Loss of power.....in low RPMS

Went out for the regular Sunday drive. After I brief hard acceleration through 1st,2nd and 3rd (shifting @ approx. 4000RPM) I noticed that the engine response was sluggish through 1st-2nd-3rd in the lower RPMs. There is no smoke, oil leaks, and the engine seems to idle properly. In neutral and no load the engine seems to rev fine. No pinging,popping or other engine noises.

I have noticed the exhaust noise is also a little different while it is sluggish through 1st to 2nd. The best way I can describe it, is the car is sluggish (slow throttle response) and the noise change is like a put, put, put, as the revs increase the noise is less noticeable.

The car is a 81 SC 3.0 stock. The car recently has had the valves adjusted, and has been running smoothly up until the drive today.

I am hoping I did not break anything internally during the hard acceleration.

Any comments/suggestion would be appreciated.

Thanks

Someguys back a few hundred threads were discussing the petroleum quality during 'peak' traveling and summer conditions. I think the pitch was that emissions would be high in the sky if 'they' didnt choke up on the quality of gas when it was being used the most.
Your tachometers' not jumping is it?
HA
skip in Va

Have you checked your ignition timing?

You also might consider checking the vacuum advance/retard diaphrams. A car that old, it wouldn't surprise me that the diaphram would have a leak by now.

Yes, you need to check the ignition advance profile throughout the rev range. If the ignition timing is what the spec book says it should be, then I would recommend checking each individual sparkplug wire with an Ohmmeter ... I have heard of both intermittent and 'open' resistors in the BERU connector, and the CDI-unit can jump accross the gap while warming up and in cool weather. The wires should measure 3-4000 Ohms end-to-end, steady, not varying in any way!

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Warren Hall
1973 911S Targa

No, you didn't hurt anything during your hard acceleration. I agree with the 'return to basics' advice. Ignition problems more commonly occur at higher, rather than lower, rpms. Nevertheless, ignition timing. ignition wire resistance, ignition curve, are good things to check. You can usually verify taht your ignition system is working okay. This done, you know the problem must be in the fuel/air mixture.

I'm guessing an over-lean mixture at low rpms, at least popping suggests that to me if there's no smoke.

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'83 SC

I recently(past two weeks) have had the same problems in my 71. It would sputter and bog down like crazy below 3K rpm. ABove that it would run great. I know it was not the carbs since they were just rebuilt and the car had run perfectly when the tuneup was done last month. In the tuneup I adjusted the points, gapped the plugs and reset the timing. I started checking plug wires and found that two of them had resistance values of less than 500 ohms. The others were in the 1200-1500. Not anywhere what they should be. I changed the wires and reused the beru connectors.

I was still having the same problems.

I then recheck my points and they were dirty. It had only been about 3 weeks since they were last cleaned and gapped. I still can not figure out why they are so hard to keep in adjustment. Since I did not want to continue the clean/regap of the points I opted to go for the Crane optical ignition.

I started the installation yesterday and was delayed by rain. I will let you know if it solves the problem. I am not sure if your car has a points system in the distributor, but your problem sounds ignition related to me.

BTW if you are looking to purchace these items, plug wires are $16 and the optical ignition is $55 direct from crane cams
(http://www.cranecams.com) This is much better than the $80 and $130(respectively) from most mailorder places. Good luck solving your problems.

Jamie
71 911T targa http://www4.ncsu.edu/~jpnovak

Perhaps you dislodged some carbon and it is keeping an exhaust valve from completely closing (the odd sound you are hearing). If all the basic tune-up items fail to fix the problem, try a bottle of techron and wind it up to 5000-6000 rpm.

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Graham Archer
83 911SC Cab

sounds like you are running on 5 cylinders, the plug wire/connections seem like a good place to start

It sounds like a bad ignition wire connector to me. I'd start there.

Had same problem. Replaced all ignition wires with "Magnacore" brand wires, and problem is gone.

Leon 78SC

[This message has been edited by leon (edited 08-28-2000).]

i wonder if your cat. pipe headed south?