Pajero Vibration on Idle

[Hbahrameh]

Hi friends. Actually i have 2 problem which is on of them is same. By the way i have pajero 3.5 v6 24valve 6g74.

1- i have engine vibration on the idle. I checkd the engine mounts . Timing belt and also timing. Spark plug and wires changed . Oil changed . Vacuum leakage  checked by splashing water around the manifold. Fuel pump checked and also the injection parts got clean. But still i have engine vibration at 700-850

2- after one hours driving  engine start to lose the rpm to 550 even 500. Also in traffic jam is horrible . When the gear is on D rpm reach to 500 but all these problems comes after 30 or 1 hours driving in the  Traffice . Your feeling is like the  car lose the power. But in the highway no problem. 

Also i clean the icv valve and throttle body.  EGR . I get tired i dont now what should i do. Becuse i cant stuck down in the traffice also i afraid  to use the AC on the Traffice. Because when i get more load from engine i lose more rpm. 

[Gaurav]

I can certainly (90%) relate this issue to faulty ICV (Idle Control Valve), as I had the same and done exactly same things like you. ICV cannot be cleaned, you have to replace with brand new one from Habtoor. I know its damn expensive, but that's the only cure.

Btw, which year your Pajero is and how many kms is it driven? Do you have race adjuster under the throttle body wire (screw system), so that you can increase RPM to test and see if it helps.

[treks]

Gaurav is right about this. There is no cure except to to replace the Idle Control Valve. On models that can be adjusted the relief is usually short-lived, so just replace the ICV with an OEM part.

[Rahimdad]

@Hbahrameh I can vouch for what Gaurav is saying as I have seen him suffer after having slightly better response from all the treatments advised, when we checked the pressure from the valves there were those that were failing to produce the figures and need to change the ICV before seeing any good results. Now Gaurav's Pajero is running like a dream and is on stock power as when it left the showroom floor.

[Hbahrameh]

dear friends 

thanks for your quick answer.

well. when i turn the steering wheel the RPM goes up very gently and also when switch on the AC. RPM goes on 930-940 . but after 1 hours driving in traffic engine voice change to like a mustang  and rpm is come around 550 - 600 also when i came to the  home i opened the hood and turn the air screw a little bit open to increase the rpm . but i open it (1 turn) to reach to 800 and tomorrow morning when i turn on  the car after idling rpm stay on around 960- 980 and again i turn back the air screw to where it was. and rpm comes to 900. so if you believe that the icv has problem i will change it. but i feel there is some problem like the ECU delay or like this. be cause when i press the gas rpm goes to 4000 and release it rpm comes to 1100 and then engine try to find idle around the 920  and when shift the gear to D rpm comes to 810. i thing engine is dizzy. 

[Gaurav]

I lived on that adjustment for over a month too and felt exactly same as you explained. I also felt that Engine or ECU has some issue. In my case it was even more weird that once I start in morning RPM used to be dead low like 500, so bump up to 900 with screw and after 15 mins when car is warm it reaches to 1400. This exact is the job of Idle control Valve to keep maintaining ideal RPM in cold or warm engine in idling. I found that setting of 1200 when warm was perfect as when cold it drop to 600 without stalling the car, but again in some crazy days all these hacking goes for a toss and again car stall as idle is dependent on the air temperature to create perfect fuel+air mixture.

As I mentioned before it is certainly ICV and many garage and mechanic knows this but INTENTIONALLY don't disclose this to rip your wallet. I have experience 3000 dhs quote (without warranty) from Cars Clinic aka Salim Ali Bin Haider Car Repair  - 30 years old garage in umm ramool, just to initiate the guesswork program and then cost me further to cure this issue. Few weeks later after bit of research I changed the ICV (600 dhs) and car was super smooth.

Btw, I paid 250 dhs and 1 week wait just to get below misleading diagnosis.

[Barry]

Hahaha @ the above diagnosis. We don't know what's wrong so we're just going to change everything. 

[Gaurav]

@Hbahrameh  Any update if you have fixed your problem.....?

[Hbahrameh]

Hi gaurav

thanks for your reply 

The ICV will reach on Thursday.so i will update u by friday. By the way, one qustion what is the exact adjusment for air mixture screw ( air bypass screw) ? 

Thanks again buddy.

[Gaurav]

When you fix a new ICV, RPM will be little rough and don't worry it will slowly re-learn the ideal idle RPM. After 5-10 km in stop and go drive pattern unscrew the whole RPM adjuster, car will stall for 2-3 time and after that automatically adjust the RPM when cold and hot. After all that's what the job of ICV (Idle Control valve).

Some people also says if it doesn't re-learn then unplug the battery terminal completely for 5-10 minutes and it will reset all ICV reading. In my case 6G74 engine, ICV re-learn the perfect setting in 15-20 minutes drive in internal roads where you slow down and speed up every 300-400 meter (not highway).