[GTR Jon]

Sorry if this is in the wrong section but i was wondering if anyone could help me with this problem.
Most of the time my R32 GTR idles perfectly and drives perfectly but every now and then it can be idling fine and then for no reason the revs drop and it sounds like its about to cut out!? If i rev it they rise but still lumpy though sometimes this fixes the problem too. Same when driving, it can be pulling well and then it will just back off and if i dip the clutch it will cut out, when i release the clutch it will fire up and sometimes then be ok and sometimes still feel like it wants to die??
I've put new plugs in last week. When i got it though the maf was not connected so i plugged it back in. Tonight when it was idling and sounded like it was gonna cut out i blipped the throttle and then the revs started sitting higher than normal, i tried unplugging the maf which caused the revs to rise a bit and then it levelled off and was fine. Plugged it back in and it was still idling perfect. Does it sound like the maf or is it more likely to be a bad earth somewhere?
Sorry for the essay though i might aswel describe the whole picture while im at it.
Anyone had this problem before?

 

[stehub]

mmm it sound like you have a loose wire maybe around gearbox is the earth strap near that, i would say its an earth related issue.

 

[kennyc]

what kind of dump valve you got?

 

[GTR Jon]

Cheers for the help mate, that confirms what someone else has told me it would be too! Best get looking.

 

[GTR Jon]

what kind of dump valve you got?

I doesnt make any kind of chuff so im assuming its just the standard one!?

 

[slegros]

Check the coils as well, I had a bad one and the symptoms were similar although not exactly what you mention. R32's and early 33's are notorious for bad coils.

 

[GTR Jon]

Its worth a look, though it does have a very new looking set of splitfires.

 

[tyndago]

Bad MAF will do something similar. Like you suspect. Also could be small vacuum leak. Check around the base of the injectors first.

 

[GTR Jon]

Right i've checked the coil packs and all are fine, i've replaced the battery and found a loose earth but its now sorted and the problem is just getting worse. On a short run out earlier i had to put the hazards on 3 times!
When i got the car there were 2 plugs not connected which i now know are for the o2 sensors. We unplugged the sensors today and it seemed to fix the problem with putting them back on causing it to die. However while driving home without them connected it died on me again!
I can put my foot to the floor and it struggles to get over 1200 rpm, if i sit for a bit or leave engine off for a bit its ok but while driving it varies from a lack of power at times to actually slowing down when i push the throttle.
Could it be that the faulty o2 sensors are causing it to run like that and with them not being connected the same happens as there is no reading and therefore also causing it to run like sh1t.
Also it has a new idle control valve and inlet manifold gasket.
Could it be the ecu? It has a Garage Saurus sticker on it!?
This is really frustrating me so i'd be very grateful for any help at all. I've only had the car on the road a few days and its even more annoying than the weather!

 

[stehub]

oh man does the car run fine now and again then all suddenly it runs poor ?? is this what you are saying like it has mind of its own ??? sometimes runs fine then runs shit ??

could it be the plug gaps ?? but you say it sometimes runs ok ??

 

[stehub]

i think you for surely have an elctrical fault or sensor related or even vacuum leak am sure a technical gtr person on this forum will be able to help you more jon.

 

[GTR Jon]

Yeah it can run perfect and idle perfect and then for no reason just goes to sh1t. Sometimes if you rev it a bit it'll sort itself out and other times it'll have none of it. Occasionally it will also jump from idling at 1k rpm and then sit at 1200 rpm for no reason also. Though usually after it has just tried to cut out!?!?!
I would like to just take it to Abbey or somewhere, but i really dont fancy my chances as i'd probably be on the hard shoulder every 10 mins!

 

[tyndago]

Yeah it can run perfect and idle perfect and then for no reason just goes to sh1t. Sometimes if you rev it a bit it'll sort itself out and other times it'll have none of it. Occasionally it will also jump from idling at 1k rpm and then sit at 1200 rpm for no reason also. Though usually after it has just tried to cut out!?!?!

90% of the time its a bad MAF. Does exactly what you are saying. Comes and goes, good sometimes, then just wont rev.

It won't throw a check engine light as its within parameters, but its normally telling the ECU a lot of air is coming in, it goes rich and dies out.

The boards in the MAF have issues.

 

[GTR Jon]

So do you suggest i just try replacing the maf? How many are there on the GTR? and any idea on the price? What about the o2 sensors is it worth changing them while i am on? Could it be possible that it is running worse now as i did not put as much octane booster in with the optimax? As it was running much better when i put more in but i ran out at the last fill up so it only got half as much! Or am i just being stupid?
Sorry for all the questions lol.

 

[stehub]

another possible cause engine temp sensor (ecu one)

 

[tyndago]

So do you suggest i just try replacing the maf? How many are there on the GTR? and any idea on the price? What about the o2 sensors is it worth changing them while i am on?

There are 2 MAF's on a GT-R. They fail enough to be called a common problem. Try the old method...with the engine running and idling tap each sensor and see if the idle changes. If it does, then its a sensor 100%. I have seen a bad sensor pass this little ghetto test though.

02 sensors. Most cars I run have aftermarket ECU's so I just unplug them , turn them off, or replace with a true wideband 02 sensor.

Stock ECU's can get a little ****ed off though. You might find out that when you change the MAF, the 02 sensor issue may go away. One thing disconnected to mask another issue.

s it was running much better when i put more in but i ran out at the last fill up so it only got half as much! Or am i just being stupid?

You answered your own question there.

 

[GTR Jon]

Ok thanks for the help! I'll change the mafs and report back :thumbsup:

 

[GTR Jon]

Update: Cleaned both airflow sensors with carb cleaner and the car is running fine! Big thanks for all the help lads. Saved me endless grief and money! :thumbsup:

 

[stehub]

cool now when do we see the pics of your car mate

 

[GTR Jon]

As soon as there is a little bit of sun to show the paintwork . Done some research and it has been sprayed Acura/Honda NSX midnight purple
Looks lovely but in this weather there's no point in taking any pics as they dont do it justice.