straining to get up mild grades

[alexander]

So if the Knock Sensors are at fault will it always throw a code?Because they haven't.

[maxnix]

Alexander, please complete your profile with model year and model.

If you have a 1996 with OBD II, then it should. Earlier models with OBD I will not.

[alexander]

Good question.I don't have a clue.Need some help.

[96Qowner]

Well, Marin wants you to bring the car back, so have them hook up Consult and find out exactly why you're getting such lousy combustion. It should be obvious. You're getting 12mpg on the highway for pete's sake.

There's clearly some major sensor failure or sumpin. All 96s have OBDII, so it should be easy to spot, especially for a Senior Infiniti tech. It's time to remind them that you've been a great customer so far.

And check with us, tell us what they want to do, before you authorize another $1000 or more. They may just want to throw money at it, since you haven't balked at the cost yet. It shouldn't cost anywhere near that much for this problem. For instance, dealers will often replace all the coils, something no NICO member has ever had to do.

[Q45denver]

Well, Marin wants you to bring the car back, so have them hook up Consult and find out exactly why you're getting such lousy combustion. It should be obvious. You're getting 12mpg on the highway for pete's sake.

There's clearly some major sensor failure or sumpin. All 96s have OBDII, so it should be easy to spot, especially for a Senior Infiniti tech. It's time to remind them that you've been a great customer so far.

And check with us, tell us what they want to do, before you authorize another $1000 or more. They may just want to throw money at it, since you haven't balked at the cost yet. It shouldn't cost anywhere near that much for this problem. For instance, dealers will often replace all the coils, something no NICO member has ever had to do.

Good point. I'm not sure you even need a Consult if you have OBDII? Most systems in the car last a lifetime if you consider the lifetime of an average contemporary luxury car to be 200K.

[Q45tech]

ODB2 is no friendlier than OBDI since the codes tell you little without the exact voltages....................kind of like counting the flashes from ecu led.

OBD2 has twice the number of sensor so twice the probability of a failure.Sensors to double check sensors for failure.

[alexander]

Just spoke to the service rep at Marin Infiniti who talked the their senior tech, and he said if there was a Knock sensor problem, it would not effect acceleration/performance on a hill at highway speed.He wants to raod test it.

Maybe this guy ain't too senior or hasn't seen one of these old Q's in awhile.My Q is not 'Active' or a 'T'. But it's gettin tired getting poked at. And that's unusual for a san fran Q.

[maxnix]

No 1996 are active, but I think there was a t model.

[bullittandy]

I hope to God that here is a miscommunication somewhere b/c if that tech really did say that a bad knock sensor would not affect acceleration then he's a dope-thats the ONLY symptom-other than a code.

[maxnix]

True, it will certainly affect the performance and MPG by over enriching the fuel delivery, and possible burn out the catalytic converters.

Ever thought about going to Niello or Peninsula?

[alexander]

Just got off the phone at Infiniti of Marin to double check that I did understand that statement and service rep reassured me the tech said 'bad knock sensors would not effect performance/miles.'

Off to Niello. Their tech has been there since 1991

[maxnix]

That's got to be an improvement.

Moderator Szhosain knows a little about those other bay area dealers.

[bullittandy]

True, it will certainly affect the performance and MPG by over enriching the fuel delivery, and possible burn out the catalytic converters.

Ever thought about going to Niello or Peninsula?

It effects performance by retarding the timing and if they (K/S) don't work then the computer adjusts the fuel mixture-it doesn't keep dumping normal amounts of fuel with retarded timing.

Also, I'm fairly confident that the cats are not going to "burn out" because of a bad knock sensor.

Again, those kinds of statements are as bad as the stupid sh*t that newbies say. Brian buddy, you have a position of respect and expertise and so act accordingly.

[Q45tech]

It is the very rare technican that spends the time to data log ignition advance vs rpm in WOT situations. Even rarer to do it hundreds of times [and hundreds of hours away from shop] so that they understand the EXACT PARAMETERS and how sensor inputs change the ecu vs air temp and density, coolant temp and KS operation.

This is the work of the engine designers and ecu reprogrammers.

Thousands of man hours went into ecu programming to get it just right for the typical owner under different conditions.

