Odd exhaust behavior
Thread Starter
|
Cross-Country
Joined: Jul 2021
Posts: 53
Likes: 12
Odd exhaust behavior
Just had a new Ford NOS secondary air tube manifold installed. There is no comparison between this much superior now-discontinued part and the cheap replacements I could find.
But, when I first start the engine, it sounds like there is a huge leak in one of the pipes somewhere that gets louder under load.
After driving about a mile, the sound of the leak disappears and the exhaust is quiet as it should be, because everything is totally stock.
If I shut it off and restart it, the noise followed shortly by quiet cycle repeats.
I verified the check valve that is screwed into the secondary air tube manifold near the front, and it blocks all flow from the manifold, only allowing air from the pump to enter.
The MIL has not yet come on, but does this sound like some kind of fault in the combination valve/secondary air system somewhere?
ADVthanksANCE
-Jack (exhausted in central Texas)
'96 F150 Eddie Bauer 4.9L RWD
But, when I first start the engine, it sounds like there is a huge leak in one of the pipes somewhere that gets louder under load.
After driving about a mile, the sound of the leak disappears and the exhaust is quiet as it should be, because everything is totally stock.
If I shut it off and restart it, the noise followed shortly by quiet cycle repeats.
I verified the check valve that is screwed into the secondary air tube manifold near the front, and it blocks all flow from the manifold, only allowing air from the pump to enter.
The MIL has not yet come on, but does this sound like some kind of fault in the combination valve/secondary air system somewhere?
ADVthanksANCE
-Jack (exhausted in central Texas)
'96 F150 Eddie Bauer 4.9L RWD
Last edited by profwwacko; Aug 1, 2021 at 09:14 PM. Reason: No sig.
Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
You should know, being in Texas, what I mean by shooting from the hip. Here goes. EGR is bad and causes a vacuum leak and stops when it opens??? PCV bad or not in place from the work done??? O2 sensor??? Normal vacuum that comes with these trucks???? Someone with knowledge about your issue and give you more accurate ideas. It sounds like it stops happening when it goes into closed loop. Above post came in before I sent. I agree 100% about codes being checked.
Thread
Thread Starter
Forum
Replies
Last Post
91fordinline6
Ford Inline Six, 200, 250, 4.9L / 300
4
Dec 14, 2004 01:41 PM
kelan
Ford Inline Six, 200, 250, 4.9L / 300
4
Nov 18, 2002 09:15 AM
