Still Jerking and Bucking 1996 Q45

[bigdog76]

Reference to the previous post on my car problem.

zerothread/196791

Need Help on this bucking jerking issue.

I ran the FSM test on the MAF harness to the ECU with a voltage meter

#3 and #4 on the harrness to #55 and #54

The harness has continiuty and the MAF is ok to according to the ohms it was reading. I followed the FSM til the end of the check.

I dont know if there is a short in it or what.

The mechanic ran the test on the computer and it spit out the code for the Knock sensor bad on Bank 1

I dont want to throw away $600 at this and not fix this jerking problem.

Everyone on this forum including thoses that went to the dealer are saying the MAF is the culprit or the Harness is not getting good contact.

Fuel Pump is failing I rather throw my $600 at the fuel pump and a new/ used ebay MAF then the knock sensors

Has anyone heard of the knock sensors causing this problem on the jerking?? Usually when the computer throw knock codes the ecu goes into safe mode but that would just make the car run richer and give it more fuel right??

So I dont see it being Knocks

Any adivise before I spend $600 on the knocks or a dialysis from the dealership??

I have cleaned the MAF with CRC MAF sensor cleaner I cleaned the connectors I added the Di-Grease to the pins and connector. When I giggle it when it runs it doesnt change the idle at all it still smooth.

Any advise would help solve this problem I dont want to throw good money at the wrong parts.

[goody90q45]

I've got one bad knock sensor on my Q right now and it runs fine- doesn't buck and jerk. I'm not sure how she would run with both KS out.

It looks like you have a digital volt meter and know how to use it so do youself a favor and take a couple of measurements. It will take about 15 minutes.

First, measure the resistance of the KS at the harness connector. It's in a group of three or 4 connectors on the PS of the engine. Follow the instructions in the link below. They are probably going to read 550K (good) or no resistance (0= bad). If I remember correctly, on my CA Q my KS connector may have had only six pins, not eight.

zerothread?id=42356

Second, measure the resistance of your injectors. It's measured at one of the connectors mounted in the same cluster as the KS connector and also has 8 pins. This time put the + probe of the DVM to the battery + and measure each of the injectors at the pin. All should be in the 10-14 range. If you have more than one with a really high reading your car will buck and jerk.

You can determine which connector is KS and which is FI by visually following the wires back to their individual connections under the plenum.

These readings won't be exact but they will tell you enough to help make a better decision. Let us know your readings. Good Luck

[Q45tech]

Bucking and mild jerking under mild acceleration 45-70 mph in 4th gear .....light throttle especially if ac on as the ecu low octane map [reduces power]............probably not noticeable in a WOT start or pass.

Q always have multiple problems because owners are so numb they don't fix things until they pile up.

[elwesso]

Please dont cross post, i deleted your thread in the Q45 forum.

The MAF is the likely cause, however the KS can do it sometimes as well...

I honestly cant say you got any reasonable advice in that other thread, im sorry I didnt see it.... what a mess!!!!!

I need to know when it does it most often. Does it seemingly do it at random? I recently had a MAF fail on me, and what it would do:

- Car would stall occasionally, especially soon after startup.- Car would jerk under a constant cruise, regardless of what gear it was in.

what i want you to do is drive around town in 3rd gear instead of drive and see if that improves it. If by increasing engine RPMs you alleviate the jerking, then the likely cause is the KS. The reason is because the KS retard the engine timing and the engine does not put enough power. Its the same feeling when you dont give the engine enough throttle on a manual transmission and it jerks big time and either recovers or stalls....

I had bad knock sensors on my 1st 94 and drove it like that for a year and never experienced that issue, but in other cars ive driven with bad KS it has jerked but usually its not that bad.

If it still comes at random, then its probably your MAF. NOTE THAT 96 USES DIFFERENT MAF THAN 90-94. Very important, as its a different connector..

My advice to you is replace what we know is bad (the fuel pump) and that could likely cure the cause. You dont want to have to spend $500 EXTRA (in addition to the fuel pump) because you let the pump fail and it takes out the control module.