[maxnix]

Also, I'm fairly confident that the cats are not going to "burn out" because of a bad knock sensor.

So you don't think extended rich running and subsequent overheating of the catalytic converters will affect them?

[bullittandy]

So you don't think extended rich running and subsequent overheating of the catalytic converters will affect them?

That's a misrepresentation of my post.

Please refernce whatever PROOF you have that (be it FSM, actual data, etc etc,) that when the K/S fail, the engine runs SO rich that the cats are destroyed. (thats what you said-"possibly")

Please do not respond with theoreticals, only ACTUAL experience/data-don't bother with all the things that could "possibly" happen-thats too lengthy.

[96Qowner]

I did some searching and found a few threads on bad gas mileage:

96q knock sensors

14.9MPG!!! SHEEESH

MAF sensor with poor connections makes the engine do many weird things

[alexander]

Took the Q to local service tech who did a good job on the rear crossmember, and a recent valve cover replacement.Quite satisfied with their work.They checked the knock sensors for resistance and got576 kohm and 568 kohmspecification is 500 to 620.So they seem OK.They will now look very closly at the timing/retard to see if there is an issue there, and torque converter lock-up.

[alexander]

Posed a qustion about all this to the master tech at Niello Infiniti (since 1993)He said to do Alpha readings.Can someone explain this, he might take awhile to get back to me.

[maxnix]

You might do a highway mileage test where you fill up, drive an hour or two up I5, preferably with cruise on, turn around and drive back, refill then calculate highway mileage.

Around town you can burn lots at idle, which is 0 mpg.

[BadQ45t]

using infiniti stealerships in the Bay Area, you must be a wealthy man.....I haven't had my Q in Peninsula Infiniti is 2 years and than it was just for oil changes.

You need to break that dealership habit, you just cannot keep (IMHO) taking cars that are more than 10 years old to dealership if you live in a place like the SF Bay area...now if you were Iowa or Montana, sure, but here they are up well over $100 per hour and they charge very EVERY LITTLE THING. Pensinsula is a great dealership, nice service guys, loved them during the warranty period....but now Richard's Auto in San Bruno gets all my money (at $85 per hour thank you and they do great work).

[alexander]

Well... having the MAF replaced plus plugs and timing .... got the mileage up to 24.1 today (freeway) (last week was 13mpg) ... and that was on I-280 around Woodside and Los Altos (Google area) which has quite a bit of grades and trying to avoid all the Audi R8's screaming up on ya.So pleased with outcome.$4250.00 well spent for a car worth $1800 on KBB site.

I'm happy.

[goody90q45]

.... got the mileage up to 24.1 today (freeway) (last week was 13mpg) ... and that was on I-280 around Woodside and Los Altos (Google area) which has quite a bit of grades and trying to avoid all the Audi R8's screaming up on ya. So pleased with outcome.

What do you mean you let an R8 pass you!! Your Q should be the leader of the pack on a sea level grade (LOL). The I-280 is a fun road to cruise in the Q and usually has very light traffic considering it's in the SF Bay area. Every time we drive it my wife spouts that the only reason it was built was so the Hillsborough residents (Jackie Spier?) didn't have to fight traffic on the 101. Glad to see you're sorting things out.

[maxnix]

Well... having the MAF replaced plus plugs and timing .... got the mileage $4250.00 well spent for a car worth $1800 on KBB site.

Ahh, KBB is always high. I'll give you $1,600 cash!

[qship96]

Nah, replace a few more thousand in brand new parts, and I will give you $1900 for it!!!!

[96Qowner]

Well... having the MAF replaced plus plugs and timing .... got the mileage up to 24.1 today (freeway) (last week was 13mpg) ... and that was on I-280 around Woodside and Los Altos (Google area) which has quite a bit of grades and trying to avoid all the Audi R8's screaming up on ya.So pleased with outcome.$4250.00 well spent for a car worth $1800 on KBB site.

I'm happy.

Awright!

But your first post says you'd already replaced the MAF?

[alexander]

The 12-13mpg was what I was getting before MAF was replaced.Combined city and freeway looks to close to 19mpg. Not bad.

Any more bids coming in? Still have $20,000.00 more parts to replace!