Knock Senors Bad! Could it be the Fuel Pump too?

[bigdog76]

I have a 1996 Infinity Q45. Alittle history the car the last 3 weeks or so is jerking and bucking at lower speeds. After which the car dies and then I have to restart. That has happen maybe 3 times.

The car starts right back up and then im on my way. It doesnt happen all the time though

I read all the posts on it being the possiable MAF sensor harness or MAF.I clean the MAF sensor and harness plugs good with CRC electrical cleaner.

No luck problem is still happening.

I took it to my mechanic and he hook it up to the computer and it saying bad Knock sensor on BANK 1.

I went ahead and ordered both knock sensors and the harness and all the plenum gaskets from Everything Infinity (they are on the way now).

Do the knock sensors cause this problem or can this be related to the fuel pump?

I know my fuel pump is probley in dying need of changing as I am hearing the humming coming from the trunk. My car has 191,000 miles and I dont know if it was ever changed.

Iam about to throw say $500 at the knocks to get all that work done. I just have a bad feeling that wont fix this jerking problem. And the fuel pump is like 200 and change.

If theses knock sensors do take care of the problem should I just wait til the fuel pump goes out to replace it?? Or am I facing more problems down the rode.

Also the hoses that are behind the plenum in the knock sensor job Sherl at everything Infinity said all of them are like $200 or so that comes with some gaskets or something. Are theses curcial to change at that time ot can I wait??

Help and advise to help me out???

[maxnix]

1.) I went ahead and ordered both knock sensors and the harness and all the plenum gaskets from Everything Infinity (they are on the way now).

2.) Do the knock sensors cause this problem or can this be related to the fuel pump?

3.) I know my fuel pump is probley in dying need of changing as I am hearing the humming coming from the trunk. My car has 191,000 miles and I dont know if it was ever changed.

1.) Replace all hoses while you are there, unless you want the labor expense again very soon.

2.) Probably not, but you are wise to replace them if they are at fault or old or if the engine has ever been hot.

3.) When did you last replace it? Be sure to replace the O-ring and fuel filter too. Best to do before FPCU is fried also as it is more expensive. Seems like your technician is neither ASE certified nor an Infiniti technican, else he would have measured fuel pressure vs. RPM.


Modified by maxnix at 9:46 PM 9/10/2006

[bigdog76]

Well Im trying to alievate this jerking issue.I will replace the fuel pump as soon as i can afford that

theses hoses are like $200 for all of them ouch maybe I can wait on thoses and go after the fuel pump.

MAF Sensor is that a possiable culprit to the jerking?

i just replaced the fuel filter last year so i should be good there right?

[Q45tech]

What happens when you don't open a INDIVIDUAL CAR SAVINGS ACCOUNT and add an amount equal to your gasoline expenditures every week for vehicle maintenance [plus tires/brakes] and repairs.

Go along oblivious mile after mile damaging the systems without thoughts of how much each mile is actually costing with no concern of how you will fix things.

We have a beautiful paint interior 96 with 140k we bought for $500 all it needs is an engine, transmission [?] and another $4,000 in rehab. Been sitting rotting for almost a year, we can't bare to rip it up for parts. A $50,000 car destroyed in 9 years by lack of maintenance.

[bullittandy]

If you have a technical answer-then give it!! I think we should have a forum called "Q45 sermons" for those that insist on chastising owners of 10 year old cars with nearly 200,000 miles for not treating them like they're brand new.

-Replace the knock sensors, fuel pump and hoses-they will have to be done anyway in 1-20,000 miles. -The knock sensors cause sluggish performance-not stalling.-The MAF connector is likely to blame for the stalling.

[bigdog76]

The MAF is what everyone is telling me. I bought the CRC MAF sensor cleaner today Which is a step up from what all the adminstrators on here orginally are saying to buy the CRC electronic cleaner.

I also bough the delectric grease to apply to the plug and harness .

Took it for a spin and it is working for now. but I dont think for longI found a MAF with 80,000 on EBAY for $45 that could be work a shot too.It was for a 1994 what year Infinitys have the same MAF sensors???

I was told that having an aftermark air filter (K&N Filter) cause more debris to get thru cause problems with the MAF Has anyone heard this problem ??

[maxnix]

I was told that having an aftermark air filter (K&N Filter) cause more debris to get thru cause problems with the MAF Has anyone heard this problem ??

Yes, read the posts. It is also the excess road tar and oil that fouls the sensor. OEM is by far the best if changed annually.

Beware of those who are not experienced and give simplified, ignorant and wrong answers. It's not their car, it's your car, so maintain it to your standards. The information is all here in the previous posts, expecially by Q45tech. Read them and you shall be rewarded.

[bullittandy]

I was told that having an aftermark air filter (K&N Filter) cause more debris to get thru cause problems with the MAF Has anyone heard this problem ??[/QUOTE]

They don't allow more debris-its the excess oil on the filter that causes problems. K&N filters use oil as the "filter." If you've ever used armor all on your dash and been amazed by the dust that collects-thats the idea. Some people have problems with K&N filters out of the box due to excess oil fouling the MAF wire. Many of the problems come from owners using too much oil on the filter when servicing the filter. I used one on a 96 SHO with zero problems for 35,000 miles and then re-oiled and fouled the MAF wire. Cleaning the wire and the filter fixed the problem. K&N filters are worth 1-25 HP depending on application and probably don't filter any better than OEM. On a Q45 OEM makes sense.

The information in this post is sourced from K&N and the owners's personal experience.

[Q45tech]

If you study the marketing stories that K&N uses, they appear to go out of their way to find the absolute WORST Domestic OEM set ups of 20-30 years ago and use them to compare their product to show some improvement.

