help 1990 bronco runnig bad
Thread Starter
|
New User
Joined: Jun 2008
Posts: 2
Likes: 0
help 1990 bronco runnig bad
I have a problem with my 1990 bronco it runs fine untill the temp hits the right spot ever morning then it acts like it needs a tune up it skips bad. When i dirve it in the am it starts at the same time ever time. I have had it in the shop for a tune up and that did not fix anything. The guys at the shop have done everthing they could think of and can not find out what it is doing this. It will run fine sitting still no matter how long it sits there but as soon as you start down the road it starts. If you cut off the OD it helps some and at high speeds(65-70mph) it is not as bad.
Any help would be great thanks medic1098
Any help would be great thanks medic1098
Posting Guru
Joined: Oct 2005
Posts: 1,017
Likes: 3
From: Longwood, Fl
O2 sensor
I had kinda the same problem with my 93. Put a scanner on it and found 2 problems.
In 90, I dont know if the 02 sensor was the type with a "heater". What happens (sounds like your symptoms) is the engine cranks and must run on MAP until the 02 sensor heats up and controls the mixture. A scanner will show the sensor giving erratic readings after warmup, (should only be erratic before sensor warm-up) if that is the problem. Mine did just that.
Also, your ECT sensor has to tell the engine when the temp reaches the correct temp after warmup. An incorrect ECT sensor will allow the engine to think its in "cold start" mode all the time, which richens the mixture.
Look at an EVTM, to determine which sensor actually goes to the PCM. I seem to recall that only one temp sensor goes to the PCM for that purpose.
LOL, replacing both O2 and ECT sensor cured my problems. Now it burns lots of $4.00 fuel just fine
In 90, I dont know if the 02 sensor was the type with a "heater". What happens (sounds like your symptoms) is the engine cranks and must run on MAP until the 02 sensor heats up and controls the mixture. A scanner will show the sensor giving erratic readings after warmup, (should only be erratic before sensor warm-up) if that is the problem. Mine did just that.
Also, your ECT sensor has to tell the engine when the temp reaches the correct temp after warmup. An incorrect ECT sensor will allow the engine to think its in "cold start" mode all the time, which richens the mixture.
Look at an EVTM, to determine which sensor actually goes to the PCM. I seem to recall that only one temp sensor goes to the PCM for that purpose.
LOL, replacing both O2 and ECT sensor cured my problems. Now it burns lots of $4.00 fuel just fine
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
See Ford Fuel Injection for a DIY method of pulling the codes, they also have lots of info on the various sensors and test proceedures for these. You may have a sensor problem or it could be something more basic, but starting with the codes will eliminate a lot of possibilities.
