Outer Limits 4x4 Board

hey this morning i was messing around with my carby trying to make it idle better when cold and i adjusted the screw shown in the picture number 14 (Because it looked like it wasn't doing anything..i.e Never touched it's stop)... I was driving tonight and i noticed that when i had my head lights on that the carby would rapidly jump between 2000 and 2500rpm like i was reving the engine.. I poped the bonnet and found that the little arm (Number 11) was moving in and out every 2 secconds). When i turned the lights off it idles normally.. Any ideas on why this is happening?

Might be helpful? Doesnt exactly match your pic but if you follow these steps to correctly adjust your #14 screw you should be fine.

Idle-Up Operation
1. Start the engine, and allow it to reach normal operating temperature.
2. Ensure that the idle speed is correct
3. While turning the tail lights, license plate lights and side marker lights ON, ensure that the idle-up actuator rod moves down (11&12)(indicating that the idle-up is working).
4. Ensure that the heater fan, rear defogger, and air conditioner (if equipped) are all turned OFF. Turn the headlights ON, then check the engine idle-up speed (rpm). The idle-up speed should be 900–1000 rpm. If the idle-up speed is not as specified, adjust it by turning the adjusting screw (#14)
5. Turn the headlights and other lights OFF.
6. Turn the rear defogger ON, and ensure that the idle-up actuator rod moves down, as in Step 3. Perform this step also with the air conditioner and the heater fan. In all three cases, the idle-up actuator rod should move down and increase the vehicle's idle speed to 900–1000 rpm.
7. If the actuator rod does not move as indicated, there is a problem with the Three-Way Switching Valve (TWSV), the TWSV circuit, or the actuator itself. also in your case BVSV

Opps, double post deleted

I've got this problem at the moment :( $105 for a new TWSV from Suzuki.

I know my TWSV is the problem because I've checked:

1) Voltage to TWSV solenoid goes to constant 12.4'ish (doesn't waver) when headlights etc are turned on, so TWSV should pull in and stay in

2) Bypassing the TWSV and connecting the TWSV source vacuum valve directly to the idle up actuator - idle up occurs and stays constant

So I have constant voltage and source vacuum to the TWSV, so the only problem for mine can be with the TWSV itself. Am going to pull it apart on the weekend and see if there's an air leak somewhere.

your TWSV is not letting vacuum through

I pulled apart a spare stuffed VSV i had of my vit (same sort of device). is basically just an elecromagnet valve. When the valve has no current a spring holds it shut. then the coil is energised the magnet pushes against the spring opening the valve and vacume gets to the idle up diaphram (a long as the car is warm and BVSV is open). If you pull it apart you could find one of 4 things (since you know it has Voltage)

1. its seized shut and just need lube
2. its blocked and needs clean out
3. your have vac leak in the TWSV and vacuum isn't getting to the idle up diaphram. (you might need to replace some o-rings (thats what my VSV's have top and bottom))
4. the electromagent itself is stuffed = U.S. & replace

Edit: thinking about it a, VSV of a EFI vit shoud do the trick if you have one lying around, if you were perth i'd loan you my working spare to test.

Nah, the problem is exactly the same as suzukigav's - the idle advance diaphragm pulls in, then releases, pulls in, then releases, about every 2 secs. Both inputs to the TWSV (electrical and vacuum) are constant, so it must be the TWSV that is stuffed and causing the idle advance to regularly cut in and out.

I suspect that either there's an air leak (most probable) or that the electromagnet is stuffed and spring tension is pulling the valve shut a second or two after the electromagnet opens it.

Will let you know once I've had it out on the weekend.

For the moment I've just disconnected the TWSV, connected the 'source' vacuum line to the idle advance diaphragm direct so that idle advance is permanently on, and then adjusted the screw back to approx 1100rpm idle. That's getting me by for the moment.

I had the impression that suzukigav's idle up was okay until he adjusted his idle up screw in the search for better cold idle.

I suspected that the idle up had been wound on too much so that when he turned the lights on the idle up would activate causing the revs would go to 2500rpm which would cause the idle up to cut out causing revs to drop to 2000rpm at which point the idle up would come back on and the cycle would repeat. I may be wrong in your case

easy enough to test. hook your TWSV up to battery and check and see if it holds open. then block one side with a peice of vacuum hose with a BB in it and see if the TWSV holds vacuum while open.

Given that your idle up is set at 1100 rpm (a bit high but close) what happens when you disconnect the contant vacuume, do the revs drop to a healthy 750ish (if not adjust normal idle screw until it is). If they do try hooking the TWSV back up without re-adjusting the idle up screw. then turn the lights on. If the revs come back up to 1100 then your idle up system is working correctly.

Just my thoughts, not necessarily correct.

PCRman you are correct... It was ok until i adjusted the screw...

suzukigav wrote:PCRman you are correct... It was ok until i adjusted the screw...

yep thought so. Have you wound it back off (with the lights on) until your revs are 1000 ish?

Problem solved Thanks PCRman