6cyl-97maxima

Ok guys, here we go. I've been having an issue with my 97 GXE Max's performance. For the past year I have noticed a progressive decline in performance. When it first started, it wasn't very noticeable and I thought it was just in my head. But as time went on it started to become more and more apparent. Now its so bad that I can't even bother to try and pass slow drivers anymore.

Symptoms: -very noticeable powerloss.
-gas millage is horrible
-light throttle works but anything over 1/4 throttle and the powerloss becomes an issue.

-slight/very mild roughness to idle when stopped in drive.

- when I tap the throttle for a split second, in park or "N", the rpms will drop normally until it hits 1000rpm, at which point it will pause/hold there for a second before returning to the normal 750rpm idle.

- I can sometimes hear a strange noise, (like a whooshing/gushing noise at wot. Kinda like how it would sound if you were to blow through a straw as hard as you could. ( this could be because of the leak at my flex section however)

- power is much better when the car is dead cold, as it warms up the power drops significantly!

- around the same time the powerloss occurred my a/c stopped working. And the belt would squeak on start-up.

Things I have tried:
- replaced the spark plugs with ngk coppers. (A visual check of the plugs showed a nice brownish tan burning tip).

- visually cheked coil packs, (they look brand new and there wasn't a drop of oil in the plug cylinder). They were all Hasian(sp) coils though.

- changed fuel filter. (Rusty or brown colour gas came out the bottom)

- cleaned MAF sensor & TB
- sprayed MAF cleaner around vacuum hoses with engine running. There was no change in idle rpm.

- checked PCV valve and it seemed bad, it rattled and didn't fully seal when blowing through it. So I do plan to replace that.

- checked and cleaned grounds

ECU codes:
- p0325 (knock sensor)
- p0141 (downstream o2)
- evap. Code (filler neck leaks)

I have been doing a ton of searching and its helped a lot. But I feel I am at the point now where having my own thread would be helpful as I can now be walked through the steps as to what to do from here.

Thanks in advanced

njmaxseltd

iTrader: (19)

Those are your clues, lets address them.

The whooshing - Do you have an aftermarket Y pipe and if so take it down and check for a collapsed lining in the flex section.

But the second one might even be a better clue, the fact that it's OK cold and drops off when it's hot.
That is classic for a plugged catalytic converter. You can have a mechanic check that by measuring the vacuum at the intake when the car's acting up or by looking at the MAF signal during acceleration. If the cat's clogged, the MAF readings will be very low. The engine is an air pump, if part of it is plugged, it can't pump air and you don't have power. Easy to spot for somebody who knows what their doing.

Good luck!

6cyl-97maxima

Clogged cat is where I was leaning too as well. I just didn't say that that's what I thought it was because I wanted a non-influenced opinion. I am still running the stock y-pipe with likely original pre-cats. So one of those pre-cats are probably plugged.
OK I do have an obdII reader and an app. That allows me to look at MAF readings in real time. At idle, (once warm at 750-800rpms the MAF reads a steady 3 g/s. One time I looked at it when I was heavy on the throttle and I saw it spike right out to over 100 g/s. What are the parameters I should be watching for with the MAF readings? Like how much g/s at idle, light throttle, medium throttle, and WOT? Once I know what the normal MAF readings should be, then I will be able to compare to my MAF readings.
Thanks for the help so far! And helping to verify what I suspected. Once I review the MAF readings I will then feel more comfortable tearing the exhaust apart. And another good reason to upgrade to a warpspeed y!
Thanks
Nathan

njmaxseltd

iTrader: (19)

I don't know the specs, but if you've seen it over 100 with heavy throttle, you should see a much lower reading if the cats are clogged. You'll also see the MAF reading change from cold operation. To hot operation. That's a signature of a clogged cat.

6cyl-97maxima

Well I'm going to take the car for a drive while way watching the Maf readings. Then ill report back with my findings. What do I watch for to see if the readings are going from hot to cold operation

Thanks so far

6cyl-97maxima

OK, so I did some quick MAF readings over my lunch break. I didn't get as many readings under variable conditions as I would of liked to, as its hard to watch the road anood watch the readings at the same time. But here is what I got...

