Pinging Valves at Cruising Speeds

[Libraman2k1]

I am having problems with my valves pinging at cruising speeds of 40mph on up--I have adjusted the crank angle sensor advanced and retarded--I have replaced the EGR valve and the O2 sensors--I have put octane booster in the gas and fuel injector cleaner and I have checked the fuel pressure regulator--I havent checked the knock sensors or the fuel pump but I made sure that the timing was at 15 degrees-After bringing my car to an infiniti dealer in louisiana, he replaced 2 lifters and 2 coils and then this pinging/clattering of the valves began--I am now getting only 250 miles per tank full when I was getting 350 on my 92 Q45--can you help me guys??

[Q451990]

After bringing my car to an infiniti dealer in louisiana, he replaced 2 lifters and 2 coils and then this pinging/clattering of the valves began

They actually pulled the heads and replaced two lifters!?!?! When you say coils, you mean the spark plug coils? They're not prone to failure.

You need to make sure the plenum, runners, EGR valve passage going into the plenum, etc. are cleaned back to as-new condition. You should definately check your knock sensors... the dealer should have checked it with Consult. Make sure the timing is truely set at 15BTDC. The CAS adjustment is very sensitive. Also, have the injectors checked (power balance test on Consult) and flushed if it's been a while. If you aren't familiar with the "power balance" test search for it with the red button in the upper right hand corner... there have been several threads on this lately.

One other thing to consider... new spark plugs? Only use factory plugs... bad results with anything else!

Heath

[Mayhem_J30]

he probably meant valve springs when he said coils...'probably'

[Libraman2k1]

No, they actually replaced 2 lifters and 2 coil packs on the left bank because of an "arcing' condition which I think was a scam--the lifters are still tapping at times and the valves are still clattering like I have bad gas in my tank but I dont--I had my car put on an analyzer today and it came out clear--I just found out that the knock sensors will not show up bad on the EECU so it will not initiate the check engine light--Is this true?--Next thing I am going to do is to check the resistance of the injectors and the knock sensors --Someone had an illustrated version of how to do this-I am gonna try this before I take this to another Infiniti dealer---any other suggestions I would certainly appreciate--thanks--Reggie

[DAEDALUS]

That is true...there can be non-critical errors that don't flag a CEL. These must be read with a Consult at the dealer. The resistance checks are a good indicator but don't guarantee anything. Don't forget the sensors are only to compensate for the knocking condition...if your engine is knocking, you need to find out why and then fix the root problem.

[nisstek]

Sounds like you have checked everything but cylinder pressures AKA compression test. Its possible carbon biuld up has raised the compression causing the spark knock

[landtodd]

I'm with nisstek. Do you drive aggressively enough to keep the carbon cleaned out? Are you comfortable trying that sometime?

[Libraman2k1]

Oh yeah--I drive fast and I do test the performance of my car from time to time--I have driven it about 145 MPH just to test it--Seems like it can go faster but didnt want to get a ticket--this car will kick *** but I sure hope I find out what is wrong with it--I will not sleep well until I do--i think that it is something quite simple like a bad injector or a bad wiring harness--whatever it is, it happened when the repairman took my valve covers off and replaced my 2 lifters--QUESTION?>>> If the knock sensors are not working, couldn't I just retard the timing on the CPS to make the valves stop clattering at highway speeds??--I would think that the knock sensors work in conjunction with the CPS--

[Libraman2k1]

I have now tested the resistance on my fuel injectors and ALL of them are reading >13 ohms--some are at 14 ohms or 14.5--I dont think that all of my injectors are bad--I feel that the wiring harness is bad because I tested the resistance through the harness--do u guys know who might have a wiring harness for a 92 Q?

[DAEDALUS]

You're probably right, but verify that first. Remove the center plastic cover just in front of the plenum. Right behind the cover you'll be able to see the #1 and #2 injector harnesses. Remove these after removing the little wire clips that hold them on. After the harness is off, you'll be able to measure each injector directly at its terminals. Also, did you measure your multimeter leads by themselves?You can get the harness from Scottsdale. Call them up at 1-888-216-5328. Should be less than $40. You will probably also want to order new plenum seals (8). I *think* you can replace the harness without completely removing the plenum, but I'm pretty sure you have to at least unbolt it to get enough clearance to remove the old harness. Let us know how it goes.

[Chally]

This pinging/rattle noise, when does it happen?ie: Under acceleration only, anytime, at certain revs under load...???

If it happens all the time, it is more likely a mechanical knock.Be interesting to know what they did under the covers...

[Libraman2k1]

thanks for the info daedalus-will measure directly across each injector--Chally, the valves only clatter when the engine is warm and only at cruisng speeds past about 70 MPH--Now, If I run my car at a high speed (over 100 mph) which heats the injector harness up more and increases injector resistance, then the valves will clatter at about 40 MPH on up--I sure hope that it is just the wiring harness causing the problem--I have 1 of the best multimeters on the market and it gives very accurate readings--Other than that, my car is ok except for a vibration at about 10 mph when accelerating--

[Chally]

I've never heard of a harness giving problems you have described. They are generally not affected with different temps.

You didn't say if it was under acceleration.

Does it still make the noise when cruising at the said speeds?If so, it sounds like the engine is running TOO lean, OR.. something has been fitted incorrectly around the lifters area.

It may be a good idea to get an experienced mechanic/technician, to go with you & get his opinion.

[maxnix]

Does it still make the noise when cruising at the said speeds?

If so, it sounds like the engine is running TOO lean, OR.. something has been fitted incorrectly around the lifters area.

It may be a good idea to get an experienced mechanic/technician, to go with you & get his opinion.

Maybe Chally is on to something here. Did you replace the fuel filter? Maybe a rail flush and injector cleaning is indicated, especially if you can identify which cylinders are generating the noise.

[Libraman2k1]

Ok guys, got some info from Infiniti--my fuel is pumping correctly at idle but drops off below specs at acceleration--the fuel pump is humming a little more louder than usual when the car is running --what do u think?--fuel pump or fuel pump control mod?--whatever it is this will explain the lack of power and valve clattering due to a Lean air/fuel mixture--