SPONSORED LINKS

Car runs poorly after warming up

Tiny
BRIAN MARKWICK
  • MEMBER
  • 1990 FORD FESTIVA
  • 1.4L
  • 4 CYL
  • FWD
  • MANUAL
  • 265,000 MILES
Car has had new battery, alternator and battery cables done. Starts no problem, runs well until warms up. Once warm, chugs and sputters hard and runs worse with any electrical running (radio, lights, heater, etc) seems to be running solely on battery once warm. Cannot figure out root cause and it is driving me mental.

Thanks.
SPONSORED LINKS
Thursday, February 23rd, 2017 AT 1:46 PM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
Everything you described could be caused by the charging system, especially if the generator has one bad diode. That will cause it to develop a maximum of exactly one third of it is rated current, which might be just enough to keep up with the demands of the electrical system, but the resulting excessive "ripple" voltage can interfere with computer sensor signals.

A quick test is to fully charge the battery, then, while the engine is running, unplug the smaller wires going to the generator. If the symptoms clear up or change, have the charging system professionally load-tested.
SPONSORED LINKS
Was this
answer
helpful?
Yes
No
Thursday, February 23rd, 2017 AT 6:39 PM

Please login or register to post a reply.

Related Engine Runs Rough Content

How to Read Codes
VIDEO
How to Read Codes
Instructional repair video
Check Engine Light
GUIDE
Check Engine Light
Why is my check engine or service engine soon turned on? In this guide we talk about what this is associated with this notorious light, what it is used for and what you...
VIEW MORE

Sponsored links