I’m looking for technical help or recommendations on: Double lambda sensor pre-cat, Engine running faulty, lots of white smoke
Hello!
Recently my dad and I rebuilt the engine head on my 1.6 after getting it skimmed, lapping the valves, new gaskets, etc… However it still seems to be running very smokey (lots of white smoke, but it doesn’t always happen? Possibly oil and petrol trapped in the cat?), it idles at high and also struggles to stay on, as if it’s stalling/cutting out while idle.
We’ve tried a few things, tested all the spark plugs, fuel injectors, MAF, engine block pressure and everything seems to be alright. However we then found a single lambda sensor plug that hadn’t been plugged in but was cable tied to another wire, thought this could be the issue? Although we don’t remember doing this and assume it was the owner before us. (As he’d cable tied a few things in the engine bay and obviously cut a few corners elsewhere when working on it)
The quad pin lambda sensor is already plugged in near the coil pack, however we are unable to locate the single pin lambda sensor but are also just wondering why there are two lambda sensors pre-cat? Is this normal?
We are going to try and get underneath the car as I’d read online that the single pin connector goes around the back of the engine somewhere, although I can’t find much more solid information about this, especially for a Monaco edition. The previous owner had replaced the old head and a few other things so we thought maybe he had replaced the exhaust or manifold too?
The last thing is we found another cable at the front of the engine near the cam cover that was also cable tied and have no idea what it’s for, I’ll upload a few pictures.
Hope all this made sense, thank you very much in advance!
Sorry to say that this is not the issue.
The round female connector in your last photo is for power steering. If like me you have a later basic 1.6 MK1 car, no power steering, so orphaned connector. I believe the Monaco was a 1996 basic 1.6 model with no power steering?
There are two lambda boss points on the exhaust. The high point on the manifold where the single wire lambda was fitted to early cars and the lower point on the front pipe where the four wire sensor was mounted for later cars like yours and mine. The top boss hole in the manifold is usually capped with a bolt but in your case someone has blocked it with a an old lambda sensor with the cable cut off from the look of it. The single wire connector near the cam cover/heater pipes looks like a single wire lambda wire and connector; it isn’t doing anything, so I would remove it.
Actually, re-examining the photos, you do not appear to have a lambda sensor plugged in? The lower sensor appears to be in the correct position but is a single wire lambda sensor and not connected. You need to remove that and fit a four wire sensor, correct for your vehicle. I don’t know what is plugged in to the four port plug near the CAS but you may find it is just the wire from the sensor body that has been used to block the top boss hole in the manifold. That does look like a 4 wire body with the wires cut off?
If as I suspect, the engine is running without a lambda sensor, fueling will be all over the place, mainly overfueling, so you would have running issues.
Thank you very much for your response! That was very helpful!!! The 4 pin is connected to the lambda which is in the top. So we shall swap those around and block off/remove the single one.
And yes, the Monaco is a pretty basic, stripped down edition so there’s no power steering and a few other things, wondered why there was a random cable tied to the front Rocker.
Thanks again for your help, appreciate the answer, hopefully this might help a few issues.
Unfortunately, although the four wire lambda is not in the best position, if it is connected and works, it should still do its job.
There is an error flash code for a lambda sensor but not sure what it checks. Your four wire functionality can get lazy or the heater circuit can fail.
I would definitely try your plan of a replacement sensor as that one looks very corroded.
Use the right lambda socket and a breaker bar to remove and expect problems. I had severe problems removing a sensor from the front pipe and it was some sort of miracle that a replacement sensor could be refitted. Hopefully I will never have to touch it again.
That single wire sensor should come out without issue as would never have originally been fitted in that position on the front pipe but the one in the manifold may be there to stay as a bung.
When I replaced the lambda sensor on a Fiesta my daughter had, I used a special socket with an open section on the side to accomodate the cable.
I found this flexed with serious pressure on it and had to resort to wrecking the old sensor so I could use a conventional socket on it to get it out Ivdid use the special socjet to fit the new one though.
The ones I used, picture below, were cheap but effective and not the issue. I had the equivalent of a scaffold bar levering on them, fighting against a galled thread, so no way the fault of the tool.
I kept running the engine to get it hot, allowing it to cool, lubricating the thread, all the while heaving on it with a long lever and it eventually gave way
