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Matt
Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 20600
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Vauxhall insignia 2009: i'm utterly desperate. I have

Customer Question

Hello i'm utterly desperate. I have had repeatedly car going into limp mode and everytime it is reset goes for about 300 miles then into limp mode again. Vauxhall says i should send injectors for testing because they are detecting slight misfire. enginds is not running great. I want to send the injectors for checking but as it is a bit expensive i want to be sure every other fault has been eliminated. EGR has been checked by and independent mechanic and injectors have been flushed however he detected slightly lower flow on two injectors.
Submitted: 1 year ago.
Category: UK Car
Expert:  Matt replied 1 year ago.
Hello

I doubt a slightly low flow on 2 injectors is enough for a misfire condition

can you just confirm what engine size and fuel type this is please?
Customer: replied 1 year ago.

Its a diesel 2.0 , 2009. 59reg

Expert:  Matt replied 1 year ago.
Hello

OK 1st check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issues and its best to have the boost pressure measured actually measured with a boost gauge to check that the turbo is healthy and that the sensor is reading correctly

Also worth checking that the glow-plug relay is switching off as they can stick on and leave the glow plugs also on - on some cars this can force it into limp home

also consider changing the fuel filter as if this partially blocked this will reduce pressure

If the above are all OK then try checking for airleaks after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and leans the engine out causing rough running. As its a mechanical fault it tends not to turn on the fault light and you can sometime hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas around each joint in turn. If the engine rev's up you've found your leak.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

its also worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue

On no account touch the sensor wires with anything physical as they are extremely fragile

Expert:  Matt replied 1 year ago.
Hi Stephen

do you still need help?