First post here. I have a 90 Bronco, 5.0 with a hunting idle on hot/warm starts. Takes about 2 minutes to settle down. Occasionally, it will be so bad it will stall.

On cold starts, it works perfect as it should 100% of the time. Been chasing this problem for a while.

Any suggestions would be much appreciated.

Thank you,
Tom

 

Might want to start with the TPS as well as the coolant temp sensor, O2 sensor, even seeing if it is throwing codes or not. Maybe even the crank position sensor too but not sure if that would have anything to do with it. Won't hurt to check.

 

Thank you for the reply FordBoy.

The TPS tested good. I have replaced the coolant sensor. Also replaced the IAC, the upper intake gasket and the ERG sensor. These changes have been done over time. I've owned the truck for 28 years now.

It throws no codes. Not sure if it has a crank position sensor.

Thanks,
Tom

 

It should have a crank sensor. I think it controls the computer to some degree telling the computer that the truck is running. Did you test the oxygen sensor? Does the exhaust fumes smell weird? Does it smoke when it is hunting?

 

Haven't tested the o2 sensor. Exhaust seems fine. It's never smoked. When it's a cold start, it's perfect. Slightly higher idle and a gradual lower to perfect idle. Have considered it might be the catalytic converter.

Never runs hot, at least according to the gauge. I have used a thermal tool to check the temp guage and it seems accurate.

I do have a curious loss of coolant over time. Thinking I may have a lower manifold leak. No reason to believe a head gasket. Not sure if that could be a contributing factor.

By the way, went to my local Ford dealer and asked if they could check it out. They told me it was too old for them to look at it. I was quite surprised with that response.

 

Oh I'm not surprised. They don't even stock parts for those trucks anymore. Take it to an auto repair station instead. As for the coolant leak, you may have a cracked head or block...maybe. I don't know...i've never heard of a problem like yours. Your best bet is an auto repair station.

 

Thanks. Not many I trust. At $100 an hour and replacing everything till we get it fixed can be a little daunting.

I'll keep chipping away.

 

Ok sounds good. Sorry I couldn't help.