Momentary Engine Race at Startup

[ssfrebo]

This may be a normal condition for a Ford, but I would like some confirmation from the long time Ford Explorer Owners. When I start my 99, XLT SOHC, the engine idle races up to just under 2000 RPM then comes right back down to normal idle speed. The transient is very short in duration (couple of seconds or less). Is this normal? It can't be good for the engine on a cold start. It had me concerned so much I immediately switched to synthetic oil which pumps quicker (no wax). Then throw in the dieseling sound from the tensioners, and it just makes me cringe whenever I start this thing. (Its in the shop today for tensioner replacement).

 

[Alec]

Does this always happen, and does having the A/C on affect it? These motors do like to idle a bit high on a cold start, but 2000 rpms is a bit much. Though if it quickly goes away I'd say it's just normal warm-up. Any other issues?

 

[ssfrebo]

This happens primarily after the engine has cooled off. When hot, the transient is not nearly as pronounced. I've only owned the vehicle about a week, and have not used the AC yet...its cold now in this part of the country. As a comparison, my Honda minivan (v-6) does almost the same thing, but only reaches about 1700 RPM in the start transient......Scott

 

[mosinman]

start up idle

Yep, sound just like my 99 SOHC, without the tensioner noise. Had that service and the lower intake gaskets done last year. It is much less pronounced during warm weather. Seems to be SOP for this motor

 

[VairKing]

My 91 OHV does this too, when I start it up in the morning it surges up to 1500 RPM then goes back to idle after a few minutes.

 

[addkev]

My 99 SOHC does it too I had Ford look at it and they swore that it was perfectly normal.