MAF readings in g/s (grams per second).
Cold engine at idle:
RPM: 1275, Throttle %: 1%, MAF g/s: 9

Warm engine at idle:
RPM: 700-712, Throttle %: 0%, MAF g/s: 3

Warm engine at light acceleration:
RPM: 1600, throttle %: 10%, MAF g/s: 23-24

Warm engine at medium acceleration:
RPM: 2537, Throttle %: 50%, MAF g/s: 60

Warm engine at heavy acceleration:
RPM: 5300, Throttle %: 88%, MAF g/s: 145-148.

Hopefully these readings will help you guys lead me in the right direction.

PS: what is a normal amount of load the engine should be under? At idle in park/nutural, is 21% as soon as I shift to drive it jumps to 32%, when I get on the gas lightly it spikes to 60%, if I'm half on the throttle it will spike to 100% easily. I can't remember what it is at WOT but If it could read higher than 100% I bet it would be at 250% during WOT!

6cyl-97maxima

Anyone that can help me make sense of the above MAF readings or can tell me if my engine loads are normal and if they coould be the cause of the performance issues.
Do others think I may have a plugged cat, I just really want to get my MAX back to the fun powerful car that I miss.
What other systems I could check and compare with stock specs.
I'm really hoping that the members on this forum will stick with it/me until the problem is resolved.
I owe my mechanic $1200.00 and can't get him to look at my MAX until paied. So I really need to figure this out myself!
Please let me know where to go from hear and what to check next.
Should I just go ahead and gut my cats and see if things get better?
Anymore advice would really be helpful!

Thanks
Nathan

PS: another symptom that I have noticed, which may or may not be related, is when I go to start the car I will turn the key all ACC stuff powers up like it should. But sometimes I will get a no crank condition, if I turn the key off and back on and try again it will then crank and start no problem. Is this related? Possible CPS issue? Could this be part of my overall power problem?

6cyl-97maxima

The power loss problem has gotten a bit better, but its still nowhere near where she should be. It seems more responsive and bogs/hesitates less I can pass a car if I need to now. But sometimes the bogging/hesitation comes back mostly when I'm at a higher speed or accelerating up to speed heavy on the throttle then suddenly let off and get back on the throttle quickly then it gets bogy/hesitant. If I ease the throttle down, instead of slamming it down, I will get less hesitation/bog. Works much better when colder.
Now back to the fact that its running better sometimes, I can't really think of what I have done exactly to make her a bit better, these are the things that I did since I posted last...
Since I run my car dry on gas more than I liked to, I decided to change out the fuel filter, (which I already mentioned, in a pervious post), when that seem to make a small, (possibly placebo), change I then thought that it wouldn't hurt to start running fuel injector cleaner through the system. I usually only put $10-$20 in per fill, so I do the math and add the correct amount of injector cleaner for the amount of supreme gas I am putting in. so I did two treatments that way, then lost the bottle with the rest in it. so I started putting apx. 1/8th of a cup of clean ATF fluid in with each fill, (did this apx. 3 times). then today I got another bottle of injector cleaner I did one more treatment.
I checked the injectors VIA. listening through a screw driver method, every single injector had an nice "click, click, click" to them and no injector clicked slower or faster than another. so IMHO the injectors are electronically good at least, but may have gotten dirty causing a disrupted spray pattern?


The only other thing I did since my last post is wash the engine bay..."shrug"


Any suggestions on what to try next? I'm still trying to get my hands on a Backpressure tester, but I can't afford one, there expensive. I may try to make one with a cheap vacuum gauge that does go up into the positive range some, and attach my compression tester line to it so it can screw into the o2 bungs.
How do you clean the CPS sensor? is there a gasket I have to replace?, (I will search but figured I'd ask anyway)
I did get a chance to check my pcv valve and its old, it rattles and when I blow through it the valve doesn't seal 100%, so I intend to replace that too.


Thanks guys

memphisballer

iTrader: (7)

I may have missed it but did you replace your knock sensor and harness because you listed it as your current code?? A bad knock sensor will absolutely cause a bog/hesitation and jagged power curve.I know this from experience.Your MAF g/s readings are spot on and a new MAF will produce similar G/s readings from light to full throttle.

