95 astro 4.3L vin-W

hello everyone
I have a 1995 chevrolet astro vin-W with spider injection. S.E.S light came on and has a code of 35.Idle air control can not control idle. Replace IAC and adjusted it to 1 1/8 from mount surface. Still shows code 35 . At kOEO IAC position is at (47) and shows a reverse position. At operating temp(195) and idling the scan tool shows that the iac is in reverse direction and at position (0). At 30 to 40 mph the scanner show the IAC still in reverse but at a position of 40-50 range. when idling and warm i removed the air intake assembly and put my finger(with much difficulty ) up in passage and the plunger was oscillating very rapidly . I could always feel the end of the plunger though. Also idle required is (650) and actual is(850). The exhaust O2 cycles between rich and lean and spark advance is all over the place. So maybe someone can enlighten me. Also looking for the pid chart for this vehicles if possible. Hopefully I gave enough information ,if not ask a way

With a code 35- the first place I look is for the upper intake plenum to be sucking air- usually right in front left of center-on a "W" engine-- look for a blackened/stained spot- have seen several gasket failures- where pieces break away and allow air to be sucked in- the fix is a new gasket- you can test by laying an uninflated balloon against the area in question- I have seen them bee held in place and the idle return to normal- also look for any other vacuum leaks- like vacuum hoses and PCV hose etc....

thanks for the help. Will be checking for vacume leaks and such today. Will let younow what I find.:)

I just finnished checking for vacume leaks and found a leak exactly were you said it would be. On the intake left center of the throlle plate. You information is invaluble. I can not thank you enough.

Glad to know we can win one once in awhile- I work on cars for a hobby- and that gasket leak first hit me back in about 1998- pulling a horse trailer to my daughter's 4-H show- funny how you remember that stuff- first time I ever had a SES light on my van- Being able to help others out makes me feel goooood---plus it helps to have had almost everthing that can go wrong on an Astro- go wrong-- but I do have over 300,000 miles on my '94............

It took me about 6 hours to install this gasket. But all and all it was not bad . Had alot of cleaning to do. Plenum had alot of oil/carbon in it so I figured while I was there I might as well clean the heck out of it and not worry about it again. It sure is nice when you get the right information and everything goes smoooooooth. Thanks again

Every plenum I have seen are absolutely filthy inside- except for the ones with spider leaks- the gas washes the filth away- I typically do not clean them-unless they are off the engine- I merely work around the embedded crude- I'm too afraid that if I loosen that stuff up- it will come back to haunt me- such as in plugging up a vent, or a valve or the like- believe me- every plenum out there is full of it- and most run fine- so to each his own.....I would say I have had my plenum off at least a dozen times- got it down to a science when I had wiring problems to my spider assembly- got to the point I reused the same gasket over and over- good to know your back in business.......

I am also a work on stuff as a hobby. Have a few projects going now.I thought about the stuff causing me problems down the road so I made sure that I dissassembled everything and brushed all ports with heavy cleaner. Had to take it in for an E-check today and all gasses were well with in range. It seems to be running very well. Have you ever had problems with your steering? This van has a powersteering pump brake assist and my steering seems to be alittle stiff. Have not had a chance to look into it. Been having loads of mechanical problems with my other van (1996 chrysler T&c lxi 3.8L) The number one coil driver is constantly grounded. Sent computer out for repair once and had to send it back. Have not herd anything yet.

only steering issues have been the infamous idler arm- which was replaced with the improved MOOG part 6 yrs ago- no problem since--