Adamk8824

When my car sits for a few hours it loses fuel pressure. The pressure is normal when it is running.

I think fuel is getting into the cylinders as it is rough when it starts and has a very very small knocking for 5 seconds. Car takes 5-7 seconds to start

I have replaced:

Both fuel dampers (with new OEM o rings)
fuel pump
fuel filter
fuel pressure regulator (OEM)
fuel pressure regulator o ring (OEM o ring)
fuel sender unit
gas cap (OEM)
fuel pump seal

the only thing that can possibly be leaking would be injectors or injector o rings? What do you think. I replaced everything else. If it were a line seal, I dont think I would have the knocking from what appears to be fuel bleed into the cylinders. Thanks!

maxiiiboy

Your post is a great example of how not to ask for help. Your post is so bad it hurts reading it.

So, given the pain we have endured, give us some leeway: First, you did not tell us what the problem symptoms are. Instead, you told us what you think the problem is, and how you think the imagined problem should be fixed. Then, you immediately asked us to approve your solution. Are you kidding me/us?

Let's start from basics:

• What are the symptoms of your problem? - be concise and specific. Symptoms only - no hypothesis of your own allowed.
• What were the symptoms way back - before your replaced all those parts listed above, probably needlessly?
• Obviously, you have a strong believe that the problem is fuel-pressure related. Why do you think that? For example, you said that "when my car sits for a few hours it loses fuel pressure". Why do you think this is a problem?

Adamk8824

Because I'm losing fuel pressure which makes the car hard to start. Everything is in the original post.

MadMax SE

First off what grade of gas are you using? This car needs premium to run correctly, other grades will knock in occasion What the other guy means is you didnt post any useful symptoms (ex. uneven exaust tone, shaking more at certain rpm than others, smells, etc. If its running rough and barely starts look at the plugs. if they are wet with gas then your dumping fuel as you thought. if they are black as heck or anyother brand than denso or ngk plugs you will have those issues. this

Adamk8824

Just bought 6 new FIJ0001 Hitachi injectors and an intake plenum seal. I will buy 6 new NGK plugs as well. Will report back once installed. Whats the best NGK plugs?

New engine, 50K miles on it. Plugs are new, 50K miles. Dont know the brand, will replace.

Rough start, long crank, rough idle (not too rough). No other symptoms. Everything else is fine.

MadMax SE

I would idle around 700-800 rpm with my bad plugs and it sits happily at 1k rpm now(5speed version) with the ngk v power i have in now. aslong as you use the proper heat range on the plug any ngk type will do. i would personaly get the v powers. oh and what grade gas do you use, anything lower than 91?

MadMax SE

heck i would get your battery and alternator tested aswell. check all grounds to make sure there not corroded. i had an alternator fail on me in a previois car and right before it failed the car had huge driveability issues like sloppy shifting, hard starts, low rpm ide, and soo much more. ohm testing the coils wouldnt hurt either, theres a thread on that somewhete on here.

Adamk8824

I use 87 octane. I am thinking about getting these plugs. Is the gap and heat range ok?

(NGK 4469 LFR5AIX-11 IX Iridium Plug)

http://www.ngk.com/product.aspx?zpid=9868

• Heat Range: 5
• Longevity: 40-50k
• Gap .043"

I have no patience and bought 6 new plugs as well. Should have new plugs and injectors installed on saturday. Will report back.


I have asked for help on her, and had 3 different mechanics try to fix the long crank issue, all have failed. This would be great to fix.

mclasser

Yikes! Throwing all those parts at the car is one hell of an expensive way to diagnose a problem.

Year/mileage would be helpful.

Adamk8824

2002 maxima 3.5L
177K
New engine and transmission (50K on each) (got both with 0 miles)

I hope its not the alternator. I did short out my battery twice. Had to buy a new one. My amplifiers wire touched while driving.. doh.

I'm doubting it's the alternator as the car starts up right after you turn it off.

sebastian2041

Yikes 87 octane.... Prolly bad plugs since you probably burned them
By using low octane

MadMax SE

Get that 87 out of there!!! everyone that posts these running issues is almost always using 87. you need 91 and heres why. 91 has less of a chance to detonate under pressure. we run 10-1 compression so we need the det resistance. that knocking could be detonating and will absolutely wreck plugs and run like crap. always refer to the uset manual for gas grade type.

Adamk8824

Ughh ill run 93 after plugs and injectors are replaced. I always felt guilty pressing the 87 button

MadMax SE

how is your mpg and power? usualy it will dump fuel if your using 87 to compensate for not using 91 to suppress knock. Running realy rich can kill your catalytic converter aswell. those ngk plugs should work well.

Adamk8824

Dude I get 240 miles per tank! Idk what that equates to but i used to get 320. Power seems alright, could be a bit quicker compared to other maxes ive seen on youtube going 0 to 60.

I get the code p0420 every 4 months. Reset it, and it comes back 4 months later. Odd. Runs fine and passes emissions.

MadMax SE

Thats happening due to the 87 im guessing. my acura cl with a huge downpipe leak was getting that kind of mileage on 91 gas and with a smaller gas tank. The ecu will pull your timing and will reduce power to prevent knocking on the 87 especialy under wide open throttle. If the above poster is right about the plugs being killed i wouldnt doubt the precats are on the way out due to always running pig rich to not detonate. Raw fuel is literaly the death of cats

Adamk8824

ugh i cant afford 2 new precats. Im gonna be stuck driving it until the light wont go away or something happens sadly. I do have a flex pipe leak. Getting the new one installed soon.

