Uneven idle, low tickover

mhinch · 07-25-2007, 11:23 PM

I've searched this forum since getting my carrera in November last year, all of the advice and posts I found where very helpfull. My car performed well,but suffered from a 600 rpm tickover. All the jobs I performed showed improvement to the general running ie, changed plugs,cap and rotor, re-callibrated airflow meter, cleaned and checked ICV, and replaced vaccum pipes. Tried spraying carb ceaner around the inlet areas but this didn't give any clear results....................however I still had a problem soooooo I bit the bullet and decided to strip the inlet manifolds off the engine in situ and check the gaskets and this is what I found................... 3 out of the six inlet gaskets had sucked obviously causing vacuum leaks.........I'll get it back together and report on the situation by next week. I'm taking the opportunity to replace a weeping cam oil feed pipe, set the tappets and paint the valve covers and change the oil while I'm in there. I've got pics of the sucked in gaskets, but can't seem to upload them while the forum is in its transitional upgrade stage.

Mark

mhinch · 07-27-2007, 07:25 AM

Heres the pics

mhinch · 07-27-2007, 07:26 AM

and more

rnln · 07-27-2007, 08:17 AM

Before you opened it up, did you try the carburetor cleaner method? (spray carburetor cleaner, idle change).

stlrj · 07-27-2007, 10:03 PM

That's why when I redid mine, I eliminated the gaskets and ran a bead of Ultra Gray sealant on both sides of the insulator.

Cheers,

Joe

mhinch · 07-27-2007, 10:45 PM

rnin, I tried the carb cleaner method several times to try and track down the problem without conclusive results, I got raised tickover when I sprayed the cleaner around the back of the LHS of the engine, but when I stripped verything down the back two gaskets appeared to be ok. I think the carb cleaner was being sucked in at the servo vacuum pipe which looked ok until I removed it and discovered it was cracked. So in my opinion the carb cleaner method is not conclusive, hence the post. I recomend that if you have a tickover problem replace the inlet gaskets as a matter of course.
The other problem I noticed was that when tightening the barrel nuts down, my ball end socket would not engage fully on a couple of studs, ie the studs are fractionally too long.So I added some extra washers to allow the allen key to sit further into the barrel nut which allowed me to torque up the nuts fully.

Joe....it'll be interesting to know how long the sealant lasts, when did you do this?

Mark

rnln · 07-27-2007, 11:16 PM

Mark,
May I ask is there many parts you have to take off in order to take the manifold off for this task?

mhinch · 07-28-2007, 10:43 AM

rnin, its quite straight forward, heater blower and trunking off first, you need to loosen the dizzy cap to access one of the bolts,then I unplugged the sensor wires and injector wires from the fuel rails. right hand side inlet next, six barrel nuts at the base and a jubilee clip on the rubber boot not forgetting the fuel hoses (I unbolted the fuel damper at the bracket and just moved it out of the way to save unbolting the the fuel pipe) The LHS was a bit more awkward....access to the fuel regulator bolt is easier if you have the dexterity of a gynacollagist, the grip of a free climber and fingers the length of ET's. A mirror helps to locate the bolt. Don't forget to unplug and marked all wiring locations and release the throttle pushrod at the ball joint underneath the AFM. Step by step its relatively easy, but a white board and marker pen would be helpful to write your progress down so you can then work in reverse without missing anything out. HTH

Mark

stlrj · 07-28-2007, 10:51 AM

Quote:

Originally Posted by mhinch

Joe....it'll be interesting to know how long the sealant lasts, when did you do this?

Mark,

It's been sealed for over 10 years now and lets me sleep at night.

Cheers,

Joe

mhinch · 07-28-2007, 10:55 AM

Joe, typical you tell me now when I've just finished putting it back together, I've not heard of ultra gray sealant on this side of the pond, but I'll add it to my shopping list for December when I'm in Vegas.

Mark

rnln · 07-29-2007, 01:19 PM

Mark,
thank you.

scottb · 07-29-2007, 02:24 PM

Permatex Ultra Grey: http://tinyurl.com/lk38b

scarceller · scarceller's Garage

Want to be sure I understand this issue: The problem was low RPM (600RPM range) and the problem was 3 sucked in intake gaskets? So a really large air leak cause low idle? Ussually small air leaks cause high idle but I guess if the leak is large enough you get Low idle? is that correct?

Just really good info to know.

Thanks.