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Matt, Mechanical Engineer
Category: Ford
Satisfied Customers: 22896
Experience:  BEng hons Mech engineering, in auto industry 22 years
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hi I have a transit 350 135ps reg hg05 yyr the problem im

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hi I have a transit 350 135ps reg hg05 yyr
the problem i'm experiencing is a slight wobble at idle when hot
if I stop the van for a few minutes and restart the idle is fine
but as soon as it gets to peak temperature 88/90 degrees
the problem reappears the injectors have all been done and I checked the map sensor
the other day expecting it to be crudded up but it was surprisingly clean...the egr has been blocked off...other than the idle problem the van runs superbly

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This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.
As its a mechanical fault it tends not to turn on the fault light and you can sometimes 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 /propane around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
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

Air leaks are very temperature dependent as gaps can open or close up as things expand with heat, so the weather and engine temperature can effect them.

This leads them to be quite intermittent in the case of mild leaks

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

do you still need help with this one?
Customer: replied 4 years ago.
Hi matt im waiting for some parts im convinced its the maf i cant access it at the moment as the head has gone off of one of the fixing screws and i dont want to touch the other one till i know i have a replacement filter box as i cant afford to be without the van i will let you know the outcome,,, reason i think its the maf is if im freewheeling very slowly like you do in traffic sometimes . The idle is fine but as soon as i completely stop you can see the rpm needle drop very slightly and the stutter will start . I put this down to the fact that while im moving there is air flow but once u stop the airflow decreases.. So im going to clean the maf i have a filterbox coming that also has a sensor in it. I'll be in touch

just get back to me on here
Matt, Mechanical Engineer
Category: Ford
Satisfied Customers: 22896
Experience: BEng hons Mech engineering, in auto industry 22 years
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