knock sensor replacement..

[boonseyQ45a]

Hello all...... I am about to do a KS replacement, is there anything I need to know or should do since I am at this point??? Does the Harness go bad, if so where should I test it and buy one if needed?? I also know that there is a "Y" connecting coolant pipe and i should replace those hoses... i have done a sonic clean on the injectors as well earlier and changed the fuel filter and sparks plugs.... I am hoping that i have given enough or so information to proceed this procedure... any other advice would be appreciated...

thanks,mitchell

Modified by boonseyQ45a at 6:30 PM 2/10/2009
Modified by boonseyQ45a at 6:30 PM 2/10/2009

[96Qowner]

Ugh, you're going to have to do the full plenum job.

To get to the knock sensors, you have to remove the plenum. To remove the plenum, you have to disconnect a whole bunch of hoses, many of which are now brittle and will shatter. So, you're going to have to replace all the hoses, too. And yes, do the harness whether it needs it or not. (It needs it).

Here's Wes's article from Q45.org on plenum R&R:

http://www.q45.org/plenum.html

That'll give you an idea of what must be done. The Forum can answer any questions you have.

[Q451990]

For parts, http://www.infinitipartsusa.com is a great source. Call 888-216-5328 to order if you have difficulty navigating the site...

Heath

[maxnix]

Here is a great resource on the job for an early active.

zerothread?id=212964

Great time to replace VC gaskets.

Expect to spend a lot of time cleaning. Send intake plenum and lower runners to a shop with a bath. Check EGR port to see how well they did.


Modified by maxnix at 12:28 PM 2/10/2009

[boonseyQ45a]

ok just finished with the KS replacements and replaced the Y pipe hoses (2), put everything back together and the car still runs horrible... car doesn't past 30-35mph, uphill is even worse... the engine light came on (never came on before the KS)... came to work today and check the code on the car... code was 55... 55=System OK (1990-1995 Q45 only).... but the engine light is still on..... the car acceleration is unresponsive, once i give it a little gas it wants to die out, instead of going forward like it should, it seems as if it wants to go backwards, have anyone experience this yet or have heard of this kind of mechanical brakedown?? its just frustrating when this is the only ride you have for your DD.... engine lights is on but ecu code reads 55??? wierd, any help would be appreciated....

thanks,mitchell

[96Qowner]

Is the fuel pump noisy? Listen for a swarm of bees from the trunk. Check fuel pressure.

[boonseyQ45a]

I hear a humming but only when the ignition is on the "ON" position, is that the humming?? I can hear it but it also stops after 3-4 seconds after the car is running, is that the humming you are talking about or should the humming be more constant? The car also have 156k and I have sonic clean the injectors and replaced the fuel filter as well, this is around 152k.... how do i check the fuel pressure? can i disconnect one of the hoses after the fuel filter and put a fuel pressure regulator on to see the pressure? where should the specs be at?

thanks,mitchell

[96Qowner]

That humming is the fuel pump, and yes, it should shut off after the system pressurizes in the first few seconds. They get very loud as they age and corrode, and rarely last much longer than 120K miles.

You really need to check your fuel pressure. Do you have the FSM?

http://www.nicoclub.com/FSM/Q45/

And not getting a CEL must be a definite clue.

[maxnix]

ok just finished with the KS replacements and replaced the Y pipe hoses (2), put everything back together and the car still runs horrible... car doesn't past 30-35mph, uphill is even worse... the engine light came on (never came on before the KS)...

No other hoses or gaskets? Did you inspect them by removing them?

Sure you have no vacuum leaks?

Ohm test injectors? Flow test them?

[boonseyQ45a]

That humming is the fuel pump, and yes, it should shut off after the system pressurizes in the first few seconds. They get very loud as they age and corrode, and rarely last much longer than 120K miles.

You really need to check your fuel pressure. Do you have the FSM?

http://www.nicoclub.com/FSM/Q45/

And not getting a CEL must be a definite clue.

96Qowner: I'll check the fuel pressure this week when i have time, the car is parked for now and i'm just borrowing my friend car for the moment, its just odd that the engine light is on but the code is 55 which equals to systems ok??? any clue why????

No other hoses or gaskets? Did you inspect them by removing them?

Sure you have no vacuum leaks?

Ohm test injectors? Flow test them?

when i first bought the car (152k now156k) i did a injector service on them (off the engine) and they ohm'd at 12.5..... might have a vauum leak but been too busy so check it out this weekend....

[qship96]

Are you saying you have had the plenum off 2x now in the last 4,000 miles?

[boonseyQ45a]

Are you saying you have had the plenum off 2x now in the last 4,000 miles?

ok ok, i had taken the plenum off about 5-7 times in the last 4k miles, a lot if you ask me... didn't exactly replace ALL of the hosesgasket but the ones that I cut or was cracked I have replaced, probably ,should have replaced all of them, not the best mechanic or solution but is that part of the problem??

not taking care of the hoses underneath the plenum is that a bad start?? i just want this car running for a DD but it seems like everytime i drive this car or have something repair on it, something else creeps on behind me and bite me in the A$$..... a few weeks ago i had a code 33 and 34 (o2 and KS), i gotten as far as the KS and found out that the wire was corroded, so I cut and spliced the wire with a new wire (12 gauge i believe) and replaced both KS with the new ones... I also replaced the Y pipe coolant hoses above the KS, and put everything back into place.... started the badboy up and it ran but once you step on the gas it would burp and not wanting to go anywhere but only slowing down.... rechecked the codes and it reads 55=systems ok??? wtf ok my *** and the engine light is still on??? tell me that??

