Exhaust/ EGR problem? - Off-Road Forums & Discussion Groups
Ford 67-96 F-Series, 78-96 Bronco All discussions of 67-96 F-Series Trucks and 78-96 Broncos

LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 10-04-1999, 10:11 PM
Posts: n/a
Exhaust/ EGR problem?

-1990 Bronco full size, 5.0 L, 302 auto..114,500 miles-
When first started it will run rough with surging and hesitation to the point of stalling on occasion.
After about 30 seconds to a minute after starting a high pitched "whine" noise comes from the exhaust along with an excessive exhaust smell.(not the rotten eggs sulphur smell, just heavy exhaust.)
Around town the truck drives alright but on the highway the hesitation is much more noticable.
Also get a check engine light occasionally while driving.
The Bronco has been running great until this has started....
I have not checked the EGR valve or anything yet, just wondering if anyone had any other thoughts or similar experiences.

Sponsored Links
post #2 of (permalink) Old 10-04-1999, 11:00 PM
Posts: n/a
Re: Exhaust/ EGR problem?

i had the same problem. Sounds like you have a bad oxygen (02) sensor. Since your check engine light is coming on, i suggest you immediately go do one of two things:
1) go buy a ford code reader, which will diagnose the problem for you. You hook it up to the engine's computer and it retrives a code which you look up the definition for in the provided manual. ($45)
2) have the codes read at a mechanic or your local ford dealership.

in case you are unfamiliar as to what the 02 sensor does here it is in a nutshell:
the 02 sensor simply senses oxygen. it is a part of the speed density setup in your vehicle. it helps adjust the air/fuel mixture as close to the proper ratio as possible. if it senses too much oxygen, the computer senses that the a/f mixture is lean. if it senses too litle, it lets the computer know the a/f is rich. then the computer adjusts the mixture accordingly.

If it is your 02 sensor, and the problem has been around for awhile now GO CHANGE IT IMMEDIATELY because running a too lean or too rich a/f mixture in your engine is NO GOOD for the engine. ...especially a lean mixture.

keep me posted
90 302/E40D

post #3 of (permalink) Old 10-04-1999, 11:45 PM
Posts: n/a
Re: Exhaust/ EGR problem?

One thing I've noticed about the egr setup is that the tube that goes from the manifold to the valve is in a fiber glass sleave. With the code reader I kept getting an egr trouble code. When I went to change the valve I realized that the tube was completly severed. My friend at a Ford Parts Dept said that its pretty common problem. That could be your problem and why you hear a hissing.

You might also want to check your air bypass valve.

Please post your findings.

Sponsored Links
post #4 of (permalink) Old 12-17-1999, 10:06 AM
Posts: n/a
Re: Exhaust/ EGR problem?

Did you ever figure out what this was?

On the way to work this morning I noticed the truck didn't feel right and then the check engine light started flashing. It stopped but then started up again about 25 miles later.

If I remember right, the last time I looked at my O2 sensor it looked fairly new.

I haven't had a chance to check the codes since I'm at work. I'm thinking that I may have something similar going on.

post #5 of (permalink) Old 12-17-1999, 02:59 PM
Posts: n/a
Re: Exhaust/ EGR problem?

Mine was the fuel pressure regulator. When I pulled the codes I got a (#42) O2 sensor/rich condition detected... The fuel pressure would register fine on the gauge then after 10 seconds of constant running it would peg on the high side of the gauge. Allowing way too much fuel into the injectors.
The plugs and O2 sensor were black as can be because of this. New regulator, oil change, clean plugs and the truck runs great!

post #6 of (permalink) Old 12-17-1999, 05:06 PM
Posts: n/a
Re: Exhaust/ EGR problem?

Thanks for the info. I just did a quick check of the engine-off codes and got a normal 11 from the first test but pulled a 33 from the memory (EGR problem).

I'll do a engine-on test when I get home but it sounds like one of the above posts (that EGR sleeve/tube or maybe the sensor/valve is shot).

post #7 of (permalink) Old 12-20-1999, 09:55 AM
Posts: n/a
Re: Exhaust/ EGR problem?

FYI update. It was my EGR valve. It had become stuck closed (it has probably been that way for a while, I guessing).

I hate that nut on the bottom of the valve. It took hammers, breaker bars, and lots of swearing to get that thing off.

A little cleaning and everything's OK.

Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome