PChar

I did use the search option but needs more advise. I am experiencing some throttle lag, I cleaned the ISV and the MAF or AFS. My car still lags trumendously when I depress the fast pedal, it takes a few second litterally with a slow building "schtrooopfsss" sound before it revs. It does the same if I pull at the throttle body.

Can this be improved otherwise? I read somewhere you can readjust/realign the maf spring or guide. But before I tear up into the MAF I'd like to confirm waht other options I have to improve throttle response.

Thanks

Rocket Rob

Has it always do this or is this a recent change? If its a recent change, has any work been done on the car? Once it does rev up, do it have the same power level as before? I'm wondering if you may have a clogged air & fuel filters or perhaps the catalytic converter. But if either of these were the fault, the overall power would be low.

PChar

Rob the power appears normal,.. to me. I have a cat bypass, and the air filter is the cone type I just replaced it for a new aftermarket type. I'm wondering if it's too restrictive. But overall the car worked great last year with good response. This past winter I installed a light weight FW, SW chip, cat bypass and a single belt Rothsport pulley hub.

I'm not sure any of these mods would have anything to do with the lag in response, but I am leaning to the MAF/AFM, may need to be overhauled??? Anyone knows if the barn door MAF thing can affect the throttle response if improperly clean/adjusted,... ?

Thanks

m3vs911

I have a similar problem too.
the symptom seems to be gone when the Rev is over 3000 rpm.

when cold car the car seems alright but as soon as the the temperature builds up, the throttle response will get worse.

PhatPhlatSix

This hesitancy is fuel-injection related and in the ecu mapping. This is what I discovered when I had the same problem.

In the ECU, there is a map of throttle-transient fuel-enrichment vs cylinder-head temperature. For some reason, porsche zeroed the throttle enrichment fuelling when the temp is at normal working levels. So, when the engine is warm, if you try blip the throttle at engine speeds below about 2000rpm, the engine bogs. Above this speed, the engine doesnt need that extra fuel.

Goughary

Most of your problem is likely the single belt pulley.

Change that back and then see if it's still there. With the single belt conversion, the alternator is spinning slower, and therefore making fewer amps below 3k rpm. So you get a very weak spark at low rpm.

If that turns out to not be the issue w the throttle response - leave the dual pulley setup anyway so you don't cake the entire inside of you cylinders with carbon from driving around town with weak burn...if you leave the single belt, get the rpm up to burn out the carbon - all the time. These cars cough and chug at low rpm on the single belt conversion.

Anyway- next up- if you still have bad throttle response, check the voltage from the battery/alternator, check the caps and rotors, change fuel and air filters. Then look for vacuum leaks, and then check fuel pressure, and then, if all else fails, open the afm and play with the needle, and then if that fails, come back here and there will be another list...hall sensor etc...

But- I would bet money on the single belt conversion....

-Teme-

Would a faulty or dying oxygen sensor be an alternative root cause?

freedman

Why would going single belt have any effect, the factory use this on the RS without issue

Thousands of others have run it on modified cars without issue as well

Ive run it for the last 2 years, and it has mad 0 difference to the way the car runs, and it certainly doesnt cough and chug at any RPM

Feudal Serf

Poor throttle response: I have dealt with that before. Turned out to be a couple things.
Frayed throttle cable and poorly seated plug were the culprits.

If you are sure your pedal box and cable are properly adjusted then it's either ignition or fuel mixture.

Ignition: poor battery voltage can do it. Had that problem myself and found poor initial start and lengthy C4 pump time.
Keep the battery fully charged with a c tek automatic charger.

The ignition is super sensitive on our cars.
I use a durametric scanner. When one upper plug was poorly seated the ecu retarded the timing by 6degrees. It was very laggy as you describe.
You could have a single cylinder misfire.

I would work on some diagnosis before you pull out the "parts bazooka"

Plenty of threads on how to investigate ignition.

Fuel:air :
Fuel filter can be replaced I suppose.

Scan tool can read O2 readings and head temps and short and long term fuel trims.

Prob not the ISV

I'd check function of idle microswitch.

How does the car idle? Smooth or rough.

Has there been any work done on the car recently?

Good luck
FS

kreeshp

I also am running the single belt mod without ill effects to throttle response. Have had this setup for the last year, about 4000 miles - no problems with engine performance or electrical anomalies and I keep it on a trickle charger whenever it's parked.

biggynuts01

Could it be a sticky barn yard door?

HDA

RIIIIISE FROM THE GRAAAAAVE

have a 964 with lightweight flywheel, MAF kit and corresponding chip.

She goes like a scoot but I have noticed a couple of issues.

The throttle response from idle is horrible. Once I pass 3/4k it is fine but down low there is a delay that drives me crazy. Makes for interesting take offs from traffic lights. What could it be?

The second issue is a “sputtering” above 6000 rpms in 4th gear. It doesn’t do it in 3rd or 2nd.

Any ideas where to start to look?

I was thinking the idle/throttle switch.

Distributors are fine, cables, plugs, brushes and caps are all new.

spartansix

The sputtering at high load makes me think you might want to look at your coils.

HDA

Interesting. They are original coils. Wouldn't they do that also in other gears?

TexasPorschelover

993 coils are a great upgrade. I am getting terrific throttle response - made the following upgrades

New rotors/caps/wires/plugs
993 coils
Bosch Gen2 injectors
911Chip
New ground wires (trans and battery) (this can be helpful for other minor issues)