| Author |
Message |
magoo (Magoo)
Advanced Member
Username: Magoo
Post Number: 2648
Registered: 2-2001
| | Posted on Wednesday, April 24, 2002 - 11:15 pm: | |
Rob, Are you hell bent on microscoping this "potential" flaw. I guess if you are go full bore but I would consider how my car has been running in the past and ask myself if I am satisfied with it. Sometimes these things can become an obsession. I am a perfectionist. My son once asked me , "Dad how many things have you screwed up being a perfectionist?" Been there done that. BRGDS, |
TomD (Tifosi)
Member
Username: Tifosi
Post Number: 594
Registered: 9-2001
| | Posted on Wednesday, April 24, 2002 - 12:22 pm: | |
it should but the assumption is the calabration on everything is correct |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 1477
Registered: 12-2000
| | Posted on Wednesday, April 24, 2002 - 12:11 pm: | |
Like I said down the thread. Isn't the dyno getting the engine RPM's off the spark and not the faulty tach?
If the dyno shows a hp drop at 7200 RPM, isn't that accurate.
I don't know, I'm just asking.
Thanks. |
Craig Dewey (Craigfl)
Member
Username: Craigfl
Post Number: 361
Registered: 1-2001
| | Posted on Wednesday, April 24, 2002 - 6:39 am: | |
Magoo... I agree, but if I were concerned, I would measure the compression force on each valve (the way it sits in the car) before I ever went any further. I'm sure you could see a broken spring with a significant force difference. |
magoo (Magoo)
Advanced Member
Username: Magoo
Post Number: 2620
Registered: 2-2001
| | Posted on Tuesday, April 23, 2002 - 10:55 pm: | |
Tell you what Rob, If my car ran that good and on speculation that one spring may be broken, and maybe not, I wouldn't bother it. Not to knock you guys and your theory but the car runs great otherwise. And it may be characteristic of this engine. |
Christian (Christiank)
Member
Username: Christiank
Post Number: 313
Registered: 1-2001
| | Posted on Tuesday, April 23, 2002 - 9:02 pm: | |
Rob:
I had the same problem and it seems to be common for the 32 valve cars. The problem is that the tachomoter is often off and you are actually reving higher than what it shows. Bret is right, 32 inner and 32 outer valve springs. Bret, welcome to the club (it still hurts).
Christian
|
BretM (Bretm)
Intermediate Member
Username: Bretm
Post Number: 2443
Registered: 2-2001
| | Posted on Tuesday, April 23, 2002 - 3:50 pm: | |
There's inners and outers for each valve. 32 outers and 32 inners. They run about $1000 for a set so it would suck if this was the problem. Actually the dealership had just about the best price on them which was interesting. I'm replacing all mine during this major rebuild thing because they were a bit tired and all is apart. |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 1475
Registered: 12-2000
| | Posted on Tuesday, April 23, 2002 - 2:11 pm: | |
wouldn't it just be 32 springs? |
Christian (Christiank)
Member
Username: Christiank
Post Number: 311
Registered: 1-2001
| | Posted on Tuesday, April 23, 2002 - 11:16 am: | |
It could still be a broken valve spring. Remember that you have 2 valve springs on each valve so you wouldn't notice it during normal driving. I hope that's not the problem as you should change all of them (64!) if this happens. |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 1472
Registered: 12-2000
| | Posted on Monday, April 22, 2002 - 11:35 am: | |
As far as I know they are all USA cars. I know mine is.
My dip stick has a little rubber base that seals tight, I'm not sure how snug without looking at it. |
magoo (Magoo)
Advanced Member
Username: Magoo
Post Number: 2584
Registered: 2-2001
| | Posted on Monday, April 22, 2002 - 11:21 am: | |
About the oil stick being out somewhat. There is some pressure in the crankcase to begin with under normal running. Since you were possibly redlining the car at times this creates more pressure. So my point is the oilstick in my car fits so that I have to push it in firmly. There is a "O" ring around the base of the dipstick handle. Is it holding the stick down in the tube or is it just riding there freely. |
magoo (Magoo)
Advanced Member
Username: Magoo
Post Number: 2583
Registered: 2-2001
| | Posted on Monday, April 22, 2002 - 11:14 am: | |
Rob, A crazy thought but were the other cars USA cars or graymarket cars? I'm thinking Cams etc. Just a guess. |
Craig Dewey (Craigfl)
Member
Username: Craigfl
Post Number: 357
Registered: 1-2001
| | Posted on Monday, April 22, 2002 - 9:59 am: | |
Don't forget to change your fuel filter if you haven't done that. I do suspect the cats -- time to buy those "test pipes" from Nick! |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 1470
Registered: 12-2000
| | Posted on Monday, April 22, 2002 - 8:32 am: | |
Thanks very much for everyone's input. |
M Grande (Grande)
New member
Username: Grande
Post Number: 26
Registered: 12-2001
| | Posted on Monday, April 22, 2002 - 7:36 am: | |
Congrats on the great numbers Rob.
From my previous life as a drag racer on EFI Ford engines, a significant and abrupt drop in HP at upper RPM's usually meant that the fuel pump was maxed and the pressure dropped to the point of not being able to supply the engine with enough to keep the HP up. Problem was remedied with a piggyback or secondary pump on the feed line.
Another cause on the later EFI systems is related to air meter maxxing out but I don't think this applies to these engines.
