) and let the clutch slip until it really gets rolling(I heard "Bad driver" jokes for days the first time my buddy witnessed me slipping it while cold) once it warms up it runs substantially better. The bucking problem no longer exists and it pulls decent aside from the fact it is pretty fat. Backfires(made you jump kinda backfires) through the exhaust are common on power shifts even when warmed up. I'm throwing all the EGR codes but the only performance code I'm throwing is Cyl 8 failed balance test. I hope to investigate cylinder 8 this weekend.

    I don't know a lot about Ford's EEC so i am hoping someone here may be able to help me connect my dots. What sensor feedback or ignition component could cause ignition to cut out when cold? I haven't dug into it yet but i am hoping cyl 8 has a stuck injector which may explain my fuel consumption but wouldn't explain what i believe to be a loss of ignition when cold.

    Any ideas? The engine has been abused and has had many hands on it before myself, I have a 5.8 in the works but until it is finished i was hoping to dip my feet into autox with this 5.0. but right now aside from some exhaust fire on power shifts the car is not very respectable lol
     
  2. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    Clean the MAF. This can be a culprit.

    But biggest issue I see already is you didn’t mention a tune. The head swap and egr delete will throw issues and codes until you get a chip and have the emissions turned off and adjust for the difference in the heads.


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  3. dirtracer115

    dirtracer115 New Member

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    I have checked the MAF and verified it was clean already. I pulled the plug on #8 and it looks perfect so i may have an injured slug. I will have to get my hands on a compression tester and verify. For it to be burning through fuel like it is the plugs look perfectly tan. I haven't put my eyes on the ECU yet to verify it isn't chipped but since it is throwing EGR codes i would imagine it wasn't. You think my upgrades are enough that the MAF system cant compensate? I was under the impression for light modifications the MAF was more desirable because it would compensate a lot more than a SD setup. I didn't imagine it would be making substantially more than stock since it still has the stock intake.

    The car looked like it had a recent tune up when I got it but I popped the dizzy cap and looked over all of the ignition wiring I could see. The dizzy looks brand new inside but I did notice one of the wires going to the coil is half broken. So i guess next I'll see whether I am chipped and solder the coil wire back together.
     
  4. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    I doubt it’s chipped. You woudnt be throwing a egr code if it was chopped and they turned off emissions.

    Your not at a level that power is the reason for tuning. It’s more about drivability at this point. EECis looking for the egr and trying to control it. It’s throwing the fuel ratio off while thinking an egr should be there.

    Your factory maf is fine for now. Be careful just looking at the maf. Just because it’s not cruddy doesn’t mean it’s not dirty.


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  5. dirtracer115

    dirtracer115 New Member

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    The weather wasn't permitting today so i couldn't dig into it any further but requiring a tune to fix it is a bummer. Considering a hit or miss mail order tune is almost $300 I would rather put an EGR back on it lol
     
  6. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    Message adder on here at https://64bittuning.fwscart.com. He might still be able to burn you a chip to do it. Worst case scenario I could sell you my chip. It’s already setup for no emissions and it made a huge difference in my car.


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    Last edited: Feb 9, 2020
  7. dirtracer115

    dirtracer115 New Member

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    The 351 i am building will get a carburetor so I am really just trying to get it to run as clean as i can for cheap to play with until it is done. It looks like the EGR components are still on the firewall so i may throw a valve back on the intake and if that does clean the fuel up i will leave it. I put some thought into your point and it makes sense. The EGR opens at part throttle so at part throttle the ECU goes rich to compensate for the substantial increase in air the EGR delivers behind the TB. Which would make the tune fat most of the time at part throttle. In cold weather when the tune is even richer it would be even worse which would also explain my warm up issue.
     
  8. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    Have you thought about stand-alone when you do the tall deck?? Plenty of tb style options and easy tuning.


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  9. 01yellercobra

    01yellercobra Active Member

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    Why wouldn't you keep the fuel injection? You can get the stock computer to work with a tune. I think you'd just have to source a Lightning intake.
     
  10. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    There’s plenty of available intakes that will work with the stock Ecm and a tune. It’s all just about what you want to do.


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  11. dirtracer115

    dirtracer115 New Member

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    I have looked into it pretty thoroughly and did initially want to run a megasquirt pnp but considering I can carb for half the price and am a far more experienced carb tuner than EFI I can get the 351w up and running quicker and easier. I have a family of 4 and am def not rolling in dough so if I can get my engine up and running a year earlier with a $1500 carb and ignition setup I am going for it. I cant buy a stand alone and an EFI intake for $1500 let alone all the other hardware to hit my goal. I'm shooting for 400 whp out of an E85 drinking 11.5:1 CR 11R headed 351 so I will also need to spring for a TKO, build my rear end, and make several more chassis upgrades before the car will be gear banging ready.

    It's always about the budget lol. I've had 2 other 94-95 cars that were gotten rid of due to financial strains(and back facing car seats) so almost 10 years later I'm much better off and plan on keeping this one for the long haul. SN95s were the new mustang when I was coming of age and 20 years later I still think they are one of the best looking mustangs ever sold. With that said I very well may convert it "back" to EFI at some point down the road while it is up and running and i can collect the parts without pushing back the finished product.

    Oh and I found an EGR valve and after a little trial and error figured out how the vacuum lines routed so tomorrow morning when it is in the 30s we will see if it has improved. I took it for a little drive today when I finished and it felt a lot crisper pulling off but I don't think it was but 50ish degrees out so we will see.
     
  12. dirtracer115

    dirtracer115 New Member

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    UPDATE TIME
    EGR was not the issue. In the past week it has reverted back to all of the previous symptoms. When I reinstalled the EGR I pulled the battery cables to reset what the ECU had learned and am wondering if that is why it briefly felt better.

    I took the car to an Autox event today and was reminded the car is running ridiculously rich. At idle for 10 minutes I am leaving stains on the asphalt under my axle dumps from raw fuel. Sitting on the grid for 5-6 minutes before my standing start if I don't give the engine a few good revs to clean the plugs off it spits trying to pull off like it does to me in the mornings leaving for work. In 4 60 second autox sessions(small course) and maybe 30 minutes of idling I used almost a quarter of a tank of gas on the gauge. So I guess I am going to start looking into causes of a rich mixture, especially at idle.
     
  13. dirtracer115

    dirtracer115 New Member

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    Issue solved
    The fresh tune up the car got before i bought it included the completely wrong spark plugs. 8 heat ranges too cold and that's why the car was loading up at low rpms and cold temperatures.