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Nissan Primera GA16DE 1997 - Poor performance #

Posted by Richard Endean on November 22, 2010, 4:55 pm

Year of Manufacture *: 1997
Engine Size and Code *: GA16DE
( Optional ) Scanner Used: Blink codes

Starts and idles fine but sluggish when you try to accelerate. Basically sounds retarded. No fault codes, fuel pressure ok, exhaust not blocked, cam and ignition timing ok plugs ok. Gas readings ok at idle but don't seem to go rich when you blip the throttle. Checked TPS and AFM outputs and injector duration increases to about 8ms when you accelerate.

You can drive it but it just ain't quite right.

Any ideas?

Dick

Re: Nissan Primera - poor performance

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on November 22, 2010, 6:47 pm, in reply to "Nissan Primera - poor performance"
Peter Mutlow

Evening Dick,

Faulty AFM is being shouted at me by the symptoms you describe. Has the AFM been scoped and what is the max voltage reading? Someone may come along soon and suggest fuel flow although to be honest I can never understand the correlation between flow and pressure.. Might be worth changing fuel filter if you are happy with the AFM.

Regards

Pete M

Re: Nissan Primera - poor performance

Posted by aidan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on November 22, 2010, 7:38 pm, in reply to "Re: Nissan Primera - poor performance"
Aidan Birley

Dick

What is the manifold vacuum at idle ?

Does the o2 sensor go rich when accelerating ?

Cheers Aidan

Re: Nissan Primera - poor performance

Posted by Richard Endean <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2939' width='330' height='300' border=0 style='border:none;'> on November 23, 2010, 4:34 pm, in reply to "Re: Nissan Primera - poor performance"
Richard Endean

Thanks guys,

I checked the afm with a Fluke meter and it went to about 3.8 / 4.0 volts. I haven't checked vacuum but to answer Aidan's question, no, the 02 does not go rich when you blip throttle - it switches fine at idle but is fairly weak at no load steady throttle.

The fuel pressure staying steady at full load makes me think there are no flow issues - and someones recently fitted a filter.

I'm inclined to agree with the afm suggestion but not had any experience with this type. If I scope it should I expect a similar trace to the Bosch hot wire types?

Ta
Dick

Re: Nissan Primera - poor performance

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on November 23, 2010, 6:55 pm, in reply to "Re: Nissan Primera - poor performance"
Peter Mutlow

Evening Dick,

I assume the filter was fitted to try and cure the problem. I would expect to see a similar trace to that of the Bosch hot wire variant. Now to confuse things... I would expect to see a higher voltage than 3.8/4.0 volts maybe up to about 4.5v. However the AFM will only record the amount of air passing through it so if the throttle was wide open and there some other fault with the vehicle such as blocked exhaust etc, you won't get a max reading from the AFM. So a low reading on an AFM could be a sympton..rather than the cause.

The fact that the O2 sensor does not go rich when you blip the throttle also indicates an AFM problem...assuming everything else checks out ok.

Regards

Pete M

Re: Nissan Primera - poor performance

Posted by Richard Endean <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2939' width='330' height='300' border=0 style='border:none;'> on November 23, 2010, 8:42 pm, in reply to "Re: Nissan Primera - poor performance"
Richard Endean

Thanks Pete,

Tried removing cat etc. and it just gets noisier! I'll scope the afm when it's back in but it certainly looks promising. I'm guessing I'll have to fit a complete throttle body as it doesn't really look 'removable'.

Thanks again,
Dick

Re: Nissan Primera - poor performance

Posted by aidan birley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on November 23, 2010, 10:34 pm, in reply to "Re: Nissan Primera - poor performance"
Aidan Birley

hi

>>> The fact that the O2 sensor does not go rich when you blip the throttle also indicates an AFM problem...assuming everything else checks out ok <<<
I would agree with that statement from Pete,

Still think a Vac test would be a GOOD idea

Cheers Aidan

Re: Nissan Primera - poor performance

Posted by Gwyn Williams <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5354' width='330' height='300' border=0 style='border:none;'> on November 23, 2010, 11:02 pm, in reply to "Re: Nissan Primera - poor performance"
Gwyn Williams

I might not have the right AFM, has it got a filament type sensor? If so,try cleaning it very gently. Have found lots with muck burnt onto the elements. there are two sensors inside the throttle body. Let us know! HTH, Gwyn

Fuel Flow v Fuel Pressure

Posted by Peter Warman <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=Peter+Warman' width='330' height='300' border=0 style='border:none;'> on November 25, 2010, 1:24 pm, in reply to "Re: Nissan Primera - poor performance"
Peter Warman - Administrator

Hi Peter

"Someone may come along soon and suggest fuel flow although to be honest I can never understand the correlation between flow and pressure"

This may be a good one for the Technical Theory board

I have been reading through a very long thread on iATN about this very subject, here is a good quote:

"The best way to demonstrate it, take a water hose and barely turn the water on and put your thumb over the end and notice how much pressure you know have, but you have almost no volume of water coming out of the hose, same with fuel, you can have a clogged filter and plenty of pressure but not volume"

I think many Techs struggle to get their head around the pressure and flow thing

So is using just a Fuel Pressure Gauge enough? or do you always need to check the flow as well (under load) ie: with a Coda

Peter

Re: Fuel Flow v Fuel Pressure

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on November 25, 2010, 8:00 pm, in reply to "Fuel Flow v Fuel Pressure"
Peter Mutlow

Evening Peter,

Thanks for that...to save hijacking Dick's thread, I will move this onto the Technical and Theory Forum.....once I have alleviated myself from this headache and extracted myself from my back-side..

Regards

Pete M

Re: Fuel Flow v Fuel Pressure

Posted by Richard Endean <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2939' width='330' height='300' border=0 style='border:none;'> on November 25, 2010, 11:21 pm, in reply to "Re: Fuel Flow v Fuel Pressure"
Richard Endean

Well, I did a bit more testing on this thing today and I am happy to concur with the afm diagnosis. I couldn't get to 4V at any point. So, a quick call to the dealer for a starting point.....1200 quid !!

Tried the usual suspects for aftermarket and no go. I thought about Gwyn's suggestion of trying to clean it but the car drove in and I wanted it to drive out so couldn't take any chances.

So that's where the story ends for now, the customer is trying ebay & breakers for a replacement.

Back to the hose pipe analogy on pressure and flow, if the pressure remains constant when you increase demand by removing your thumb (or opening throttle) there is sufficient flow - there is no hidden science here. In an automotive situation, it's not always possible to create maximum demand whilst measuring pressure but that's a different problem. My Primera was gasping like a good 'un whilst the pressure stayed spot on spec so there was absolutely no need to check further.

Thanks all for your input,

Dick

Re: Fuel Flow v Fuel Pressure

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on November 29, 2010, 1:41 pm, in reply to "Re: Fuel Flow v Fuel Pressure"
Mark Carter

Hi, Pressure can mean air, as in aerated fuel and not pure fuel, Flow is important and should always be checked as the head scratching starts.

Regards mark.

Modern cars, Its all wizardry and witchcraft

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