Looking for some help - engine stumbling under load

Go down

Looking for some help - engine stumbling under load Empty Looking for some help - engine stumbling under load

Post  maillemaker on November 22nd 2019, 11:38 am

Hi all,

I have been pulling my hair out with a 1990 E-350 Ford based RV. It has a 460 CID EFI engine.

The engine bucks and stumbles under load (in higher gears), usually between 35-45 MPH. However, it will sometimes buck and stumble at high rev (lower gears) such as when merging onto an interstate. Problem mostly seems to happen when the engine is warmed up.

Things I have replaced so far:
  • Fuel filter
    EGR Valve
    EGR Valve Position Sensor
    EGR Valve Solenoid
    Coil
    Spark Plugs
    Spark Plug wires
    Distributor
    Ignition Control Module
    Engine Temperature Sensor
    Catalytic Converter
    In-tank fuel pump (about 4 years ago).
    Idle Air Valve
    MAP Sensor
    Fuel Pressure Regulator


The OEM FPR is running about 40 PSI idle, about 48 PSI under max load. I put it back in. I had replaced it with a new one and it was running about 30 PSI idle, about 38 PSI under load. There was no change in symptoms between the new one and the OEM one so I put the old one back in.

I bought a new computer, and part numbers match, but when I put it in the engine ran much worse. So I put the OEM computer back in. I exchanged the first computer for a new one, thinking it might be bad. I have not opened the box on the new computer yet as once you break the seal you can only return it for core fee.

Any ideas?
Steve

maillemaker

Posts : 8
Join date : 2019-10-07

Back to top Go down

Looking for some help - engine stumbling under load Empty Re: Looking for some help - engine stumbling under load

Post  rmcomprandy on November 22nd 2019, 11:50 am

maillemaker wrote:Hi all,

I have been pulling my hair out with a 1990 E-350 Ford based RV.  It has a 460 CID EFI engine.

The engine bucks and stumbles under load (in higher gears), usually between 35-45 MPH.  However, it will sometimes buck and stumble at high rev (lower gears) such as when merging onto an interstate.  Problem mostly seems to happen when the engine is warmed up.

Things I have replaced so far:

  • Fuel filter
    EGR Valve
    EGR Valve Position Sensor
    EGR Valve Solenoid
    Coil
    Spark Plugs
    Spark Plug wires
    Distributor
    Ignition Control Module
    Engine Temperature Sensor
    Catalytic Converter
    In-tank fuel pump (about 4 years ago).
    Idle Air Valve
    MAP Sensor
    Fuel Pressure Regulator


The OEM FPR is running about 40 PSI idle, about 48 PSI under max load.  I put it back in.  I had replaced it with a new one and it was running about 30 PSI idle, about 38 PSI under load.  There was no change in symptoms between the new one and the OEM one so I put the old one back in.

I bought a new computer, and part numbers match, but when I put it in the engine ran much worse.  So I put the OEM computer back in.  I exchanged the first computer for a new one, thinking it might be bad.  I have not opened the box on the new computer yet as once you break the seal you can only return it for core fee.

Any ideas?
Steve

I would simply start by removing and having the injectors tested and cleaned.

rmcomprandy

Posts : 5472
Join date : 2008-12-02
Location : Roseville, Michigan

http://www.rmcompetition.com

Back to top Go down

Looking for some help - engine stumbling under load Empty Re: Looking for some help - engine stumbling under load

Post  maillemaker on November 22nd 2019, 12:46 pm

I would simply start by removing and having the injectors tested and cleaned.

I'm going to do that this weekend myself. I've got a tester that should be in today, and I'm going to pull them and blast them forwards and backwards with carb cleaner.

maillemaker

Posts : 8
Join date : 2019-10-07

Back to top Go down

Looking for some help - engine stumbling under load Empty Re: Looking for some help - engine stumbling under load

Post  BBFTorino on November 22nd 2019, 4:07 pm

Do an ohms test on each one of them and check their values against the specs. One (or more), could be functioning fine in certain conditions, but could be weak when the duty cycle increases.
Just a thought.

BBFTorino

Posts : 811
Join date : 2015-12-31

Back to top Go down

Looking for some help - engine stumbling under load Empty Re: Looking for some help - engine stumbling under load

Post  maillemaker on November 23rd 2019, 9:45 am

I am not having any luck finding what the ohm spec should be for a 1990 Ford 460. I know that I can test each one (which I will) and look for the odd man out.

But it is not in my Chilton manual nor the shop manuals I have.

Thanks,
Steve

maillemaker

Posts : 8
Join date : 2019-10-07

Back to top Go down

Looking for some help - engine stumbling under load Empty Re: Looking for some help - engine stumbling under load

Post  maillemaker on November 23rd 2019, 9:48 am

OK I found this:

https://www.trickflow.com/search/product-line/trick-flow-tfx-fuel-injectors/make/ford/injector-impedance/14-4-ohms/engine-size/7-5l-460

All of their listed 460 fuel injectors are 14.4 ohms.

Steve

maillemaker

Posts : 8
Join date : 2019-10-07

Back to top Go down

Looking for some help - engine stumbling under load Empty Re: Looking for some help - engine stumbling under load

Post  maillemaker on November 23rd 2019, 5:56 pm

Problem is fixed. It was the Air Charge Temperature Sensor.

Steve

maillemaker

Posts : 8
Join date : 2019-10-07

Back to top Go down

Looking for some help - engine stumbling under load Empty Re: Looking for some help - engine stumbling under load

Post  BBFTorino on November 23rd 2019, 10:37 pm

Did it show a code for that?

BBFTorino

Posts : 811
Join date : 2015-12-31

Back to top Go down

Looking for some help - engine stumbling under load Empty Re: Looking for some help - engine stumbling under load

Post  maillemaker on November 24th 2019, 12:30 am

No. Nor did it show a code when the Engine Temperature Sensor went out about 6 months ago and was idling poorly when cold.

Steve

maillemaker

Posts : 8
Join date : 2019-10-07

Back to top Go down

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum