Jerk When Running Long Distance - Speed Limits Of 65 - 80 And The Rpm Is In 1500 To 1600

[sampa]

Hi All,

I have a Nissan car with QG15DE Engine. The issue Comes when I travel out of Colombo As my investigation this happen when the engine get heated up properly.

Per my experience all auto transmission cars when they reach the speed limit about 65 - 70 KMPH the RPM will drop down to 1500 - 1600 and car will move forward smother with less weight on the engine.

In my car when I travel out station i will get a Jerk when I reduce the gas and try to give gas again (Tate step off from the accelerator for few seconds and put back the step on accelerator) .

This will happen during speed limits of 65 - 80 and the RPM is in 1500 to 1600.

I don't think this is an issue with Gear box since it was change recently. Will this can be a problem wit MAF or TB

Highly appreciate your comments

Thanks,

Sampa

[maheshw]

Hi All,

I have a Nissan car with QG15DE Engine. The issue Comes when I travel out of Colombo As my investigation this happen when the engine get heated up properly.

Per my experience all auto transmission cars when they reach the speed limit about 65 - 70 KMPH the RPM will drop down to 1500 - 1600 and car will move forward smother with less weight on the engine.

In my car when I travel out station i will get a Jerk when I reduce the gas and try to give gas again (Tate step off from the accelerator for few seconds and put back the step on accelerator) .

This will happen during speed limits of 65 - 80 and the RPM is in 1500 to 1600.

I don't think this is an issue with Gear box since it was change recently. Will this can be a problem wit MAF or TB

Highly appreciate your comments

Thanks,

Sampa

you mean you have changed the gear box or atf change only ? when was your last EFI tune up?

[VVTi]

Check you plugs or the COPs... if they are cracked you might be getting a stray spark at high loads.

[NZer]

Check you plugs or the COPs... if they are cracked you might be getting a stray spark at high loads.

I too think this is the issue.

[GayanR]

First get a engine scan done at A*W.....don't go on replacing things...i had a fb14 the same thing happend to me...it was the maf sensor...

[sampa]

Hi All,

Thanks for your valuable thoughts. Plugs was change about 700 KM ago and ATF is also at the same time. EFI Tune up was done about 3000KM ago. And the Gear box was replaced about 20000 KM ago. Before replacing the gear box this issue was there and after the replace it is still there.

I also was thinking this might be due to MAF sensor. But not very sure.

Thanks

sampa

[VVTi]

Plugs may have been changed, but have to checked the COPs (Coils on Plugs) ? if the so called EFI tune was done 3000kms ago, and the GB was replaced 20000KMs ago, clearly the EFU tune did not work, if you claim the trouble was there from the time of the Gearbox change.

I would get the MAF and the COPs checked. Plus have you cleaned/replaced the fuel filter?

A jerk is a sign of fuel starvation or a miss.

BTW, why was the GEarbox changed?

[sampa]

Hi Dude,

The GB was replace due to the gear shifting had an issue. It was suddenly getting in to Neutral while the Gear is in the Drive mode. I checked the fuel filter, it seems like it has replaced recently, I checked the pulgs as well. This issue was there for long time now. It can only re create when I go out of colombo only.

I think I should check the MAF. Any idea whom I can go to check this out

Thanks

Edited October 8, 2013 by sampa

[maheshw]

+1 to VVTi

i too feel that you have not done your jobs propely. how was ur scan report ? any errors ? just chk your plugs+wires+fuel filter and MAF.

[Rumesh88]

I think I should check the MAF. Any idea whom I can go to check this out

While you are at it could you pl check if your QG15DE is fitted with a Swirl Control Valve (SCV - a dash pot close to intake manifold on passenger side). Some QG15DEs like NEO and its successors had this.

[MkX]

This sounds like a fuel starvation problem to me as well. As stated above check MAF sensor. If you haven't changed the fuel filter recently (say with in 12 months) change it and see.

Edit : Based on the info given by you the scenario is 65 - 80Kmph and rpm 1500 - 1600 and travelling for longer period of time. This is the condition that most engines use least amout of fuel.

A clogged fuel filter will not respond immediately for sudden acceleration in this condition, thus result in fuel starvation. However check all above and if you are to change something start it with the fuel filter (provided you din't change it recently)

Edited October 9, 2013 by MkX

[sampa]

Hi

Thanks for the thoughts, Fual filter was change recently. after the filter change I used only 95 octain petrol. Any idea can I clean the MAF sensor in a QG15de engine.

[VVTi]

Why are you using 95 Oct for a car that will run perfectly fine with 90?

You can clean the MAF by removing it, spraying some contact cleaner and fixing it back. Just dont touch the inside of the MAF.