leatherneckm

Ok, i've been having this problem for a while and i'm at my wits end. When I start my car it starts really hard. When it does start the idle comes up real slow. Takes around 5 secs to go from starting to 800 rpm. After this the car runs great. It has just been tuned up, has a brand new MSD system (complete), new O2 sensor, new MAF, underdrive pulleys, TPI airfoil, K&N filter, etc. Car has no problems other than this hard start. It has been going on since before any of these mods were put on, problem hasn't gone away, but it hasn't gotten any worse either. 88 TPI 305 T/A 700 R4

Vader

Leather,

I'm guessing you might have a problem with the cold start valve (injector) or the control for this injector. The injector is located on the left side of the engine, buried between the two sets of intake tubes on the manifold base. The control (temperature sensor/timer) is located at the front of the intake, in the coolant crossover between the two heads. If the cold start is not functioning, you will have a very lean condition for the first few moments after starting, and the starting itself can involve some lomg cranking times (sound familiar?) All of these problems go away after the coolant is above 105°F. (Sound more familiar?)

The good part is that the control and injector are easy to remove without a lot of major disassembly. The injector can be tested on the car by removing it from the intake base, making a jumper from a spare injector connector, and energizing the injector while the fuel rail is pressurized.


IMPORTANT! Be VERY careful when doing this, since the fuel cloud will be very well-atomized and ready to explode with the first ignition source - like the spark from disconnecting the injector electrical connector! You might want to try to contain the fuel cloud in a large clear plastic bag for safety.

If the injector sprays a fuel mist, it is functioning. You can test the output of the cold start control by inserting your meter probes in the connector for the cold start injector. If you get a 12VDC signal for 3-8 seconds when turning on the ignition, the control is working. Be aware that the control will only do this once, and only if the coolant temperature is below 100°F. This can be difficult to catch, and if the injector seems to be functioning, the control is the likely suspect. Of course, before replaceing the control, you should verify that you have a 12VDC source to the control.

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Later,
Vader
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leatherneckm

Thanks Vader, once again, you da man. If you remember my post a while ago "Need help, weird old crap" Where "demon possesion" was listed as a possible cause, it turned out to be the alternator. Strange, but true.