| Author |
Message |
    
Carl Muckenhirn (Carlmuck)
| | Posted on Wednesday, March 06, 2002 - 11:02 am: | 
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I'm hoping that my problem (vibration under moderate load in the 2000-2750 RPM range) is NOT an exhaust valve. Are there any direct tests one can use, without pulling the valve covers and manipulating the valves directly, to see if this is the problem. I'm going to have the disco in to replace the exhaust (cats and all) so I could have a look with an inspection camera at the back side of the exhaust valves, what should I see?
If it is an exhaust valve, has anyone had any success with anything short of pulling the heads and cleaning it all up?
Another question, in trying to diagnose this I've been monitoring the short term fuel trim (had misfires on the B bank) and B is always significantly leaner than A. I originally thought it was an O2 sensor, but changing it out didn't help. Is the information from OBD-II a measurement of the fuel mixture, or a reading of the ECU's setting?
thanks,
carl. |
Jon Williams (Jonw)
| | Posted on Wednesday, March 06, 2002 - 11:39 am: |
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First problem, doesn't sound like a valve, but more like a harmonics problem. It's present on my engine and on several others I've ridden in/driven. Usually caused by a misaligned crankshaft balancer (or an out-of-round one). The doughnut on the front axle has nothing to do with this, by the way.
Second problem, the fuel injection system (Lucas Hot-Wire) as developed by Bosch fires each bank of injectors at one time. So you're left bank fires, then your right bank fires. Not as qreat as sequential MPI, but it works. Fuel trim is controlled by a reisitor in the ECU. The OBD-II readings should be what the ECU setting is, but with OBD-II you obviously have GEMS, and I'm not as familiar with it as I am with the Lucas EFI module, so I really can't help much more than tell you you're problem is likely a resistor in the ECU. |
Carl Muckenhirn (Carlmuck)
| | Posted on Wednesday, March 06, 2002 - 03:58 pm: |
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The reason I think it is not harmonic is that under the right conditions everything smooths out, when the vibration kicks in i experience a loss of power.
carl. |
jwarner
| | Posted on Wednesday, March 06, 2002 - 10:37 pm: |
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SEAFOAM - Get it at NAPA. Follow the directions. It's a lot cheaper than cameras or valve replacement. My 96' Did the exact same thing under a load usually, at less than 3k RPM. it would hesitate baldly and sometimes the check engine light would come on. I used two treatments of Seafoam and no problems since. That has been about 6 months ago. It's worth a shot. |
Carl Muckenhirn (Carlmuck)
| | Posted on Thursday, March 07, 2002 - 06:26 am: |
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Thanks, I'll give it a try.
carl. |
JMcD
| | Posted on Thursday, March 07, 2002 - 06:54 am: |
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JWarner, what is seafoam?? What does it do???? Thanks, JMcD |
Leslie N. Bright (Leslie)
| | Posted on Thursday, March 07, 2002 - 09:14 am: |
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Yeah, I've seen Safoam, even tho' I can't find BG44K...
Might try it......
-L |
Justin
| | Posted on Thursday, March 07, 2002 - 04:04 pm: |
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It sounds kind of like my 96 is doing the same thing, it vibrates a bit during the 2500-3500 range and I have experienced quite a loss in power. I will try the safoam stuff but I also wonder what it would take to replace or repair the harmonic dampener..has anybody done this or is it strictly a shop project?
Thanks for the help.
Justin |
Bruce
| | Posted on Thursday, March 07, 2002 - 04:58 pm: |
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Jwarner,
Seafoam huh? Since I have not found it yet, maybe you could give some instructions for both fuel and oil additions? I understand as oil treatment, this stuff thins-out the oil, so use it as warm-up only treatment before you change your oil. In other words, don't drive around with this stuff in your crankcase. As a fuel additive, use it just before you refill your tank for higher concentrations to break-up the carbon deposits.
Can anyone lend some advice please?
Bruce |
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