MadMax SE

Oh, i forgot you went 50k on the 87..... theres two options for when the cat dies. delete the cats and use an o2 simulator, you get power and no more annoying codes, or buy stocker stuff and enjoy.

Adamk8824

cats have 170K on them. I have a front precat sitting in my closet. It costed me $80. Im nervous to have it installed because its cheap from ebay and not OEM. Probably will wear out in a year.. :/

MadMax SE

You may not need them replaced, if the leak is before the rear o2 sensor then it will missread and throw a code. thr exaust leak and the 87 would directly lead to poor mpg and power, those injectora must be dumping a reckless amount of fuel.

Adamk8824

interesting. had the leak since i have had the car. thanks for the info. On saturday im going to have new flex pipe, new injectors, new sparks and a full tank of 93

MadMax SE

That leak may have saved your primary cat from seeing all that rich exaust. it leaked before it hit it hopefully. in that case the rear cat may be in very well condition. Better buy a neck brace aswell, youll need it for your newly found torque.

sebastian2041

So 93 over 91 octane is fine?

MadMax SE

Yeah, basicaly anything 91 and over it can run. some places advertise premium as 91 or 93 but aslong as its premiun it should be fine.

Adamk8824

I just filled up with shell v power 93 octane and felt a power increase instantly when at wot. Idles a little better. Its obvious it still has a huge flex pipe leak though, steering wheel shakes and my entire hood vibrates and rattles like hell. Ugh my poor engine....

Child_uv_KoRn

iTrader: (7)

I had a crank sensor cause long starts and misfires. It's unlikely, but you can test it just by unplugging and starting it.
Sorry, I don't have any other ideas. If you do a quick restart and it still struggles, then it's not fuel injector. VQs will start and run fine enough on 3 cylinders, so it's pretty much impossible that you have more bad injectors than that.

Out of curiosity, what did the old plugs look like?


It's a shame the ECU isn't spitting out any codes.
Get this issue fixed, gut cats and done.

Adamk8824

Crank sensor was replaced and didn't solve the issue. I will let you know about the plugs. They are prob cheapo and gapped wrong.

Im going to return the y pipe i bought. Its aluminized steel and will rot in 3 years. Going to buy a stainless steel one.

Child_uv_KoRn

iTrader: (7)

Oh, ok, you haven't installed the new plugs, yet. We will be anxiously waiting

MadMax SE

reset the ecu if you didnd get a chance too. it will need to learn long term fuel trims over again. just disconect the battery for a lil while. it may straighten up that idle.

Child_uv_KoRn

iTrader: (7)

5.5, he has to do the pedal dance.

Adamk8824

I have replaced my air filter with a K&N dry filter 3" cone. I had a spectre 3" cone previously.

I have also filled up with 93 premium.

This has made the engine run much smoother. It accelerates much quicker. The old filter was clogged BAD and the 87 octane was like running the engine on water...

The car starts much easier, but still has a rough start (not a long crank anymore).

I'm guessing this is the y pipe leak.

New y pipe, injectors, and spark plugs, coming soon.

I went from 190 miles per tank.... to 200 miles at half a tank. I will probably get 330 miles out of this tank of 93.

I cant imagine the mileage with the new parts. Kinda excited.

My intake manifold is cool enough to hold my hand on it and not take it off.

The engine accelerates so fast I feel the engine (head gasket) or transmission is going to explode.....

NmexMAX

iTrader: (22)

How did you pull that off?

Adamk8824

head gasket and timing chain were toast. Got a re-manufactured engine with 0 miles.

Transmission started going into neutral when driving (right after the new engine). Got a new transmission

NmexMAX

iTrader: (22)

Refurb'd from?

Mattx

iTrader: (2)

I want to know how he more than doubled his gas mileage switching from 87 to 93 and an air filter.

MadMax SE

His car is supposed to run 91 and above, read above to see how. his car was running like crap and the 87 just made things worse. that engine has only 50k so it only makes sense that he has decent mpg with an exaust leak. An air filter can make you run leaner aswell if not tuned, using less gas. if your filter is clogged enough you can run pig rich. now that he is using 91 the cpu set greater timing in all rpm and is more efficient when burning. between the shot plugs, exaust leak, and old air filter we dont know how much timing was pulled in the first place but it was enough for op to notice.

Mattx

iTrader: (2)

I don't care what his issue is more than doubling your gas mileage is highly unlikely. Actually I'd say more like impossible.

Adamk8824

I will upload a pic of the old air filter.... you will then understand why it "almost" doubled.

I am at 266 miles and i still have 1/3 of a tank left. I will let you know the total miles per tank.

As soon as the gas light comes on, I count that as 1 tank. I do not count any miles after the light is on.

Looks like I'm going to get 330 miles this tank, instead of 190.

Once the y pipe and everything else get put in, I will prob get 350 miles per tank

engines USA

MadMax SE

330 a tank isnt enough to say its impossible and think about it, now that it makes more power it can sustain lower rpm operation. for all we know, op had to mash the gas to get the equivilent acceleration as he does now with the tune up and new gas. In this case can we agree that change in driving habits and pressing the gas less can save fuel. If its an auto then that loss in power can cause the torque converter to not lock up at the lower rpms, which is throwing away mpg.

MadMax SE

Youll get a nice bump in torque with the y pipe so you can press the gas a little lighter. Has that knocking issue gone away or is it still knocking away?