Originally Posted by Schrade
No one got the proper technique for vacuum leak detection... :confused
FIRST (fully warmed up motor); block the pedal, or block the throttle linkage. YOU HAVE TO DO THIS TO GET A STEADY IDLE , around 1,250 rpms, or a little higher. If you don't, you can fish starting fluid, a propane hose, or WD40, or Krylon, or hair spray, or pee, anything, until you need a sweater in Hades, but if the motor is lopin' already from a vacuum leak, you ain't gonna' find any vacuum leak, unless it's so big that Little Jack Horner can stick his thumb in it and pull out a pineapple NOPE.
AFTER you get a steady idle, THEN, you can spray starting fluid everywhere - that's the best detector, because it's vapor pressure is very high - a LITTLE at a time, until you get the SURGE. Follow the vacuum lines to the EVAP cannister too. You might even have to follow the EVAP lines from the EVAP cannister to the gas tank too, but that vac leak will show up as a DTC 32 EGR fault, and won't normally show as loping idle, unless the EVAP cannister has been by-passed (been there, saw that uh-huh YUp).
If you get a surge in a tight spot, and can't tell exactly where it is, light a book of matches, blow out the match heads while they're still burnin', and feed the smoke to the tight spot.
Fear not the starting fluid; you cannot put the can down fast enough and light the matches fast enough to catch the starting fluid, because the vapor pressure is so high.
Bookmark this post YUP.
Well, it speeds up about a mph, and then it slows down an mph. Very annoying.
Sometimes the idle speed is just about dangerous when I'm driving. I punch the accelerator to see if it is sticking, but it does not seem to be. I have to get on the brake to slow the thing down. Then--I'm going by memory now, the motor seems to slow down. Not good.
No sir, if I put it at 100 kph, she goes to 102, then backs off to 99, and then we start the whole thing over again. Your thoughts...?
Read the whole thing. Thank you. Wrote it down and will find the problem on Teusday. Will report back. I couldn't get the resistance values though. I did note that on the picture, the leads were on the first and third from the bottom.Curing Your C4’s Cruise Control
If the speedo works good, then it is probably a hard problem in the cruise control. Here is a link to some easy tests that are worth a try, they may be of some value to your problem. Good luck with it.
Dealers:
