S4Denver Posted October 19, 2012 Report Share Posted October 19, 2012 I have a 94 S4, recently found I had a blown intake gasket ( had high RPM's), replaced , upgraded injectors, now runs fine all parameters are within spec's on freescan. My question is the vacuum at idle is only 6-8 Hg it also flutters very badly? I know in a V8 that would reference a bad intake valve, but no noise at all from intake and car runs fine? is this normal for this 4 cyl? also since repair my BOV is not operating, have checked it is not a mechanical issue as it works with a vacuum pump I do not know what the readings were before repair it ran fine so I never scaned it or bothered to look. I know there are no vaccuum leaks so why the low vacuum that flutters like a bad valve? Quote Link to comment Share on other sites More sharing options...
sailorbob Posted October 19, 2012 Report Share Posted October 19, 2012 I see about 0.7 bar MAP at warm idle. Don't trust the Freescan values, they aren't accurate. Quote Link to comment Share on other sites More sharing options...
S4Denver Posted October 19, 2012 Author Report Share Posted October 19, 2012 Reading was with mechanical gauge, taken both from upper and lower passages on intake, thought it might be caused by IAC but bottom passage read the same, reference to freescan was just to verify that it was running well, nothing outside of limits, so why the low reading and fluttering as if there was a bad valve? is this normal for this engine? Quote Link to comment Share on other sites More sharing options...
sailorbob Posted October 19, 2012 Report Share Posted October 19, 2012 Fluctuating isn't normal, this is a screen shot of a datalog from a different car. The MAP varies by no more than 0.01 bar (again, at warm idle). Quote Link to comment Share on other sites More sharing options...
sanj Posted October 23, 2012 Report Share Posted October 23, 2012 Follow the small plastic hardline going to the MAP sensor and measure it there, you will be amazed how much that small diameter tube dampens the fluttering. Quote Visit Sanj's Lotus Esprit Turbo SE pages Link to comment Share on other sites More sharing options...
Andjons Posted March 2, 2013 Report Share Posted March 2, 2013 I also have high RPMs, and I don't think it's the IAC valve. You mention a blown intake gasket. What are you talking about, and where is it? Quote Link to comment Share on other sites More sharing options...
ramjet Posted March 3, 2013 Report Share Posted March 3, 2013 Split hose? Quote All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit. Opinions are like armpits. Everyone has them, some just stink more than others. For forum issues, please contact one of us Moderators. Link to comment Share on other sites More sharing options...
Andjons Posted March 3, 2013 Report Share Posted March 3, 2013 Which hose? I have no EBPV and have done the necessary mods to the vacuum lines. I have reset the IAC and followed the suggested procedure in the Freescan manual. When I start up, the idle is regular, but about 1400. When I stop at lights, for example, the idle doesn't go below about 1300-1400. If I switch off and start up again, the idle is a comfortable 1100 or so. Aaaargh! Quote Link to comment Share on other sites More sharing options...
Andjons Posted March 3, 2013 Report Share Posted March 3, 2013 To add to my previous post - IAC value is about 38 at idle, and MAP is around 38-40. Quote Link to comment Share on other sites More sharing options...
Vulcan Grey Posted March 3, 2013 Report Share Posted March 3, 2013 You IAC sounds good (engine at 80C andidle, correct?) My MAP at 5300ft altitude is .38bar (in freescan). A high idle is also controlled by the Throttle jack capsule. Have you removed that and the linkage on the butterflies? On my engine that linkage was sticking, causing a high idle after driving on the highway, so I removed the capsule and the linkage, and then lubed the throttle linkage. Even with the throttle jack removed, the IAC will still be able to demand a higher idle for cold starts. That is normal (and desired). Quote Travis Vulcan Grey 89SE Link to comment Share on other sites More sharing options...
Andjons Posted March 30, 2013 Report Share Posted March 30, 2013 (edited) In his post at the top, S4Denver refers to a "blown intake gasket". I am trying to work out which gasket he is talking about. Anyone offer any suggestions? Edited March 30, 2013 by Andjons Quote Link to comment Share on other sites More sharing options...
andydclements Posted March 30, 2013 Report Share Posted March 30, 2013 Inlet manifold gasket? Turbo plenum gasket? Quote Link to comment Share on other sites More sharing options...
Techspy Posted April 8, 2013 Report Share Posted April 8, 2013 I am interested in knowing which gasket as well. I am having random high idle (1400rpm or so) issues after driving for awhile when stopping at lights etc. I can blip the throttle and it goes back down where it should be. Quote John 94 S4 Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.