[SOLVED] Vitz 2011: Engine shuts down on AC

[muhammedsalarkhan]

Model: 2011
Engine: 1KR-FE 993CC
Milage: 100000
Location: Karachi

ASA Everyone,

My Vitz 2011 was eating allot of oil, it was at 100000 when I got the engine overhauled. Standard pistons were not used, and slightly bigger (50 pachaas) pistons were installed.

The car runs fine without AC, but on AC in the D gear when I brake it to a stop, the engine starts vibrating, the RPMs fall and the engine shuts off.

Went to the mechanic again, checked coils, spark plugs, fuel pressure, everything was fine. But upon inspecting the cat there was allot of crushing noise upon shaking it.

The mechanic theorized that because of this the engine is choking, and so I decided upon bypassing the cat.

But the issue is still there, the engine still shuts off when on AC and stopped in D gear. The throttle response is also sluggish.

I connected a scanner and it shows extreme LTFT, around 15%.

No error codes so far.

Need an expert opinion.

Thanks!

PS: Would be more than happy to provide more information.

[syncview]

If all is well, IE good compression, good fuel pressure, good ignition and no error codes, working VVTi system, good gearbox - check its throttle body operation, these electric throttle body motors get weak overtime and response slowly causing idling issues, specially where compensation for an electrical load is needed.

High LTFT means its adding fuel, because the car is running lean - I'd sort this out before doing anything else.

[muhammedsalarkhan]

Hi @syncview thanks a ton for responding.

I got the throttle body checked, it has no issues, the mechanic even replaced it with a good condition throttle body to be sure, and it had the same issues even with that one.

The mechanic then said that the guy who overhauled your engine has installed a non-metallic gasket that is a bit thick and because of that the compression is low and the engine is not able to generate enough power.

This sounds a bit untrue to me. While I do understand that he might have installed a non-metallic gasket because of whatever reasons - incompetence included. This should not drastically reduce the compression abilities right?

Also I did a mistake in my earlier post the LTFT is not +15% it is around -15%, generally always less than -10%

Another electrician told me that because of removing cat the O2 sensors are not giving the correct readings. I also believe this to be untrue because my friend has a mira that has the cat removed but it does not have a sluggish pick.

There's also a mechanic who said that the VVTi is not advancing quickly because if I gradually increase the car's throttle it goes upto 100Kph and does not show any problems. But the pick is not that great. I wonder if this could be the issue, how can I be sure?? does the system have any error codes for this issue?

Sorry for spamming you with so many questions.

Thanks.

[Hassan1991]

First, be sure your O2 is working fine.
Test it using a good Obd2 tool.
Your secondary O2 should already have popped a check light.
I doubt mechanics even know how VVT systems actually work.
Why don't you log the issue at the moment it arises?

[muhammedsalarkhan]

Hi @Hassan1991

The O2 readings from my OBD2 scanner seem fine, no difference post cat removal, and no codes for a lean/rich mixture. But of course there is a code for cat efficiency below threshold, because the cat is not there. However this was the case even before cat removal as the cat of the car was out of order even when I bought the car.

The wirings are also a bit old.

What do you mean by "Why don't you log the issue at the moment it arises?" do you want the data recordings from the OBD2 device?

[Hassan1991]

hey.
You can log all the data using an obd2 device. That must be the first thing you should consider doing.

[rajaatta]

How many kms have been done so far from day of rebuild

[syncview]

What is the fuel pressure?

[muhammedsalarkhan]

ASA Everyone.

Sorry for being late to post this. But the original problem went away.

The issue was a faulty VVTI gear. It was not able to advance / retard the timing quickly so underload it would just go to very low RPMs in the 400 range and that would stop the engine.

Now the engine vibration has decreased considerably and the average has become really good. I'm getting in the range of 11-12 km/l within city.

There's a new issue however. The engine seems to be missing on low RPMs when cold. I've created a new thread for this issue: https://www.pakwheels.com/forums/t/vitz-2011-jerking-misfiring-on-cold-engine/3013565

Thank you so much.

[muhammedsalarkhan]

I'd say around 1k kilometers till today.

[muhammedsalarkhan]

No idea how I can measure the fuel pressure.

Can't get this data on OBD-II since the fuel rail on my Vitz2011 seems to not have a fuel pressure sensor.

[muhammedsalarkhan]

BTW after changing the VVTI gear the LTFT is under 10% it was always between -5 to 5% when I checked last. So this really convinces me that the core issue is fixed.

[rajaatta]

Check the timing it's not aligned properly either one teeth advance or one teeth is retarded.
Nothing else slight missing on cold and jerks at drive indicates a retarded timing from Cam shafts either exhaust cam is retard or intake cam gear is retard.

[muhammedsalarkhan]

ASA @rajaatta So the day I got the car there was no missing or jerking what so ever on cold or hot start. After 2 days of usage this issue started happening.

Do you think the timing might still be the issue. LTFT and STFT are well within +- 10%. The missing has gotten worse on cold now, the mechanic who replaced the VVTI gear told me that he swapped the ignotion coils and the spark plugs for better ones and also changed the fuel pump as it was leaky.

I suspect that its one of these three components. I have added some more information on the linked post here https://www.pakwheels.com/forums/t/vitz-2011-jerking-misfiring-on-cold-engine/3013565

Would be amazing if you can have a look. Thanks a ton boss!

[rajaatta]

Wsalam
Check the spark plugs and ignition coils as the problem could be in these.
Also perform compression test to ensure its not the tappet or anything else issue

[hzpkf2008]

AOA, please explain how you solved your problem especially when your car stopped while the AC is on.

[nameer.53727]

Hello brother I'm facing same issue in my vitz done almost everything but the rpm & shaking problem is too bad I'm also facing issue of oil evaporation as well you mentioned that it was also an issue

Does changing gear resolved this oil evaporation issue ?
My mechanic said there's issue with ring piston need to change head so he is currently working on it

But the pick is too sluggish thinking to change gear aswell
Your opinion would be great

Regards,
Nami

[Thinking]

Dear reset the ECU of your car (by removing -ve terminal of the battery for 10 minutes). However before doing so get the throttle body cleaned and plugs cleaned and air filter cleaned/replaced as well.

once you have reset the ecu, drive the car for 24 hours (as per your normal routine). it will re learn the AIR OXygen map and will be fine with consistent idle.

Also regarding reducing oil, its by design by toyota for 1KR FE engine (and mentioned in your car manual as well). just keep a check on oil level and keep it topped up to the marked point. do it once a week.