Cultus VXRi (EFI) RPM Drops with Light/AC after pressing Clutch

[irtazawaris2000]

@Hassan1991
Fan is showing now on SZ Viewer now.

For RPM fluctuation and drop, I took some screenshots.
I think IAC Valve is functioning fine.
Maybe there's some issue with TP Sensor. My Throttle Sensor is set on a 0.765V at idle. I was doing some R&D on youtube and someone said it should be between 0.88-0.92 (at 0.90 ideally).

(Click on images to see full screenshots)

[Hassan1991]

Usually at 0.8-0.9v you look into the service manual for exact value. I have seen mostly cultus on 0.85-0.87v.
Scroll down. Cultus TPS got idle switch. If it is not working at idle position car does the same.

[irtazawaris2000]

Idle (CTP) Switch is on at idle position.
Voltage of my TP Sensor is not even 0.80. Scanner is showing 0.745V in my condition.
Should I get if fixed? Maybe that'll resolve the RPM Fluctuation and Drop Issue.

[Hassan1991]

Adjust it either way.
In the first sceen shot iacv is at 42% but still the engine rpm is off from desired rpm.
Be sure iacv is okay. Do check for leaks.
I think the problem occurs more often when fan turns on?

[irtazawaris2000]

Sure, I'll get the TP Sensor adjusted then update.

In first screenshot, the AC was On that's why it's at 42% and 190L/min. Without AC, it's 26% and 118L/min.

Fluctuations and dropping mainly occus after driving for 20-30 minutes or more then stopping at Redlight/Speedbreakers, Irrespective of Fan/Light/AC on or off. RPM fluctuate more when Fan/Light/AC are on. Other than fluctuating, the RPM Drops too much for once then get kind of get stable when Fan/Light/AC turned on.

And sometimes if I press clutch while driving, the RPM drops too.

But all of those issues occur after driving for a some time.

[Hassan1991]

Can you make a video when issue occurs and share?

[irtazawaris2000]

@Hassan1991
Other than TPS Voltage, I have another theory:
I noticed that I face the rpm drop/fluctuation issue on idle when it's in 'Closed Loop'..
Closed loop depends on O2 Sensor temperature. (If I'm not wrong).
RPM behaves normal at Cold start when it's at 'Open Loop'.
Can it be a faulty O2 Sensor issue?

Please check the video from here: https://streamable.com/rukrl0

[Hassan1991]

In suzuki ecu goes in close loop when you drive.
Check your wiring of map sensor and tps.
Any leak in vacuum can cause same.
In this video there was no load?

[irtazawaris2000]

@Hassan1991

Ignore the previous video.
Please check the following video of RPM misbehaving:
https://streamable.com/83vyer

RPM is fluctuating between 300 and 950. And whole car is vibrating because of that.
Note: I recorded it at Traffic Redlight after driving for 1 hour. (AC was on while recording)

[Hassan1991]

Engine temp went 101C !
Check the sensors wiring, wiggle them around to see if problem reappears.
Disconnect the iacv and test drive it.

[hammadsohail]

I'm facing somewhat similar issue, rpm fluctuates on Idle A/c 'On' without A/c car idles fine,here's the video https://streamable.com/dvpm9m one more thing as you can see fuel trims are rich,have done everything still unable resolve,only o2 sensor is left is o2 sensor can be bad in my case?

Engine temp went 101C !
Check the sensors wiring, wiggle them around to see if problem reappears.
Disconnect the iacv and test drive it.

[Hassan1991]

Do the same check the wiring and iacv.
It is not rich it's lean, ecu is adding fuel that's why trims are positive.

[hammadsohail]

I still remember one time after throttle service rpms were too high, mechanic had played with the throttle screw which is located under the throttle cable, I think that issue was stuck IAC at that time but he messed up the throttle screw setting, service manual clearly states don't touch that screw, I didn't know anything about it and he did some adjustment and rpms were fine, so now the question is this rpm up/down on A/c is happening because of that screw setting is messed or something else like IAC may be bad or Vacuum leak? If it was vacuum leak I think Rpm should not be stable without A/c too, right? and if that throttle screw could be the reason how can I redo its actual position that was from the factory and how can i test IAC? If testing procedure is through multi meter on ohm setting,i have done that it shows correct reading when i bench test it or is there any other way of test IAC

[Hassan1991]

That shouldn't be messed. Also you cannot adjust it back with iacv connected because iacv continually adjust the rpm.
There can be vacuum leak. Check the voltages on sensors as well. With ac on.
Yes you can if you can provide a pwm in the signal wire with 12v ground as reference.

[hammadsohail]

Yes you can if you can provide a pwm in the signal wire with 12v ground as reference.

Please explain this

[Hassan1991]

You have 3 wires from iacv.
+12v
Ground
Pwm Signal
Provide +12v and ground, after that you need a microcontroller and a mosfet to provide pwm signal to iacv. Frequency of the pwm channel matters as well but you can play around it to atleast test the iacv opening and closing.

[Hassan1991]

Example.

[Hassan1991]

Or you and use 2 pwm signals from a microcontroller.
One to the ground pin of iacv and other to the signal pin of iacv.
Both providing pwm low side signal. Iac will move 0 to 100% depend upon pwm signals.

[irtazawaris2000]

I have changed the Throttle Body and the issue has been resolved.

I drove for almost 60KM and stopped at multiple Redlights, Speedbreakers and Traffic but issue hasn't reappeared again.

I recommend visiting them in Islamabad if someone's issue isn't resolved despite trying everything:

[Hassan1991]

Congrats.
Have check the iacv before that?
Check if there's a gap in the coin at fully close position in old throttle.