Jump to content
SAU Community

Recommended Posts

After many many problem with my skyline i finaly found a vacume leak which i was hoping was the cause of my lean idle, lag and super richness on boost. I removed the charcole canister which is brocken and the car seams to run slightly better. Idle is still lean lag is still there but actual driving of the car feels alittle better.

After parkig the car in my drive way after testing how it went I noticed when i pressed the brake pedal the rpm droped. So I pressed it multiply times and the rpm dropped below 500 nearly stalling the car.

Any ideas here? Is this another air leak?

Link to comment
https://www.sau.com.au/forums/topic/335750-vacume-leak-in-r33-gtst/
Share on other sites

sorry to hear that my borrowed intercooler didnt solve your problem dude, i still feel you need a real turbo for response :P

Have you had any change in the behaviour of the braking.. how do ur brakes feel compared to the other silver skyline?? Sorry to say the check valve stops boost entering the brake system so its unlikely to be your problem unless your check valve is broken. Generally if your car goes to stall when you press the brake your brake booster has a leak in the diaphragm.

The brake booster has vacuum pressure on both sides of the diaphragm, when you press the brake pedal in, it lets in atmospheric air pressure into one side of the diaphraghm , the unbalance in the pressures gives you your brake boost. Maybe check your brake lines and get a vacuum tester and check the vacuum at the end of the brake line with the brake pedal both pressed and depressed.. id be keen to check mine as well as its one of the only few places i havent checked for my small air leaks. I think the engine would get a small amount of air from the brake system when the brake is released as the atmospheric air pressure side of the diagraghm gets repressured to vaccum.

Apparently your car can also stall from a few other things in the brake system, like blocked lines, split hoses and a master cylinder leak.. but i dont really see how with my limited knowledge, hopefully an actual mechanic can give us some additional information.. i only learn these things as things on my car break and im looking for answers:P

Jarrod

I have seen this happen on many older cars, pressing the brake pedal repeatedly will either make the engine rev, or stall.

I would check the lines going to the booster and the booster itself as Jarrod mentioned. Listen for a vacuum sound when you depress the brake, that's the booster, you should only hear it while applying pressure. If you still hear vacuum when the brake is depressed and stationary, that could indicate a leak.

Laz

wtf is wrong with 16-19 on idle

For starters, I am using an rb20 ECU, a 0 on any cell on the fuel map is a theoretical Stoich so yeah it may go slightly leaner but not the constant 17-19 i was getting on the way to work today. So i either have a leak, or yeah may be an electrical problem. I might check for voltage drops on the injectors.

Little update on this problem.

I have disconnected my narrow band sensor and fed my Techedge widebands narrowband sim output into the loom. Car is running a lot better mostly sticking at around 14.9arf Still at idle tho its hitting mega lean and slowly moving back to 14.9afr.

I should not have had to replace the sensor as its only a year old. I think it may have been damaged by being too close to the turbo.

Back to the lean idle problem I am thinking there are 2 possible problems.

1. I do in fact still have an air leak. And now that the closed loop is working properly it is able to bring the afrs back to where they should be.

2. My idle needs to be reset.

Will continue to play with it.

afr shouldnt be a constant number at idle i hope you realise . it should swing from rich to lean and back again repeatidly . and i hope its fully warm when your doing this

every time you release the brake pedal you are letting more air into the plenum than the ecu wants in there . hance idle changes

Yes I know when in closed loop the afr should swing rich to lean to rich etc. If you knew exactly how it worked then you would know that anything richer that stoich is seen as rich by the ecu and anything leaner than stoich in seen as lean by the ecu. Meaning the rich to lean to rich swinging should all be very very close to stoich. When monitoring using a wideband you don't actually see the swinging like you would a narrowband guage all you see is a twitch in the numbers/graph.

When having the idle issue my idle is sitting at lean no swinging nothing like that. And yes of course the car has been warmed up first.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • That is surely the biggest gathering of Stageas in North America, ever!
    • Remember kids - if you can't afford to buy 2 GTRs......
    • I know people cry at the price of the Getrag 12-14k for a conversion now, but it really is a nice mid point. Not going to get change from 10k on a gearset installed.  $30k++ for sequential.   I know you run the risk of a damaged used one and parts are hard to get but as a street car gearbox its really hard to beat. If you enjoy a more traditional manual, its the choice no question.     
    • Time to decide what’s more import, your power level or your budget because you’re going to struggle to keep both 
    • Our Southern Highlands Cruise is proudly registered with “R U OK?” Day.  Sometimes the best way to check in on your mates is by getting out for a drive together. Sharing a common passion like cars creates the perfect space to chat, connect, and support each other.  A simple “R U OK?” can make all the difference. Let's enjoy the drive, the company, and look out for one another. PLEASE WEAR YELLOW FOR “R U OK?” DAY Sunday 14th September 2025 9:30AM Meeting Crossroads Homemaker Centre 10:00AM Cruise Departure Via Old Hume Hwy 11:45AM Arrival at Mittagong RSL Club Meet Location: Crossroads Homemaker Centre Final Destination: Mittagong RSL Club *Disclaimer* There will be a lead and follow car so no one should get lost. If you would like to attend or bring others along please put your name down and a +1 as numbers will be needed prior! This is NOT a race and we will all be adhering to all road rules. If this is what you want please come to one of our many track days. This is an official SAU:NSW event and will be run under a CAMS permit. One of the things that really sets our club apart is our commitment to being true enthusiasts. When on normal roads we strive to maintain good relations with the authorities as well as the public in general. When attending one of Skylines Australia NSW events please try to: • Be aware of surrounding environment and act accordingly. • Drive courteously on the state’s roads as a true enthusiast should. • Understand how important it is to maintain the good name of SAU NSW and thus, treat others accordingly. • Any misbehavior will not be tolerated and you will be asked to leave.
×
×
  • Create New...