now I do hear that humming from the trunk, not loud but if i listened to it carefully, i can hear it... i figure i should replace the fuel pump since that can be the cuz of the acceleration being bad.... right??

just for the NICO members, I don't have a garage, i live on my own and yes i have been guilty on taking shortcuts with my amazing "Q" (even tho it is giving me a **** load of headaches i still love it), as much as i taken the plenum off (5-7times in 4kmiles), should I just replace the car or just replace the recommended hoses on/below the plenum??

on the fuel pump, can i just buy a walbro 255 lph fuel pump and customize it to fit my car or should i stick with OEM parts $370 freakin dollars and call it a day?? if someone on here had done an walbro fit please let me know how......

any after thoughts and advice would be appreciated..

Thanks,mitchell

[qship96]

Factory original fuel pump is about $250 from http://www.everythinginfiniti.com

They also offer 25% off all genuine Infiniti parts.

the Q is super reliable, but will bite you if you try to take shortcuts. The smallest hose/electrical connector you overlook while performing maintenance will be the one that causes performance problems.

[goody90q45]

.......its just odd that the engine light is on but the code is 55 which equals to systems ok??? any clue why????....

Mitch I'm going to go out on a limb and say that you did something wrong in the screw turning sequence on the back of the ECU. Hopefully you've left it plugged in and laying on the floorboard until you get through these issues.

I say I'm going out on a limb because I see that you've successfully pulled codes in the past. At this point the first thing to do is to check the long blue ECU connector. Is it tight within about 1/8" of being flush with the ECU mating surface and most important is the connector straight to the ECU? We've seen a couple of owners tighten the connector crooked, not seating parallel to the ECU and the engine runs but very badly. Worst case is the ECU connector is cracked in half.

You've been able to pull codes before but make sure that the ECU screw is in the full CCW position before starting. With the ignition in the ON position and the engine off, turn the screw fully CW, wait 3 seconds, turn it back fully CCW and read the codes. When you're done, repeat the process (CW, 3 seconds, CCW) and the red light will be solid. If you repeat the process a 3rd time you will get code 55, and if you repeated it a 4th time you will get a solid red light again. When you're done it's important to leave the screw in the full CCW position (Sly ) displaying a solid red light.

The FSM instructions are a bit confusing and I got code 55 the first time I checked my codes from turning the screw one too many times. Give it a try again and see what you come up with.

ok ok, i had taken the plenum off about 5-7 times in the last 4k miles, a lot if you ask me..

I feel your pain. I had the plenum off my last 90Q five times in 9 months replacing one injector at a time. (Keep it to yourself Brian. ) Only drove it about 4000 miles.

[goody90q45]

.......started the badboy up and it ran but once you step on the gas it would burp and not wanting to go anywhere but only slowing down....

I left off the 3/4" hose that runs from the drivers side valve cover to the underside of the air tube after one of my plenum removals and the engine ran like yours.

A crack in any one of the larger hoses from the valve covers, through the PCV valve and back to the air tube via the underside of the plenum will do the same. There's very hot gasses going through this system and it's my experience that these hoses get very brittle and loose. Check them all closely for cracks and leaks.

[96Qowner]

Yeah, it's beginning to look like it's NOT a bad fuel pump. If it doesn't sound like a swarm of bees, it's probably ok.

Your problem started after the last plenum pull - probably a hose or connector or harness issue.

[maxnix]

Yeah, it's beginning to look like it's NOT a bad fuel pump. If it doesn't sound like a swarm of bees, it's probably ok.

Fuel pressure test is definitive.

[boonseyQ45a]

Fuel pressure test is definitive.

This car has been giving me problems since day one and I am running out of patience, borrowing this friend car this other friend car the week after and the money and time have been frustrating... I love this car but just of thinking about taking it apart again just, just, just crazy...... this month alone I have lost 2 loved ones (one 7 months and one 83yrs old), back in denver and im in michigan..... this traveling back and forth is wearing me low and dry in cash.... and in michigan everything is running dry and low, i just need something to get me to work and back and so on.... I just wanna sell it now to whatever price I can get it for..... its just not for me now...... someone that have a lot more patience can purchase it...... i will keep my fellow NICO memebers posted, my mind is just filled with stressed right now.......

[Q45tech]

When the car was brand new the target market made more than $150,000 per year and had $500,000 in liquid assets. If circumstances have changed or you over bought used, probably time for a change.

[boonseyQ45a]

ok fellas i rechecked the code it reads 51 injectors analysis... so i checked the ohm on the injectors and #2 have no reading and rest is at 12.0-12.5 ohms which is within specs... also did the knock sensors as well and they are reading 555-566 which is within specs... at this point is there anything else i should do for the #2 or is that just my problem right there????

[goody90q45]

It looks like you have a dead injector but fortunately #2 can be changed without removing the plenum. You might want to check the resistance directly on #2's injector pins rather than through the harness connector just to verify your readings and make sure it's not just a bad connector.

[fixer]

1 dead injector will make the idle a little rough and about 30% loss of power. it will not keep the car from going over 35 mph, I think you may have another issue. be sure to recheck all 8 of the plenum gaskets. sometimes they look good when you take them off but when you try to reuse them they crack and cause a serious vac leak. also make sure tps and maf connectors are plugged in properly

[maxnix]

Plenum should always be new!

After 8 years, the rubber is cured hard.