98 4.0 OHV rough idle when cold ??

[raggedyann]

I cleaned the IAC, which seemed to help some. But still idles rough when cold to the point it dies at times and other times it will lope down and then picks back up.
I will pull codes today as last code I don't remember but it was a "lean" code.

anyways which sensors ,etc. controls idle ?? ive cleaned the MAP also.
While getting gas I noticed the hose to tank has a leak, will this cause bad idle ??

 

[cvar]

I had that same pesky rough idle and sometimes stalling at stop lights, for 2 years, esp. during cold weather. I cleaned or replaced IAC, DPFE, EGR hoses, vacuum lines, etc. It turned out to be a leak in my upper intake manifold gasket.

Nah, a fuel filler hose leak won't cause the lean (0171, 0174) codes.

 

[raggedyann]

thanks cvar, what did u do to detect the lower intake leak ?? vacuum test or just spray brake cleaner or similar ??

 

[cvar]

After replacing all that other stuff, I still couldn't find my leak. I tried spraying brake cleaner, and I tried smoke, and I tried listening for leaks. Nothing. Awk! I failed at that. I gave up & brought it to the dealership, and they diagnosed it and installed a new upper intake manifold gasket for about $500, in 2010. Presto! Problem fixed, and it passed state inspection.

 

[raggedyann]

I just tried brake cleaner, couldn't detect anything either.