Micra jerky at low speeds

[CMF_Richard Guy]

Hi everyone. New member here.I have a manual K11-petrol,1L, 1998, 100,000 km I'm hoping someone can recognize the following symptoms and give me some suggestions; when you come into a roundabout for example ( engine hot) and take your foot off the accelerator it's not smooth - you are thrown forward as the motor 'clunks' into engine braking. Then when you even just touch the accelerator to move into a gap it's the exact opposite - there's a slight hesitation and then you are thrown backwards as the motor 'clunks' in again ( with too much fuel arriving in the cylinders?). Also if you roll along in 2nd and very gently touch the accelerator on and off you rock backwards and forwards in the driver's seat! It can't be doing the transmission any good - very jerky. Other observations; it's most pronounced in 1st and 2nd and it's barely noticeable when the engine is cold. If you roll along for a while in 2nd with your foot off the accelerator ( flat surface ) and then put your foot down it's accelerates off as smooth as anything! Apart from this problem it runs really well ( always starts, 6L/100km)
I don't think it's 'loose' transmission because it happened from one day to the next - after I mucked around with the throttle body so I presumed I'd upset something ( airflow sensor etc). Put in a brand new throttle body ( 80 pounds from Hong Kong ) but it didn't change anything. So I'm wondering if it's not just dirty injectors and it's just a coincidence that it happened when I cleaned the throttle body ( my son's car got dirty injectors from the local petrol station here recently).
Any ideas? Thanks

 

[CMF_Rudy]

engine mount(s)?

 

[CMF_Richard Guy]

OK, thanks Rudy, I'll look into it

 

[CMF_Tinky]

+ 1 engine mounts .Accelerator throttle cable adjustment too tight.

 

[CMF_Richard Guy]

Had engine mounts checked - they're OK. Loosened accelerator cable myself - no difference.
Had injectors cleaned ( they pumped cleaner through with motor running ) - no difference at all.
Like I said the problem started after I mucked around with the throttle body ( don't worry, I regret it! ) ie unplugging and plugging the throttle position sensor and the idle control valve with the motor running to ' see what happens'. Could I have upset the ECU? The mechanic at Nissan plugged in his computer but could only tell me that they're weren't any fault codes. I tried resetting the ECU by unplugging the battery overnight but that didn't change anything either.
Does anyone know how to reset these ECUs or if I've damaged mine? Thanks

 

[CMF_frank2]

sounds like a sensor issue to me richard, have you set the throttle position sensor ? (.5v when closed iirc)

 

[CMF_Tinky]

Fuel filter ? Don't think what you have done could damage ECU.

 

[CMF_Richard Guy]

So, the Aussie in France back again... set throttle position sensor ( from car manual 500 ohms fully closed ie with engine hot ) - no difference so I tried various positions but it doesn't seem to change anything. Then changed the petrol filter - no difference either. When I changed the filter I couldn't see any evidence that the mechanic had taken off hoses to clean the injectors - on Monday I'm going back to see the mechanic ( and his boss ) to ask him to show me exactly how he did it because I reckon I've been duped! They know I can't prove it but I think he just put the bonnet up for a while and probably took the cleaning fluid home to make a bit of cash!
The only leverage I have is the satisfaction survey ( it's part of a chain of garages ) - I want them to do it again ( so it still may be dirty injectors ). Wish me luck!

 

[CMF_Richard Guy]

They cleaned the injectors properly this time ( I watched!). But it didn't change anything. I changed the spark plugs myself ( the old ones looked OK - dry with a bit of light grey coating ) - still made no difference.
It's strange that the motor seems to be running worse with the brand new throttle body ( and using more petrol) than with the one I had on from the wreckers?
The original problem is still there ie. jerking backwards and forwards when you touch the accelerator ( it feels like the petrol arrives too late and too hard - a slight hesitation and then the violent jump forward into acceleration).
Any suggestions?

 

[CMF_Tinky]

High resitance joint in one of the plugs you removed from the T/B, fuel pump relay, dizzy ???? just clutching at straws

 

[CMF_AB-NRML]

Could it be a vacuum leak. Hose not connected, not seated properly, cracked hose... or a gasket under the throttle body?

 

[CMF_Richard Guy]

Thanks for your input guys but unfortunately now I have another problem - I have to change the clutch! Can you believe it.? It won't disengage. At least I know what I have to change!!
Tinky - I already changed the plugs on the TPS and air flow sensor ( used the plugs from my original throttle body ) but it didn't fix the problem - it was one of the first things I tried. It's true I haven't checked the fuel pump relay or dizzy - I'll have a look.
AB-NRML - I'm pretty sure there's no vacuum leak downstream from the butterfly valve because in my searching for leaks I noticed that if you create the slightest leak the motor stalls immediately. And above the butterfly valve there's only the hose to the charcoal canister which I blocked just to test it and it made no difference. But you're absolutely right to suggest a vacuum leak because I feel way out of my depth when it comes to air/fuel pressure issues in the motor and I could be overlooking something ( that's what drives you crazy!).
Anyway first I have to get that clutch changed!

 

[CMF_Richard Guy]

This is a message for Kate ( I answered you by email but it bounced back!),
What a surprise! Sorry I can't help you but I'm still trying to fix my little Micra - the new clutch didn't change anything of course - except that it's taking me to work everyday! In fact since I changed the throttle body it's been using under 6 litres / 100 km - a litre less than before so I should be happy - it's just that the jerkiness is still there!! I'm pretty sure that the solution is to do what they call a closed throttle relearn and I think to do this you need the software to reset the ECU - I just can't bring myself to take it to Nissan and lose control of the situation ( and pay a lot )! I think I caused this problem when I stupidly unplugged and plugged the various plugs around the throttle body while the motor was running to ' see what happened'. If this causes the ECU to ignore the sensor it uses default values - not precise values - but this is only MY theory - my plan is to leave it with a local mechanic to see if he can reset everything.
Please let me know if you get any leads - it's so nice to hear from someone with the same frustration! I'll let you know if I have any success,
Richard

 

[CMF_Bishop]

I'd not fully rule out the throttle body being at fault, even with good fuel economy, those dry solder cracking issues on those pins can effect a rebuild/reman unit as much as a new unit.

Also, you could be facing an issue with the dizzy, a fault with it can cause all sorts of issues, I replaced mine before doing the throttle body resolder, turned out mine was fine, but they can cause a host of different problems.

 

[CMF_Lobster]

Fuel blockage?

 

[CMF_niilo]

Hi Richard.

Am on with same issue - K11 -93 model.

Changed fuel-pump & regulator, but that issue still sometimes shut off engine on traffic lights.
But the "jerkiness" which existed before has almost gone after above replacements.

Going to replace throttle-body from my crashed spare-Micra on some days to see if that helps.