Japanese designs have always been low loss because they focused on EFFICIENCY because their public is ANNUALLY taxed on displacement.

A 2-3 liter engine in Japan is a GIANT ENGINE and taxed accordingly.

Anyway a 274ci [4.494 liter] cannot consume much air even at [6,000-7300 rpm] [grams per sec x 1.76 = CFM]Generally, a hot engine at normal idle will consume 1 gram/second of air per liter of displacement. Therefore, the MAF reading (at idle) on a 4.5L engine should read approximately 4.5 grams/second on a scan tool. AT IDLE THE Q CONSUMES only 8 CFM of air.

It takes 1.2 CFM to produce 1 Flywheel HP........so to idle [no ac in park] the engine consumes 6-7 HP.

[maxnix]

They don't allow more debris-its the excess oil on the filter that causes problems.....

If you read that nifty study on air filters that Q45tech posted, yes they do pass more contaminants because they don't filter as well as OEM.

[bullittandy]

Has anybody dyno'ed a Q45 with the stock filter and then a K&N replacement? That would be a better indicator than theoretical explanations. Why? In experimental science, they use the word "efficacy,"In applied science they use the word "effectiveness." What works on paper and in a lab usually translates into the real world effects- sometimes it doesn't. Sometimes "efficacy" does not = "effectiveness." I don't know about all of the cars that K&N uses in their marketing. I can say that I've owned a 1996 Taurus SHO which I replaced the stock airbox with a cone K&N, which according to V8SHO.com is worth about 5-6 HP at the wheels. I also added a K&N to my 2001 Ford Mustang, which numerous magazines have dynoed, picking up 3-5 rearwheel HP. Those are facts- ignore them if you like.

[Q45tech]

Since dyno's are so variable [and totally untrustworthy in repeatability] in results due to unrealistic operating conditions [stationary with tire stressed down and deformed to keep the car from flying off the machine and little air flow] a better more scientific method is to read [graph] the MAF voltage under a realistic highway acceleration say 50- 85 mph [6300 rpm] or say the last portion of a quartermile [all in second gear]..........1/4 minus 1/8 mile time.

This takes away all the potential manipulation.

I ran a K&N cone filter for 40,000 miles and it has been sitting on the shelf just at it was removed back in 1998.............in a place of supreme dishonor.

Ethically I couldn't even bear to give it away.....bad karma you know.

[maxnix]

In experimental science, they use the word "efficacy,"In applied science they use the word "effectiveness." What works on paper and in a lab usually translates into the real world effects- sometimes it doesn't. Sometimes "efficacy" does not = "effectiveness."

Reeaaalllly!!? I never have read the word "efficacy" in a peer reviewed scientific publication, but neither have I read even a small per centage of all the valid scientific reviews published.

Usually one sees the word "effect" corrolated to some quantitave data as a result of some experimental control variance. The well designed scientific experiment where all variables are controlled and only one is manupilated should not be confused to out side of the laboratory phenomena with many variables and no controls. Only with the scientific method of the former can sound deductions be made that have implications for the latter.

"Efficacy" is just (as some would say) a copasetic way to say "effectiveness. "

[bullittandy]

Since dyno's are so variable [and totally untrustworthy in repeatability] in results due to unrealistic operating conditions [stationary with tire stressed down and deformed to keep the car from flying off the machine and little air flow] a better more scientific method is to read [graph] the MAF voltage under a realistic highway acceleration say 50- 85 mph [6300 rpm] or say the last portion of a quartermile [all in second gear]..........1/4 minus 1/8 mile time.

Dyno's, like theoretical formula's APPLIED to real world scenario's ARE variable. While dyno's are variable I think that 3 runs with a stock filter and then 3 runs with a upgraded filter (whatever that may be) is a pretty good indicator of HP gains. In terms of variability, and I'm quoting from memory now, most dyno runs I've seen are pretty consistent, i.e, reliable. In addition, I've never heard of a K&N filter being added to a Mustang where it didn't gain at least 3-5 HP. On a stock Supercharged Cobra they are worth 15-20 HP!!! How do you explain that ??

P.S. I use Mustangs as an example because they are a large sample.

[bullittandy]

Reeaaalllly!!? I never have read the word "efficacy" in a peer reviewed scientific publication, but neither have I read even a small per centage of all the valid scientific reviews published.

Usually one sees the word "effect" corrolated to some quantitave data as a result of some experimental control variance. The well designed scientific experiment where all variables are controlled and only one is manupilated should not be confused to out side of the laboratory phenomena with many variables and no controls. Only with the scientific method of the former can sound deductions be made that have implications for the latter.

"Efficacy" is just (as some would say) a copasetic way to say "effectiveness. "

I should have noted that efficacy refers to psychological studies and effectiveness refers to real world application of psychological theory. Sorry for misleading you. You're right to say that it is very comforting to believe that a "well designed experiment" controls for all variables but that's a very naive idea about science. It's IMPOSSIBLE to control for all variables and thus REAL world experimentation is SOMETIMES needed (such as different air filters). However, I'm not asking you to put a K&N on your car, I'm simply saying that on two cars that I've owned I've read actual dyno reports where 3-10 HP is available by adding a K&N filter. No more no less. (Plus ithey sound great-I know Iknow you think that's stupid)Is it worth that much on Q45? Maybe not, Q45 tech brings out a critical point that the Japanese are very concerned with efficiency and thus MAY have designed their air intakes to be so efficient that NO compromises were made for sound/noise/fuel economy/packedging/matrial costs etc, etc, etc.