Car rpm doesnot remain stable on AC

[Arish]

I'm facing the very same problem with my civic. Changing plugs and cleaning the throttle body won't help. Just replace the MAF sensor or clean it. And your problem will be solved.

Can you please let me know where is this MAF Sensor located, like a brother showed through the picture , I have a civic 96 and am having the same problem, done with the throttle body, distributor and fuel pump, but no luck. it still drops rpm with AC on on CNG.

[Xulfiqar]

your civic does not have a MAF sensor - its got a MAP sensor on the throttle body, and it very rarely fails - when it does, you will have a check light and fault code for it.

[revengez]

your civic does not have a MAF sensor - its got a MAP sensor on the throttle body, and it very rarely fails - when it does, you will have a check light and fault code for it.

Right....

I don't think so that issue is of MAP sensor as car is normal on petrol as per @OP. Also as you mention, there is engine check light code for it.

There must be some issue with CNG setting.

[Arish]

your civic does not have a MAF sensor - its got a MAP sensor on the throttle body, and it very rarely fails - when it does, you will have a check light and fault code for it.

Dear Xulfiqar, But there is no check light appears in the speedo meter, still the RPM drops.

[Xulfiqar]

clean out the IACV - and please verify that your A/C wiring is not hacked up. the A/C compressor signal is routed through the ECU to increase revs from the idle air control valve.

[mahmood]

clean out the IACV - and please verify that your A/C wiring is not hacked up. the A/C compressor signal is routed through the ECU to increase revs from the idle air control valve.

hacked up is the only last thing remaining to check which is causing my rpm not to go up while turning on AC, but it didnt stall, engine comes under stress but then stabalize in un easy condition, it gotta be something else, i tried changing 3 different MAPs with same code, no luck, IACV is good too, no codes, voltage stable at all sensors, no check light and that makes no sense but i didnt get rpm increase (A)

[Xulfiqar]

your throttle stop screw is messed up badly - (the one that has an allen screw and a locknut, the CNG mehanics love to mess it up)

adjust the entire induction system on petrol, the TPS voltage, the throttle stop and finally set idle from the Base idle set screw on top of the throttle body - you should set the idle speed at 850 rpm. Verify at the rubber plug rpm connector near the brake booster. When switching on the compressor the rpm should remain at 850 rpm. Please verify it does that. If not then look further where the problem is, 60% of the idle problems are because of the fiddling of the throttle stop screw, which then wears out the throttle body bore.

You should also check the PCV valve, it creates vacuum leaks if faulty.

[Devort]

What if i seek the assistance for margalla 97 ?
my car is having same trouble .. its just going down on CNG all of sudden but on petrol is perfect ... i tried getting adjust the RPM and changed the filters too but no success

[ENGINEERzz]

Note it in the pic below.

whts da function of it?

[Xulfiqar]

If you looked at the post below it, you wont ask, its a manually adjusted air bypass to set idle engine rpm - after which its the IACV's job to maintain it.

[ENGINEERzz]

^^thnx xulfiqar bhai

[car_bus2008]

after alot of jiggling with my car.my mechanic solved the problem by tuning the cng kit and said me that change the oil brand.

From Mikking to Mobil Askari Lubricants.

And surprized to see the results no more underpowered engine feeling.No Tappets noise.

[onlyfaith]

^^ amazing to see that poor engine oil may cause these problems..

[mianahsan786110]

brother i have faced same problem with my cultus 2012 model ... my mechanic clean throttle body.. clean air filter .. clean plug... and also scan the car... no other problem but when ac is on car rpm down and atlast turn off....
kindly reply

[dani_kk]

Refrigerant switch isn't connected thats the reason hook it up and wire it up with ecu, rpm will get stable.

[mianahsan786110]

so ac compressor wire connect with the car computer....???