2004.5 Nissan 350Z rough idle problem

[PalmerWMD]

When fully warmed up my Z idles rough.

By fully warmed up I mean not just the coolant temp came to operational value but the oil pressure dropped to its fully warmed up value.the AC has to be off ( as it raises idle).Once I turned off headlight and the symptom increasedas load+rpm dropped.

When problem occurs, idle is right around 700 rpm

The symptom is a rough(ish) idle with even an occasional pop coming from the exhaust like a backfire.

The car is lean though, it throws no codes IAW consult and just seems to miss at idle.

Collins Nissan declared it a non problem as no codes.A local Nissan dealer here in Edgewwood Maryland, R Nissan is much more thourough.

They agree its a problem and seem committed to fixing it.After lots of ohming and conculting they tried a MAF exchange.

Car <seems> to be running better now, but cant tell for sure until I have driven it more, they want me to keep them posted if the MAF fixes it and if not try other solutions.

Other Z's that had this problem have fixed it with either a grounding kit or new coils+ECU.One time a couple of o rings on the injectors needed replacing and fixed it.Another time a plug was loose and let in unmetered air.

I wasnt gonna post this cuz drivability problems are notoriously hard to do over internet but am very open to input.

Fred...

[PalmerWMD]

They exchanged the MAF which a known good one out of a new Z from their lot.

Problem is 2/3rds fixed.

Fred..

[navysnail]

if they arnt too hard to get to, i would just use some electric parts cleaner and a scotch brite pad to clean the main grounding points as that may help if they have a little dirt or corrosion on them from oxidation of aluminum.

[PalmerWMD]

When the grpounding kit goes on it will be well-mounted and I am hopeful I wont have any more issues.

Fred..

[s13sr20chris]

you know this is funny because i have not had this issue with the z33 yet. most of theese newer maf's have been messing up lately but i have not had one on a z33. i will say though that they all seem to have a little shake to them. im glad you posted it even if i have nothing constructive to add at this point. i am interested in the result.

fred- keep an eye on your valve covers. i have seen a bunch of them leak.

[PalmerWMD]

1)you know this is funny because i have not had this issue with the z33 yet. 2)most of theese newer maf's have been messing up lately but i have not had one on a z33. 3)i will say though that they all seem to have a little shake to them. im glad you posted it even if i have nothing constructive to add at this point. 4)fred- keep an eye on your valve covers. i have seen a bunch of them leak.

1)Do you see a lot of Z33's come in?2)Are the MAF's on the other new Nissans same as on Z33?3)So you had a lot of Z33's in and they were idling poor? Mine even had some backfiring type sounds to it as it was idling poor.4)I will. Come spring I will switch to a thicker oil. currently using M1 5w-30, its hot runnign viscosity is lower than that of other 30 weights maybe go to Syntec 0w-30 (the german kind) and M1 0w-40 or even the new Belgian Syntec 5w-40, this should lessen threats of leaks.

Fred..

[s13sr20chris]

i dont see z33s for much other than maint, tires, and grease streaks on the windows.the other mafs appear to be of the same style but they fail more frequently. never had one backfire. i just seem to notice them all running a little bit rough. kind of like th z31 turbo. just rough. yours sounds out of the ordinary though.

[PalmerWMD]

Luckily, it runs a lot better now. revs smoother too.

Fred...

[PalmerWMD]

Check out this post, comments?:zerothread?id=105197

[NISTECH]

I have not seen any 33's come in concerned with idle quality problems, though I have talked to some enthusiast that own them and have done the grounding kit. After the fact they said they noticed a improvement in the quality of the idle and over all acceleration performance. I honestly just blew them off as I figured it was just their imagination trying to justify the purchase of the kit.

As chris said though we have been seeing quite a few maf failures lately primarily on the AD200 part # in the A33 maxi. They have updated that part number and issued a reproram for the ecm to resolve it. I think the program cuts back the amprage on the meter on initial start up incase there is moisture on it so it wont distort the pick up wire. As far as other models we have seen them but not in a pattern like the A33.

A common idle problem we do see on various models is oil levels being 2 high. let your car sit for 20 mins off and check your oil level, I would suggest running it about a MM or so down from the top of the crosshatched area on the stick. NOT below the crosshatch but within it.

[PalmerWMD]

I think I sopke too soon on the Maf.

Fix was maybe 1/3 to half of problem not 2/3rds.

drivability seems improved a bit but idle still poor.

At leastthe loud pops out of the exhaust seem fewer now.

[PalmerWMD]

A common idle problem we do see on various models is oil levels being 2 high. let your car sit for 20 mins off and check your oil level, I would suggest running it about a MM or so down from the top of the crosshatched area on the stick. NOT below the crosshatch but within it.

on side ofthe stick oil is all the way up, but I am going by the side on the stick with the cross hatches.

Usually wait 20-min to 1 hr before checking and am very careful about even terrain (as my old Q was sensitive in oil level measrement it seem to slight unevenness in terrain)

I hope that measuremnt of mine is accurate and reflects whats really in the pan.Did a change yesterday, let drip longish time only filled in 4 2/3rds to prevent overfill despite the5 qt capacity.

Drove it let it sit 30 miniutes checkd oil, looked like it neded another 1/3rd qt so I added the last oil.Total re-fill now exactly 5 qts.

I hope my grounding kit helps. I dont want R nissan to eat eat a huge loss by diagnosing my problem, maybe 'll try to force collins to keep it a couple days butI know they wont do anything beyiond plugging in the consult