ranger_guy_82

I've been having this problem ever since I bought the truck in March and now it seems like its getting worse. It really runs bad when you first start it up after it's been sitting a while--say overnight. After it warms up it gets better, but still enough to slightly shake the truck back and forth when your sitting in it. I have done pretty much everything I can think of. Which includes-- spark plugs, DPFE sensor, sea foam like 10 times, upper/lower intake gaskets, all hoses appear to be fine. It kinda sounds like either a fuel problem or a sensor problem....Any ideas???? 1997 Ranger, 4.0L, 5 speed, 148k

mtneer57

If it smooths out at higher RPMs you might try an Idle Air Control Valve, but this usually causes the Check Engine light to come on. If rough through all RPMs, could be a vacuum leak.

ranger_guy_82

It's just rough at cold idle. Especially when first started. Runs fine while driving. No hesitation or missing.

ranger_guy_82

I think I should just go ahead and replace the upper and lower intake gaskets....Man, I hope that helps...It's not gonna be warm that much longer...:(

mike0179

My 99' 4.0 had a cold start problem also, it was the o-rngs in the upper intake. It would start and idle rough for several seconds untile the o-rings expanded just enogh to stop the air leak, after that the truck ran perfect.
I read on another forum that is was a big problem on 97's. I hope U find the problem.

mike

ranger_guy_82

Thanx for the info....I am planning on replacing the upper and lower intake gaskets, and the fuel rail gasket while I'm at it....I am also gonna check the EGR Valve and replace the Canister Purge Valve.....If none of that helps, then fucc it....I give up....But I appreciate all the suggestions!!!!! I also wonder if I might have a leaky injector or fuel pressure regulator??????

ranger_guy_82

Well, I fixed whatever was wrong. I removed the upper intake and used a baby bottle brush and some carb cleaner to clean out the ports. Then I retorqued the lower intake. It seemed loose to me......The lowest my torque wrench goes is 20 ft. lbs (1/2 in.) so i just torqued the bolts to that. And cleaned out the ports on the lower as well....Put it all back together with a new upper intake gasket and it fired right up just fine!....Not to mention it smoked waaaaaay more than any time i've used seafoam in it....It must be extra clean....Tons of power now!

WaltUotinen

I had the same problem on my '97 Explorer 5.0 V8. Sometimes it would barely idle and stall out unless I kept a foot on the accelerator while at a stop. This seemed to happen only on cold and/or wet mornings, and the problem would go away as the engine came up to normal temperature.

I removed the Idle Air Control valve (IAC, on top of the intake manifold, righthand side; 2 10mm bolts). The valve plunger and return spring had a lot of dry black carbon deposits. It was very hard to move the valve with a pair of needle nose pliers. Since a new valve is upwards of $50, I tried something cheap and simple: WD-40. After lubing up the shaft and spring and letting it sit about 10 minutes, I worked the valve back and forth a few times with pliers (it moved very easily now) and reinstalled the valve (with some high temp silicon RTV on the gasket, which had cracked on removal).

That was about a month ago and the problem seems to have gone away, despite some very cold, wet and even icy conditions since.

Best regards,
Walt