• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

4.0 SOHC first start idle 2 low


mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
New rebuilt engine installed at first start the engine wont idle can hold it running with the peddle but let it off it dies it throwing codes P0112 & P0102, checked the plug for the MAF sensor wasn't clicked all the way but that didn't help I don't believe I have any vac leaks.


Any ideas would be appreciated


Ed
 


RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,291
Reaction score
8,296
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
Yes both codes would come from MAF wires not being connected, Air temp sensor is part of the MAF sensor on your year.

Vacuum leak would make idle high.

Fuel injected engines can't use an idle screw, no jets to meter fuel by air flow, so they all use an IAC(idle air control) Valve.
It will be on the upper intake where throttle plate is, it looks like an electric motor, because it is.
It opens a valve in an air passage that bypasses throttle plate, computer controls this motor.
Make sure wires got plugged back in.

Another thing is the ECT(engine coolant temp) sensor, computer uses this sensor to tell..........engine temp.
Cold engine needs more fuel and higher idle or it will stall, that is what the Choke plate did on carb engines, but again, no jets with EFI, so computer has to know engine temp to run engine in Choke Mode, then run it normally after engine warms up.

The engine should still have 2 temp devices in 2005 I think, one for the computer(ECT sensor) and one for the dash board gauge(ECT sender), Ford did combine them into one sensor around this time.

But 1 or 2 it/they will be on the thermostat housing, make sure they are plugged in
 

mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
Yes it has 2 temp sensors, Will check on Thursday when I'm off work.

Thanks

Ed
 
Last edited:

mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
TPS sensor wouldn't cause any of this?
 

RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,291
Reaction score
8,296
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
TPS shouldn't cause a low idle, it can cause a No Start, and sluggish acceleration and/or lack of power.

And if TPS voltage was out of it's range, .7v to 4.9v then CEL would come on with code for that problem
 
Last edited:

adsm08

Senior Master Grease Monkey
Supporting Member
Article Contributor
Ford Technician
TRS 20th Anniversary
Joined
Sep 20, 2009
Messages
34,623
Reaction score
3,613
Points
113
Location
Dillsburg PA
Vehicle Year
1987
Make / Model
Ford
Engine Type
4.0 V6
Engine Size
4.0
Transmission
Manual
2WD / 4WD
4WD
Tire Size
31X10.50X15
A big enough vac leak can cause a no-start, or cause a stall after just a few second of running.

I saw a 4.6 once that would only run at WOT after a head gasket job. The parts store sent us the wrong intake gaskets and the guys working on it (this was in tech school) didn't catch the difference. It was leaking so bad it wouldn't run from being too lean.

Try resetting the computer. If it will run better at first then starts having issues again suspect the MAF. They can be damaged during removal, or they can just get crap over the opening. Both can cause your symptom.
 

mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
Sending the wrong gasket would really suck, But I'm sure its not the case here since there just big oval seals. I've checked the PVC and lines, also put on a autozone IAC and the RPM went to 2k at start up and would not come down from that speed, think its a bad valve? you know it is autozone.


Thanks

ED
 

RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,291
Reaction score
8,296
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
IAC Valve opens all the way for starting, then within a few seconds closes to set idle based on engine temp.
The colder the engine the higher the idle, above 1,500prm might not be unusual at 32degF.

Unplug IAC valve and it should close causing engine to stall.
 

mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
Will try Thursday
 

mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
Well ended up installing the original IAC back on and cleaning the MAF sensor then I took it for test drive it was missing on acceleration brought it back and pulled the plugs and found one of them was black they were new plugs, so I decided to put new set in. After that it sounded the best it had yet idling with just a little tiny bit of hesitation, so went for another test drive made it 2 blocks down the road and the power wasn't there so I decided to turn around and the engine died would not restart so towed back to house. Decided it was a fuel problem so not having a fuel pressure gauge to fit the rail I stuck a small Philips in the valve with ignition on and it had nothing hardly any fuel coming, going back before first start I bleed this way and fuel blasted out so now it seems the pump has took a crap, I did change relay for pump, then I pulled the front fuel filter line turned key on and it came out really slow no pressure at all I would think it should shoot all over right? New fuel filter was installed the day the engine originally took a crap in November.


Thanks

Ed
 
Last edited:

enjr44

Active Member
U.S. Military - Veteran
Joined
Mar 24, 2013
Messages
1,143
Reaction score
9
Points
38
Age
79
Location
Renton, WA
Vehicle Year
02 2X4; 08 FX4
Make / Model
Ford
Engine Size
4.0 SOHC
Transmission
Automatic
The first indication that I had for a bad pump was low idle on first start. After about a year, it then went to no start!!!
 

mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
Removed the bed for fuel pump test/replacement have 10.9 volts at plug at fuel pump, turned on with hose disconnected it put a small weak looking 4 or five inch stream of fuel out I'm sure if was putting out 70-80psi it would shoot quite a bit more than that so I found a spectrum pump at napa for $288.00 and another place sells airtex for $240.00 but have heard a few people say airtex are crap never heard of spectrum. Anybody have any recommendations?

By the way the bed removal was 10 times easier than I thought, because the last time I changed the pump I did from below wont do that again!
 
Last edited:

RonD

Official TRS AI
TRS Technical Advisor
Joined
Jun 2, 2012
Messages
25,291
Reaction score
8,296
Points
113
Location
canada
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
Voltage at pump should be battery voltage, it is a direct wire connection to battery when activated.
So check battery voltage with the same meter.

Fuel Pump(FP) Power path is:

Battery"+"----FP fuse(20amp)-----FP Relay----------inertia switch(in cab)--------Fuel pump-----ground(in cab or on frame rail)

FP fuse and FP relay are both in engine fuse box

I would start at battery end and check voltage along the pathway to see where it drops.



The "flow" from the pump seems OK, the "pressure" is from the fuel injector restriction, so is back pressure, and that could only be tested if you attached a pressure gauge to the fuel pump hose.
I.E. oil pumps don't put out 30psi of pressure, they have variable "flow", engine RPM, oil pressure comes from the small gaps at the bearings and oil passages, as long as the flow into the system is more than than the flow out there will be back pressure, and that back pressure is what you see on an oil pressure gauge, or a fuel pressure gauge.

If you could find the Liters Per Hour(lph) specs on the pump then you could run the pump for a minute and see if it pumped out 1/60th of that spec.
I think Returnless spec was 100lph, so over a liter a minute should pump out(1.5l), and by your description that is happening.
The older Return line system fuel pumps were 60lph I think.

But the low voltage is my concern, was that with pump connected or just testing the wires without the pump?
If without the pump running then voltage could drop down below 6volts which would not pump much if at all.
 
Last edited:

mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
Testing wires at pump


Sent from my iPhone using Tapatalk
 

mred3

New Member
Joined
Nov 3, 2015
Messages
64
Reaction score
0
Points
0
Location
Gridley, CA.
Vehicle Year
2005
Make / Model
Ford
Engine Size
4.0 sohc
Transmission
Manual
Have pump on now have filter off its pumping less then the old one


Sent from my iPhone using Tapatalk
 

Sponsored Ad


Sponsored Ad

Staff online

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Truck of The Month


Kirby N.
March Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top