Hi, I have a few questions about some strange behavior my maxima has been displaying lately. I've tried some searches but couldn't find much useful info, feel free to link me to other discussions if what I'm about to say has already been discussed.

First off, when I shift into drive and hit the accelerator, the engine seems to take a second or two before it responds.....right after I push on the pedal it feels like the car lurches forward a little bit, the it slows back down, lurches forward again, slows back down, and then finally takes off. I have no idea what could be causing this, but I hope it is not a precursor to more serious problems.

Secondly, whenever I punch the accelerator, for instance when I'm on the onramp to a highway or trying to pass someone, I get a weird *clicking/rattling* noise. I don't know if it's normal, but it's pretty loud and annoying, and only happens when I've got the throttle open quite a bit.

Thirdly (and this has nothing to do with the throttle), there are some big pieces of plastic that are hangind down from beneath the engine and scraping the pavement when I go over dips. Is there anything wrong with just ripping these plastic pieces off or do I need to have them replaced/resecured.

 

The plastic pieces are just dirt/water guards. It's probably advisable that you secure them somehow, but if you rip them off, it's not the end of the world.

Clicking/rattling, kinda like pinging? How many miles are on the car, and have you ever had the fuel system serviced? (fuel filter replaced, injectors cleaned, etc.)... I know fuel system problems can result in hesitation while taking off on any car (my dad's '97 Mazda 626 has this right now, it's very hesitant to take off, and it pings NON-STOP ALL-THE-TIME, mechanic told him the fuel system needs a complete cleanout/workover)

If it were just hesitation, I'd suggest checking some other systems (MAF sensor, etc.) but combined with pinging (if that's what you're hearing), the fuel system comes to mind.

Use premium gas and see if the clicking/rattling goes away, if you don't already use it. If it does, get the fuel system serviced by the dealer or a good mechanic.

 

Could also be the coils too...If so I'd replace all 6. Theres a TSB out for that also.

 

True, forgot about that
Hesitation and pinging... both symptoms of the coils right?
BTW, does anyone have real data regarding the test results of a bad coil? i.e. can bad coils (or coils starting to go bad) be identified for sure by a resistance/impedance check on the coil's connector?

 

The car has about 71,000 miles on it. Other than oil changes every 3000 miles, I took it to the dealer at 25,000 and 50,000 miles for scheduled maintenance. I can't recall for sure if they've changed the fuel filters or cleaned the inejctors, but I will try using premium fuel to see if it helps.

 

Before I replaced my one bad coil, I took all three front coils out and measured resistances between the pins. Unfortunately, they all looked similar in this respect, that's why in the topic "Ignition coil problem" I said this resistance check recommended in the Haynes book did not help me much. I believe my coil fault was intermittent (so I keep the coil, just in case I might need it if another one goes totally bad)

Here are my measurements:

Meter scale: 2000 Ohms

cyl 6 coil:

1 --> 2 = infinite
2 --> 1 = 1347
1 --> 3 = infinite
3 --> 1 = 1531
2 --> 3 = 1460
all Spark Plug (SP) combinations = infinite


cyl 2 coil:

1 --> 2 = infinite
2 --> 1 = 1345
1 --> 3 = infinite
3 --> 1 = 1535
2 --> 3 = 1512
all Spark Plug (SP) combinations = infinite


cyl 4 (troubled) coil:

1 --> 2 = infinite
2 --> 1 = 1373
1 --> 3 = infinite
3 --> 1 = 1552
2 --> 3 = 1461
all Spark Plug (SP) combinations = infinite

It seems that there was some inductance (windings) because the numbers posted here did not hold steady during the measurements - due to the current my ohmmeter was putting through the circuit.

*) NOTE: the pins are numbered here as follows (look at the 3-pin connector)
1 - is the "+"
2 - is the "G"
and
3 - is the "IB"

 

I'd love to crack open a bad coil and look at it from the inside... (anyone wanna ship me one? )
Ignition coils are inductive in nature; they typically contain 2 coils, a primary (+12VDC passes through here when energized), and a secondary coil (significantly more windings than the primary...)
I believe the VQ coils also contain a Power Transistor built-in, so the impedance you were testing was likely the onboard power transistor, not the coil windings themselves so much... the Power Transistor allows the ECU to switch the primary current on/off with a low-power signal, kinda like a fast-switching solid-state relay. I believe this is all true of the VQ coils, though I should do some research before I spout this as fact

 

I can get you my bad coil - where should I mail it to?
(sorry, I remembered you wanted to crack one open, but it took me a while to find this thread with the "search" function not working on this forum anymore...) - send me a private message with the address I will send you the coil.
Cheers!

 

my guess would be NO. nissan claims the fuel filter NEVER needs to be replaced...so not likely they did it unless you asked. probably also the case with the fuels injectors, etc.

like said before...you may want to consider that as well - can't hurt.

getting ready to run some BG 44k through mine and clean my throttle body.