Hey.. My car has done this ever since I bought it... I don't often think much of it, since it's good once it's warmed up.. It's all gone by the time I'm out of my neighborhood in the morning, but it's still annoying at first...

When I start my car up after a long (few hours +) sit, it just runs crappy.. Throttle response is nonexistant, and 10-20% changes in throttle sometimes don't register at all until a full second or two later... ERR!

I assume this has something to do either with it being in open loop, or being cold. (Actually, it's in open loop BECAUSE it's a cold start, right? ).

Any ideas on this? My oil pressure is always MUCH higher after a cold start than after it warms up... Granted, the stock guage probably isn't accurate, but I've had it tached past 60 (goes to 60) while still in my neighborhood in the morning.... idle is at like 50... after it warms up, 30-40 is normal it seems..

Thanks,
Tesla

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91 T/A 305
STB, Airfoil, Hooker cat-back, pseudo-cold air to K&N, Accel coil, !cat, !smog pump.
300 lb*ft of rice churning power.

 

Oil pressure swing like that is normal.

You need an O2 Air/Fuel meter to find-out if you're running rich or lean. Or use a multimeter on your O2 signal line... If > about .45V, richer than 14.7:1, if less than .45V, leaner thatn 14.7:1...

 

You can't use the O2 sensor when the engine is cold.
The only thing that immediately comes to mind is maybe you have a clogged/dirty injector. When it's cold, i's either making acylinder run lean or it's spray pattern is so messed up that it's not making that cylinder happy. Other than that, i'd just go over the basic adjustments and tune-up stuff.
...ed

 

The O2 sensor will work fine when the engine is cold... Only take one minute max for it to warm up. The ECU will not use it until it goes into closed-loop.

Further, if you have a heated sensor, you can put positive source to it before you start the engineto get the sensor to warm to perating temp and the sensor will read properly from the first engine crank...

[This message has been edited by FastBroker (edited September 15, 2000).]

 

Ahh... I was thinking of building an A/F monitor anyway, so that works out pretty well...

Say... on that lil plugin place under the dash....is there a pin that comes straight off the O2 sensor? Or am I going to have to get my splice on?

-Tesla

 

I believe you'll have to splice OR borrow a scan tool and read it that way. If you are serious about tuning, build/buy the AF meter and install another O2 sensor in the opsite bank of the one you have now, unless you have two, now. This way, you can toggle betwen the O2 sensor that the ECU is using and the O2 sensor that is "reading" what your ECU is making your exhaust look like...