Rattling noise in front when gas applied. ????

[BennyM]

What the didly is this rattling noise? I only hear it when I either don't apply enough gas starting out in 1st, or the engine gets put under load in gear (pulling up on wheel ramps with minimal gas), or if I blip the gas with a quick jab even out of gear I can hear the rattle for a moment. I cant find where the noise is coming from, but it's starting to bother me. I don't really know how long it's been doing this either, but it seems to get louder. I'm gonna check the plugs tonight, but besides that, I can't think of anything. Any ideas? thanks.

[Paul in NZ]

pinging or pinking

[BennyM]

didn't realize. K, I've been using 93 Octane gas and the EAT chip for years. Don't think those changed much. Could this be caused by a lose crank position sensor? Otherwise, I'm gonna assume it's a vacuum leak.

[jplacson]

OMG!!!! I've been wondering about this since I bought my car a couple of months ago!!!! HAHAHA... I actually figured it was engine knock from short shifting... I'm still getting used to the performance of my 520i... I had an older 320 which still ran of a carb, and I'm still used to that one.

I'm starting to get the hang of it though. I hear it less and less now. I guess I never suspected knock or ping since engine knock/ping on a 4 cylinder is a LOT more evident (the car actually shakes) than on an inline 6, where all you hear is a mild rattle.

[MicahO]

It could simply be carbon buildup creating hotspots in the combustion chambers. Try things with the original chip for a while and see if the less agressive timing curve makes the ping go away. Mark's chips shouldn't cause pinging under normal circumstances, so you might want to try some different gas, or perhaps a jectron/ventil-sauber one-two punch over the next two tanks to see if things can be cleaned out?

Italian tune-ups may also work some magic, though I think those are endemic to those who frequent the board ;)

--Micah


didn't realize. K, I've been using 93 Octane gas and the EAT chip for years. Don't think those changed much. Could this be caused by a lose crank position sensor? Otherwise, I'm gonna assume it's a vacuum leak.

[BennyM]

I thought about putting in the old chip, but I don't see what that would gain me if I prefer Mark's chip.

Also, I recently put a ban on the gas station I've been going to because the pumps and autowashes are constantly breaking. So, I'll be running some new gas.

On that note, I have run Jectron and the like in the past without any noticeable difference in how the engine runs. Besides, don't they say on those bottles to run after every 2k miles, not after 2 refills? Perhaps I misunderstand.

I got some carb cleaner and am about to go check for vacuum leaks.

Later,
BennyM

[ryan roopnarine]

i would think that mark's chip operating properly is dependent upon the engine working correctly in the first place. after two hours of running it, i've finally been able to get the chip to ping on 100% 87, but only at 2krpm, and even then, its faint. more importantly, is that i had a slight vac leak that would bring down idle rpm to about 580 or so before i put the chip in....afterward, despite not fixing the leak completely, the car is idling at near proper levels without any input on my part other than letting it run...there might be some aspects of idle that mark's chip will correct if incorrect, which might hide your problem. luckily for me, i know that its the icv hose, so alls i got to do is secure it properly after i clean out the intake (spring break starts friday). yours might be a little tougher. i plan on doing the troubleshooting with the chip out (but batt connected). also, have you done both the jetron/ventil combination? the jet is fuel injector cleaner, the ventil is specifically for valve backside carbon cleaning...might help you in the long run. i bought a $3 ultrasonic cleaner from a thrift store and i'm going to put my injectors in it for a little while and see if i get a benefit or not. im also gonna scrub the backsides while i have the intake off....and clean the tbody out with brasso...anyway, methinks the quickest way to narrow down your idle issues is to take your EAT out so it can't mask anything big, and subsequently waste your time.

[MicahO]

I try not to run both of those items at the same time, preferring to put in one solvent for one tank, then the next one at the next tank, which is all I meant about the timing. I also don't agree with their every-2K-mile advice. If you are running good gas these days you shouldn't really need it that frequently. Hell, at 20mpg (which I average tank over tank) that would be a bottle of one solvent or another every 5 or 6 tanks! I do one bottle of each every spring and an oil change when I'm done with the second treatment. Do I notice a difference? Not really, but it would take a large difference in power to actually be felt in the seat of the pants...... Can it hurt? Not likely, so what the heck.