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924s bogs down at full throttle

Recently at fast acceleration my 924s completely bogs down when throttle is slammed to the ground. If I ease into the pedal I get no issues. I changed the fuel filter and did all the spark including the wires but no difference. Should I change the fuel strainer as well? My initial thought was the timing belt might have stretched but it was done 8 years ago with no issues since. Only put around 70000km on it so I still have some time though I have not inspected the condition of the belt yet. What do you guys think?

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Old 03-05-2018, 02:49 PM
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8 years is a long time between belts, regardless of miles. Perhaps you have some debris in your tank, lines or fuel filter choking off fuel supply..hell, maybe even a marble
Old 03-05-2018, 03:15 PM
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Originally Posted by Toast54 View Post
8 years is a long time between belts, regardless of miles. Perhaps you have some debris in your tank, lines or fuel filter choking off fuel supply..hell, maybe even a marble


Do you think it's fuel related for sure? I was maybe even hoping it would be the afm as my idle is a bit rough sometimes.


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Old 03-05-2018, 03:27 PM
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Could be an ICV, or vacuum leak.. any number of things. Clark's Garage is the place to start troubleshooting
Old 03-05-2018, 05:49 PM
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8 years... you should be approaching your 3rd set of belts in that time frame.
get those done ASAP.

check fuel pressure, fuel filter, try tapping on the AFM a bit maybe its sticking inside.
Old 03-06-2018, 11:43 AM
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If the TPS is not working at WOT does the afm compensate?
Old 03-07-2018, 07:36 AM
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the AFM only works at WOT up until ~4500rpm, after that the AFM door is wide open too so it's not measuring anything, DME just runs off pre-programmed fueling tables at that point.
Old 03-07-2018, 08:23 AM
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Originally Posted by v2rocket_aka944 View Post
8 years... you should be approaching your 3rd set of belts in that time frame.
get those done ASAP.

check fuel pressure, fuel filter, try tapping on the AFM a bit maybe its sticking inside.


Is there any way of checking the timing belt without having to jack the car up and remove the timing covers? You have me worried now. The previous owner being my father had the belts done in 2010 and was told they would be good for about 10 years. Ps. I think my original problem is being caused by the TPS. I tested the sensor with my multimeter and the ohms are not consistent with the position of the throttle. Trying to find a new one now, holy crap they are not cheap.


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Old 03-10-2018, 07:40 PM
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open the hood and look down, with a compact ratchet wrench+10mm socket and really sticking your arms in there you can remove the 7x 10mm bolts that hold the front,upper timing belt cover on and take a look at it.

but no...all 944 timing belts 1982-1991 are 3 year/30k mile maintenance items.
some folks go by 45k miles, but i've done enough belts to see how wiped out the things are by 30k to not chance it myself.
Old 03-11-2018, 09:24 AM
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Originally Posted by v2rocket_aka944 View Post
open the hood and look down, with a compact ratchet wrench+10mm socket and really sticking your arms in there you can remove the 7x 10mm bolts that hold the front,upper timing belt cover on and take a look at it.

but no...all 944 timing belts 1982-1991 are 3 year/30k mile maintenance items.
some folks go by 45k miles, but i've done enough belts to see how wiped out the things are by 30k to not chance it myself.
Got some pics of the timing/balance shaft belt. You've probably seen more of these then I have so I'll let you be the judge on condition. What do you think?

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Old 03-13-2018, 04:55 PM
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It certainly sounds fuel related.

You can measure the fuel pressure with a fuel pressure gauge such as this one https://www.ebay.ca/i/263289079101?chn=ps&dispItem=1 and with help should you need it here: https://www.youtube.com/watch?v=6nRxc7a0xMw

Specs are available here: Fuel Pressure - Checking If this passes muster then it's off to the Fuel section: Clark's Garage Home Page
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1977 924 Guards Red (parted and sold)
1987 924s Alpine White (sold)
1987 924s Kopenhagen Blue (a work in progress and on course to become my track car)
1987 924s Garnet Red
1982 928 Silver (sold)
Old 03-14-2018, 07:33 AM
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Most likely intake-hose leak. Connect voltmeter to AFM line at DME-connector and monitor while you're driving. What happens to AFM-voltage when you go WOT and it stumbles?
Old 03-14-2018, 01:09 PM
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Originally Posted by DannoXYZ View Post
Most likely intake-hose leak. Connect voltmeter to AFM line at DME-connector and monitor while you're driving. What happens to AFM-voltage when you go WOT and it stumbles?
I'm going to definitely check that out I did not think of doing that. How do I connect the voltmeter though? If I'm disconnecting the AFM line to measure voltage from it isn't the DME going to be confused?

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Old 03-14-2018, 07:26 PM
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Leave everything connected.
You can use a hook-probe on the wire.
Or remove DME connector rear-cover and back-probe wire.
I solder extra wire to terminal to provide external wire for monitoring with datalogger or gauges.
Old 03-15-2018, 01:23 PM
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