what is causing my rumble?

[sirrus]

Guys,

I still have not solved my engine issues post winter-storage:

http://www.s14.net/forums/showthread.php?s=&threadid=17722

The engine isn't really 'knocking' so much as rumbling at idle and througout the rev range. It sounds like a friggin chopper or even a mustang (blub blub blub blub blub).

What would cause this sort of rumbling? I have checked all my ignition components and replaced the battery. The fuel pressure is in the right range (~42psi) and I'm debating on draining the tank but this rumble is spot-on consistent so I really have a hard time thinking it's bad fuel.

Plugs were slightly fouled (fuel) after a long idle - which is normal for the S14 from what I've read - but I have new ones ready to go in if that's the problem and the plugs still looked fine before and right after all this started.

Despite the relatively consistent psi, could a faulty FPR cause this sort of rumble?

Thanks for any help. The nice weather coming around the corner is gonna drive me insane if I can't go out and drive like I'm insane...

[///Mflossin]

leaking header?

[sirrus]

Originally posted by ///Mflossin
leaking header?

Checked the manifold nuts and they're all there and relatively tight. I am going to double check them this afternoon since I'm double checking everything but so far they don't seem to be the culprit.. :(

[noro]

Is the engine block itself smooth or it's shaking? Also while you're at it double check the spark plugs and regap em... or just put new ones ($1.7 is not a big deal)

[sirrus]

Originally posted by noro
Is the engine block itself smooth or it's shaking? Also while you're at it double check the spark plugs and regap em... or just put new ones ($1.7 is not a big deal)

I would say that the block is shaking only because from above it seems dramatically more than normal, but I will double check this along with the plugs this afternoon. Compression is good BTW; haven't done a leakdown though.

The cost of new plugs isn't a big deal; getting them is. I don't know of a local place to get the X5DCs so I order them online and it usually takes a few days to get them here. That's why I don't want to just throw in the new ones to have them immediately get fouled up.

[petro]

if something is not right on the intake side it can do this.

For example, if there is a tear in the intake bellows hose.
If the AFR plug is not connected properly (easy to forget to plug back in) or maybe if the door is sticking
If the rubber vertical plugs are not seated to the TB adjusters...

It can run really rough with any of these issues.

[sirrus]

Originally posted by petro
if something is not right on the intake side it can do this.

For example, if there is a tear in the intake bellows hose.
If the AFR plug is not connected properly (easy to forget to plug back in) or maybe if the door is sticking
If the rubber vertical plugs are not seated to the TB adjusters...

It can run really rough with any of these issues.

Inspected the AFM manually and made sure it was plugged in. The door swings fine and I've inspected the intake boot (virtually brand new) as well.

I haven't looked at the vertical plugs so that's a new area for me to cross my fingers on; thanks.

[noro]

I just bough a set of NGK (which are to me just as good) from autozone

[petro]

could leaking intake gaskets cause this?

[sirrus]

Originally posted by petro
could leaking intake gaskets cause this?

I suppose it's possible, but this seems too consistent throughout the rev band :(. I would expect something more erratic, similar to a bad fuel issue. Plus, I replaced the intake gaskets last summer/fall.

_Something_ happened either during winter storage, the valve adjustment, oil change or air filter replacement I did in early Feb. I don't think the gaskets wouldve blown that severely during 3 garaged months of a mild winter...

Is it possible for the AFM to flake out like this? or the DME? It sounds kind of like a 'timing' issue but everything is in spec (shims, oil is spotless - no metal shards or anything, voltage, etc).

I just don't know what else to look at short of seriously taking some things apart or drowning myself in fuel.

[UK215M3]

Could you be more specific about the 'rumble' ?

is it misfiring or running rich or lean ?
Have you taken it to a garage? useful to stick a 4 gas meter up the pipe to see.

Sorry if this has been allready suggested.
What is the condition of your ignition components, i.e. cap/ rotor / leads/ coil???
Is your ECU dry?

It is possible moisture has penetrated something.

[hardtailer]

put a mechanics stethoscope (or a screw driver with a good handle pressed agaist your ear) on each injector and listen for a steady clicking/ticking. If one doesnt do that it's not injecting properly. tap it with the screw driver and see if it improves.

Are all spark plugs tightened properly?

[t13vom]

..Rumble...

Check for a collapsed motor mount or transmission mount. The other item I would check is the A/C compressor (clutch assembly.). Yes they are abstract but I have seen it before described the way you have.

[sirrus]

OK. Double-checked everything last night.

All injectors seem to be firing; all plugs are in tight and gapped correctly; no visible obstructions in either the plenum or airbox and intake boot is 100%; rubber plugs on TBs are OK; motor mounts were fine when I checked them 2 weeks ago; no moisture near the ECU; all ignition components have checked out.

I would say that it is running rich, at least at initial startup based on the smell (and plugs) but that goes away after a minute or 2.

As far as the "sound".. All I can say is that before the winter, I would fire her up and she would just purr. No erratic idle, no major vibrations; just an S14 in good shape. Now, the engine sounds like it's trying to purr but with the rhythm of this guy: :yeah: Sorry I can't explain it better.

I appreciate all the help.

[t13vom]

...rumble...

If you would like to have a second set of ears listen to it I am across town from you... I think I saw you occationally when I lived behind the Safeway off of Fairview...