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Matt
Matt, Engineer
Category: Car
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Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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Guys..pulling..steering..the accelerator started acting

Resolved Question:

Hi guys,

I have a 3-year old Diahatsu Terios. Yesterday on the way home I had some problems: A pulling sensation in the steering...felt like a flat tire, but didn't have one. Then the accelerator started acting unpredictably--racing, then not. Hard to manage the car. It got worse and worse. Fortunately, I was almost home and managed to get it parked before it became undriveble. Not brakes. They were fine, thank goodness. Might be transmission in some way. It seemed very "jumpy." I just had it fully serviced (30,000 mile do everything service) last week. Could they have not connected a hose or forgotten some kind of fluid? Wierd. Never had a car do this.

Thanks
Submitted: 3 years ago.
Category: Car
Expert:  Matt replied 3 years ago.
Hello

this sounds a bit odd so it may be a combination of faults I'd start by checking for worn suspension joints - jack the car up so the wheel is off the ground ( you'll need to do this for all 4 corners) and shake the tyre from top to bottom and from side to side (with someone holding the steering wheel on the front) there should be no play in either direction. Any play in 1 direction will usually require a joint to be replaced, if there’s play in both directions then the wheel bearing may be at fault. If theres play only up and down its the strut top mount - to find this one you have to shake the suspension strut it self up and down with the wheel off the ground - so you may need to remove the wheel to check this one.
Now with the car jacked up on that side with the wheel about 2 inches off the ground use a steel bar under the wheel and lever the wheel up and down slightly, you should be able to look at the end of the axle and see if the suspension arm is moving up and down separately to the axle.If so replace the bush

Also check for a worn drive shaft joint - typically these won't produce any vibration unless badly damaged but they can be noisy for a long time beforehand, turn the steering to full lock and look at the drive-shaft rubber boot there should be no rips or tears in it and the suspension should be clean and dry of any grease. If you reverse at a reasonable speed with the steering on full lock a worn joint will 'click'.

let me know what you find
Customer: replied 3 years ago.
Why would this cause my engine to race and accelerator to be unpredictable? Should I have the car towed to the dealer (about 3 Km away) or do you think I could drive it over there if followed by a friend? I honestly don't think it's the tires/wheels. I think it's something to do with the engine. But it does have that wierd pulling effect. I had something vaguely similar to this when a mechanic changed the oil and pinched off the brakeline and forgot to remove it. Very heavy pulling. But that happened immediately. This thing happened in about aXXXXXhome and got progressively worse. And the work on the car was done several days ago.
Expert:  Matt replied 3 years ago.
Hello

I'm thinking that if you've failed a driveshaft joint then this will cause the engine to race away and its only moving foward by virtue of the 4wd system tying itself in knots

Its very easy to check a joint as if you lift the bonnet and look at the shaft whilst your assistant gently pulls away you should see if both shafts are turning at the same speed

If it was just engine related then it 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 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 /propane 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

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

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

if the garage is only 3km away then I'd suggest having your friend tow it over there rather than try and limp it over there as you may do more damage

So try check joints as I've mentioned 1st and let me know

Customer: replied 3 years ago.

Thanks, Matt,

 

I'll get the car over to the shop somehow and see what they say. I'll get back to you with what happened.

I've been hitting some speed bumps pretty hard and also been weaving around them pretty fast. Maybe I did wear something out. I'll let you know.

Toni

Expert:  Matt replied 3 years ago.
Good luck
Matt, Engineer
Category: Car
Satisfied Customers: 17283
Experience: Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
Matt and other Car Specialists are ready to help you
Customer: replied 3 years ago.
Thanks. I didn't sound like an idiot when I took my car in. What I had done was accidently press the 4x4 button and was trying to drive on the open highway at high speed in four-wheel drive. The mechanic gave me a driving lesson for which I was humbly thankful. And thank you.
Expert:  Matt replied 3 years ago.
Still at least nothing serious

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Matt
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Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.