Hey guys, im posting in the all-motor forums cuz well......your smarter than the peeps in the general 4th gen forum, and i think this is something more technical than the usual intake, y-pipe or knock sensor post, anyway....When im in gear and at WOT (usually in 2nd or 3rd gear) i once in a while hear a loud smack like metal hitting metal coming from the engine, when this happens the car hesitates and it feels as if im hitting some kind of governer.....Also the car sometimes feels as if it has no power while consistantly hesitating almost like bogging(power....no power...power. etc.)....i was wondering what you guys think, i am pretty sure the car is knocking....it doesnt feel like a random misfire to me and i am not getting any codes....am i running to lean??? Anyone else experience anything like this.

 

Sounds like spark knock.

It could be a number of things, therefore there are a number of fix options.

Lean A/F could be one of them.
Low octane another.

I do not see why you would be running lean, as you have no aftermarket ECU to alter A/F or timing.

How often is it occuring?

One option is to run some 91 or higher premium fuel, or try colder plugs.

 

ECU could be jacked and think everything is good and thats why no codes. also could be running too advanced if the ECU is goin nuts. wouldnt the ECU throw a code if it was knocking? or do 4th gens not have ks?

 

Jacked ECU huh? Ok ...

A32's have a KS in the exact same location as your 3.5L. 'Nutty' ECU's are pretty uncommon.

Mine never throws a code for knocking, and it does so quite often in the summer due to the JWT ECU I have.

 

the goofy ECU thing was just a way out in space option. what the point of a ks if it doesnt even sense?

 

the knock sensor senses for knock(lol) and pretty much tells the ecu to retard the timing until the knocking stops

 

It occurs maybe once every couple days.....im running 91 chevron(never ran anything else).....i have the expensive ngks(lol) dont remember which ones i believe they were iridium or something and i have had them for about 25k miles....its just weird that im knocking with a car thats not that heavily modded.....could a bad maf be giving out a wrong reading and causing this?

thanks for your help man...

 

Just a thought, but if there was a slight vacuum leak in one of the lines to the upper IM (i.e., after the MAF and TB, allowing unmetered air to get in), might that not cause the engine to run lean and cause knock (assuming that the KS wasn't doing its job?
I was under the impression that in stock configuration and using the recommended octane, if everything else in the engine control system is working as it should be that you won't experience knock and the KS doesn't kick in any adverse signal to the ECU.

 

What rpm's or speeds does it happen at usually?

Are you bouncing off the limiter?

 

check the ignition coils too, sometimes a bad coil can cause knock/pinging

any CEL codes? (i.e. misfiring cyl #x)

 

yeah i had the same problem with both my 99's. its the coils...

 

coil pack?? wouldnt that be a misfire....it doesnt feel like a misfire to me.... and it happens between 4k and 6k...no im not hitting my limiter and i dont have any codes....thanks for all the replys

 

dude your coils are bad just change them... it happens to all 99's,

 

uhhh, ok? i dont see what ur saying. if the knock sensor was "sensing" then it would retard the timing right? well his isnt doin that.

 

How do you know his ECU isn't retarding timing? You don't kthx.

 

yeh...if it was working in a perfect way it would keep retarding the timing until it stops knocking. since he is still knocking it must not be workin

 

the ks could also be broken... Geo Metro > 99 Maxima

 

thats what i was saying

 

Retarded timing doesn't guarantee that the knock will stop. It just lowers the risk of engine damage.

 

if it kept retarding until it stopped knocking and the knock continued, could it possibly retard it until the engine goes into "limp home" mode?

 

i dont think it would do that... like i said before geo metro > 99 maxima

 

Please, if you do not understand how a system works, do not advise on it ... "Limp home mode" AKA safe mode AKA open-loop mode. Its not as if the ECU could retard timing indefinatly, it does have operating ranges that limit its working parameters. Anyways, like nismology said, the ECU retarding timing doesn't guarantee that the knock will go away, since there are OTHER factors that could cause the knock.

Also, if the KS is bad, then chances are, the ECU is ALREADY running retarded timing (this is the reason why people feel a gain in power when they replace their old/broken KS). A broken KS would cause some hesitation on the powerband, but what he's describing sounds like it could additionally be bad coils. I was having the same problem because ONE of my coils was bad (split in half bet'n the coil and the connector tube), replaced it and all is back to smooth delivery. Check your coils, and change that KS, then tell us what you found. Best of luck.

 

thanks for the replies everyone....ya when the car does the consistant hesitation it feels as if it could be a bad coil(miss-fire) but when it makes the loud smack it feels almost like fuel cut...more like knocking then a miss-fire....im gonna change my plugs tmrw and while im in their im gonna check my coils, if the coils are good new knock sensor it is, and i do not look forward to changing the ks(GOD DAMN 99 CALISPECS!), once again thanks to those of you with inteligent responses.

 

I'm just gonna have to ignore this post...

 

Unplug the KS an install a 470k ohm resistor in its place and drive it for a week and see if it still does it. If it doesnt then go on to next thing. You got to start somewhere. I would start here, because you can pickup the resistor at radio shack for 99 cents.

 

thanks for the idea, but i'd rather not drive my car without a knock sensor.....if my car knocks i want the time to be retarded.....