Alex Sol

I've had a great summer driving around with the fresh rebuild / reseal.

Been to a bunch of different events and mainly just street driving.

i'm finding that i still have slight hesitation getting past 2500 rpm and it seems to make no more power but lots more noise above 5,500 rpm

is this a chip issue? i have a cat delete and secondary muffler delete and EvoMS intake K&N cone filter. A bit loud with no sound insulation in the trunk - old stuff all started to break apart. i do have an aftermarket chip in the ECU with the label 911Chip. It would be set up for pure stock setup, cat converter and 2nd muffler

The only other couple of changes that might affect:

MSD coils -perhaps swap back to original Bosch units? i have some black and silvers kicking around. They are still within spec when measuring resistance.

AFM door slaps closed at high rpm shift change from 1st to 2nd gear... from time to time - this AFM is rebuilt from Fuel Injection Corp in CA

Warm or cold, the 964 will stall in any gear (typically gears 2,3,4) on decel when i lift off the pedal to downshift. it happens once a day... and i'll just bump start with the momentum that i still have

Five0 Motorsport injectors - they are sized to be the same as stock 19lbs/hr or some spec but could they be 'blowing' out the spark?

Belts too tight? not likely though my AC is working nicely and car runs a little less smooth with the AC on

I have new msd coils, plugs, wires, rotor and caps so i think the ignition should be good. Distributor rebuilt last year

porsche mania

Sorry Alex, don't have any answers for you but would be interested to hear about anyone else with a stalling on deceleration problem. Mine does this, only occasionally though, normally after being on the motorway for long periods and you start to go back down the gears when approaching slower traffic

justin-in-athens

I would definitely check to see if the resonance valve is functioning properly. You can use a scantool or listen for it when the ignition is first turned on. It will cycle the valve from closed to open.

edit: I just read the AFM was rebuilt, so that is probably not the issue.

Kappi2907

Vacuüm problem. Also check WOT.

crg53

Since you no longer have the stock airbox in place, my question is, "do you have the vacuum canister, that activates the resonance valve, in place".

540964

Have you checked for codes using a hammer or scan tool? Check for hall sensor, if that code comes up then check the wires at the sensor connector. Or just unplug the harness from the sensor at the primary distributor, pull back the rubber boot and verify the wiring. Caution- insulation on the individual wires may be intact but the wires broken inside. 2 of 3 Hall effect sensor wires were broken on my harness, I spliced them using a kind of crimp butt splice, then cleared the fault using scan tool and the car runs much soother and delivers power. I too have five0 injectors, they seem to work perfect. Good luck.

HalV

Do you have a LWF?

Alex Sol

thanks for comments.

i'll check the hall sensor as the wiring can be old and brittle.

i have regular fly wheel so that is not the cause of the stalling

My idle air control valve is relatively new and 'catches' the motor as it's about to stall but there are times when i'm in third gear and still revving about 3,000 plus rpm and the car just dies... strange and somewhat dangerous except i am aware when it happens... the dash lights up like a christmas tree

i do have the vacuum canister that runs the resonance valve, so that is not likely my issue...

540964

I read somewhere, probably on this forum that when the hall sensor is compromised, ignition timing is retarded 7 degrees. On my car the wire insulation appeared to be okay but the wires were broken inside the insulation. After repairing them I cleared the hall sensor code using scantool, the car runs amazingly better.

By the way, has the airflow meter wiring mod been done on your car? If not that my be another thing to consider and check.

Feudal Serf

Hi Alex

If you have access to a scan tool that would be a great way to acquire data so your efforts can be focused.
Resist the temptation to shoot the parts cannon at the car.

Ignition vs air/fuel broadly

A retarded timing and Hall effect sensor code can occur together when there is ignition irregularities.
That would be one direction. Rarely do the sensors fail, they are inside distributor, these sensors are 3 wire, 12v, ground and signal. The signal is a square voltage wave. Can't really test the signal without an oscilloscope, but feed and ground easy enough with DVOM.


If you have no scan tool access:

Another broad direction is air/fuel mixture.
You have some mods here.
If you are running an O2 sensor, a simple test is to disconnect it at the wiring harness (round connector clipped in on left side) and drive for a bit. Provided there are no major vacuum leaks, this will run the fuel trims rich.



Random thought on your drivability problems.
There is a wire harness modification for the AFM, I believe TSB 9005 ???, This is for 89 and 90 years and modifies the harness plug so there is no interference with the oil vent lines.
Since you've modified the intake, should be easily visible and worth checking.


Good luck
FS

porsche mania

Yes, full rs set up. I had discounted the flywheel as the car idles great hot or cold and has none of the usual associated issues. If that's the case then it's something I can live with as it's not happening often and then only if the car has been sat at speed for a long time with a constant throttle then stalls when dipping the clutch to drop down a gear, only seems to do it once though, even if I go down two or three gears.

Alex Sol

i did in fact have a hall sensor error and cleared the error. car still runs a little sluggish. might just be i'm running cheap gas.... ???

540964

Retrieve the codes again, if hall sensor error comes up again check the wiring.

Alex Sol

bringing up an old thread. i swapped my fiveomotorsport injectors out and put my stock injectors back in and much better response and gas mileage. rich fuel smell also much less. i'd suggest the fiveo injectors are sending too much fuel and putting out the spark in some cases causing the sputter. i haven't made too many runs to red line as i's still breaking in.

Alex Sol

quick update: i was driving at night and returned home to check the oil. saw arching at the coil to distributor cap.

cap is almost brand new... maybe 2000 kms on the one....

centre coil connection basically burnt off and likely running only one cap / one set of plugs this whole time.

slapped in a spare and .... amazing difference.

full power, pulls all the way to redline

life is great!!