[maxnix]

Please dont cross post, i deleted your thread in the Q45 forum.

My advice to you is replace what we know is bad (the fuel pump) and that could likely cure the cause. You dont want to have to spend $500 EXTRA (in addition to the fuel pump) because you let the pump fail and it takes out the control module.

Thank you, and good advice. Always repair what you know is bad before trying to diagnose poor performance. It is much easier when known bad components (variables) are eliminated.

Simple, right?

When you do the KS and harness, you will want to do all the under plenum hoses and gaskets also, unless you like to pay for repeat labor.

[bigdog76]

It does it randomly and not everyday. Jerks and bucks mostly after the car sits for like 30 min and then I get back in it to drive and it starts the jerking.

I will replace the knocks since the ECU is saying Knock sensor bank 1.I will go ahead and replace both knock sensors.

Has anyone one ever bought knocks on ebay they are $60 each?

The car has 2 knocks sensors are both of the knocks the same part exactly because on ebay they are only selling one type of knock sensor for my car?

I will replace the knocks and the fuel pump. I want to do the hoses to but they want $200 for the all the hoses and the gaskets at Everything Infinity I dont know if I can stretch another 200 bucks right now.But it will cost me more later in the long run.

If that does not fix the problem is it more likely the MAF itself or the MAf Harness?

Does anyone have know where I can get a 1996 Q45 MAF with low miles on it for a good price. I want to save myself the $432 that Everything Infinity wants for it.

If I install the new fuel pump it is not going to make my FPCM go bad after install is it?? I know theses car once you put something in new the old parts says se la vi .

[maxnix]

That would be C'est la vie!

New fuel pump won't damage FPCU. Damaged FPCU wont damage new fuel pump.

If you don't get the KS from Joe, get them from http://www.sparkplugs.com You really won't want to repeat that labor again. A real false economy. Should read Q45tech's post on how parts that don't meet OEM standards get into the 3rd party retail parts inventories, sometimes with OEM packaging.

Get everything else from Joe.

MAF connector is the most likely culprit in that assembly, but much less so after late 1994 plug design revison. Assume same standards apply to 1996.
Modified by maxnix at 8:31 PM 9/13/2006

[Jesda]

Fuel pump and FPCU issues will cause it to sputter and die and leave you on the side of the road, or hum very loudly, not buck and jerk. I strongly suspect the MAF.

Dennis (Q45tech) has said that 95-96 MAFs, despite new and sturdier connectors, fail more often anyway. Keep preventative maintenance is to keep the air box clean and use only OEM air filters, replaced regularly.

If you're wary about spending big bucks, just buy a used 95-96 MAF from car-part.com. You can find them for $25-$100. That'll save you some change to get your fuel system taken care of!

Best of luck to you.

[bigdog76]

Sounds Good

I will be getting the knocks done and then Iam atacking the fuel system and the MAF next

thanks for all the help and advise

[bigdog76]

Carparts.com didnt carry any MAF sensor according to there websiteAny other suggestions

[bigdog76]

What do you think about buying a used MAF from the online wrecking yard sites? They warranty them for 60 days and I did buy a speedometer cluster once and that turned out good.

[bullittandy]

Buying used parts is always tricky, especially when you aren't exactly sure what the problem is. However, if you wouldn't be bothered by returning the MAF then I think an online used source would be a good gamble. I'd be willing to return two to be sure that they weren't the problem.

[Jesda]

I've had success with junkyard MAFs. Im surprised Car-part.com didnt have any under "Airflow sensor" or "Airflow meter". They usually have a bunch.

[bigdog76]

Theses Knock sensors are they both the exact same part number on Bank 1 and Bank 2 ?

I noticed some on ebay for $60 buck each but Im weoiry of buying them.

I bought some from Everything Infinity Nissan and they are like $126 a a piece

I was thinking of returing them and saving $120 bucks.

Or should I keep what I got?

[elwesso]

theyre both the same for both sides.

