johnnyreb
Well-known member
Sma--your doing real good. Trying and not afraid to get your hands dirty. Your learning quickly and getting the hang of it. I have confidence in you.
Just bought this 1986 Bronco 5.0l with manual trans, UPDATE - Couple more questions, Help!
- Thread starter Smafugula
- Start date
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Guys - I know it has been months but wanted to update yall. And also ask some more questions lol (should I make a new thread?)
1986 Bronco 5.0l EFI
So the backfiring has been fixed, for now, hopefully. It turned out to be the ignition throttle switch that caused a full rich scenario in the motor, which in turned caused a backfire issue on de-acceleration. Also EGR smog pulley system causing coughing while idle.
My next question for the Bronco geniuses on here is how to fix this Coolant temp sensor issue. I haven't dug too deep yet but figured I'd poke y'all with the symptoms and see what comes back.
Gauge was showing dead so I replaced sensor, it worked for maybe a day? Came back later and gauge was all the way dead again. Now I have a new sensor handy and have tried to follow the wires, do they go back to where the OBD1 reader hooks up? Anyways, any thoughts? Thanks!!
1986 Bronco 5.0l EFI
So the backfiring has been fixed, for now, hopefully. It turned out to be the ignition throttle switch that caused a full rich scenario in the motor, which in turned caused a backfire issue on de-acceleration. Also EGR smog pulley system causing coughing while idle.
My next question for the Bronco geniuses on here is how to fix this Coolant temp sensor issue. I haven't dug too deep yet but figured I'd poke y'all with the symptoms and see what comes back.
Gauge was showing dead so I replaced sensor, it worked for maybe a day? Came back later and gauge was all the way dead again. Now I have a new sensor handy and have tried to follow the wires, do they go back to where the OBD1 reader hooks up? Anyways, any thoughts? Thanks!!
johnnyreb
Well-known member
Its what you think is important to you. Everyone has their own opinion. The information you received hear is good. These guys will steer you right and ask. and try is how we all learn and find out who we can trust, Looks like. A little work and looking and you,ll find hoses that need replaced. Because of age and old gas need replaced.Plus fillters. Do a good maintance and write down what needs to be done and has been done--like a check off list. Then you,ll narrow the problems. Also rememer.So of the parts you get at part store,Can be checked at the store .Before you leave .Then put on the vehicle. Good luck.
Motech
Well-known member
Yes, backfiring can be from the large vacuum leak you presumably corrected, plus the MAP hose, which is right next to it. That big vac leak will rob vacuum from MAP and cause trippy readings and weird symptoms, backfiring included. Also, those old MAP hoses get squishy and **** shut on deceleration, or have splits you can't see right off, but will find if you squeeze and pinch up and down the hose.
Air injection faults also can cause decel backfiring.
And 900 RPM is still too high. I'll bet you have more vacuum leaks.
Motech
Well-known member
No, not there. They go to PCM, and also the gauge.
One thing will make gauge read low is air. If coolant is low, sensor can't measure air, and it reports higher voltage (lower temp). When this happens, PCM that old is not smart enough to figure out an engine that has been running an hour is warm, so it just believes it and adjusts fueling as if you are driving the North Pole. Pig rich that is, and will run real ragged.
According to the attached diagrams there is 2 coolant sensors. One they are calling a coolant temp switch and another they are calling Engine temp switch.
The engine temp switch goes directly to the ECM
The coolant temp switch goes directly to the gauge cluster.
So first step, make sure you are working on the correct swtich. Maybe by unplugging it and see if it affects the gauge.
If you have replaced the correct switch I would be thinking it could be the cluster connector, circuit board, or actualy gauge itself.
The engine temp switch goes directly to the ECM
The coolant temp switch goes directly to the gauge cluster.
So first step, make sure you are working on the correct swtich. Maybe by unplugging it and see if it affects the gauge.
If you have replaced the correct switch I would be thinking it could be the cluster connector, circuit board, or actualy gauge itself.
