83 944 idle/throttle problem

xero · 04-10-2002, 02:28 PM

so my 944 will idle fine sometimes but sometimes the idle will drop and when i step on the gas nothing will happen untill it's totally floored and then it goes hard, but if you let up at all it sputters and slows down anyone have any ideas?

drew1 · 04-10-2002, 04:53 PM

may be O2 sensor, I think it is out of the loop when WOT contacts on throttle switch make. Unplug it & see if car acts more normal. Also check for vacuum leaks, theres a bunch of hose under the intake manifold. A leak could let air bypass the flap flow sensor, but when floored it could be insignifigant.

drew1

mlue · 04-10-2002, 05:26 PM

Trottle position sensor ??? Air Flow Meter ???

Mark
'86 944NA

xero · 04-11-2002, 12:40 AM

Thanks Drew1 unplugging the O2 sensor totally cleared it up!!

xero · 04-11-2002, 12:52 AM

my car is much better now but it kinda feels like my timing is retarded a bit does anyone know if it is possible to adjust the timing or if there are timing marks somewhe that can be checked with a timing light?

drew1 · 04-11-2002, 05:16 PM

xero,

the only way to adjust the timing is on the DME. With the O2 sensor disconnected & running better, you may have a fuel pump, regulator, filter, or injector problem.

drew1

xero · 04-12-2002, 02:00 AM

well one of the wires on the O2 sensor was messed up i'm not sure if it was making a connection or not? and the o2 sensor is also an old one from a car that had a bad head gasket! i would have changed it but i coudn't get it off with pliers and i didn't have a wrench that fit it while i was installing the new engine so i'm thinking i just need to put in a new o2 sensor?

xero · 04-12-2002, 02:06 AM

oh yeah also i was talking to sombody today and i mentioned how i had disconnected the o2 sensor so it was just running on the defaults with no input from the o2 sensor and he suggested that my retarded timing may be a result of conservative timing curve defaults that the dme reverts to when it has no input to go by... this soulds like a good posability, but in most cars the computer adjusts the timing based on input from the knock sensor not the o2 sensor right? do 944's even have knock sensors or could disconnecting the o2 sensor cause a slightly retarded condition?

mlue · 04-12-2002, 09:11 AM

When my car had a bad O2 sensor it felt sluggish running rich but still quite drivable. The response from the engine was like night and day after replacing the O2 sensor.

Donn't complicate the problem try a new sensor a univerasl Bosch (13913) O2 sensor can be purchased for $35 to $45. You just have to splice it into the old O2 sensor harness.

Mark
'86 944NA

xero · 04-13-2002, 04:01 AM

yeah i was looking on the kragen's website at the o2 sensors, they have the universal bosche$32 and the bosche 944 $290!!!!!!!

so is the one you installed the universal one and it works good?

that sounds like my car it's totally driveable and it's fairly fast, but the throttle response is a tad lagging and it tops out on the freeway at about 120-125mph

mlue · 05:31 AM

Quote:

Originally posted by xero
so is the one you installed the universal one and it works good?

that sounds like my car it's totally driveable and it's fairly fast, but the throttle response is a tad lagging and it tops out on the freeway at about 120-125mph

I'm using the Bosch universal 13913 in my '86. This is a 3 wire sensor, are you have a 1 or a 3 wire sensor. I donn't think it makes a difference though as only the black wire carries the signal the other 2 white wires are only for the heater for the sensor.

I know you found a bad O2 sensor wire but you should also make sure the TPS is OK as I read on the Rennlist that if the TPS is disconnected or fails the DME will ignore the sensor and revert to default mixture values most likely using the signal from the AFM as a base with conservative ignition advance. This will most likely give you symptoms like you are experiencing.

I hopes the helps out,

Mark
'86 944NA