6cyl-97maxima

Thanks for the quick response! No I have not replaced the knock sensor nor have I tested it. I felt that a bad kc would only reduce your timing a little. But that was my experience with the 1st gen mx-6 GT. I guess it causes much more problems on the Max, according to what I'm being told. Maybe I'LL throw in a 470k ohm resistor in the harness and see if she works better. If so I will promptly order a new KC!

Thanks, ill report back when I try the resistor test.

6cyl-97maxima

Update: I got a nice auto ranging multimeter today...

So I plan on doing some testing on the coil. Packs, test them once while they are cold, then again when hot.
I did a seafoam treatment through my booster line, and put a little in my gas. After the car seemed to be much more responsive but mostly in lower speeds at higher speeds when I press the gas it still didn't feel right.
I'm going to go to the junkyard and buy a working knock sensor, for cheap.

maxima.713

iTrader: (7)

Why is everybody ignoring that you have a knock sensor code? That makes you lose a lot of power when it's bad.

6cyl-97maxima

Well to be honest I was ignoring it too as I've had other cars with bad knock sensor and there was only a mild reduction in power. Plus I was told in the newbie fourm that the KC was the last problem to address, as other things could lead to that code and it may go away after other things are fixed. (Leaky filler neck causing evaporated code) and bad downstream o2, I'm just going to trhow a spark plug antifouler on it. Anyway, I'm going to go to the junkers and get a knock sensor asapa

njmaxseltd

iTrader: (19)

The effects of a bad KS really can't be felt by most. Perhaps measured in the 1/4 mile, but not felt by the daily driver. His symptoms aren't that of a KS either and he does have other codes that should be addressed before the KS is replaced. The KS code is very well known to pop up when other codes are present. He needs to address those first, clear the error codes and check for the KS code after it's running correctly.

The anti fouler is a waste of time and money.

6cyl-97maxima

So what your telling me is that the evap. code (leak in filler neck), and a failed downstream o2, (the one that only measures cat efficiency), could cause the KS code? I figured that it would have to be a problem like a miss or something causing knocking/pinging.
Why is the antifouler a waste of time and money? Does it simply not work? I was planning to run a test pipe through my main cat, (no emissions testing here ) so I figured a working o2 will still throw a code when trying to read cat efficiency because there won't be a cat for it to read. Therefore I figured the antifouler trick would get rid if the MIL light and save me money by not having to buy a new sensor that is just going to tell me that I have no cat. Maybe I'm way wrong, idk

njmaxseltd

iTrader: (19)

Yes, those codes, especially the O2 could set the KS code.
Keep your cat in place, the environment will like that.
The anti fouler isn't the answer, it's a band aid at best if it works.
Think of it this way, just by putting a sleeve around the O2 and re positioning it in the exhaust system, do you really think it's not going to still "smell" the exhaust gases? Think the logic through on that.

6cyl-97maxima

OK I agree with you about gutting the cat and the antifoluer trick. If its plugged or if I get a catalyst efficiency low code after replacing the o2. then I would go the test pipe route with an o2 simulatior, (if the good o2 doesn't like the test pipe) or find a cheap replacement CAT. But only to save money until I can afford a high-flow CAT.
On a side note I decided to check the KS by checking the ohms. And it showed infinite residence. It sparaticly kicked in for a second but didn't stay in one spot long enough too get a reading before it went back to infinite and stayed there. I also decided to ckeck the voltage on the female end, going to the ECM, and got a reading of 4.985 volts, which is within spec. A resistance test to the negative lead gave infinite, which is good. So I'm pretty sure my KS is shot.
The meter I was using is capable of 40M ohms and its auto ranging so Im pretty sure its a proper meter for the test.
So what do you guys think I should do? Replace the downstream o2, and patch the leak in my flex section then clear the codes. if KS code comes back then replace the KS. Then Hope it runs right.?
Or just replace the KS right away, hope that the performance problem goes away, then fix the leak in the flex section and o2 when I can afford it? If my test was done correctly then it shows the KS is dead right?

Thanks again guys
Nathan

njmaxseltd

iTrader: (19)

Not sure your KS test was good, it's supposed to have very high resistance, I believe over 40M. I could be wrong, somebody please confirm...
High flow cat will do you no good on our cars, put that money back in the bank. The stock cat flows plenty, it's nothing more then a big honeycomb inside. Check the inside of the flex, make sure it's not collapsed.

When was the last major tune up? Plugs, etc?

