Insanity due to car judder

smaktardis

Hey Y'all,

my car is driving me mad. any tips would be appreciated. its a 1996 micra with 110,000 miles - so it is nothing special but is sufficient for what i need. i have done the servicing on it for the last three years and would like to continue doing it.

Problem:
If i am driving along and i need to lift my foot off the accelerator without using the clutch, the car will judder/jerk/jolt. this judder also happens when i put my foot back on the accelerator no matter how gently and slowly i apply pressure. apart from this problem acceleration (continuous acceleration) is smooth as can be, thankfully.

For example, in slow moving traffic going along in second gear. cars ahead are slowing down but not enough for me to need to apply the brakes. i lift my foot off the accelerator. hey presto; an involuntary head nodding juddering repetitive little annoyance. traffic pulls away a bit so i need to accelerate agin and hey presto; another involuntary head nodding juddering repetitive little annoyance.

ART6

Sounds like a clutch problem. Broken springs or out of alignment clutch plates can cause those symptoms. If it is that it's not wise to leave it. One case I came across was a car doing just that but otherwise seeming to accelerate etc alright. But then a piece of clutch spring managed to swipe the end off the crankshaft rotation sensor, leaving the owner with one very dead car in the side of the road, and a big bill for repairs.

JoeySully

check all air hoses for cracks. could be air flow sensor also.

Darragh29

Could be caused by a few faults.

(1) Possibly oil contamination on the clutch disc linings, caused by a leaking crankshaft oil seal. This will usually cause a shudder when accelerating or slowing down.

(2) Worn engine or gearbox mountings. Get your mechanic to check.

Type 17

Sounds like incorrect fuelling (too much/little for the engine speed/load).

Not sure of the exact setup of these engines, but would look first at the airflow meter and the lambda probe (aka oxygen sensor).

Extra questions to help diagnosis:

Has the fuel economy changed since the problem arose?

Any issues when you floor it in second or third on the open road?

Does it do it all the time or only when it is cold or when it has fully warmed up?

daveharnett

To add to the list of possibilities, I experienced a similar problem which was caused by a loose distributor cap.

smaktardis

Fuel economy is still as good as ever.

When i floor it in second or third it acts as normal too - accelerating evenly and up to high revs.

With a hot or cold engine this happens.

When i am using the clutch (chaning gears, moving off) it is smooth as ever with no clutch slip as far as i can tell. although maybe on a related note, if i release the clutch a bit fast there can be a little knock. just like a soft tap under my feet.

smaktardis

previously someone told me that it was surely the engine mountings. there are four altogether - front, rear, left, right. i replaced the front and it had very little effect. afterwards i heard that the rear is commonly the most problematic.

Type 17

smaktardis wrote: »

Fuel economy is still as good as ever.

When i floor it in second or third it acts as normal too - accelerating evenly and up to high revs.

With a hot or cold engine this happens.

When i am using the clutch (chaning gears, moving off) it is smooth as ever with no clutch slip as far as i can tell. although maybe on a related note, if i release the clutch a bit fast there can be a little knock. just like a soft tap under my feet.

If it was the Lambda, the fuel economy might be noticeably worse, so that looks good

Some engines ignore the Lambda when they are cold, and when you floor it, so if it happens all the time, again it is unlikely to be the Lambda.

The knock when you release the clutch fast is probably normal, but you only noticed it now that you're looking for possible causes of the jerking.

As mentioned, engine mounts are a suspect here, and the rear one gets the most use/abuse in a fwd/transverse layout like yours.

smaktardis

Savage. Thanks for the brainstorming session there folks.
i'll have to consult mister haynes about the gearbox mountings as i know nothing about them.
the distributor cap is on solid tight so that aint loose.

from reading other posts on similar probs i had hoped it may have been just incorrectly adjusted accelerator cable but all will be revealed.
Thanks.

Darragh29

OP, there is a lot of rubbish being posted up here now. You need to check engine & transmission mountings, to see if they are worn. There is no point in just replacing one and hoping that this will resolve the issue. If a mechanic is checking these components, he'll get a lever inside them and see if there is much movement between the mounting and the engine or transmission, whatever the case may be, and make a decision whether or not to change them. If your shuddering is related to the clutch, it will not be due to "misaligned plates" or "broken/loose springs", it will be due to clutch lining oil contamination. You should bring the car to a mechanic you trust and get it properly diagnosed.

pred racer

Darragh29 wrote: »

Could be caused by a few faults.

(1) Possibly oil contamination on the clutch disc linings, caused by a leaking crankshaft oil seal. This will usually cause a shudder when accelerating or slowing down.

(2) Worn engine or gearbox mountings. Get your mechanic to check.

My money would be on the second one, had it a couple of times, very annoying, same as you describe. Easy to fix though.

Bobo78

For the last 2 years since i had my car (Rover 45), i had the same problem with it. Almost every cold morning and sometimes even on normal morning i would have excatly the same problem.
When i would start the engine (first time in the morning) and when i start moving as soon as i would take my foot of the gas pedal engine would start judering and kind of jumping.
But again sometimes it would be perfectly normal. I took it 2 times to computer diagnostic and it showed nothing. So i wasnt really shure what to think or what to do.
Untill this summer man in Dillership told me it might be a coolant temperature sensor.
So just now on Friday i bought the coolant temperature sensor and i replaced it myself on Saturday.
Since Saturday this problem seems to be gone, when i start it in the cold morning it would run normally and it wouldn't judder anymore.

