High Rev Startup

[808bronco]

I've got a '96 Bronco, and when I start it up in the mornings or when the motor is "cold" (I live in Hawaii, so the motor isn't ever colder than 60-70 degrees), the revs jump up pretty high and I hear a tapping noise coming from the motor. The revs drop back to normal idle over 5-10 seconds.

But that tapping noise is what's scaring me, because it sounds like valve tapping or the heads are dry or something. The oil is full, but I'm going to change the oil again and see what's up.

Also, my check engine light has been on for a while /emoticons/[email protected] 2x" width="20" height="20" /> but I think my O2 sensors are bad. I'm going to take it to a shop to have them read the codes.

But, just wondering if anyone else has had this same issue?

 

[Justshootme84]

The high idle can be caused by a faulty TPS (throttle position sensor) or a bad/dirty IAC (Idle air control valve). The tapping at startup is prolly due to wear on the lifters, but if goes away after a minute or two, you can live with it for awhile. A full code scan will tell you if the TPS voltage is low or the O2 sensor is reading poor cat efficiency.

 

[808bronco]

The tapping sound goes away after 5-10 seconds after the engine has been running, and it only does it on the first time I start it in a while. The same thing with the high idle thing, which makes me think the two are related.

We'll see what codes pop when I get it tested. Times like this I wish that I had one of those ODB-II scanners.

 

[shyguy]

The tapping sound goes away after 5-10 seconds after the engine has been running, and it only does it on the first time I start it in a while. The same thing with the high idle thing, which makes me think the two are related.
We'll see what codes pop when I get it tested. Times like this I wish that I had one of those ODB-II scanners.

21614[/snapback]

​

I get a tapping sound too, but mine is caused by the fact that one of the pieces of the floor pan underneath is loose...and rattles....and then there's the ever present pinging from the engine on acceleration which I found out goes away if you switch to the higher priced premium gas...LOL...$1.06/liter here...which converts to over 4.00/gallon

Chris

 

[grande_guerre]

you in canada shy guy?

 

[shyguy]

you in canada shy guy?

21879[/snapback]

​

Sure am.....as far east as you can get on the continent, well after crossing a gulf....

gas prices seem stable right now.....they only change em on the 15th of the month....pricing commission here, so they have to do the formula thing.....lets hope the oil price drops a bit over the next few months...last I heard it was back to 51$ a barrel again...

 

[Broncoholics]

Does it sound like the starter motor is still running?

The tap is normal on start up until you get oil pressure up. You can try some of those duralubes, hyperlubes or Lucase oils so things stay lubed longer so you don't have dry start ups.

 

[808bronco]

Does it sound like the starter motor is still running?
The tap is normal on start up until you get oil pressure up. You can try some of those duralubes, hyperlubes or Lucase oils so things stay lubed longer so you don't have dry start ups.

21881[/snapback]

​

Nope, doesn't sound like the starter is running.

And I realize it's an oil pressure thing, but this never occured until recently.

Again, I think it has something to do with starting up in a high rev, and I'm sure once I fix that, the tapping will go away.

I think maybe I should consider some oil additive until I get this sorted out.

Considering picking up one of those OBDII scanners that you can connect to a laptop, and get all your car stats through that.