[85TurboMKII]

I am having a pretty annoying problem with my 6M-GTE. everything is fine until the boost goes above 5psi and then it sounds like a rattling noise coming from my engine. it doesn't sound like detonation. I have had that happen before. I dont really know how to explain it. it almost sounds like something is loose. but the engine never makes noise in everyday driving out of boost. I drive this car 90+ miles a day and it runs great as long as I dont step on it. I have played with the fuel a bit (only richer of course). and I have retarded the timing down to 4 degrees. and still no change. the engine runs cool, no loss of coolant, some loss of oil due to leaking and rings starting to have blowby under boost. but other then that the car doesnt smoke or run harshly at all. this totally has my mind boggled.

any ideas?

thanks

 

[pdupler]

I'd bet its detonation. My 6m-gte cannot boost without the MSD pulling timing back regardless of the fuel mix. I've got 1.5 degrees per pound from 2 to 7psi, so thats a total of -7.5 degrees at full boost. If you try to take that much out of the base timing it'll run like crap if at all. Lots of factors, but a boost retard device is an easy way to tune. I've not been happy with the quality of my MSD stuff tho so if you get one, try Crane or Mallory or Holley.

Phil D.

 

[85TurboMKII]

is what I dont understand is that I have had it like this with stock timing for the past year and a half and I have run it up to 12psi without any flack from the bottom end....this is a new thing as of about a week and a half ago. I even dropped the timing down 6 degrees from stock and still didn't make any change.

I'd bet its detonation. My 6m-gte cannot boost without the MSD pulling timing back regardless of the fuel mix. I've got 1.5 degrees per pound from 2 to 7psi, so thats a total of -7.5 degrees at full boost. If you try to take that much out of the base timing it'll run like crap if at all. Lots of factors, but a boost retard device is an easy way to tune. I've not been happy with the quality of my MSD stuff tho so if you get one, try Crane or Mallory or Holley.

Phil D.

 

[DKJones96]

maybe early stages of rodknock? loose harmonic balencer? i have this rattle at idle but it's intermitent and has gone away with the use of a synthetic blend freeing up my lifters.

 

[Eric]

DK,
I'm having a very similar pesky problem...only at idle too. What oil are you using? I probably need to get my car on the highway for a while to let the MAX Life oil take affect, I live too close to work I guess.

Eric

 

[Flyin' Hawaiian]

it's winter time, so maybe your area is starting on their oxygenated fuel, or maybe just some bad fuel. Try some octane boost or some high octane fuel. If you can get your hands on some 100+ octane fuel, try a few gallons out to see if the problem lessens or stays the same.

 

[DKJones96]

i'm using castrol syntec. are your lifters sticking open? mine are i'm gonna pour half a quart of mystery oil in that sucker beore my trip today.

 

[williamb82]

if its only over 5psi and timing isnt affecting it unfortuneatly i think it may be a rod starting to knock. id have to hear it to be sure. btdt. then again, did you fill up with a different brand gas or something this past week? hard to say for sure without hearing it. btw, i tried calling the other day but no answer. lmk if you find out what it is. if not maybe you can bring it over this weekend.
william

 

[rabidchimp.com]

Check your fuel pressure. Perhaps your regulator is hibernating, and your fuel pump could be taking a dump as well.
-Aaron

 

[williamb82]

he's got a walbro and a vortech fmu. both ~1year old or so.
william

 

[85TurboMKII]

it ended up being the fuel pressure. the regulator was hibernating. I just readjusted it and all is good. so it did end up being detonation afterall it just didn't sound like detonation.

thanks

Check your fuel pressure. Perhaps your regulator is hibernating, and your fuel pump could be taking a dump as well.
-Aaron

 

[rumptis]

I hope you didn't do any real damage to your engine.

Glad you figured this out I'm sure it will save someone in the future.

 

[BillyM]

good call rabidpimp.

--BillyM

 

[Supra Bob]

Ok.. I'll ask it..

What do you mean when ya say the FPR was "Hibernating"? Not a term I have heard before in conjunction with an FPR...

 

[rabidchimp.com]

Bears hibernate, until you mess with them, or winter ends. This guy didn't want to wait until winter was over, so he messed with his FPR. Now its awake.
-Aaron (never used the term "hibernate" in reference to a car before yesterday)