Rattling noise from under the hood...

[k.c.g.]

k, well i have a local ck4 4g92 sohc,,,bought it about a month ago. Did a regular tuneup oil, oil filter, plugs, air filter etc, changed the transmission fluid also.
Not to long after started getting a rattling noise under the hood,,,went to the alignment place got everything checked,,,all mounts changed,,,engine transmission and shock. Still getting the noise so i went o a muffler shop,,,all shields etc in tact.
Did all the research i could do on and off this forum,,, CONCLUSION engine knock. the only thing i could remember the previous owner had 50 body castrol and i replaced it with 20/50 valvoline. No checklight coming on so i assume the knock sensor ok correct me if i am wrong. If the timing was off dosent the knock sensor fix this prob. Also had ngk heatrange 5,,,changed them to 6. Older plugs were in good condition,,,no oil burning btw.
Also noticed everytime i kick down as soon as the rpm raises it drops a little then starts to pick up...

What could be the prob and the possible solution......any help would be much appreciated

[Ted_v2]

get a mechanic's stethoscope and take a listen.

btw i had a similar problem with a weird rattling noise and it turns out it was one of the fuse boxes cover, Weird but damn that was noise

[k.c.g.]

4real,,,that could make so much noise......
i could be on the worst roads an wouldn hear a thing until i mash the gas and barely...

[MISHI]

The question you should ask is if it is engine, does the rattle increase with revs?

and does it get slightly louder with the rev and then stop?

if it sounds like holding a spanner and rapidly hitting a metal part in the engine bay then possibly it is a major issue.

If you know the sound, do a youtube search for engine noise or engine knock and see if that sound is similar to what you hear. May help a but more.

Also get th car up to speed and possibly neutralize it. Then listen for any knocking noise. A suspension noise would be a dull "knock on a heavy door" sounding noise unlike the spanner noise I described earlier. And it will not change with revs... only with the condition of the road.

[k.c.g.]

yup,,,once i accelerate the noise is present,,,more i mash louder the sound but once the speed levels out the knock is minimal,,,if i rev on neutral it isn't there...Did some research and its definitely knock,,,a mech checked it out an his advice was to use premium gas,,,i def cannot afford that,,,timing set properly and everything....Another mech said he would have 2 run some tests to find out exactly what is the cause since is not the timing which is the major cause.........

[jayakamarksman]

Connecting rod bearing or tappets need servicing

[like a boss]

I cant explain in detail... but the sound u hear is pinging.... somethingin to do with d ignition.... my mechanic ajusted my distributer an it stopped.... as i said i cant give details but thats wat my mechanic called it (pinging).... (ignition problem) so u tell or ask yuh mechanic bout pinging an tell him wat i said ... hope it helped

[de_dougla_smurf]

Two or three things worth considering.

If the tappits are slack, it can cause the noise you are hearing, get the head checked out.

Secondly, i can assume that you are having some oil flow problems, ie, a failing oil pump. From what you said, the engine only makes the noise under load, while driving as opposed to park or neutral.

Sounds like a high mileage engine to me which means you should get a through engine job done.

Thirdly, i dont know what are OEM recommendations for your plugs off hand, but using the wrong plugs can also introduce the problem you describe.

One more question, how is your engine temperature? Did you ever overheat? Did the last owner over heat? Check for bubbles in coolant after car starts.

Im sorry tht its not a one size fits all soloution but such is the nature of troubleshooting.

Will try to assist accordingly.

[k.c.g.]

Thanks fellas,,,well smurf,,,the plugs are the correct ones,,,also spoke to the previous owner and he said he never encountered any probs so he never did anything besides a regular tuneup....

Gas filter was never changed and injectors were never serviced....

Spoke to a couple mechanics well and they didn't sound like the wanted to help,,,they jus said use premium...

The last mech i spoke to took time to explain what could be the possible causes and said he would service the injectors,,,run through the fuel system and then have a pressure test done....

Also like jayakamarksman said might be tappets and all....

Should be visiting the mech sometime this week so i would keep u all posted......

Thanks....

[Master of Disaster]

Have a fuel pressure test done 38 psi should be about correct at ilde , 2nd my friend had this problem b4 with a 4g93 . problem is not to do with the knock sensor . timing is 1 aspect . wtb the timing belt want changing or the tensioner is not good .and finally we rewired the whole engine because the engine harness was not good , doh matter what we did couldn't solve the problem changed down to the crank angle sensor as well . best solution is try another brain , if that doesn't work , well ,

[MISHI]

Well if your initial mech says it's pinging (sounds like you shaking a few coins in a plastic bottle when you put your foot down) then the quality of fuel will have a lot to do with it. Investigate what is the standard octane rating for the 4G92 SOHC ( I believe it is 95 RON).

Tappets would make noise driving or not so I doubt it is that.

Detonation


Rod knock (if you hear this that is a big problem.


Do a cleaning of the throttlebody etc. Then use a fuel octane boost and a FULL tank of premium to see (just as a comparison test)

[k.c.g.]

