1991 Ford F-150 stuttering and rough idle

LEWISCYPHER

MEMBER
1991 FORD F-150
6 CYL
4WD
MANUAL
185,356 MILES

I was driving my truck and it started idling rough and stuttering under medium accelaration, if I put it to the floor it hesatates for a second then accelerates good. This problem didnt occur gradually but started suddenly. The check engine light is not comming on so I assume the emissions control sensors are working? Tried putting a set of plugs and wires in it today with no change.

3 Replies

JAMES W.

MECHANIC
2,394 POSTS

Check your EGR valve to see if it is hanging open a little bit. You may have to remove it phisically to see if it is closing. Next, you can do a resistance test on the throttle position sensor, TPS with an ohmeter. With 185K on the truck, it can wear a spot on the coil and creat a "weak" spot. The ECM will usually pick this up and trip the check engine light, but sometimes it won't until the condition gets worse. Hope this helps.

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Sunday, November 16th, 2008 AT 7:15 PM

LEWISCYPHER

MEMBER
5 POSTS

Ok I checked the EGR valve seemed like it was closing. Just to be sure I made a gasket that covered the port to the fuel injection manifold. There is only one port so I figured that would be ok for diagnostic purposes. There was no change. I also picked up a TPS It was only 25 bucks so I bought one and to no avail still running rough at idle and hesatating on acceleration. Any more ideas?

Thanks in advance!

Was this

answer

helpful?

Yes

No

Tuesday, November 18th, 2008 AT 6:17 PM

JAMES W.

MECHANIC
2,394 POSTS

Lets check for a vacuum leak. With engine at a warm idle, take a can of regular carb cleaner and spray it along the intake where it meets the heads. Also any intake ports and lines. If you hit a leak anywhere the RPMs will pick up and the motor will smoothen out for just a bit. Let me know, Jim.

Was this

answer

helpful?

Yes

No

Tuesday, November 18th, 2008 AT 11:37 PM