Hi, did a search couldnt find anything about this.
Im trying to get my 1.4 '97 306 through its MOT but its failing on the emmissions.
For the MOT ive just changed the Lambda sensor and Cat and its recently had a new coil pack, air filter and plugs and leads.
The exhaust doesnt seem to have any leaks and my mechanic has cleaned off all the sensors.
During the test it needs to be revved a bit to get the co2 level down but after it does fine on the fast idle test. As soon as you take the foot off the accelerator for the idle test the co2 shoots up and it fails.
When im driving it, also, if i slow down for a corner and change down a gear it sometimes backfires.
The plugs get pretty sooty too!
Youll be my hero if you can help me out!
|
This really needs the ECU codes/live-data reading to see what's going on; but firstly, what engine code is it. In '97 there were several different fuelling systems fitted to the 1.4's.
Look at the letters of the chassis number at the base of the windscreen and see if it contains a sequence like KFX; KDW; KDZ; KDX or similar. Each different system has it's own foibles that might cause this idle richness.
|
|
Its got KFX in the code...
|
|
|
|
NB
On that year KFX should[?] be the first of the Marelli multi-point systems. On those the main check points for high idle CO are: blocked breather hoses; the oxygen [Lambda] sensor and it's plug/wiring: the ECU's coolant sensor and the MAP sensor in the end of the manifold. If it's still got one fitted on the fuel rail; the fuel pressure regulator and it's vacuum hose could also be worth a check.
Just about the only effective way to sort this problem is to connect a scanner to the ECU and, as well as checking fault-codes, watch the live-data and see which sensor is giving implausible information. There is a small chance on these that the ECU could have been spiked by a coil-pack fault; so if the sensor parameters are all OK, having the ECU tested is one option. It's more usual for that fault to affect the idle speed stability, so leave that to last.
The backfiring on the over-run symptom is concerning too; are you 100% certain that there's no air-leak into the exhaust manifold or the front-pipe - the slightest leak there would fit those emission readings to a tee.
|
Thanks mate I will look into it and get back to you.
If anyone else has any other suggestions keep em coming!
|
|
|
|
