• 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.

94 2.3L w/ 17# injectors - Intermittent Rough Idle


wizkid00104

Active Member
Joined
Oct 15, 2007
Messages
1,720
Reaction score
13
Points
38
Location
West Newton/Penn Hills, PA
Vehicle Year
1994/2002
Make / Model
Ford
Engine Size
2.3L/5.4L
Transmission
Manual
So this past weekend I replaced my stock injectors with 17# ones. The truck has 223k on it. At the same time, I replaced my spark plugs and wires. I already checked and the wires are correct.

The truck runs good, but my vacuum was down after the replacement. It usually idled at 19 inHg and now it is closer to 15 inHg. It idles really rough and will occasionally stall. I figured it has to be a vacuum leak since it worked fine when i disassembled it.

I replaced all vacuum connectors and tubes that were dry rotted. I replaced the upper manifold gasket and torqued the bolts to 22 ftlb. I replaced the EGR gasket tonight because I thought that was problem.

After driving it, it idles smoothly for ~45 seconds then the vac drops to 15 inHg and starts running really rough again. Its like something in the computer is adjusting the way the engine runs after it sits idle for a bit. There is NO CHECK ENGINE LIGHT on.

It is a 94 2.3L 5 speed, no A/C, Jet Performance Module (installed 5+ years ago), and MSD ignition coil for the exhaust side plugs. It has a Magnaflow repalcement cat and a 2.25" Cherry Bomb exhaust. O2 sensor was replaced last fall.

I am thinking... Reset the computer and remove the Jet module, snug up EGR bolts, and then get a vacuum pump and start checking components for leaks. I am just stumped because it worked before and not after.

Here is the link to the post in my build thread: http://www.therangerstation.com/forums/showpost.php?p=1574659&postcount=505

Please provide thoughts!!!!! I am running out of ideas..... :icon_confused:
 


wizkid00104

Active Member
Joined
Oct 15, 2007
Messages
1,720
Reaction score
13
Points
38
Location
West Newton/Penn Hills, PA
Vehicle Year
1994/2002
Make / Model
Ford
Engine Size
2.3L/5.4L
Transmission
Manual
I also thought about get another MAF and boring the measurement hole to match the new injectors.
 

Mark_88

Well-Known Member
Joined
Aug 11, 2007
Messages
18,554
Reaction score
240
Points
63
Age
68
Location
Ontario, Canada
Vehicle Year
2007
Make / Model
Dordge
Engine Size
3.3 Fuel Injected
Transmission
Automatic
My credo
Love Thy Neighbor
Sounds like your computer is sensing the extra fuel and trying to cut it back...or you could be correct about the vacuum leak and it has evaded you so far.

With this model year not sure if you could put a scanner on and get real time data to see if the computer is trimming the fuel supply...I have a link that might help...ooops...link is no longer valid...

Since you have a vacuum gauge there is a list at the bottom of this one that might help...

http://www.gregsengine.com/using-a-vacuum-gauge.html
 

alwaysFlOoReD

Forum Staff Member
TRS Forum Moderator
TRS Banner 2012-2015
TRS 20th Anniversary
Joined
Apr 13, 2009
Messages
13,868
Reaction score
5,027
Points
113
Location
Calgary, Canada
Vehicle Year
'91, '80, '06
Make / Model
Ford, GMC,Dodge
Engine Size
4.0,4.0,5.7
Transmission
Manual
2WD / 4WD
4WD
I agree with Mark re; injectors too big now. If the rest of the motor is stock then, IMO, the injectors are the problem.
 

wizkid00104

Active Member
Joined
Oct 15, 2007
Messages
1,720
Reaction score
13
Points
38
Location
West Newton/Penn Hills, PA
Vehicle Year
1994/2002
Make / Model
Ford
Engine Size
2.3L/5.4L
Transmission
Manual
I understand they are bigger, but I would think that would cause a constant problem of idle, it's the intermittences that confuses me now. And I only increased the size of the injectors because others did it successfully, even going to 19#.


Sent from my iPhone
 

wizkid00104

Active Member
Joined
Oct 15, 2007
Messages
1,720
Reaction score
13
Points
38
Location
West Newton/Penn Hills, PA
Vehicle Year
1994/2002
Make / Model
Ford
Engine Size
2.3L/5.4L
Transmission
Manual
That was a really good article mark, thank you.


Sent from my iPhone
 

alwaysFlOoReD

Forum Staff Member
TRS Forum Moderator
TRS Banner 2012-2015
TRS 20th Anniversary
Joined
Apr 13, 2009
Messages
13,868
Reaction score
5,027
Points
113
Location
Calgary, Canada
Vehicle Year
'91, '80, '06
Make / Model
Ford, GMC,Dodge
Engine Size
4.0,4.0,5.7
Transmission
Manual
2WD / 4WD
4WD
Do you still have the old ones?
 

wizkid00104

Active Member
Joined
Oct 15, 2007
Messages
1,720
Reaction score
13
Points
38
Location
West Newton/Penn Hills, PA
Vehicle Year
1994/2002
Make / Model
Ford
Engine Size
2.3L/5.4L
Transmission
Manual
Yes. They could stand to be cleaned. I presume the suggestion is to swap them back in to see if the problem goes away?


Sent from my iPhone
 

MrGiggles

New Member
Joined
Jun 28, 2016
Messages
50
Reaction score
1
Points
0
Vehicle Year
1998
Make / Model
Ford
Transmission
Automatic
Spray the injectors down with brake cleaner, if the idle changes, they are leaking vacuum. Do the same to any areas that could have a leak.

The PCM will adjust for the bigger injectors within a specified range, if it has to adjust past that threshold, an A/F mixture rich code should set. If you don't have a code, that's not likely the issue. You are on the right track looking for vacuum leaks, something must have been disturbed during the swap.
 
Last edited:

Mark_88

Well-Known Member
Joined
Aug 11, 2007
Messages
18,554
Reaction score
240
Points
63
Age
68
Location
Ontario, Canada
Vehicle Year
2007
Make / Model
Dordge
Engine Size
3.3 Fuel Injected
Transmission
Automatic
My credo
Love Thy Neighbor
You're welcome...hope it gave you some ideas.

I did a bit of reading on this and found quite a bit that says to go back to stock injectors if you have problems...the solutions to resolve and allow you to use the bigger injectors can be expensive...

The trick is that when we increase fuel we also need to increase the air intake so the air fuel mixture remains the same 14.7:1 (I think that's the number).

To increase air flow you need to either adjust the valve duration, put in bigger valves, or go with forced induction...tuning the chip might help some...but it might cost you a small fortune if you are not careful.

This is not a huge jump in size...but enough to cause problems...but there is always a consequence in these things.

If you can program the chip to modify the fuel flow that might help...but I have no idea where to start on that subject...here is a link that might help...more reading but some good information there...even if it is a Jeep site...

http://www.wranglerforum.com/f210/jet-chips-help-214439.html
 

alwaysFlOoReD

Forum Staff Member
TRS Forum Moderator
TRS Banner 2012-2015
TRS 20th Anniversary
Joined
Apr 13, 2009
Messages
13,868
Reaction score
5,027
Points
113
Location
Calgary, Canada
Vehicle Year
'91, '80, '06
Make / Model
Ford, GMC,Dodge
Engine Size
4.0,4.0,5.7
Transmission
Manual
2WD / 4WD
4WD
Slightly off topic, I'm doing an engine swap for a bud. He has a 78 f150 with a 400. He cooked both the tranny and motor. When I took out the 400 I found the wire for the oil pressure sending unit pinched under the intake. The engine had just recently had an intake and carb swap. I never heard the engine run previous but I bet there was a vacuum leak. I'm not saying you did the same but it is worth checking around with mirror and flashlight. And propane works too for finding leaks.

Sent from my XT1032 using Tapatalk
 

wizkid00104

Active Member
Joined
Oct 15, 2007
Messages
1,720
Reaction score
13
Points
38
Location
West Newton/Penn Hills, PA
Vehicle Year
1994/2002
Make / Model
Ford
Engine Size
2.3L/5.4L
Transmission
Manual
Spray the injectors down with brake cleaner, if the idle changes, they are leaking vacuum. Do the same to any areas that could have a leak.

The PCM will adjust for the bigger injectors within a specified range, if it has to adjust past that threshold, an A/F mixture rich code should set. If you don't have a code, that's not likely the issue. You are on the right track looking for vacuum leaks, something must have been disturbed during the swap.
This may be a dumb question, but what does the brake cleaner do? Get sucked in an combusted? Is that how you hear a difference?
 

wizkid00104

Active Member
Joined
Oct 15, 2007
Messages
1,720
Reaction score
13
Points
38
Location
West Newton/Penn Hills, PA
Vehicle Year
1994/2002
Make / Model
Ford
Engine Size
2.3L/5.4L
Transmission
Manual
Slightly off topic, I'm doing an engine swap for a bud. He has a 78 f150 with a 400. He cooked both the tranny and motor. When I took out the 400 I found the wire for the oil pressure sending unit pinched under the intake. The engine had just recently had an intake and carb swap. I never heard the engine run previous but I bet there was a vacuum leak. I'm not saying you did the same but it is worth checking around with mirror and flashlight. And propane works too for finding leaks.

Sent from my XT1032 using Tapatalk
Hmmm.... also a good suggestion. Sounds like I will be taking it back apart one way or another. Thanks!
 

wizkid00104

Active Member
Joined
Oct 15, 2007
Messages
1,720
Reaction score
13
Points
38
Location
West Newton/Penn Hills, PA
Vehicle Year
1994/2002
Make / Model
Ford
Engine Size
2.3L/5.4L
Transmission
Manual
Ok. I got a vacuum pump and did some testing. Fuel pressure regulator held 20inHg for 5 minutes as did the brake booster. The solenoid for the EGR did not the (EVR). I tested remove it from the truck and connected it to 12V to it and it popped the fuse. Resistance is reading 0.6 ohms through the coil, so the valve is definitely shot. It should be between 20-70 ohms. This would certainly seem to be where my leak is coming from if the valve is bad. I need to check the electrical and see if a fuse blew as well.
 

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