6cyl-97maxima

I just changed the plugs and fuel filter last week. I haven't done the air filter yet but it looks OK. I change my oil every 5000km's. Transmission fluid looks great.
I did a search and it was stated that anything over 10M ohms is enough. And it should read between 550-650k ohms? I think, although I could of read wrong. Can someone confirm this please?
Hmm I never thought to check the inside of the flex section, it does look pretty bad on the outside. The outer mesh is completely rotted off.

maxinout93

Sounds like u have some problems, I also had the power loss/hesitation not cold but between warm up. But mine is gone now. EBay and amazon have knock sensors for $10 or less. I would replace that, along with suspect coils/ they don't always throw a code. Also clean throttle body/ that also helps/ egr tube. Replace bad o2 sensor/ pcv valve/hoses if old and dry rotted / fuel filter ect. Must remember that these are old cars and sometimes previous owners don't take care of them like they should. I'd start with a full tune up.

njmaxseltd

iTrader: (19)

Ok 550 - 650k sounds right, so if your at over 10M, it's done. I'm still not convinced that's your power loss issue yet...

6cyl-97maxima

Nor am I, I think the KS is only part of the problem. I think ill test my coil packs next. All of them are haishin (not sure how to spell it). Isn't that brand the one that people have had trouble with, sometimes even right out of the box?

6cyl-97maxima

Fuel filter has been replaced. Spark plugs were changed which i did myself. Complete braking system was done including lines, (I now owe the mechanic $1200 for that job, if it wasn't winter here I could of done it myself). As far as replacing vacuum lines, they don't seem to be all that brittle, and wouldn't I have to pull the motor to change them all? Or are all the vacuum lines accessible from the top of the motor with it in the car
I'm fairly certain that the previous owner took good care of the car, as I have all the maintenance records. I suspect he was only selling the car because he had purchased a brand new Altima. The dealer must of really low-balled him on a trade in price. Since he was cool with $350
I have to change the PVC valve as I know its bad, (it rattles, and and doesn't check/seal completely.
I'm going to order a cheap E-bay KC, I just hope there not simply a 470k ohm resistor dressed up like a KC.

dwapenyi

iTrader: (3)

A bad KS will not cause hesitation. My car had it for about 1000 miles when I bought it and everything else was good. When the KS is bad, the computer makes note of it and adjusts the air/fuel mappings. Essentially the computer assumes you are using 87 octane in your tank all the time. 10% or so power loss with a bad KS at most but no hesitation. Of course this assumes that everything else is in great shape.

In your situation I would change the primary O2s and the FPR. If you want the last bit of performance from your car, then change the KS, but do it last, and get OEM. Avoid ebay KSes.

The day I change the 2ndary O2s on my car is the day I receive a check from the EPA lol

6cyl-97maxima

I agree with the KS thing, it should only bump your timing back a little to avoid knock/ping/pre-dentation since the KS can't give a proper reading, or in my case no reading at all.
As far as the primary O2's I would more than likely want to test them first and see if their weak, because I know they are not dead for a fact. My maf g/s readings are spot-on, so I rather just test the primary's first before spending $150> for sensors that didn't really need replacement. see I'm on an assistance budget that I get for going to school to get a trade. So I just can't throw parts at her, I need to know defiantly what the problem then fix that problem.
Now here is the good news...When I left school today I started the car and it seemed to idle ok, then after I got across the bridge and the car was warmed up it started missing really bad, at 2 grand and over, or stopped in drive. So the check engine light flashed. I was very happy about this Because I knew the ECM finally through a misfire code. I promptly pulled the codes and got a cylinder 5 misfire. So I now know where to look
Again are the Hashian coils the aftermarket one that people have problems with, sometimes right out of the box, or is that the brand that come with the car off the assembly line?
I guess I'll have to search the stikies for testing the coils with a multimeter. So I can confirm that it is indeed the coil. I guess I should wait until the engine is warmed-up and the missing starts occurring again, then test while its missing. I will do a cold test too, but I suspect that it will read ok when cold and bad when warm. then I will swap the #5 coil with #3 and see if the misfire moves to #3 cylinder. But if the coil checks out good. then I'll have to check the injector for cyl #5.
Is #5 on the front or rear bank? like does it go 1-2-3 on the front bank, then 4-5-6 on the rear bank from left to right? Or does it go #1 (front bank at the left), #2 (rear bank at the left), #3 Middle front bank, #4 middle rear bank and so on?
Ill search but while I'm searching it would be nice to get some advice just in case I don't turn up anything in my search.


