Hi I posted here almost a year ago about a surge/hunting idle problem. Here is the
link to the post. Finally took it to the shop and had it put on a machine. The tech said there was a vacuum leak on the driver's side intake. Well I replaced the intake gaskets and the truck still had the same idle problem. I decided to go ahead and drive the truck until I had some extra money to take it to another shop. Well the other day it thru a code 32 - EGR system failure. Took the EGR out and it seems the piston would get stuck open. I replaced it hoping maybe it was the cause of the bad idle. I started the truck and it still idles the same.
Now here is the new kicker. After warming the truck up, while the truck was sitting in park, I caught the speedo moving as I increased the gas. I got the needle to go over 5mph while setting
in park at part throttle.
Now I have spent the better part of 2 hours searching info on VSS. During my research I found that the VSS not only feeds the speedo, but the cruise control, ecm and on some vehicles a variety of other devices. My cruise control doesn't work, (I had almost forgotten as I don't use it). It occurred to me that perhaps the VSS or connecting wiring might be the cause of the bad idle and surge. If anyone has experience in testing the VSS or can confirm what problems can occur when faulty it would be much appreciated.
Here is the technical stuff:
1990 GMC suburban
fresh 454 tbi (less then 6000 miles)
all stock with many new sensors and pigtails $$$$$$
Thanks All
Brad
Linear Mode
