03 2v Lethargic

wmfateam

Active Member
Joined
Aug 23, 2013
Messages
866
Reaction score
244
Location
Gilbert, AZ
2003 GT, had just replaced the fuel pump, cleaned injectors, new plugs and a couple coils(NGK coils) that were broken when swapping intake manifold. Car was running fine, sounded/felt very healthy. Then last week after a month or so of driving fine, I started it up, it fired right up and then the exhaust note changed like an electronic exhaust flap closed. AKA like it went a little quieter. Not the sound of the idle coming down after a cold start, but like the engine was trying to move through sand. Like lethargic. Then when driving has that same feeling as it is driving to drive through sand or uphill.

I have shit skills/knowledge when it comes to engine diagnosis so I am reaching out as I start to dig into it and asking for any suggestions or directions in which to test. When hooked up to a scanner that can monitor live data, there is no misfires, no codes except for the fact I have no cats, fuel pressure is high 30's.
 
OP
OP
wmfateam

wmfateam

Active Member
Joined
Aug 23, 2013
Messages
866
Reaction score
244
Location
Gilbert, AZ
Oil change lately? Check engine light?
No check engine light, no present codes and no pending codes. Oil has been changed twice in last 100 miles as it was motor swapped 100 miles ago and I am just trying to make sure it is clean inside. Explorer 2v with Mustang PI intake and long tubes.
 

96blak54

Moderator
Staff
Joined
Feb 21, 2011
Messages
13,090
Reaction score
5,088
Location
Lawrenceburg Kentucky
Especially is the engine was rotated counter clockwise(perspective from the engine front) when installing trans. The crank sprocket will jump a tooth

Also I found oil types like "high milage" type oil will cause the lifters to over react and kill rpm performance. Strictly 5w-20/5w-30 synthetic only. No "high milage" branded oil
 
OP
OP
wmfateam

wmfateam

Active Member
Joined
Aug 23, 2013
Messages
866
Reaction score
244
Location
Gilbert, AZ
Especially is the engine was rotated counter clockwise(perspective from the engine front) when installing trans. The crank sprocket will jump a tooth

Also I found oil types like "high milage" type oil will cause the lifters to over react and kill rpm performance. Strictly 5w-20/5w-30 synthetic only. No "high milage" branded oil
It does have Valvoline synthetic high mileage in it right now. I'll give it a couple oil changes with standard synthetic and get it hot in between changes. I appreciate that. The high mileage was on sale and I just bought the cheapest name brand synthetic oil since I was going to be changing it multiple times.
 

RAU03MACH

Legend
Joined
Apr 23, 2019
Messages
8,191
Reaction score
8,349
Location
NEW MEXICO
I can check it, but do these motors every have the timing jump after running fine for a month? I'm used to timing belts personally.
So when I did the cobra engine there was 150 thousand miles
The chains were loose on the sprockets
As mentioned by black if you were to turn the engine counterclockwise it lossens up more
And chains can jump a tooth or more
Something to think about
I am going to do the ones in the truck I just picked up
Just to be on the safe side the whole kit
 
OP
OP
wmfateam

wmfateam

Active Member
Joined
Aug 23, 2013
Messages
866
Reaction score
244
Location
Gilbert, AZ
So when I did the cobra engine there was 150 thousand miles
The chains were loose on the sprockets
As mentioned by black if you were to turn the engine counterclockwise it lossens up more
And chains can jump a tooth or more
Something to think about
I am going to do the ones in the truck I just picked up
Just to be on the safe side the whole kit
Shit, I've never thought to turn the engine when installing a trans. I feel like that is more work to get back out from under the car instead of just turning the driveshaft in the trans. I'll start with the oil change and then pull the valve covers off while the crank is at top dead center. Thank you for your input!
 

96blak54

Moderator
Staff
Joined
Feb 21, 2011
Messages
13,090
Reaction score
5,088
Location
Lawrenceburg Kentucky
I did the exact same thing with one of my builds. It went from strong, high rev to WTF happened!!! and that was after I did a 500mile oil change to some high mileage Castrol..... that was on sale. My best analysis?......oil weight has direct effect to the lash adjusters. Thicker oil will pump them up. Not a bad thing on the intake adjusters, but the exhaust pumping up will kill rpm. Opening the exhaust valve early is a direct effect to rpm and hp
 

SnakeBit!

Active Member
Joined
Mar 6, 2014
Messages
893
Reaction score
136
Location
Florida
I will still say, no cats and long tubes, the ECU is not getting the proper information for the air fuel mixture. I'm surprised it has not thrown a code. That might be an issue since it should be so maybe there is an issue with the ECU.
 

RAU03MACH

Legend
Joined
Apr 23, 2019
Messages
8,191
Reaction score
8,349
Location
NEW MEXICO
i have seen a lot of people running long tube no cats no tune
the cars run fairly strong
i personally cant tell difference between long tube and short headers its same to me
 
OP
OP
wmfateam

wmfateam

Active Member
Joined
Aug 23, 2013
Messages
866
Reaction score
244
Location
Gilbert, AZ
I did the exact same thing with one of my builds. It went from strong, high rev to WTF happened!!! and that was after I did a 500mile oil change to some high mileage Castrol..... that was on sale. My best analysis?......oil weight has direct effect to the lash adjusters. Thicker oil will pump them up. Not a bad thing on the intake adjusters, but the exhaust pumping up will kill rpm. Opening the exhaust valve early is a direct effect to rpm and hp
Dude, changed the oil to standard 5w-20 Castrol GTX Synthetic and it is right back to normal. THANK YOU SO MUCH FOR BRINGING THAT UP!!!! Drove it around and was so excited that I forgot I needed brakes still and had a "fun" test drive, lol.
 

96blak54

Moderator
Staff
Joined
Feb 21, 2011
Messages
13,090
Reaction score
5,088
Location
Lawrenceburg Kentucky
Not many know how the lashers function. They simply think the lasher take up gaps with the followers to the valve. Actually, they do take up gaps and keep things tight, but also have a character with oil pressures and opening points from the cam lobe. In short, the lashers only receive 15 psi of oil and thats at high rpm. in the single digits at low rpm. It doesnt take much oil psi to over actuate the lashers and a heavier oil will do such a thing. This causes the lasher to over act and change the valve timing. Our big cam lobes and follower valve system design was ment to be a variable valve timing. If you do feel frogging and want to test this, swap out the exhaust lashers for earlier 10w30 style. Youll pick up power and rpm
 

Latest posts

Forum statistics

Threads
78,343
Messages
1,525,834
Members
15,690
Latest member
happliye

Members online

No members online now.
Top