Thanks Guys, I think we almost have this problem figured out!
Nathan

dwapenyi

iTrader: (3)

Tired O2s are not dead O2s. Tired O2s dont throw codes and you will get readings that look OK from them. When the O2s are working properly, they rapidly change readings. Tired O2s are slower to respond to changes......your car winds up feeling sluggish because of it. Again, tired O2s dont give codes. If you know that the primary O2s on your car are more than 5 years old, you should change them. You can replace just 1, the front primary. I did that on my car and my friends 99 I30. Both cars noticed a liveliness that had gone missing before.

You will find that coils are bit of a vague science. Its good that your CEL told u cylinder 5. Just replace that one. Other times, however, you may a find a coil that is kinda sortof bad. It works fine when cold but acts up when warm or hot. Only thing you can do is replace one at a time with some used OEM ones until your car acts better. The tests u will run will be inconclusive unfortunately. Been there done that

I would replace the fpr too. Chances are your car has oem from factory. How does the car start? When u turn the key does it jump to life or does it take a few turns for the car to come alive? That could be a symptom of a tired FPR. My FPR was so bad that on the highway, if I decided to floor it while in 5th gear, sometimes I would get a backfire. All gone with the new FPR. And it starts like a champ now.

6cyl-97maxima

yes I felt that there was a mild miss for a while I was just waiting for it to get bad enough to throw a direct cylinder code, and now it has
Well I just tested coil #5. And with the positive probe on the positive pin and the negative prob on the middle pin, I got infinite resistance, which is normal. When I reversed the probes I got a reading of 3.385m ohms. Which is out of spec, as my searching said that it should be between 1.3- 1.7M ohms.
I think testing the for is a good idea, just cause. But wouldn't that cause a p0300 code instead of a direct cylinder misfire? Either way I'm going to test the FPR and fuel pump jest because it sounds like a good thing to check on a 17 year old car.
So here is my game plan... start looking for a good OEM coil pack. During that time ill be testing the FPR and fuel pump.

6cyl-97maxima

Update: I went to the junkyard today and picked up a coil pack for #5 cylinder. On the drive there it was missing really bad. once I got the coil pack ($45cdn), I installed it right away at the junkyard. right away the car started easier and everything overall felt smoother, the misfire is now gone. but even though the acceleration was much smoother, and overall much better, however it still doesn't feel right, its just much better. once I got home I kept the car in drive with my foot on the break and the idle would occasionally drop a bit then come back to normal. So now I'm thinking I should start checking the FPR and fuel pump. also I think I should replace the primary o2's (I just hate replacing parts that "could" still be good.
The good news is the car is running much better, so I'm closer to getting her where I want her.
Anymore advice would be much appreciated!
Thanks
Nathan

6cyl-97maxima

Update on another drive I got missfire cylinder. #5 again..., argh, idk what to do it looks like there is a white residue on the base of the boot, even though I cleaned all the coils when I changed the spark plugs last week. What would be the cause of the residue?
Here is a picture of the old coil with residue on it:
Could this be collant? And if so where would it come from, my UIM gasket?

6cyl-97maxima

I just finished looking inside the boot and the spot where the spring connects to the coil and there is moisture inside the boot and in the spot where the spring connects to the pack. What would be the cause of this?


Edit, I decided to pull all my rear coil packs and look down into the spark plug cylinder. There is water in all of the rear bank plug cylinders! most of it is sitting in a little groove at the very top. but by the look of the walls and coil boots, a little of that water has made its way down in around the spark plug, especially cylinder 5. Could I have done this when I washed the engine bay? I searched before I decided to give it a wash and everything I came up with was it is ok to hose down the engine bay, not pressure washer but just standard hose pressure. IDK what to do...how do I get the water out of there?

