Running wrong

[spud1979]

Anyone any ideas, my mpi engine has suddenly starting chucking as I'm driving along. I done nothing different with it recently. Now when I'm driving it's chucking like mad. I changed the leads and plugs yesterday which made no difference. It has also gone very heavy on juice. Cost me €28 alone from Wexford to Dublin the other day and then another €28 back, crazy. Anyone any idea of what's causing the problem, need to get it sorted ASAP as my daily drive to and from Waterford

[coolmini]

First things first.
Check that you have spark on all spark plugs. Take them all out and rest them on the head. Get someone to crank the engine while you look at the spark plugs.
Next is the negative earth connection for engine . Is it in good nick.
Is the lambda sensor still connected and working if not it may over fuel due to adjusting the mixture from a lean reading.
Generally check all connections for the engine ie sensors like coolant. Again could over fuel as ecu might think engine is still cold. Same with air inlet temp sensor.

[coolmini]

Actually another easy check is to see if the injectors are leaking. As that happened to me. Take the full assembly from the manifold and disconnect the injectors electrical connection only. Turn the ignition on which should start the fuel pump then check to see if there are any leaks.

[spud1979]

Ok thanks

[woody]

Get it onto a diagnostic reader.
Always the best place to start with fuel injection, will save you the time and cost of replacing parts that are not faulty.

[coolmini]

Any luck with it.

hope its behaving itself

[spud1979]

Still no luck. Had ken Irwin looking at it over the weekend at the auto test in Waterford. Says it's one of four things. First was fuel filter, changed, no difference but was full of grit. 2 change plugs and leads. Done no difference. 3. Coil, sourced one today so will try it tomorrow. 4 some sensor on the flywheel. I'll try 3 first and hope that works. Fair expensive on petrol at the moment

[Dylan8660]

You'll find the flywheel sensor is a hall type (there is one sensing the cam for #1 TDC too), it measures the difference in magnetic field from the reluctor ring as the flywheel spins. Generally they are very reliable but if it has got clogged with dirt this can affect performance. Fairly easy take out and clean job, you'll find it underneath and to the rear of the starter motor (top bolt can be a pain to get back in), cam sensor is on the back of the engine, passenger side. Check the condition of the wires while your there, paying attention to where it enters the plug.

[coolmini]

He sensor on the flywheel sometimes collects metal dust and needs to be cleaned. But if that sensor is wrong the car won't run.
Same with the camshaft sensor.
I would still look at temp and map sensors along with checking the injectors as above.

[coolmini]

H and if diagnostics are available the O2 sensor could be the culprit

[spud1979]

Wasn't the coil anyway. Gone off now to be connected to a computer. Hopefully brings something to light

[clubmankev]

I know it's a long shot, but did you check the flux capacitor?

[coolmini]

Ha ha ha haven't heard that one in a while

[coolmini]

Did you get sorted.

[spud1979]

No. Getting the fuel injectors tested tomorrow

[woody]

What did the diagnostics say?

[spud1979]

All clear woody. Only thing I found in checking stuff was grit in the fuel filter when I changing it.

[coolmini]

Diagnostics said all good it means you're getting a false reading from the O2 sensor in the exhaust. Did they check the value of the 02 while plugged in with diagnostic and engine running?

[spud1979]

Just I drove it to Dublin and brought it to the guys in minifix and when I got up there was perfect, so typical. Next morning back to chucking like mad. It's actually worse since I changed fuel filter.

[woody]

Does it happen at idle or only when driving( harder you drive the worse it gets). Possible fuel starvation which wouldn't show up in diagnostics. Faulty pump or relay or bad connection.

[spud1979]

Worse when I actually release the throttle. The choke ain't working now either. It's def something to do with fuel. It's grand when I've the foot down

[woody]

Over fueling? If you look at the plugs are they all the same or are 1,2 different to 3,4. ?That could indicate an injector is faulty. If there the same the it could be fuel pressure, blow out the return pipe. When you had it on diagnostics I presume you did a live test of the sensors and outputs.

[spud1979]

That's what I'm thinking woody, over fueling as it bursting through the tank. Plugs are all brand new along with leads. It went off for the injectors to be tested today so I'll see the results in the morning

[coolmini]

Is the car running or when cold?
As in car starting up before engine reached operating temp.

[spud1979]

No same when got and cold. Garage think they might have found a problem in the wiring loom. Hopefully that's it