high and erratic idle

16bit · Postby **16bit** » Fri Feb 14, 2020 12:49 pm

hello all.

have just finished installing a skunk 2 intake manifold on my nb8a.

after putting everything back together (intercooler piping is not connected properly but all of the sensors etc are plugged in and in place) i started the car and it is idling really high. about 2.5k rpm then will some times go down and become quite jumpy.

one thing i noticed is the tps will not clip in anymore, i may have damaged the clip on the tps its self. it will plug in just fine but won't make the clicking noise as i think one of the bits broke off on the tps, not the plug.

so basically other than the intake manifold everything else is largely the same and should function just fine.

the VICS is obviously not connected but I have put added its vacuum line back in.

i can't think of why it will start and stay started but just idle really high other than the tps.

16bit · Postby **16bit** » Fri Feb 14, 2020 3:47 pm

upon further investigation i had not yet installed the throttle cable bracket. that had 2 holes through to the intake its self. could that cause the high idle?

plohl · Postby **plohl** » Fri Feb 14, 2020 3:49 pm

I'm leaning towards vacuum leak...

Are you using the standard throttle body? do you have a ecu with useful logging?

edit after seeing your new post.... use your finger to block the whole, see if the idle drops.... Also, that's super sh*t if they are through holes into the intake. You don't want a leak because the throttle bracket isn't sealing correctly

16bit · Postby **16bit** » Fri Feb 14, 2020 3:52 pm

stock throttle body and no. i have a piggy back ecu with stock ecu.

plohl · Postby **plohl** » Fri Feb 14, 2020 4:00 pm

if you rule out vacuum leak, check the wires at the throttle connection. they might be old and cracked, causing an issue.

I have no idea piggy backs.... but, is it using MAF or MAP for the tune?

Do you have a wideband sensor and gauge? if it's leaner than normal and high idle, probably vacuum leak...

16bit · Postby **16bit** » Fri Feb 14, 2020 4:07 pm

i will test if bolting on the bracket works tomorrow - baby is sleeping at the moment and the car is under its bedroom and really loud.

it uses a maf sensor and map sensor technically. i think it uses the map sensor for the 5th injector for when the car comes on boost.

thanks for the help, hopefully lugging the two holes fixes the issue!

16bit · Postby **16bit** » Sat Feb 15, 2020 10:40 am

i am sure you all didn't get much sleep last night but i can report the idle is no longer a million rpms. bolting on the bracket and thus getting rid of the vacuum leak fixed the issue.

so when i started it the idle was around the correct rpm of 800 or so.

however its very, very rich now and a bit lump as a result.

i suspect it might be rich because the supercharger is not connected and seems to blow about as much air as hair dryer at idle. so i think its missing that extra air going which is why its super rich and lump. sounds like it has cams.

i must say i am pretty proud of myself having taken all that sh*t off for the intake, re doing fuel lines, doing a remote oil filter, doing a diy coolant re route and there is not a single leak.

go me.