Not starting.

jamesrabel wrote: ↑Wed Jul 13, 2022 11:07 am I can hear a faint hissing sound on strong accelerations once its warm. I noticed something on the air filter housing : the plastic tube that connects to the air throttle has a broken tongue on the tube POSSIBLY leading to a very small gap, could this be leading the ecu to believe there is an air intake problem?

Hello jamesrabel. A quick patch up of the potential hole will prove things either way.

My car has yet again reverted back to not starting at all, with the air throttle flapping everywhere. This is despite the fact i put the original air throttle back on, im lost for words. Not only that but as long as the car wont start i cant find the air leak....

Intermittent electrical faults can often be traced back to poor connections at the plugs and sockets involved. Just unplugging and plugging back together can be enough to clean the contacts.


With the flapping valve it could well be a poor connection making that flap.

I have a haynes manual, thanks to that ive been able to check nearly every single engine connector and all seem in good shape, no corrosion.
It is possible that the potential hissing i heard around the injection area is from the vacuum hose? With the air filter housing I have, its tube connecter to the throttle has a broken plastic component possibly letting small amounts of air in, but i have not heard any noise in that area.
Is it possible with a mix of both, the MAF sensor just cant supply the engine with sufficient air?
What exact components could tell the maff sensor to flap? And why the hell does it make a loud buzzing noise when my cat actually decides to start? There are too many symptoms for me to figure out whats going on, all the computer readings on the car indicate maf sensor/throttle issues... but it has all been changed and verified....

If there is an air leak it would be a loose inlet manifold or the vacuum line to PCV or the brake booster has come off.
Here is what's involved in removing/checking the inlet manifold.Click HERE
A lot of cars have vacuum lines running from the inlet manifold to various actuators and stuff, but the TU3JP engine does not! Only to the booster. If it has come off your booster the brake peddle will be very stiff.

The electronic throttle body will "squeal" when the ignition is on and can be heard if the engine is not running. Usually it cant be heard above the noise of the engine.

When the engine is warm and running, the purge valve may be heard "clicking" or "rattling".

The PCV (Positive Crankcase Ventilation) hoses collect oil vapor from the top of the rocker cover and send it into the engine to be burnt.
If the hose connected to the inlet pipe is damaged dust will get into the engine. But that's about all.
If the hose connected to the inlet plenum is damaged it will effect the performance of the engine. Should still start but wont perform very well (it's the same as a vacuum leak).

The TU3JP engine control module senses the amount of air being drawn into the engine by the MAP (Manifold Absolute Pressure) sensor. If you disconnect this sensor, the engine control module will go into "fall back" mode and the engine may run better. If it does, then the sensor is broken.

You should pull the spark plugs out and inspect them. They may give you a clue.

The other "usual suspect" is the crank angle sensor. This is on the front of the engine between the engine and the gearbox. The shape of it depends on whether your car is a manual or automatic.

Coil packs can cause trouble too.

Thank you that has given le a few ideas. When i sayd the car rarely starts, its once every 40 or 50 tries so the car just doesnt work. I tried running it witouth maf or map sensor, still to no avail. Not starting one bit.
Im glad the humming noise is normal. When the manifold made the humming noise when turning ignition, i knew it would work. OtherWise, the air manifold flaps around, thats when i know the car will NOT start.
I have bought a obd2 reader because i cant bring it to the garage anymore since its immobilised.
Another friend of mine who repairs hundreds of cars suggested the crankshaft position sensor, usually a clean does the job. Also been told that the lamba sensor before the catalyser can cause this issue aswell. Must not forget the error coming from the engine is a faulty manifold (its not the manifold), and for this model of car, this error could point to faulty oil pressure sensor, lambda, map or crankshaft sensor. Its definetly eletrical, so im gonna work down all 4 sensors 1 by 1, reset faults every time and hope my car works.
The air leak on the car wasnt sufficient to not start the car, but i was worried the ECU wasnt letting the car start due to faulty air intake, but that cant happen because the main symptom of this breakdown is the unusual manifold flapping. If the air intake was faulty, it would only declare the fault AFTER trying to start the car, not as soon as i put the ignition in. So it has to be eletrical.

Crankshaft is a bit of work for me, i only have a poor parking lot with very rudimentary tools, i will have to purchase the necessary items to work around the crankshaft. Thank you for your help, its been very usefull.
If you have any other ideas i would be glad to hear them!

I have attached a photo of a connecter behind the engine, underneath the manifold. What the hell is ut and why is that not connected to anything?

You will often find unconnected plugs on the engine bay loom. This is not a problem unless someone has got to it first.

The extra plugs are often used on options not fitted to all engine, for example; some have extra emission control features in different countries but use the same loom.

Again, thanks for your priceless info. I tried changing crankshaft sensor to no avail, got a voltmeter and obd2 coming in the mail soon, gonna see how much i can get done with both and keep the board up to date on the car. I hope whoever else has problems like this with their C3 can solve their issues thanks to the thread.

Yet again, find myself in a stupid situation. Car still doesnt start. Ordered OBD2 ready, a pretty cheap one that had good reviews. Figures that my c3 doesnt seem to support obd2, I heard something about VAN/CAN but i dont seem do get it. Any ideas on what software is needed to read and erase errors on this particular model?
(Obd2 reader works on my wifes car)