'87 Bronco II sputtering under throttle when cold, goes away after its warmed up

[Ottieotter]

Hi all, figured I should go ahead and ask about this. I've got a '87 Bii with the 2.9 and 5-speed manual that always sputters and cuts out under throttle when cold, even on warm days. The sputtering only happens while under load, engine revs fine while in neutral. The fuel filter was replaced about a year ago, and I'm not sure if the truck has had the fuel pumps replaced as I never got any history on the truck when I bought it. I'm thinking its fuel system related, though I want some input from people that may have also had this issue before I go throwing parts at it.

 

[SenorNoob]

A fuel pressure test is always a good idea, but I think if it were low the problem wouldn't matter if it were warm or not.

 

[Jazzer]

My ‘87 2.9 does the same, even though it has a new coolant temperature sensor that was tested in a pan of boiling water and shown to be good. I assume it’s a problem with the ecm, but not sure. It hasn’t bothered me enough to fool with. I just let it warm up.

Maybe someone else on here has had a fix.

 

[Ottieotter]

A fuel pressure test is always a good idea, but I think if it were low the problem wouldn't matter if it were warm or not.

Will do, I don't have a fuel pressure gauge so I will have to go rent one

 

[gaz]

Prescribe to letting it warm up. One of my first observations about the (Ford) 60° V6 engines was that they ran like crap until they were up to normal operating temp.

They are a fussy breed, run like crap cold but don't you dare let one get hot!!

 

[rusty ol ranger]

Prescribe to letting it warm up. One of my first observations about the (Ford) 60° V6 engines was that they ran like crap until they were up to normal operating temp.

They are a fussy breed, run like crap cold but don't you dare let one get hot!!

They are fuel injected they should run as good cold as warm.

OP, Check fuel pressure and pull codes.

 

[Ottieotter]

They are fuel injected they should run as good cold as warm.

OP, Check fuel pressure and pull codes.

How do I pull codes? I'm not really familiar with OBDI systems

Edit: I don't think my gauge cluster has the CEL if that is important at all

 

[gaz]

They are fuel injected they should run as good cold as warm.

OP, Check fuel pressure and pull codes.

I do not know why you believe this. The engine was engineered to perform optimally at it's design temperature. This is after the myriad of different metals have expanded and can perform as designed, prior to this temp, the simply can't perform optimally.

I've experienced superior performance standards with vacuum controlled carburetor controlled fuel systems, though not with this particular engine family...which also perform at their peak once the engine reaches normal operational temperature.

 

[Ottieotter]

Should...but they don't!!

Mine seems to start and run fine while cold and not under load, it's when the engine gets put under load that it starts falling on its face until its warmed up enough

 

[gaz]

@Ottieotter
Try letting it warm up to temp before driving it.

 

[SenorNoob]

Doesn't that kinda imply low compression until it warms up enough for expansion to do it's thing?

 

[Ottieotter]

Doesn't that kinda imply low compression until it warms up enough for expansion to do it's thing?

I'll do a compression test on the engine as well as a fuel pressure test once I get the tools to do both. Part of me is thinking that this is either from the age of the truck or how the previous owners maintained it. Apart from what I've done to it, the only other things I really know about this truck is owner I bought it off of pulled it out of a barn where it sat for about 8 years

 

[rusty ol ranger]

I do not know why you believe this. The engine was engineered to perform optimally at it's design temperature. This is after the myriad of different metals have expanded and can perform as designed, prior to this temp, the simply can't perform optimally.

I've experienced superior performance standards with vacuum controlled carburetor controlled fuel systems, though not with this particular engine family...which also perform at their peak once the engine reaches normal operational temperature.

They are designed to run at operating temp yes, just like any other engine.

But saying "its ok it runs like shit when its cold because its a colonge" is nnot correct.

Literally one of EFI's main purposes is cold driveabilty. Even me being one of the biggest proponents of carbs will say EFI does better when cold (although i do think the difference is often blown out of proportion)

How do I pull codes? I'm not really familiar with OBDI systems

Edit: I don't think my gauge cluster has the CEL if that is important at all

Google "innova EEC IV reader". They are like 35 bucks but really beat the multimeter method.

Plug it in to the test port under the hood and follow the instructions provided with the scanner. It might lead you in the correct direction without shotgunning parts at it

 

[Ottieotter]

They are designed to run at operating temp yes, just like any other engine.

But saying "its ok it runs like shit when its cold because its a colonge" is nnot correct.

Literally one of EFI's main purposes is cold driveabilty. Even me being one of the biggest proponents of carbs will say EFI does better when cold (although i do think the difference is often blown out of proportion)


Google "innova EEC IV reader". They are like 35 bucks but really beat the multimeter method.

Plug it in to the test port under the hood and follow the instructions provided with the scanner. It might lead you in the correct direction without shotgunning parts at it

Would I be able to get an adapter to make a bluetooth OBD2 scan tool work? I'm completely fine with buying a separate tool just for this, but I just thought I would ask just I case I can make the scan tool I already have work
Also, I guess today I learned OBD1 systems do have codes

 

[rusty ol ranger]

Would I be able to get an adapter to make a bluetooth OBD2 scan tool work? I'm completely fine with buying a separate tool just for this, but I just thought I would ask just I case I can make the scan tool I already have work
Also, I guess today I learned OBD1 systems do have codes

I dont know for sure....but i kinda doubt it. EEC-IV (obd 1) spits out simple 2 or 3 digit codes and offers very basic info.

But yes they will produce codes, and that reader comes with a book (or it used to, i assume it still does, if not there are EEC IV code lists everywhere online) that will generally put you atleast in the neighboorhood of whats wrong.

But with no check engine light you have no idea if its throwing codes untill you plug it in lol.