Missfire/hesitation/jolting on throttle lift off

[spree]

My Turbo has been doing this slightly ever since I have had it. At certain speeds it is more noticeable but it basically misses a little bit when you pull of the the throttle and the car feels like it has a little hesitation/jolt that makes it feel like it is undecided about what gear it wants to be in as I guess it also unsettles the auto box.

I have just changed the plugs and the fuel pressure regulator. Plus I cleaned the ICV when I got the car as that was causing a funny idle.

I am planning to disconnect the LAMBDA and see if that makes a difference and I'm going to give the throttle body and ICV another clean out anyway plus swap the ignition leads and check the distributor cap and rotor arm.

I am also think maybe worn engine mounts might be contributing.

Any other ideas?

[glasgowjim]

worn engine mounts are not the cause . If the back engine mount is broken you will likely as not feel the car engine throwing forward or back especially if you change the speed suddenly.

This sounds like a problem I had a number of years ago and is more common than you think.

check the engine temp sensor connector for broken wires or bad connection its the one at the spark plug Number 1.

Do a real good check as the wires get brittle as does the plastic connector and it causes an intermittent misfire as if the engine sneezed or miss fired occasionally . It was so noticable that my daughter called her 480 skippy after this fault.

[glasgowjim]

If it is the mounts then a careful visual inspection will reveal the damaged mount. Might have to go under car to see the real engine mount.

[spree]

I just changed that actually Jim as I had a hot starting problem and low idle when it was very warm.

Hot starting is fine now and it seems to idle ok. I do have an occasional issue where or doesn't want to start easily if the car is just a little bit warm. I.e. if I quickly nip down the shops and then start it again but it doesn't happen all the time...

I'm presuming that as those issues were fixed and the car is now reading the correct temp on the info center, that this sensor is ok.

The wiring seems fine to the sensor too.

[doingitsideways]

My 460 Turbo does this too.

Most noticable on very light throttle I.e when cruising at say 30-35mph.

The guage/info centre has it's own sender, as does the fan. The ECU sender is the one Jim mentioned and not related to the others as far as I know.

I had partly put mine down to the alternator being goosed.... That reminds me, still no alternator shaped parcels arrived at Chateaux Sideways!

Steve

[ChrisDK]

It sounds like what I have experienced, although mine is a N/A. Especially cruising at 30-35 mhp like Steve says. The solution was a new MAF (mass airflow sensor) it has't misfired since.

Chris

[spree]

My 460 Turbo does this too.

Most noticable on very light throttle I.e when cruising at say 30-35mph.

The guage/info centre has it's own sender, as does the fan. The ECU sender is the one Jim mentioned and not related to the others as far as I know.

I had partly put mine down to the alternator being goosed.... That reminds me, still no alternator shaped parcels arrived at Chateaux Sideways!

Steve

When the main engine coolant temp sensor went on mine, the same one that you bought the dodgy ebay one for to fix yours but it turned out to be the wiring. It did effect the temp readings at the info center. I don't think its that. So this rules out the temp senders as they are fine and have been recently changed from another car that did not display this particular issue and changing it fixed the symptoms that were manifesting. This is something else.

I am going to swap the MAF sensor next as suggested above!

Sorry about the delay with the alternator. I actually ended up being sent away to work in Istanbul last week and everything went by the wayside.

I am back home now and will get on this tomorrow mate. I'm really sorry.

[spree]

It sounds like what I have experienced, although mine is a N/A. Especially cruising at 30-35 mhp like Steve says. The solution was a new MAF (mass airflow sensor) it has't misfired since.

Chris

Yes mine is most noticeable on light throttle but more like 35-40. I have another MAF lying around so fingers crossed! Cheers for the input.

[spree]

Swapped the MAF sensor quickly today. Made no difference so back to the drawing board.

[ChrisDK]

Sorry to hear it was worth a try. In my case, the HT lead and ditributor, top dead center sensor (do not know if it is the correct term) Cold start sensor and some other things was changed, but only after a new MAF was installed, the problem was solved.

Hope You find a solution to that really annoying problem

cheers
Chris

[spree]

Thanks Chris. I appreciate the help though!

[spree]

OK....I just got stuck at the petrol station for over an hour as it wouldn't start. I finally got it started once it had cooled down sufficiently.

So it looks like the same sort of issues have come back although the temp seems to be reading correctly in the info center. I also do know that there is a separate sender for the temp reading in the info center but all I know is that changing the coolant temp sender fixed it before...

I guess the next step would be to change the coolant temp sensor again for a brand new one...it's strange for it to fail again though! Although it was a second hand one and could possibly have been on its way out anyway..

Still open to suggestions!

[spree]

OK so I stuck a brand new sensor in it today and BINGO. It's fixed. It now drives much more smoothly and has no starting issues.

GlasgowJim was bang-on again!

I am now wondering if it was just bad luck or if there is anything about my car that could be making the temp sender sensors fail early..?!

[Flying Dutchman]

Have the same problems with my 1990 480 Turbo. Jumpy idle, starting issues et cetera. Which sender are to be replaced?

Also, engine water temperature, which is normal driving temperature? Mine says about 78-80 degrees celsius. Isn't that low?

[gltease]

my 480 turbo usually sits between 81-84

[Flying Dutchman]

Changed the "sparkplug No1 sensor" today. Got a slight improvement with lift-off on the throttle and over all a little smoother engine. Beleive it starts easier too, both cold and warm, or there were just coinsidences..? Usually have to run the starter several seconds before it ignites. Just have to see if there are some long term changes ahead.

[jamesy12345]

Have the same problems with my 1990 480 Turbo. Jumpy idle, starting issues et cetera. Which sender are to be replaced?

Also, engine water temperature, which is normal driving temperature? Mine says about 78-80 degrees celsius. Isn't that low?

sounds low to me, although mine is on the original radiator AFAIK so might be running a little hotter than intended. Maybe thermostat sticking open slightly

my 480 turbo usually sits between 81-84

yes something like this on mine also...unless in traffic then can go up to around 90 or so until fan kicks in

[aidanmorris]

Just read this thread whilst searching for some explanation to the recent "uneven" running my car has developed and it sounds like I'm in the right place but not exactly sure as to which sensor I need to replace.

Car was running absolutely perfectly until I went out on a very wet day (serious amounts of standing water) and it started missing and eventually cut out and refused to re-start. Turned out to have water in the distributor cap and a good dry and clean in there has got it starting and running again but ever since its been a.) a bit more hesitant to start (few more turns) and b.) a bit hesitant on throttle lift off. I don't think it's misfiring, idle seems OK and no problems accelerating or driving at high speed but something isn't quite right at lower speeds which chimes with some of the comments below.

Reading the other posts it sounds like it could be the Engine Temperature Sensor or Coolant Temperature Sensor or both?

Any thoughts on which one to start with and where can I get the necessary part(s)?

All advice very gratefully received!

AIDAN

[timrosser]

I'm having a bit of lumpy running too on my 2.0 celeb. Uneven idle, less smooth throttle response, normally a bit of white smoke (like redexing a carb back in the day) around 5 mins after starting. More stall prone. Seems worse in cold weather. My car is LPG converted and the problems seem worse if anything when running the lpg, its certainly more likely to stall and smoke, or stall and then smoke when it agrees to re-start.

Ive tried redex and aerosol injector cleaner with mild improvements, but am out of ideas! Any theory's welcome

Tim