JayGee

Hey guys, so I have this sound when I'm in gear and accelerating. It will not happen when I'm not in gear, it will sound like a clean rev up if I'm in neutral. When I am in gear, any gear, I get a sound that I would describe as sand being dropped on sheet metal. I've looked around the forums and the general consensus for the go-to description is marbles in a tin can. It doesn't sound like that. This is a very subtle, but to me, obvious difference and like I said, only happens when I'm in gear. What's odd though, is it seems most people detonate when they are giving it decent throttle. Now, mine MAY make the noise also while I'm getting on it, but I don't notice it. My exhaust is pretty loud. I distinctly notice it when I have my windows up and am giving it light to very moderate throttle. Like I said, it could always be there, but this is when I hear it. I was actually at the Ford dealership today looking at a part to verify that the one I recieved wasn't broken (slave cylinder, if you look at the top you'll know what I'm talking about) and when I went to crank up my engine to leave, it died immediately. I know I'm getting fuel. I have a boost gauge and wideband so I know I don't have a vacuum leak, otherwise I would be running leaner than usual correct? When I'm in boost, my psi and afr are spot on as well.

I plan on ordering spark plugs tonight. I hope to god they don't break off in the heads when I replace them. I bought the car with the supercharger on it so I don't know for sure that the plugs have been changed. I would assume so, but new plugs certainly won't hurt. I also cleaned the MAF a few months back, so that shouldn't be a problem (again, not running lean, but I saw it as a suggestion). I'll have to take the tb off to get to the driver side plugs so I'll clean that as well. Can't hurt.

If you have any suggestions I'd love to hear them. Thanks

JayGee

I can't find the edit button.

I forgot to mention, the car is not over heating. I have a temp gauge and the hottest it ever really reads is 205. The sensor is mounted between the thermostat and the upper part of the radiator. I was told this can cause it to read a little higher than the actual temperature the engine is seeing. Makes sense. That's not important though, my temps seem to be good.

Derf00

You sure it's not just the sound of the supercharger/turbo winding up?

JayGee

Yes, I'm sure.

flash_xx

Could be the plate between the engine and trans vibrating, or the exhaust. If you want to be sure it's not detonation put some race fuel in it. If the sound goes away it's pinging.

JayGee

Do you mean the flywheel? I'm due for a new clutch so I guess I'll find out in a bit if it's that. Where would I find race gas? Would octane booster suffice?

Derf00

Octane booster is a sham. Yes, check the plugs first, if they are the wrong heat setting or very worn you could get spark knock, pinging, etc. but, i've never heard of it sounding like sand on a metal surface. Sounds like something is rubbing. Is it at a particular speed?

Wheel bearing perhaps if you get to say 30 or 40+, put it into neutral and let the car coast and RPM's drop. Should be able to get a better listen to it. While coasting and still in neurtral gently tap the gas, does the engine RPM affect it?

JayGee

It really irritates me how bad I am at explaining sounds. I tried taking a video but it didn't show up and just made me feel worse. It isn't a wheel bearing though, only happens in gear on the gas pedal. All gears, all speeds, all throttle positions (as long as I'm in gear). The noise doesn't change with different gears and will go away at any rpm as long as I'm cruising. It's solely on accel. It does however get drowned out at around 45-50 mph by wind and road noise, if that helps you imagine the volume of it. I'm 99% sure it isn't detonation anymore (I read a lot more about it). When I read the "marbles in a can" metaphor, I was imagining them being rolled around, not shaken around. It doesn't sound like something is being tapped or pounded, so I don't think I'm pinging. I found a bad idler bearing and I'm waiting on a response from summit racing on the diameter of a replacement I'm looking at. I have a supercharger so the measurement is pretty crucial. That pulley shouldn't matter though since it doesn't make the noise in neutral (it does make a knocky/clatter noise that I've been searching for for months though, so that's nice to finally find). The cheapest quote I could get from a mechanic is $115 an hour just to find the problem. With the responses I've been getting on different forums, I feel like it'll take a bit to find it so that will become pretty costly pretty quickly. I'm rambling at this point but I think I answered your questions. Thanks for the reply

flash_xx

Not the flywheel, there's a metal plate sandwiched between the trans and engine, but since your problem only occurs while in gear it could be the trans.

flash_xx

I don't want to deviate from the actual problem, but since the OP asked about octane boosters not all of them are shams. Those who race regularly know there are some actual useful ones, the ones that are for "off road use only" or for "racing".

Torco accelerator, Lucas Race octane Booster and a few others raise the octane up to three numbers, not points. Three numbers is 30 points. So either one would take your gas from 91 octane to 94.

The octane number vs octane points is where they scam you. An octane number is 10 octane points. Go with the Torco accelerator, that one works so well they usually ban it from racing, at least in the classes that are supposed to run pump gas.