1900rpm idle and cut off at 4000rpm?

[matress]

hey guys
after giving the car a good hammering at calder last night, i've noticed a few problems! one of them happened on my final run, i took off and at about 4000rpm it felt like a fuel cut or an air flow cut... now it does it all the time, whenever i get near about 4000rpm on boost... any ideas? I'm running an aftermarket ECU aswell...
also, my car is idleing about 1900rpm... the 2 plugs on the drivers side of the inlet manifold are disconnected, and i'm not sure if they should be connected.
anyone got any ideas?
cheers,
Mat

 

[87vr4]

what aftermarket ecu do you have ?

it sounds like a tuning problem

 

[matress]

i've got a Wolf 3D.
its just strange though that it just started doing it all of a sudden.

 

[bazeng]

what boost are you hitting?

wolf have a boost cut setting, check that

as for the idle, possibly an leak somewhere

block all hose fittings if they are not used (on the inlet manifold)

make sure u have you wastegate hose / block off valve hose plugged in.

 

[brisvr4]

Is it cutting out completely at 4000 or is it more of a coughing stutter?
If its the latter then checking your leads might be one thing to try.
I had a problem similar and it turned out to be leads.

 

[bazeng]

good point, if its stuttering when boosting it would probably be your leads / spark

check if they are plugged in nice and tightly,also check your plug gaps / plugs...

 

[matress]

thanks for the replies guys!
it coughs and stutters real bad when i hit around full boost... it does it on both 7psi and 14psi. it feels as though it is hitting boost cut in both boost stages.
im taking it back to rank tonight for them to have a look at. if it was leads, would they just go like that? 1 minute it was fine, the next it was shizenhausen!

 

[brisvr4]

Yep they can, mine went from perfect to crap between when I shut down and restarted it
$5.00 says its leads!

 

[TrooperShannon]

$10 spark plug gaps.

 

[matress]

hehe you both lose, but you're on the right track!
melted spark plug! pete from rank reckons that when the vacuum hose for the MAP sensor blew off, it leaned out the motor and melted the tip of the plug.
the reason for the high idle was that the idle control motor got pushed out of its little socket and buggered up the idle!
all fixed now though!
thanks again to rank!
and by the way, we just realised, the plugs in the car are only heat range 5!!! getting new ones in tomorrow!

 

[TrooperShannon]

heh darn i needed that cash too!

Glad to hear it is sorted mate hope it didnt cost ya too much in the end!

 

[brisvr4]

At least it didn't blow your motor

 

[matress]

didnt cost me anything!
i was worried about where the end of the plug had ended up! i'm used to owning a rotary, where if something like that happened it'd fuck the motor in the "exhaust port." apparently its not such a drama with a piston motor, but yeah, im glad as hell that motor is still healthy!
rank's ordering me some heat range 7 plugs for me to pick up tomorrow!