EFI Bucking and hesitation problem

bronconut73 · Oct 16, 2017

EFI Guy said:
Assuming you're not feeling a misfire, it could definitely be tune related, or rather failing to properly tune for the cam. I'd like to know what cam that engine has. When you start getting carried away with the camshaft it can cause bucking, especially with a M/T.

Bucking is one of the hardest things to try to tune out, but it can be done. Unfortunately, all too often the typical dyno tuner focuses on those peak HP numbers and not making it a pleasure to drive. I've met quite a few that could squeeze every last drop of power out, but don't know how to properly tune idle on a Ford. I'm not trying to bash your guy, or anyone in particular, but it's something that I see a lot, especially if it's the kind of shop that tunes everything rather than specializing in Fords.

[Shameless plug] I do quite a bit of remote tuning where I ride shotgun with you via laptop. My cost is better than what you threw out there, and if your current chip is a brand that I can write to it can save you even more. PM me if you want to know more. [/shameless plug]

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Gawd I love this place....and EFI Guy too!

77broncodriver · Oct 17, 2017

73azbronco said:
So would faulty connection to injector, and bad gas.

You keep saying it sat for a year and that the fuel is OK. Fuel can go bad in less than a year these days with ethanol.

Pull the fuel filter and cut it open and look.

Sorry to be confusing, when I mean it sat for a year I mean I got a new car and stopped daily driving it. I parked it at my parents house and they drove it around every now and then. I just recently brought it back to my house and am starting to drive it more often which made me remember how bad it is running.

EFI Guy said:
Assuming you're not feeling a misfire, it could definitely be tune related, or rather failing to properly tune for the cam. I'd like to know what cam that engine has. When you start getting carried away with the camshaft it can cause bucking, especially with a M/T.

Bucking is one of the hardest things to try to tune out, but it can be done. Unfortunately, all too often the typical dyno tuner focuses on those peak HP numbers and not making it a pleasure to drive. I've met quite a few that could squeeze every last drop of power out, but don't know how to properly tune idle on a Ford. I'm not trying to bash your guy, or anyone in particular, but it's something that I see a lot, especially if it's the kind of shop that tunes everything rather than specializing in Fords.

[Shameless plug] I do quite a bit of remote tuning where I ride shotgun with you via laptop. My cost is better than what you threw out there, and if your current chip is a brand that I can write to it can save you even more. PM me if you want to know more. [/shameless plug]

I am going to first:

1. Check the filter
2. Check fuel pressure again (get adjustable fuel regulator if it doesn't seem right)
3. Go over all my grounds for the wiring to make sure it isn't a wiring problem
4. If the problem is still there I think it must be a tuning thing then and will get in contact with you, seems like you know your stuff! Btw I have the e303 cam that came with the crate motor. (I don't have a tune on it currently)

Does this seem like the best approach?

Thank you!

77broncodriver · Oct 18, 2017

I had some free time today to troubleshoot the bronco a little more.

I cleaned the air filter, cleaned the MAF, put in a new fuel pressure regulator, sprayed carb cleaner everywhere to check for leaks, checked grounds (battery to body, body to engine block, efi harness to intake and all looked good), checked tps (.89), made sure o2 sensors were connected to the right plugs, and ran codes.

Codes were:
33,44,81,82,84,85,95 which I think are all smog related codes right?

took it for a drive and I didn't go on the highway where I normally get the bucking but when I would slowly add throttle it would hesitate and backfire and was really sluggish.

This weekend I am going to check fuel pressure when I am driving. I would have done that today but I need to add a shader valve in the system first.

If the fuel pressure looks good (39 right?) when I am on the throttle then I think this has to just be the computer not being able to adjust enough for all the mods and I will need to have efiguy help me with a tune.

73azbronco · Oct 18, 2017

Get with EFI guy I think he can data log remotely while you drive it and see whats what.

EFI Guy · Oct 18, 2017

Code 95 is a fuel pump circuit fault. More often than not it's caused by a bad FP relay. Relays are cheap enough that I'd throw a new one in it and see if the code returns. It's probably not the cause of your hesitation unless it coincidentally fails every time you tip into the throttle, but when that code appears it's a good idea to address it before it leaves you stranded.

77broncodriver · Oct 19, 2017

One of the relays was making a weird noise a couple days ago and then it didn’t want to start at first today. I’ll definitely change the relay out this weekend while I test the fuel pressure

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EFI Bucking and hesitation problem

bronconut73

Bronco Guru

77broncodriver

Full Member

77broncodriver

Full Member

73azbronco

Bronco Guru

EFI Guy

TheEFIguy@gmail

77broncodriver

Full Member

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