Engine going into Open Loop mode Randomly - Cultus VXRi 2008

[RehanBhatti]

Yes. That could be the reason.

[aminjafer5441]

On terminals with multimeter the voltage is always above 13 volts

[engnr.mubashir]

No bro not always but it does show more voltage than OBD port.

[RehanBhatti]

OBD port show low voltage due to old and low quality suzuki wiring loom as you earlier told me in your post.

[engnr.mubashir]

@aminjafer5441 I am telling this guy as he said battery terminals show volts always abluve 13

[aminjafer5441]

Sorry forgot to mention that it always shows above 13volts only when engine is on else battery voltage is usually around 12.5 volts

[humayun.chughtai.7]

I also got a cultus 08 efi last week. Hooked up my bluetooth obd2 adapter to see why the fan is not running automatically, it was direct previously.

Khair somehow managed to check the wiring & diagnosed the issue. It was due to bad transistor on the ecu which sends signal to radiator fan relay.

Tried to find this transistor from market but it wasnt available anywhere, so went to my local ecu repairing shop, he charged me 500 & replaced that transistor from another scrap ecu.

At first I also noticed that the ecu remain in open loop while idling,I thought my 02 sensor may also needs replacement, khair when I took it to drive, ecu shifted to close loop & LTFT was also in negatives.

Previously due to direct fan, it was continuously running in open loop & was hogging fuel like anything, but after the auto fan job, its running perfectly fine. Alhamdolillah !

[humayun.chughtai.7]

Here is a pic of that transistor, which is responsible for auto fan.

[humayun.chughtai.7]

Btw guys, did the fuel pump in your cars goes off after 3-5 sec, when you switch ON the ignition but dont start the engine ?

Actually in my cultus, it keeps running continuously when I switch ON the ignition, whereas I think it should go off after 3 to 5 seconds.

[RehanBhatti]

Good to know that you solved radiator fan issue. My fan's intermittent function was a headache for me untill I bought that bluetooth scanner and figured out a bad ground to engine coolant temp sensor.
Btw, what is your LTFT readings? Would you like to share scanner's screen shots while engine running.

[RehanBhatti]

Mine goes off in 3-4 seconds.

[aminjafer5441]

Yes fuel pump goes off in 3 to 5 seconds. Probably some electrician has wired the relay to turn on when switch is turned to ignition instead of ecu signal.
Also I think the ECU of cultus VXRi is very faulty. Just recently I had to have the IC for ignition changed as it was burnt and car had no spark when starting cold engine in the morning.

[humayun.chughtai.7]

sure ... will share some screenshots today.

[humayun.chughtai.7]

ohh thats really bad, actually nothing happen to these IC's/transistors in ecu untill some desi lectrician fiddle out with the wiring harnesses in order to know which one is positive, negative & signal wire.

During this procedure, they usually fry some IC/transistor.

[humayun.chughtai.7]

Interesting findings about ECT.

So how did you got to know that something at coolant temp sensor is at fault.

I think coolant temp sensor koi values hi show nahi krta hoga on the SZ Viewer.

[RehanBhatti]

I observed sudden fluctuations in coolant temp even on engine idle. That bluetooth scanner with SZviewer app is great tool to diagnose such issues.

[RehanBhatti]

Bhai, is your engine's LTFT negative in single digit or in double digits?

[humayun.chughtai.7]

its in double digits, as far as I remember, LTFT varies around -10 to -15

[RehanBhatti]

Double digits positive or negative LTFT is not good bro. Mine is around positive 11 but I couldnt the reason of it.

[humayun.chughtai.7]

I mixed up the LTFT with Total fuel trim, took some screenshots for you. Take a look.