Well I now have a vacuum problem on my car. It is a turbocharged 3.4 pushrod. When the car is cold everything it fine. However, when the car heats it, a vacuum problem occurs. At idle the car starts to bobble rpms between 1,500 and 500. It will just keep going back in forth between the two, and it freqently will die when idleing. I had the intake off today and checked the vaccum lines, and they have no cracks in them or the rubber boots they are attached to. Any ideas what might be the problem? Could one of the sensors on the throttle body cause this problem? I also attached a vacuum gauge in place of the BOV, and the vacuum goes from normal and drops very low, and also goes up and down and up and down, just like the RPM.
Have you tried disconnecting the EGR vacuum line? The one between the EGR and the EGR solenoid. Just a guess. I'm trying to think what could open what amounts to a vacuum leak then close it down again. Malfunctioning EGR solenoid could do that.
Do you have Winaldl and a cable to look at the sensors?
[This message has been edited by Hudini (edited 05-04-2007).]
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12:19 AM
Oreif Member
Posts: 16460 From: Schaumburg, IL Registered: Jan 2000
Aside from what Hudini says, also check the EGR pipe that goes from the exhaust to the intake. They are notorious for cracking as well and are sometimes hard to see if it has the sleeve over it. A few other things as well, The hard plastic vacuum lines can get cracks/splits length wise in them which can be hard to see. There is a pipe that runs from the TB to the lower intake manifold, With boost the "O" ring that holds it in the throttle body can get brittle and crack causing a vacuum leak.
As a last resort, You can use WD-40 and spray around the vacuum line connections and see if you can locate the leak (idle will change when you spray where the leak is.)
As for sensors, once it is hot, Jump out the ALDL connection like you would when setting the timing, This sets the sensors to a default reading and if the car runs better with it jumpered it could be a sensor. Usually when a sensor goes bad the SES light come on, but have seen ones go bad and not set the light. Lastly, The ignition module could be going bad, they do get temp sensitive when starting to go bad. To verify you could get the engine hot and buy some electrical freeze spray. Cool off the base of the distributor and see if it will run right for a little while.
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07:17 AM
bluefiero Member
Posts: 465 From: Wheaton, Ill, USA Registered: Jun 2005
Well the problem has gotten worse. The car is runing VERY rich. When I rev it, you can see gas spit out from the exhaust tips. When it is just idleing it even smokes some from soo much fuel being spit out, and my air/fuel ratio gauge maxes out sometimes.
I put on a brand new IAC sensor today to see if it would help, but it did not. I have a holley adjustable fuel pressure regulator. Could the diaphragm be bad inside and cause a vacuum leak that would affect this? I am about to go in the garage and check the EGR tube and also take some spark plugs out to see if they are wet.
1. The EGR itself was not holding vacuum 2. The EGR tube had a big splice in it 3. The TPS sensor was bad 4. One of the 90 degree rubber boots to a vacuum line had a splice in it
It looks like I'll be takin it to the milwaukee mile this weekend after all :-D
