[DaveN]

I'll post video about my awesome DE days with the SC later; not why I am here but my DE instructor had a 911 C4S that couldn't loose him, he was blown away with the SC performance and the handling of my car! (nice pun insert <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" /> ) Great job Bob!



After my weekend of 200 kph I came back with an idle of 1200! I've cleaned the K&N and the <acronym title='mass air flow'>MAF</acronym>. Looked for loose vacuum hoses and the like. Can't seem to get my idle back. Before re-assembly this winter I thoroughly cleaned my ICV as well.

Thoughts?

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[banditsc]

I bet you have a vacuum leak somewhere. If the rubber elbows are original they are due for replacement. I just used some silicone hose pieces to repace the elbows, just don't replace the hard lines. Follow all the lines in the back and front of the motor and under the intake and replace those elbows. Also check all the clamps on the SC hoses.

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[DaveN]

All the SC hoses have been checked. Interestingly enough I cleaned/oiled the K&N and refitted it. Without an air filter is was at 1200 but with the new filter it settle down to 850ish for about 30 sesconds then climbed to 1100 and stayed there. <img src="/forum/images/smilies/968/sad.png" class="smilie" alt="" />

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[flash]

do you have a vacuum gauge?

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[DaveN]

Not yet <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" /> I feel I might just buy one tomorrow after a few suggestions.

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[flash]

yeah - i'd look there first. something isn't happy, and there is nothing about the kit that would lead to a sudden change like that, so i would be looking to the simple, like a vacuum hose.

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[DaveN]

I went around to all my connections squirting a can of break clean as per my mechanic. He says the idle will drop if I find a leak; no such luck. I have a permanent 11-1200 rpm idle. I did notice that while I have vacuum on most of the connectors I have nothing on the one that goes to the centre of the throttle body between the heater hoses. Maybe that one is different as it goes directly to a vacuum diaphragm.

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[flash]

that one is ported vacuum



the brakleen trick isn't definitive. you have to use way too much to make an idle difference at a hose.



it's actually better to use starter fluid. the idle will RISE when that gets in there. it takes a lot less of that to make a difference in idle.



the best test is a gauge on the port or hose (depending on whether or not it's a source point.



another thing to check is your oil filler cap.

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[banditsc]

Make sure you got all the vac lines, if I recall there are two vac ports on the intake manifold, one on the throttle body, one behind the fuel rail cover against the firewall, one at fuel regulator, one at the <acronym title='heater control valve'>HCV</acronym>, one at the AOS, one at the blow off valve, and a large one at the brake booster. Also is your throttle cable still in the proper location and not to tight?

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[DaveN]

Thanks for the check list Bandit. I think I tested them all except one that I believe is hidden under the intake mani? Throttle cable was checked when I cleaned the throttle body. This all started after a track day at an airfield with a LOT of sand and gravel on it as the field is 70 year old concrete. I cleaned my K&N removing a whole kids sandbox, that's what it looked like anyway. Oil cap is tight as I topped off the oil after I got back to the garage.

I will try some starter fluid and see if I can get a rise out of the idle.

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[banditsc]

Flash can give you a list of parts needed to make a Home Depot intake pressure tester. It will basically pressurize the intake and it will either hold pressure or you will hear leaking air. I have the plans I gave him, but it's for a 928 so he had a make a couple changes to it's design.

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[vliegwielolaf1234]

[quote name='DaveN' timestamp='1338481664' post='127628']

Thanks for the check list Bandit. I think I tested them all except one that I believe is hidden under the intake mani? Throttle cable was checked when I cleaned the throttle body. This all started after a track day at an airfield with a LOT of sand and gravel on it as the field is 70 year old concrete. I cleaned my K&N removing a whole kids sandbox, that's what it looked like anyway. Oil cap is tight as I topped off the oil after I got back to the garage.

I will try some starter fluid and see if I can get a rise out of the idle.

[/quote]



The sand part really worries me to be honest , i am really no fan of K&N filters , i have seen sand going thru these filters and doing a lot of damage to the engine .

If i can i would avoid using these filters .

The damage done with these filters where on motorbikes and mainly offroad bikes , but i see no difference sand is sand .



I really hope it has nothing to do with the sand , put some grease in the intake just after the filter next time you ride on one of these sandy gravel tracks , sand wil stick to it and then you wil know if it is an issue .



I would check your ICV again , if you cannot find any leaks , also check your wires going to your <acronym title='mass air flow'>MAF</acronym> , maybe something going on there since it has been extended to reach the <acronym title='mass air flow'>MAF</acronym> at it's new position .

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[DaveN]

<acronym title='mass air flow'>MAF</acronym> wires were checked and cleaned. Car runs like a top just bad idle now. I cleaned the ICV when I had the manifold off this winter but I can't imagine how my big mitts could get in there now and remove/clean it again.

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[vliegwielolaf1234]

[quote name='DaveN' timestamp='1338491097' post='127637']

<acronym title='mass air flow'>MAF</acronym> wires were checked and cleaned. Car runs like a top just bad idle now. I cleaned the ICV when I had the manifold off this winter but I can't imagine how my big mitts could get in there now and remove/clean it again.

[/quote]

Yeah that is going to be a lot of work i gues with the SC in front of it .

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[banditsc]

There is a nice pre filter sock that goes over that K&N, I would put one of those on if your in sandy conditions. BVA has one on his.

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[tamathumper]

Did you test the vacuum connections at the solenoids under the dash, in the passenger footwell?

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[DaveN]

I don't ever plan on doing that again, I have to get the front of my perfect car repainted now! Looks like I got hit with a shotgun. Glad I only hit the splitter with a can of black Duplicolor as it's a real chippy mess too.

I forgot about heater/firewall hoses, they are quite evident in my S2 but I didn't really see them yesterday with my flashlight when I was poking around. I hope there is nothing there as it's hard to go upside down in that car.

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[MB968]

During my recent teardown, I found 3 of the aluminum tubes that connect vacuum lines to the intake could be pulled out by hand. Doubt if this would be the issue, but you might try tugging on each of these to make sure the aluminum tube is still secured in the manifold.

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[DaveN]

Tks for the ideas MB968, pretty hard to reach those things though with the SC and my big hands. <img src="/forum/images/smilies/968/sad.png" class="smilie" alt="" />

I did get a vacuum gauge on the car today and at the 100 RPM idle I get 18 inches, run it at normal driving revs and I get about 20-22.

Is 18 about right or should it be better indicating a leak?

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[flash]

nope - that's right. i assume the needle is steady, with no wavering or pulsating.



now you get to start looking at things like the ICV and MAF



make sure the hose to the ICV is not crimped.

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