6cyl-97maxima

Well I dried the water out of the plug cylinder, during which time I discovered that I have a bad spark plug grommet seal in cylinder #3 I took it for a quick drive after I dried everything then put the coils back in. The car ran great at first, but it wasn't long before it started missing again. Man I'm frustrated, ;(

dwapenyi

iTrader: (3)

Is it water, or is it coolant? If it's water, just keep driving and the engine's heat will evaporate it out. If the water doesn't goes away, you have some sort of leak. The only liquid that could be in that area would be coolant, and if it is coolant, then you might have a blown head gasket. If that's the case, then drive it till it dies and save for a replacement motor if you want to keep the car, or just buy another car when it dies. Fixing a head gasket on this DOHC timing chained V6 is ridiculous in labor costs....just not worth it.

6cyl-97maxima

Well I hope its not a blowen head gasket. I just love this car too much. I taste tested the liquid from the area where it was puddled and it didn't taste sweet just plane. I guess its time to dig my compression tester out and check the condition of my motor. I really hoping that the compression checks out good.
And what about the bad seal in cylinder #3 at the base of the plug tube. Could that be causing a vacume leak of some sort. I noticed that our motors need to retain crank case pressure or it will idle rough. For example I one time took the oil cap off while it was running and the engine seemed to struggle a bit until I put it back. Could this bad grommet seal for #3 be causing something similar?

dwapenyi

iTrader: (3)

Just plain is a good sign Your head gasket is good.
When cars get very old, many things may be going wrong with it. Whatyou feel may be a result of all of it. Fact is, your FPR, being OEM, is tired and done. As NJMax has suggested, your cat may be done. If you've never changed your primary O2s before, they are probably tired. Your ignition coils may be failing.

Change 'em all. If funds are tight, then replace ign coils one-at-a-time with OEM used from junkyard. For primary O2s, replace JUST THE FRONT ONE. FPR is like 4 dollars, so you should just replace it anyway. Any fpr will do, does not have to be oem. There's no way to go cheap on a cat, but you can get a cattman fastcat which may be cheaper than oem.

6cyl-97maxima

OK good, so ill change the front primary o2, replace the fpr. And work on replacing coils one at a time.
What about the bad plug seal? Is that causing problems or could it cause problems??

6cyl-97maxima

Car is running much better. It missed for a bit on the 1st drive, but on the way home the miss was only mild so I think overall it getting better. My next strap is a new FPR.

njmaxseltd

iTrader: (19)

Misfired are generally coil related with our cars. Pull the stalk off all the coils, look at where the spring contacts the coil. If you see any corrosion, consider replacing that coil. I've tried to clean them up, only to have a misfire come back soon after.

6cyl-97maxima

I agree, but the missfire is not nearly as bad now, and seem to be getting better. I assume that this is because the small amount of left over moisture is slowly burning off. I will start with replacing the FPR as they're suppose to be cheap. Then when I receive my next check, I will start replacing more coils.

Thanks

PS: I really need to know about. That bad seal on cylinder 3. Will this cause problems? Or is it only going to be a problem if my rear valve cover gasket starts to leak? Is the seal hard to replace? Like can it be done from the top, or will the UIM.have to be removed in order to remove the rear valve cover to replace those grommet seals?

Thank again,you guys have been a geat help!

dwapenyi

iTrader: (3)

That grommet seal problem is not major. Remember, your check engine light went off and told you about cylinder 5, not 3.

It is common for the rear valve cover to start leaking on our cars when they age. To fix it you need to take the UIM off and when u do, replace the valve cover and rear spark plug gaskets.

These type of oil leaks are not major. So long as you keep an eye on your oil level and top up as necessary, the car will run fine. You should replace them eventually, though.

6cyl-97maxima

True my code was for 5 because it was saturated with water. I feel like I bought a coil for no reason now. Especially since it tested even higher out of range than my old one did. My old one tested infinite with positive lead on the positive pin and negative on the middle pin. Then when reversed, I got 3.125ohms. On my so called new coil pack with the leads reversed it measured 4.3 ohms. But seems to work just fine.. the highest ohm reading I'm spouses to see is 1.5 - 1.7 ohms. Well all of the rest of my rear bank coils tested infinite one way and roughly 3.5 ohms the other. Is this test really that precise, I'm beginning to think that the reversed leads test is useless. But if you get an ohm reading with positive on positive pin negative on middle pin then the coils dead.
Well I haven't seen any oil in cylinder #3 yet. Which is why I asked if the valve cover seal would have to leak first before any oil can make it past the plug seals.