Easiest way to check (I think) is to put in on the dyno again with a fuel pressure guage.
Anyway, if it is the pump and you don't usually go into that RPM range, then I probably wouldn't worry about it.
Mike |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 1469
Registered: 12-2000
| | Posted on Sunday, April 21, 2002 - 11:24 pm: | |
The tach reading was through the Dyno computer, so that was accurate. I guess they get that by counting the spark.
The other 2 328's are stock as far as we know. The previous owner of my car replaced the cats, which was done about 2-3 years ago.
I should have the video up this week, maybe the sound will be clearer. Both Bob and James said they could kinda hear something. |
Dave328GTB (Hardtop)
Junior Member
Username: Hardtop
Post Number: 104
Registered: 1-2002
| | Posted on Sunday, April 21, 2002 - 11:19 pm: | |
Rob,
I was wondering if you were reading the RPM off your tach or if there was an independent hookup for RPM. Ferrari tachs are not always accurate and I have had trouble with 328 tachs reading low. If you were using the tach in car, perhaps you were at redline and did not know it. Seems like with yours being the strongest 328 there, mechanical problem would be unlikely. Also, every motor is a little different, perhaps that's just the way yours is.
Dave |
Hubert Otlik (Hugh)
New member
Username: Hugh
Post Number: 50
Registered: 1-2002
| | Posted on Sunday, April 21, 2002 - 10:56 pm: | |
Rob,
In all honesty, I couldn't hear a distingiushed difference b/w yours and the other 328's. My advice to you would be to have the cats, headers, exhaust, and fuel filter, injectors, timing, distributor, spark plugs, plug wires, etc. checked. Sounds like something at the high end is plateuing, but this isn't to say that there is a definate mechanical problem with your car.
Also, have the compression check done, and maybe the leak down done. Also, let the oil change go for 3000 miles this time around and check the oil once a week or so, and look for consumption on that end.
Also, if indeed you had a valve spring bind, dropped a valve, etc., I don't think you could succesfully rev the motor to 7200 rpm w/out at least a noticble rattle or mechanical impariment.
Oh, and one last thing, of the other two cars your comparing yours to. Do they have any aftermarket cats, headers, cams, etc. Something that would make more power up top? I know I'm stating the obvious, but it just came to mind.
Hubert |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 1467
Registered: 12-2000
| | Posted on Sunday, April 21, 2002 - 10:36 pm: | |
You can go to the "Links" page and follow the "Norwood Dyno Day" for a link to sound files. You really can't hear anything noticable, but it's worth a try. You might compare mine to the other two 328's.
My car burns no oil at all. I don't even have to top off between changes, however, I do get it changed every 1,000 miles.
The car idles and runs perfect and I haven't noticed any unusual smoke come out. Mine does have a barely noticable metal wine at high RPM, but I couldn't even start to explain it. You might be able to notice on the sound files. |
Hubert Otlik (Hugh)
New member
Username: Hugh
Post Number: 49
Registered: 1-2002
| | Posted on Sunday, April 21, 2002 - 10:23 pm: | |
Rob,
My initial diagnosis would be to look at the catalytic converters or for a clog somewhere w/ in the exhaust. If in fact the problem lies w/in your valvetrain, your idle, as magoo mentioned, would be noticably rough, and you would hear the problem audibly, and w/ a binded valve spring, its not unlikely that you would have had piston to valve contact, and you should have heard that happen, if it did.
Do you notice any smoke under hard acceleration after idleing at a stop, or smoking under decceleration? The latter case would be indicative of worn valve guides/seals, and the former, worn/broken oil rings on the pistons. Also, blow by refers to the combustion of motor oil w/in the combustion chamber, a build up of oil pressure in the crankcase could point to a problem w/ oil passages w/ in the block. Have you noticed a marked increase in oil consumption?
Lastly, a leak down/compression check wont neccessarily tell you which piston has the faulty rings. Case in point, my friends car ate oil, nearly a quart every three days, but he still had impecible compression all the way around. However, should one of the cylinders come up much lower, then you have a correct diagnosis there.
Hope this helps,
Hubert |
magoo (Magoo)
Advanced Member
Username: Magoo
Post Number: 2582
Registered: 2-2001
| | Posted on Sunday, April 21, 2002 - 10:03 pm: | |
Rob, I would think if you had a broken valve spring that car would have a terrible idle and would have a bad miss in it that was obvious. JMO |
Rob Lay (Rob328gts)
Board Administrator
Username: Rob328gts
Post Number: 1466
Registered: 12-2000
| | Posted on Sunday, April 21, 2002 - 9:24 pm: | |
Yesterday on the dyno the charts showed my car having a significant (25-40) HP drop at around 7200 RPM. The car ran strong and even with the stock air filter ran 218 HP at the rear wheels with the other two 328's at 211 and 216 HP. However, those two cars had a nice curve well up above the redline, where mine drops off at 7200.
Does anyone have ideas of what this can be. I don't shift above 7200 much anyway and the engine is putting out good power, so I'm not too concerned in the short term. James and Bob were mentioning stuff like broken valve spring, but they weren't even sure.
They also showed me I'm getting pressure built up in the crankcase because the dip stick pops up about an inch after use. This is probably blow by and I don't know if it could be causing the 7200 RPM problem or if that's another issue all together.
What do people think? Next time I take it in they're going to do a leak down test. |