I know you might have a different problem but it may be good idea to check it out as well.

P.S. this would happen only for the first minute or so while the engine is worming up.

Type 17

Bobo78 wrote: »

For the last 2 years since i had my car (Rover 45), i had the same problem with it. Almost every cold morning and sometimes even on normal morning i would have excatly the same problem.
When i would start the engine (first time in the morning) and when i start moving as soon as i would take my foot of the gas pedal engine would start judering and kind of jumping.
But again sometimes it would be perfectly normal. I took it 2 times to computer diagnostic and it showed nothing. So i wasnt really shure what to think or what to do.
Untill this summer man in Dillership told me it might be a coolant temperature sensor.
So just now on Friday i bought the coolant temperature sensor and i replaced it myself on Saturday.
Since Saturday this problem seems to be gone, when i start it in the cold morning it would run normally and it wouldn't judder anymore.

I know you might have a different problem but it may be good idea to check it out as well.

P.S. this would happen only for the first minute or so while the engine is worming up.

Dead temp sensor means that the ECU doesn't know whether then engine is hot or cold and (in Bobo78's case) assumes that it is hot, meaning that it was under-fuelled when cold (mixture too lean), but was ok when it warmed up.

However, this is happening all the time on the OP's car, so it looks less likely to be the issue in his case (but it might be worth getting the sensor tested with a multimeter - should be close to manufacturer-published resistance across the sensor terminals when engine is either cold or has fully warmed up)

Darragh29

Type 17 wrote: »

Dead temp sensor means that the ECU doesn't know whether then engine is hot or cold and (in Bobo78's case) assumes that it is hot, meaning that it was under-fuelled when cold (mixture too lean), but was ok when it warmed up.

However, this is happening all the time on the OP's car, so it looks less likely to be the issue in his case (but it might be worth getting the sensor tested with a multimeter - should be close to manufacturer-published resistance across the sensor terminals when engine is either cold or has fully warmed up)

Look, if that rubbish is the best contribution you can make, will you forget it and go back to your beers ffs... Not a single point you have made above can explain the OP's problem.

ART6

Darragh29 wrote: »

OP, there is a lot of rubbish being posted up here now. You need to check engine & transmission mountings, to see if they are worn. There is no point in just replacing one and hoping that this will resolve the issue. If a mechanic is checking these components, he'll get a lever inside them and see if there is much movement between the mounting and the engine or transmission, whatever the case may be, and make a decision whether or not to change them. If your shuddering is related to the clutch, it will not be due to "misaligned plates" or "broken/loose springs", it will be due to clutch lining oil contamination. You should bring the car to a mechanic you trust and get it properly diagnosed.

Darragh this might be rubbish in your opinion, but the situation I described is exactly what happened to an 8 year old Escort I was involved with recently. A clutch spring had broken, and the clutch was out of line across its diameter. The owner put up with the intermittant judder until a piece of the spring wiped off the end of the crankshaft sensor. When the clutch was stripped, it waas found to have also damaged the flywheel. So, new clutch, flywheel, and sensor. Not cheap.

smaktardis

I suppose it could be something dodgy on the fuel supply too.
I changed the fuel filter about 8 months ago with one from Halfords.
The accelerator cable has just a little slackness - as it should be i believe.
The idle speed is ok too - i checked this with throttle potentiometer disconnected.

I tried to compare the engine mounts to a mates micra of similar mileage while stationary but it was hard to pinpoint anything.

Left and right engine mounts look kinda worn but have no major cracks or tears. the rear bottom mount looks solid enough but is hard to say with a couple of hundred kilos sitting on top of it.

Type 17

smaktardis wrote: »

I suppose it could be something dodgy on the fuel supply too.
I changed the fuel filter about 8 months ago with one from Halfords.
The accelerator cable has just a little slackness - as it should be i believe.
The idle speed is ok too - i checked this with throttle potentiometer disconnected.

I tried to compare the engine mounts to a mates micra of similar mileage while stationary but it was hard to pinpoint anything.

Left and right engine mounts look kinda worn but have no major cracks or tears. the rear bottom mount looks solid enough but is hard to say with a couple of hundred kilos sitting on top of it.

Fuel starvation is unlikely here, as you would get problems only when you required more fuel, not when you took your foot off the accelerator.
Contamination would affect the idle (and almost every other driving situation) so it's not that either.
The best way to check the engine mounts is to open the bonnet, chock the wheels (or rely on the handbrake, if it is strong and healthy) and then rev up the engine to about 1500 rpm and gently lift the clutch (similar to doing a hill-start) - while doing this, observe (or get a mate to observe) how much the engine twists on its mountings - shouldn't be more than about 2 cm unless you're really wearing the clutch/revving hard. Do it in first to check the rear mount, and reverse to check the front one (on a fwd/transverse layout like yours, the two side mounts aren't subject to torque-loading, they just take the dead weight of the engine).

If your mate has a similar car, do it in his too, to see if the deflection of the engine is very different.

Although you should always check everything you can think of, I don't think that your issue is the engine mounts, my money is still on mis-fuelling through a faulty sensor.

smaktardis

might be worth mentioning that this problem does not occur while i am reversing the car. I have tested this out at different speeds.

Type 17

smaktardis wrote: »

might be worth mentioning that this problem does not occur while i am reversing the car. I have tested this out at different speeds.

In that case, I would look more closely at the rear engine mount (but don't rule anything out until you're sure what it actually is)