993 poor high rpm performance

[993G]

gwsinc said:

993G said:

Well looks like sometimes its the simple things . I replaced my dme relay last fall because the original was bad. Low and behold something happened to my replacement because it went bad again. I replaced it and back to normal!

What could cause one to go bad so quickly?

Shocking a relay could cause all those problems.

I suspect it’s not the relay causing the issues, each time you unplug the DME relay it resets ECU learning so it will run off the base map till it gets more info from your sensors.

I think a sensor somewhere is sending duff information to your ECU causing running issues. Given you say it gets worse when the car is up to temperature I would look at everything affected by temperature first. So O2 sensor and intake air temp sensor first (£100 for both and easy diy).

Thank you I’ll run it some more and see if it reverts back to it’s bad running condition. I replaced both the air temp and the oxygen sensor already.

I was going to pick up a head temp sensor but I noticed they changed the plug I have to buy a 996 part.

[A993LAD]

993G said:

Hey just wanted to update you all. I changed the fuel filter yesterday and attempted to test the pump. I did a volume report and got almost 2 liters in 30sec with the jumper. I tried to test the pressure and my gauge failed. It looked like 56psi with the jumper but that’s when the leak sprung.... so I put everything back together an took for a quick drive and its runing like new?

My fuel filter was only 1 year old , maybe defective? Or just clogged . I’m puzzled but runs better now.

Thanks for all the help!

Interesting

I just had my 1994 car serviced and they were shocked to discover it still had the factory original fuel filter (based on date stamp). Despite the car having 22 service stamps in the book many at OPC. But the car was running well before the filter was changed and seems exactly the same afterwards.

[Orangecurry]

Fuel is quite clean these days. Filters were invented for 'when I were a lad' fuel quality

But yes, servicing eh, even at OPCs.

Have you had your clutch slave bled? Has your spark-plug behind PAS pump? ever been replaced?

[993G]

Well still having issues , I’m leaning towards flywheel sensor /head temp sensor/ distributor/ fuel pump.

My distributor belt is intact. I have been putting off the sensors in the back as I have to update the wire harness to 996 plugs.
Pictures attached of my cat converter both sides , I thought they looked ok?
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[993G]

Car runs awesome low to mid range and on part throttle. When I floor it or try and push past 5k when the problem starts. It does not want to rev higher.

[9xxNick]

Is there any way you can get access to a Bosch "Hammer" diagnostic unit to see if that picks up any error codes?

Whereabouts are you based?

[gwsinc]

993G said:

Car runs awesome low to mid range and on part throttle. When I floor it or try and push past 5k when the problem starts. It does not want to rev higher.

Throttle Position Sensor perhaps? Around £20, so worth a shot.

Also how’s your throttle pedal adjustment, does foot to the floor open the throttle fully?

I did my cylinder head temp sensor the other day, first get an ohmmeter and check the resistance when cold then hot, should be about 2.5k ohms when cold in this weather and under 250 ohms ish when hot after 20 mins driving. See numbers below:



Finally check for vacuum leaks, not only in the vacuum pipes coming off the top of the engine but also the jubilee clips holding the manifold together and those near the back of the engine. Ageing lines at the front of the engine can be cheaply replaced with silicone hoses.

My next tasks on mine are to check flywheel position sensor with my new feeler gauges (so it’s perfectly gapped at 0.8mm for my new LWF) and replace the ageing jubilee clips on the manifold over the next few days.

Regular updates below

Instagram.com/gws911

Cheers

[993G]

gwsinc said:

993G said:

Car runs awesome low to mid range and on part throttle. When I floor it or try and push past 5k when the problem starts. It does not want to rev higher.

Throttle Position Sensor perhaps? Around £20, so worth a shot.

Also how’s your throttle pedal adjustment, does foot to the floor open the throttle fully?



Boom !! My man , TPS sensor fixed it. I have full throttle now amazing.

My cable has some slack too, I need to snug it up but not sure how. I had someone else push the gas pedal and it moves about 1/4 before throttle is actually opening.

[gwsinc]

993G said:

Throttle Position Sensor perhaps? Around £20, so worth a shot.

Also how’s your throttle pedal adjustment, does foot to the floor open the throttle fully?



Boom !! My man , TPS sensor fixed it. I have full throttle now amazing.

My cable has some slack too, I need to snug it up but not sure how. I had someone else push the gas pedal and it moves about 1/4 before throttle is actually opening.

Glad it worked

[gwsinc]

gwsinc said:

Glad it worked

To adjust the throttle cable you need to get into the pedal box and tighten the cable at the bottom of the accelerator pedal mechanism by screwing in the cable fitting in (circled in red below). I think the lock nut is 8mm. I set it so there’s no play in the pedal whatsoever, but the throttle is completely closed at rest.



Then you need to adjust the link to pedal itself so that when your foot is to the floor the throttle is 100% open. Again it’s an 8mm nut.