[captainluigi]

a possible fix is to re-solder conections inside of maf. simply remove square cover via razor knife, de-solder copper heat shield, clean with elec. con. clnr and resolder all conections. worked for me 7k miles ago. be sure to re-silicone cover in place. this entire fix took an hr. bueno suerte!

[Q45tech]

Always have a working spare before you try to become an electronic technican via home study.

How many of you remeber and have built a HEATHKIT anything?http://www.heathkit-museum.com/other/cr-1.shtml

They use to produce a 12 page book on HOW to SOLDER.

[captainluigi]

dennis you always crack me up. you are a piece of work. re-soldering elec. cons. has to be one of the easiest diy project possible.

[Q45tech]

Years ago I had under my tulage hundreds of women [different states] who repaired CATV convertors..............I can assure you repair soldering correctly is an art.

I have seen people use acid flux plumbing solder and soldering irons so large they could seal a tin roof section or copper gutters when they should be using 15-25 watt units or worse a propane torch to solder assembly boards.

You cannot take anything for granted when you tell someone to solder something.

Just like BG44k if a little works good three or 6 cans will probably work better is the mentality of some.

You should see some of the home repairs we encounter. The one I love is forgetting the fuel pump o-ring it leaks, so they smear JB WELD all over the panel and tank. How would you like to by this used Q.

[bigdog76]

The mechanic checked the MAF sensor today with his snap on computerHe hooked up a sensor to the wire on the harness going to the MAF and the voltage was still regulating just fine smoothly increasing as we increased the RPM. Then he hooked it to the ground wire and that showed low could that be a possiable cuprit? to it working on and off.

Is there anything other than the MAF that would cause this jerking and bucking issue. Possiable injector? Fuel Pump? Knock Sensor?

Iam at my wits end. Do theses MAF working intermittedly and then check out fine and then go out as Iam drive on and off causing the jerking?

I notice that when I park the car for say 45 mins or so and get back in to drive it is when it cause this to happen.

I can replace the MAF and that might not be it at all. The harrness could be another issue.

They are replacing my knock sensors today as per the thrown codes and servicing the fuel injectors..Next Saturday Im doing the fuel pump replacement.

other than spending the $90 on a used MAF since I dont have the $432 for a new one. What other fixes could this be. I ran the test on the MAF and harness and it is checking out fine unless it is running intermittedly then it would test fine at that point then I drive it and it happens.

The mechanic wants me to bring it by when it is happening which I have tried already once I get there I cannot seem to get it to repeat the problem at that time.

[96Qowner]

How many of you remeber and have built a HEATHKIT anything?http://www.heathkit-museum.com/other/cr-1.shtml

They use to produce a 12 page book on HOW to SOLDER.

Gawd, I loved Heathkit! I built my first stereo that way - only wired one diode in backwards. Haven't thought of them in decades. Thanks, Dennis.

And about the MAF, yes, as a matter of fact, it can be an intermittant problem. I'd bet good money that if you opened it, you'd find some iffy connections - it just matches the symptoms too well. It'd be ideal if you could swap with a known good one.

Actually, you could buy a used one and resell it if it didn't solve the problem.

[bigdog76]

Took it to the dealer today.They dont think it is the MAF I didnt get it the diagnostic test done but he told me that what it is doing doesnt sound like the MAF.

Could be a ignition coil or a fuel injector?

He told me to stop running COSTCO gas because it is crap. To run 4 tanks of Chevron with Techtron 91 octane and see if that takes care of the problem. Has anyone heard of this??

If the problem persists to bring it back and see if they can reproduce the problem other wise its hard for them to diagnose the problem.

If it is one of the ignition coils there is no way to determine which one it isunless it is completely dead and there is 8 of them that are 200 bucks each

Could this be the end of my q45 if this problem doesnt stop because that is alot and I will not spend it??

[maxnix]

Ignition coils are about $180 from Joe. Better do a power balance test.

Faulty coils are pretty easily diagnosed by switching positions.

All CA gas is crap, but I've run Costco for years (WA & TX) with no problems. And yes they do include detergents. Alternative is Chevron.

