Help! 3.2 looses power at 5500 rpm while accelerating,

[djcdmv]

Ever since I bought the car last fall, as soon as the car hits about 5500 rpm it looses power as if there was a rev limiter or something. I just recently had the car in for a oil pressure sender unit install at a local European Specialist. The tech was very impressed with how the car ran except for the loss of power issue. He said it pulls hard as it should up to 5500 rpm. He thought it could have been either an injector or possibly some sort of air line problem (my words, not his... can't remember what he said right now). Any ideas? Car only has 30,000 miles and he said he was amazed at what good shape the engine was in. I replaced plugs, wires, cap, rotor, and air filter last fall and it still occurs.
So:
1. What could cause the car to loose power while accelerating at 5500 rpm?
2. If there are several possible causes, how can you diagnose what it is?

Thanks in advance!

[MH911]

My 87 3.2 does have a rev limiter. Scared the hell out of me the first time I hit it.

[db_cooper]

The rev limiter should not hit till about 6300 rpm or a little more...

If the fuel filter is old or the in tank filter is the original..they may not allow enough fuel flow at high engine speed and it will feel like a rev limiter.

You said the air filter was replaced..did the fuel filter get changed too?

Seen this before. especially a low mileage car. It did not get driven much and the fuel tank will shed some debris (rust). It will get caught by the tank filter and clog up.

Don't get upset if there is rust in the tank..its not fatal..they all do after all these years.

[djcdmv]

Originally Posted by db_cooper

The rev limiter should not hit till about 6300 rpm or a little more...

If the fuel filter is old or the in tank filter is the original..they may not allow enough fuel flow at high engine speed and it will feel like a rev limiter.

You said the air filter was replaced..did the fuel filter get changed too?

Seen this before. especially a low mileage car. It did not get driven much and the fuel tank will shed some debris (rust). It will get caught by the tank filter and clog up.

Don't get upset if there is rust in the tank..its not fatal..they all do after all these years.

The tank filter may be a possibility... Will try that next. Thanks!

[db_cooper]

When you change the fuel filter in the engine compartment...try and keep the fuel up in the filter as best you can, by removing the top connection first and speedily removing the bottom connector. Use a glass container and let it drain.

The contents of the fuel filter will tell you if you have any contamination. Some light debris is OK. If the filter has water, rust or mud..tank must be examined.

Absolutely replace your tank filter, it has been in there long enough. About $40 from our host. Get a new "O" ring too.

While your under the car..replace the fuel line between the tank and the fuel pump.

You will have to drain the tank anyways to replace the tank filter.

Remove the fuel line to the fuel pump first (your going to replace it, just remove the mounts on the fuel pump) and finish draining the tank.

Then remove the tank filter. There may be a lot of debris on the outside of the tank filter screen. If your fuel pump happens to be still attached to the tank....some of that debris will slide down into your fuel pump....and you will be buying a new one$$.

Flush the fuel fitting on the tank to fuel pump and get any crud out, install a new tank filter and then your new fuel line on your fuel pump.

Take some pictures and let us fellow Pelicans know how it turns out.

[djcdmv]

May be over my head on this one... But, I bought it planning on some DIY work, so I'll try to tackle this. Thanks for the advice and description/directions! Will photo document for all to see, though it may be a while.

[djcdmv]

I just got this respose from the PCA Tech:

First, check that you are getting full throttle. You would be amazed at the number of cars that are not adjusted properly.

If OK, remove the air filter and push the vane in the air flow meter to make sure it opens fully.

If OK, check the fuel pressure and delivery volume.

If OK, I would have the injectors professionally cleaned. Cars with low miles that sit will get injectors that get plugged or will not open all the way.

It's also possible, but not likely, that the catalytic converter is plugged, but that would not be where I would start. If all that doesn't fix your problem, write back and we can go forward.

Any of these sound like possible problems or does db cooper's suggestion seem like a good place to start. They are all a bit over my head, so I don't know where to start.

Is there a step by step for throttle adjustment out there anywhere?

[nkotselas]

Throttle adjustments are needed on many 3.2's. Have someone sit in the driver seat with the car off while you look under at the engine. have them push the accelerator all the way down. There should be only about a business card gap between the butterfly and the stop. I have a very good video I am uploading now.

Even if this is not your engine's problem, this can have a great effect on your cars power. While your'e at it check for continuity on the full throttle sensors, you may not be getting full throttle mapping.

Video to come soon.

[nkotselas]

Check for Wide Open Throttle WOT Porsche 3.2 carrera 1984 - YouTube
That was me trying to fit the business card at the end, didn't think it would work so i stopped haha

There you go.
Make sure you aren't going over the business card limit, this car damage the throttle and even lose power. There are many places to adjust this throughout the car. My bentley manual says right next to it, unscrew adjust and rescrew But I wouldn't recommend that. Do a search for more experienced advice. Here is SW page for a start.

bottom of page 4
http://www.911chips.com/C1INSTR.pdf

[djcdmv]

Thanks for the video Nick! Quite frankly, I wouldn't have know what the butterfly and stop were if you didn't post it. That's why this forum is great. There is know way I could do some of the things I've done without my fellow Pelicans. Will give it a try today!

[nkotselas]

Glad I could help, i would still recommend seeking more professional advice before going into the engine because I am still quite the amateur but the test is easy to do.

While you were doing the regular tune up did you adjust the valves? This is likely not the problem, but I just had my valves adjusted and it fixed my idling issue and the car drives a lot better, I also had 30k miles. Its also good to get the basics out of the way.

Keep us posted on the throttle adjustment

[rick-l]

If an m491 has a DME, you could also check the weights on the distributor to see if they move freely.

They advance with RPM to handle the advance the DME wants to add.

[Determined]

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[prebordao]

I have the same in my 74' around 5.5K
I was thinking of a defective rev-limiter (do they go bad ?) as it should only intervene around 6-6.2, but this got me thinking.
With a 74' car maybe the tank filter needs some attention.

[john walker's workshop]

crank sensors with too much gap can do that. also check their resistance at the plugs. 900-1000ohms.

[prebordao]

mine is cis...

[djcdmv]

Glad this came up again...

Mine wasn't the throttle adjustment. Anyone know how to check the fuel pressure and delivery volume?

[Josh D]

A clogged cat can and will affect an engines ability to rev beyond a certain rpm depending on how clogged it is. The OP mentioned only 30K on the motor, which would be low for having a clogged cat. But if those 30K miles were short trip miles before the cat could warm up, it's very possible it could be clogged at 30K.

[afterburn 549]

Maybe someone installed a rotor from a earlier car? some of those are made to fall on their face at 5500 ..I had 2 of them
I ended up putting in a VW rotor
End of problem

[KNS]

This may or may not apply to the Carrera: I had the same problem with my 911SC, when I hit about 5600 RPM the rev limiter would kick in and cut power, got my attention real quick. The circuit board in my tachometer had a problem with it (can't remember exactly what), I guess the rev limiter gets information from the tach. I swapped out the tachometer for a different one - problem solved! See if you can at least swap in a known good tach.