Judder/hesitation at low revs when crawling in traffic, 1.8 Titanium petrol.

[The Joshua Tree]

One thing i've noticed with the Titanium that i bought recently is that it doesn't like sitting in traffic at low revs, if you try to crawl forward it can be a bit stuttery and hesitant. It's a 1.8 petrol Titanium on a 2008 plate. It's fine once you get upto normal speeds, it just doesn't like crawling along at low revs.

Any ideas ?

[spurswes]

Have you given it a good run up the motorway? My Zetec climate was stuttery going up hill when the revs dropped a bit so I took it for a good blast and been perfect since

[v530anh]

This is just a guess, maybe the ecu is getting some wrong readings. Try spraying contact cleaner on the mass air sensor.

[The Joshua Tree]

Is the MAF sensor on a focus connected to the air ducting or somewhere around the collar area where it connects to the air box, I'll get some  contact cleaner later and spray both ends of the connector.

[v530anh]

It is on the collar area on mine, I also recommend Comma contact cleaner.

It is worth doing as a dirty MAF can destroy an engine.

[briscaF1]

This is interesting. I have a 1.6 Focus (2010) and it hestitates/judders just once in a journey not long after starting (but not on the first pull away from rest). It almost always happens when the air is cooler and the engine has been running for a couple of minutes (like when it's not on "full choke") then it's perfect for the rest of a journey.

Could this be the MAF?

When you say it can destroy an engine, what does this mean? Should they be replaced periodically or should they produce an error code if they are going faulty enough to cause this damage?

Thanks

[v530anh]

I believe it is a part of the regular maintenance of the car. Best to do when you change the air filter. If it is dirty it would lead to poor engine performance which would lead to pre mature engine failure.

[The Joshua Tree]

I've just had a look around where the air box is and my car doesn't have the MAF sensor in the place where i've seen them in online images and youtube videos, it's not on the neck where the air pipe meets the air box. 

[Tdci-Peter]

11 hours ago, The Joshua Tree said:

my car doesn't have the MAF sensor

The Mk2 / 2A 1.8 usually has a TMAP (Temperature & Manifold Absolute Pressure) sensor. Normally aspirated engines do not need both a MAP & a MAF. The air flow can be computed from the MAP and the rpm. In both cases (MAP & MAF), the fuel is then finely adjusted using signals from the O2 sensors to maintain the optimum mix.

So it could be the TMAP sensor. But for unsteady idle, or unsteady low speed operation, I would put ignition first (plugs, leads, coil pack), then throttle body.

[The Joshua Tree]

Thanks for the help.

I'll do what you suggested Peter, i'll start with new plugs and leads and see how that goes then if their is no improvement i'll change the coil pack.

Is their any particular brands of plugs and leads that are best suited to a Focus esp a 1.8 petrol.

[mjt]

Hi Rob, the 1.8 petrol doesn't have a coil pack or high tension leads. It has a coil built into each plug cover.

[mjt]

On 29/10/2016 at 7:22 PM, briscaF1 said:

it hestitates/judders just once in a journey not long after starting (but not on the first pull away from rest). It almost always happens when the air is cooler and the engine has been running for a couple of minutes (like when it's not on "full choke") then it's perfect for the rest of a journey

I have exactly the same symptoms with ours.

[The Joshua Tree]

Same colour as mine as well, maybe it's the colour that's causing the hesitation and judder lol

MJT, i'm not an expert when it comes to mechanics, i just know the basics. So if you were me would you start with the plugs then if that doesn't work start to change the coils, would you change them in pairs or change all 4 at once ?

Also as well as the judder/hesitation my idle seems to bounce around a bit, it drops off low then picks up etc

[mjt]

Personally I have to disagree with Peter on this one. I doubt that it's an ignition problem from what you've described. Ignition coils, plugs, HT leads (on cars that have them) are more likely to break down when the engine is under load with the consequent higher compression pressures.

You probably need to get it checked for DTCs. If that doesn't pinpoint anything you might even have to get it monitored for running data.

[briscaF1]

Hi,

 I have monitored mine. I happen to have some automotive kit (CANBUS sniffer) and I have lots of data from the car but nothing to interpret the data with (i.e. "databases" that convert the log file into some human readable).

Anyone have anything .dbc files for this purpose? Maybe if I can solve this on mine, I can assist all.

Cheers

[v530anh]

I just cleaned my MAF sensor yesterday. It seemed to have 3 sensors, also the PCV filter. As I changed panel k & n filter for a cone filter with a heat shield. I normally have judder on starting the car from first to second gear, now the ride is smooth and efficient.

Though you have a TMAP sensor. But I would agree with Peter and start with the usual suspects spark plugs and coils.

[Tdci-Peter]

18 hours ago, mjt said:

I doubt that it's an ignition problem from what you've described. Ignition coils, plugs, HT leads (on cars that have them) are more likely to break down when the engine is under load with the consequent higher compression pressures.

I would agree with Mike (mjt) there! Higher pressure needs more voltage and hence finds weak points in the ignition system.

TBH, I do not have a lot of experience with modern petrol injected cars, all but one of my petrol cars have been carbs, with coils and distributors. From those, I do know that cold, damp starts can also affect ignition systems.

For the TMAP, major electrical contact problems cause wild or out-of-range readings which usually put up a DTC & the EML, if more than very occasional. Calibration shifts (which can be due to leaks in the sensor or its hose or seals), are usually removed by the action of the O2 sensors. There are fuel trim values in the engine that adjust to compensate for this, and can be read by a good diagnostic system.

Throttle body problems are moderately common, but major errors will raise DTCs & the EML. They have a duplicated position sensor, with two outputs, and differences above a certain limit will raise a DTC. Though there is a weakness, the supply connections to the sensors are common. But if the throttle valve is a bit sticky, or the sensor outputs are a little bit noisy or variable, this could give the symptoms described, of uneven running at low throttle openings, without the EML on.

I put ignition first, 'cos it is a lot easier to eliminate this before tackling the often harder to access, and more expensive, throttle body.

But overall, like Mike says above, using a good diagnostic system like Forscan or possibly Torque, is the only way to even attempt to avoid random part changing. It can monitor fuel trims, throttle body position & accelerator pedal position, and look for DTCs that can be present even with the EML off.

Or, just simply say that petrol engines, especially once they have a few k miles on them, do not work well at low rpm. These hesitancy & judder problems seem pretty common, with no simple, common answer!

 

[mjt]

6 minutes ago, Tdci-Peter said:

all but one of my petrol cars have been carbs, with coils and distributors. From those, I do know that cold, damp starts can also affect ignition systems

Many of us have been there, Peter. Life was a lot simpler then.

In the case of this 1.8, though, as I've pointed out the plugs each have a dedicated coil built into the cap so all electrical feeds are low-voltage and there isn't the same possibilty of HT tracking across wet leads. Add to that the fact that the car is misbehaving after it's fully warmed up and I think that would rule out cold and damp. To me this behaviour looks very much more like a fuelling problem. In the old days you could have put it down to a partially blocked idling jet (actually most of the cars I owned that had carbs were fitted with SU's, brilliant bits of kit, so didn't suffer from that).

For one who claims to have little knowledge of modern petrol cars you seem to be pretty clued up to me.