Well its definitely not rod knock,,,thank god...

mishi,,,the gas tank cover has 95+ octane written on it...well my tank would take a while to finish,,, like weekend or so...
I would try the premium and see what takes place...

couple times well at the gas station i see audi's and stuff filling up with super,,,i cant afford premium lol...

The thing is when i bought the car a little less than 2 months ago it was working fine...
Just a quick question,,,would using straight 50 body castrol damage the engine,,,never had this prob until i changed the oil,,,previous owner used 50 castrol and i replaced it with 20w50 valvoline...

Btw spaceman i really hoping i dont have to go into all that,,,but taking what you said into consideration the last mech i spoke to did mention something about fuel starvation so i would have the injectors cleaned as well as the gas filter changed which was never done apparently....

Shucks,,,smurf,,,forget 2 mention the car never encountered any overheating probs...

Thanks fellas,,,would keep you all updated......

[k.c.g.]

Well,,,went through an entire tank of premuim and the problem was still there,,,went to the mech, he cleaned injectors and the egr valve, tightened the timing belt, checked all the vaccum hoses etc and the problem continued....

The knock sensor was unplugged and the problem stopped,,,you could still hear the tappets ticking but nearly 90 percent of the noise was gone,,,they replaced the knock sensor and had the same problem,,,unplugged that one and knocking gone and then advised me to leave it unplugged and get an electrician to ground it off so the checklight would come off,,,wtf....

The engine sounds a little different with the sensor unplugged but the knocking is completely gone,,,only problem is when i cross 80 the car strugglin,,,floorin it and the needle barely moving...

Tappets still making noise,,, the only thing i could think of is that the noise the tappets make combined with the slight vibration caused by a weakened mount triggers the knock sensor and the timing is wrongly adjusted resulting in the knocking......

Could this be?

What could get rid of the tappet noise btw?

[k.c.g.]

Another observation,,,when the car warms up before i drive the noise is present but only when the checklight comes when i reach out on the highway the noise goes away,,,i realize the checklight does not come on with stop and go traffic,,,only when the car reaches a certain speed or all the gears have changed through,,,well i think so....

[Master of Disaster]

Go have the mechanic remove the engines oil stump pan ,have it cleaned n also the strainer as well put it back together and do a oil change , I suggest using another brand and grade of oil ( something thicker ) NP 20-50 prob 1 of the best in durability right about now , other than shell 50 body , and have the knock sensor plugged back in and a computer scan and clear all codes , car should bump back up , if it still pursist then change the ecu,

[Master of Disaster]

There's a possibility you could be having a electrical problem , whenever we encounter these problems that just won't go away , my friend (a mechanic) usually re-wires the engine , meaning change the engine harness, ,and sometimes just sometimes it is prob the ecu as well , if a signal goes dead it causes problems to,,

[Master of Disaster]

Wait what vehicle is it your having this problem with.

[k.c.g.]

Spaceman,,,is a ck4 4g92,,,another observation,,,with the knock sensor plugged back in and the oxygen sensor unplugged the noise is cut down by about 50%,,,another ecu was used but the problem is still there.....

Knock sensor unplugged,,,O2 sensor plugged knocking is 20%
Knock sensor plugged,,,O2 sensor unplugged knocking is 50%
Both plugged in knocking 100%

[Master of Disaster]

Are you using an apexi safc to read these signals ,or what,

[Master of Disaster]

Judging from your observation , seems like its either the gas is the prob , or lack of fuel pressure , don't give me wrong , but fuel pressure could be all well and fine but wtb injectors , bad dribbing injectors will cause this , just pointing out

[Master of Disaster]

Also airflow , transmission lagging could cause engine retard , and induce knocking as well ,

[k.c.g.]

No apexi safc,,,jus my ears....

I already tried a whole tank of premium,,,didnt even ease up...

Also noticed while accelerating the revs would drop a little then start to pick up...

Could it be carbon buildup?

[Master of Disaster]

That certainly sounds like fuel , you need to have the fuel pump checked ,there supposed to. Be a filter in the feul tank ,

[k.c.g.]

Well look thing now,,,when the maf is unplugged no pinging whatsoever,,,changed it,,,still pinging,,,unplugged the new one pinging stops,,,really want to believe is low fuel pressure...

[Ted_v2]

get a gauge and see.

a bredren and me screwed out one of those gauges from a water pump and it worked

[shaun_]

K.c.g. did you ever find a solution to this problem? Currently I'm getting d same issues wit my 4g93 sohc & really not sure what is the cause. Yesterday I bought a new throttle body & air filter to see if it would correct the problem, still no change. I checked timing & problem still there. Currently resorting to checking under the tarpet cover n crank shaft. I haven't checked the brain as yet however. Also replaced the fuel filter less than three weeks ago. As I adjust the distributor the problem is still there too. It sounds like the noise is coming from the top of the engine & not the bottom, however noise & rattle sounds does travel sometimes. Any advice?