Rough idle, hard to start when warm?

SEB

MEMBER
1996 FORD E-SERIES VAN
4.9L
6 CYL
2WD
AUTOMATIC
175,000 MILES

Hi,

My van is idling rough when warm. When cold everything's fine, after 2 or 4 minutes idle starts to be rough.

When I try to start the engine when it is warm, I need to press on gas pedal to get it start after longer than normal crank time

On some occasions, I noticed that engine hesitates when I command acceleration.

Went I bought a ODB2 scanner, it gave me those codes

AIR pump have been deleted
Cat has been deleted

P0174 system too lean bank 2
P1130 lack of HO2S11 switches-fuel trim at limit
P1131 sensor indicates lean
P1150 fuel at trim limit
P1151 sensor indicates lean
P0171 system too lean
P1132 sensor indicates rich
P0385 crank shaft position sensor B circuit

Scanner is not able to self-test oxygen sensor-test incomplete

Thanks for your help.

Sébastien
Quebec City

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
48,361 POSTS

You have a bunch of lean codes so have you changed the fuel filter? if not, that is where I would start, here is a guide to help you more:

https://www.2carpros.com/articles/repairing-engine-rough-idle-issues

I would also service the throttle bore, make sure there are no vacuum leaks, and I would swap out the MAF sensor,

This guide can help as well:

https://www.2carpros.com/articles/throttle-actuator-service

Here are the fuel filter and MAF sensor locations so you can change them out. Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.

Images (Click to make bigger)