How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Jay Houle Your Own Question
Jay Houle
Jay Houle,
Category: Lincoln
Satisfied Customers: 0
Experience:  Technician at Downs Ford
Type Your Lincoln Question Here...
Jay Houle is online now
A new question is answered every 9 seconds

The mechanic stated that he thought the exhaust was

Customer Question

The mechanic stated that he thought the exhaust was restricted then he created proper flow and it ran the same way they performed a compression check and all checked out coils are good plugs were replaced and it's showing no codes or check engine light
Submitted: 1 year ago.
Category: Lincoln
Expert:  HDGene replied 1 year ago.

Hello, lets cover some basic information. What kind of vehicle is this and engine size etc.

Customer: replied 1 year ago.
2004 Lincoln Navigator 5.4 liter engine
Expert:  HDGene replied 1 year ago.

Ok and whats the truck doing, lack of power on accel, runs poor at idle and no power? No diagnostic trouble codes stored? He hollowed out the catalytic convertor?

Customer: replied 1 year ago.
Rough idle and stalling on occasion
Expert:  HDGene replied 1 year ago.

Ok and no check engine light is on, no codes are stored, it passes a key on engine off and key on engine running test? No vacuum leaks for the engine? How many miles are on it?

Customer: replied 1 year ago.
It has no codes stored it has 127,000 miles
Expert:  HDGene replied 1 year ago.

Ok there are a number of things that can could a rough idle and stalling. Problem with the mass air flow sensor, lack of fuel pressure, a vacuum leak, exhaust restriction or an issue with the base engine(compression) Not sure if this is a 5.4 3 valve engine or 5.4 2 valve engine. if its a 3 valve engine I can tell you a few other things to check

Customer: replied 1 year ago.
Fuel pressure is good and no exhaust restrictions it has new plugs and all coils are good could it be a intake gasket leak ???
Expert:  HDGene replied 1 year ago.

Yes but if it has a vacuum leak it should also set lean codes p0171/p0174 . Is it a 3 valve triton engine or 2 valve, the vin number would tell me more the timing chain could have jumped time as well.

Customer: replied 1 year ago.
Truck runs good other than a rough idle it had a lean threshold on bank one code when I first bought it
Expert:  HDGene replied 1 year ago.

Well my answers are limited to the information you give me.

Customer: replied 1 year ago.
Really don't know what else to tell you other than its idling rough and the things I have had done to it
Expert:  HDGene replied 1 year ago.

well then ill opt out and see if another expert can be of more assistance. the 17 digit vin number would help and it seems like im not getting all the information i need

Customer: replied 1 year ago.
I can get you the vin in a half hour
Expert:  Jay Houle replied 1 year ago.


Like the last expert stated we need to know what engine is in the truck. 2, 3, or 4 valve. But first thing that comes to mind is a bad injector. An injector flow test should be completed.