Try any ISO-HEET yet? Contaminated fuel could be it. Not so sure MAF is it.

Sounds like you need the services of a Senior Infiniti Technician. Might think of taking it to Jerry tucker.

[bigdog76]

Ignition Coils on the website say $92 each.

Iso-heet I havent tried. What is that??

Faulty Coils are easy to detect. Ok that is some good news.

Ya I was talking to one of the guys at the dealer but I didnt have time to do the dianostic test.

Cost $100 but they say if the car is not doing it when I bring it in then they will not see the problem either.

Any ideals besides the gas approach anyone ever have that as a fix?I cannot see the gas causing this much jerk no way

[maxnix]

1.) Ignition Coils on the website say $92 each.

2.) Iso-heet I havent tried. What is that??

3.) Ya I was talking to one of the guys at the dealer but I didnt have time to do the diagnostic test.

Cost $100 but they say if the car is not doing it when I bring it in then they will not see the problem either.

4.) Any ideals besides the gas approach anyone ever have that as a fix?I cannot see the gas causing this much jerk no way

1.) Less than half the price of FGY33 coils.

2.) Isopropyl alcohol to dissolve the water in the tank. Do NOT get HEET (methyl alcohol).

3.) Not necessarily. If he is a senior technician (trained in 1989 on the G50) and knows how to run a power balance test (read Q45tech's posts), a lot can be revealed, as opposed to urinating upwind like we are doing now. Get a print out.

4.) Water (and other contaminants) in the tank can affect performance very much, especially when fuel is low, or on cold start.
Modified by maxnix at 8:08 PM 9/20/2006

[goody90q45]

They are replacing my knock sensors today as per the thrown codes and servicing the fuel injectors..Next Saturday Im doing the fuel pump replacement.

I'm confused. Did you replace the knock sensors a couple of days ago and you still are having the same problems? If so you need to stop throwing money at parts.

Have you ohmed the knock sensors and the injectors at their connectors yet? The link to do this was in a previous post in this thread. It will take you or a mechanic less than 15 minutes to do both.

Do some diagnosis before you start throwing money at expensive parts (and labor). It will help you make a better decision.

[Q45tech]

We work on so many Q that we have developed a half dozen "testers" to speed up the process of checking individual sensors and drivers [solenoids, injectors, etc].................adapters that plug in between connectors to make it easy to read resistances and voltages.

With an amplified current probe and oscilloscope you can SEE the current waveform of any thing that has a fuse or an individual wire feeding voltage.

One you get a mental or real picture of GOOD............defects are instantaneously spotted FAST. Fuel pump, injectors, IAC, fan motors

Taking a vehicle to someone who is not expert in the model can be a frustrating experience as they spend time learning.

[bigdog76]

Well I was throwning knock codes so I went ahead and replaced themWaste of time and money according to the dealer.

Dealer said bad knocks will cause it to not pass smog. No biggie.

Should i leave it in the hands of the dealer now?

[bigdog76]

Knocks have been replaced. Fuel Pump replaced this weekend.

Fuel Injectors were serviced. (Assuming they would have told me if one was bad doubtful?)

Dealer told me I really need to bring it in when it is happening Hard to do.

This car is still jerking. They think that it is not the MAF from what i describe. There thinking more a fuel injector or a ignition coil.

This is a job for the diagnostic job or what? Is it hard for the dealer to pin point which fuel injetor or ignition coil could be bad and replace just that one that is causing this jerking issue if that is what is really causing it.

OR do most people believe it is still the MAF sensor problem .Most everyone on the site here is still pointing towards faulty MAF.

?????? Help.

One note. When the jerking does happen I floor it and give it alot of gas it usually powers on thru it accelerating and then it subsides.

This jerking almost always happens after I drive my car for a bit in the morning when its cold and then park it . Then I take it for a drive at lunch park it for 45 min and then I drive it back to work and that is when it jerks almost everyday on que. When it is the first initial drive in the moring on a cold engine it never jerks.

[elwesso]

does it seem to do it at any given speed???

im wondeirng if your feeling torque converter lockup.