Hesitation after startup

[flyguy12]

Few months ago I bought a '96 Explorer xlt, 2wd, 169k mi loaded to the gills...$1500. Since I bought it i've been catching it up on maintenance issues, new plugs and wires(looked like the first time they'd been changed), o2 sensors, filters and fluids, fixed a cosmetic item here and there and replaced a tired relay. The only real issue i've noticed out of the X is that after startup and only just after startup it hesitates if you put it in gear and apply the gas. It'll hesitate for a sec then decide to run and never gives any hint of a problem after that. My question is, what is causing the hesitation? Being that it now has 172k mi I dont blame it for thinking twice about running but it does and except for the hiccup it runs great. Any ideas?

thx,
Adam

 

[exploded99]

Not sure if you have cleaned your MAF. You may want to try that first - lots of instructions on here about that.

If that doesn't work, take a close look at the inside of your throttle body. It is probably pretty gummed up given that the truck did not get much other maintenance. Cleaning the throttle body out has helped some people on here that had hesitattion issues.

If you still have it after that, research 00m12 recall on here - I think it applies to your vehicle. It centers around replacing the o-rings in the upper intake manifold which develop leaks.

When you start the truck, your engine is "open loop" meaning the O2 sensors are not warm enough to give the computer accurate info, and it is basically running on defualt data stored in the computer. Sounds like your engine might be a little lean at startup. Once your engine goes "closed loop" and relies on the O2 sensors it probably compensates for the lean condition.

Also check for other vacuum leaks.

Hope that helps!

 

[BrooklynBay]

Do you have a hesitation going into drive? What about going into reverse? You could try replacing the rubber O rings around the low/reverse servo with Transtec viton "D" rings.

 

[flyguy12]

thanks guys for the quick response, I'll be sure to take your advice as soon as i can find a day off. And yes, the truck hesitates in both drive and reverse....idles fine, but the idle drop associated with being in gear pulls it a little low....but once it surges for 5-10 seconds it runs like a champ.

Replaced the IAC, which has corrected all but the slightest hesitation when i put the x in gear....thx again