hermtm2

iTrader: (1)

Hi.

I have 96 I30 which is 131k on it. The car dumpped a lot of gas out despite the O2 sensors and knock sensor were just replaced 3 months ago. It spent 15~16 miles/gal.(premium). I went to a shop to check the engine. They told me the rear exhaust manifold is leaking now so it would make the result.
It will be charged with $300 for only labor without parts. I would like to do that by myself. What do you guys think just go to the shop or try to do that?

Thanks.

pmohr

iTrader: (26)

You could do it, the question is do you have the time, tools, and experience to?

http://forums.maxima.org/showthread.php?t=276737
http://forums.maxima.org/showthread....+rear+manifold

MaxGordon7

iTrader: (36)

If you had a bad manifold as in leaking from a crack, it be loud I would think. I don't see why you couldn't do it, if you have a set of tools. Maybe get a 2nd shop to check it and where are you getting this I30 looked at?(dealership or private garage)
check for code
http://vbxmaxima.8m.com/ecu.html
then check out your codes here
http://vbxmaxima.8m.com/ecudecoder.html
Just to make sure no codes are showing, there are ghost codes that don't trip the light.

hermtm2

iTrader: (1)

I read the haynes repair manual serveral times. My question is I don't know how to support the engine when the engine mount is removed. I don't have an engine hoist. Do you guys know how to support the engine and tranny without a cherry picker?

pmohr

iTrader: (26)

You don't need to remove the crossmember to remove the rear manifold, but apparently it helps. If you remove the crossmember, you don't need any additional support. The TC and trans mounts will hold up the combo just fine.

91parkave

iTrader: (1)

^^^ x2 not to all you will need is a deep socket 14mm for the exaust manifold to y-studs, and y-pipe section, deep socket 12mm for the exaust manifold studs, and a universal joint adapter, oh and the cross member---17mm, now is it a PITA...yes so make sure you have plenty of beer handy, and the you can use a 7/8open end wrench to get your oxygen sensor out when you drop your y-pipe

91parkave

iTrader: (1)

BTW what codes are showing up?? before doing that pain in the *** job i would look into this problem the shop told you about...perhaps a second opinion???

The Wizard

iTrader: (43)

Everyone in here is giving solid advice.

I'll add that there's lots of very good relevant info in here too.

http://forums.maxima.org/showthread.php?t=546529

hermtm2

iTrader: (1)

I don't have any code at all. The shop told me the three possibilities which are the exhaust leak, spark plugs and filters, and timing chains. By the way the exhaust leak would be the primary things.

Tatanko

iTrader: (34)

Does the car seem down on power? Do you hear any leaks with the car running near the rear exhaust manifold? If not, I'd say it's going to be easier and cheaper for you to look at spark plugs first. They're not expensive, and they are maintenance that needs done at some point anyway, may as well replace them.

If you have no codes and you are simply not getting good gas mileage, double-check all your maintenance is up-to-date, not just the spark plugs. Air filter, fuel filter, oil and filter, etc. Make sure your throttlebody is clean, as well as the EGR. Never hurts to seafoam, either.

hermtm2

iTrader: (1)

The spark plugs, air filter, fuel filter, oil and filter were just replaced about 3 month ago to fix the problem. The shop guys told that the exhaust manifold or the gasket would be problem.

91parkave

iTrader: (1)

i call B.S, when was the last time your o2 sensors were replaced?? have you tested your knock sensor as well? fuel filter?? id look into those things as plausable cause of bad gas mileage

Tatanko

iTrader: (34)

Between his original post and the post RIGHT above yours, you'd know everything you mentioned was replaced 3 months ago.

91parkave

iTrader: (1)

^^^^^ you got me there but i still call B.S on the exaust leak causing your bad mileage

KRRZ350

iTrader: (29)

I'll see your BS and raise you the rear axle! Check for binding rear brakes, just confirmed that to be the cause of a local org members 16mpg, they should spin freely for several revolutions, if they don't even spin once. Bingo, there's your 16mpg.

njmaxseltd

iTrader: (19)

There is no corrilation between a leaky exhaust gasket or manifold and your poor gas mileage. Thats not your MPG issue. Look further into it.

Tatanko

iTrader: (34)

Very good point! That is something I am personally having looked into myself soon. I don't drive my car enough while I'm at school to really notice gas mileage much, but on trips it was down quite a bit not to mention I suspiciously went through brake pads in about a year's time

ShiftVQ35

there is something else at fault here. but if you think its the headers, might as well replace them with aftermaket ones. oh and how do you guys manage to work on cars and drink beer ? haha

91parkave

iTrader: (1)

hehhe quite easily

hermtm2

iTrader: (1)

All right. The O2 sensors, knock sensor, fuel filter, air filter, spark plugs, engine oil and filter was replaced by the brand new ones 3 month ago. In addition the throttle body and IACV was also cleaned at that time. The tire pressure was checked and the alignment was completed. I drive the distance at the same time without any extra staffs because I'm just a full time student.

As I told already when the all of the sensors was just replaced, the gas mileage was normal like 20~21 miles/gal.(premium). After 1 month the car was come back to 15~16 miles. It is the exactly same mileage before all of the sensor wasn't replaced.

Thanks.

Tatanko

iTrader: (34)

You know, I'd almost blame the change from "summer" to "winter" gas mixes since it would correspond time-wise, but I don't think it would make that dramatic of a difference.

hermtm2

iTrader: (1)

The gas mileage is getting bad... so 12 mpg/gal now... I have no idea...