jagone

I have been fighting this issue for a couple of months. Trying to sell the car but I want it to be "right" when I do.

I start the car, it fires right up and idles smooth, no misses. Put it in gear and it either stumbles right away, or as soon as I hit the gas. It feels like it is gonna stall but I let off the gas and it starts moving then I can give it gas slowly. When I get in closed loop mode everything is perfect. I can stomp it right from a dead stop, or anywhere in the RPM range, and all is fine. I don't have a scanner but I haven't got any ser. Eng. lights the whole time I've had this problem.

Here is what I have changed so far:
installed TPI Fuel pump and new filter
plug wires/ cap/ rotor button ( a couple wires were chaffed so I changed 'em all)
new TPS
cleaned IAC

rocko350

it sounds like a fuel pressure problem. too rich when cold. possibly too much fuel pressure that the int and blm have adjusted for when warm. any trouble on a warm restart?. search for the ohm check on a ect sensor. there was a resistance table posted for it but i dont remember where.

jagone

Rocko, no problem at all on a warm restart.

Fast355

iTrader: (2)

Did it do it before the modifications or just after. Also after the modifications, has it run normally and just started acting up?

Finally for grins, put a CTS in it. The last one I bought was under $10.00, and they are located right up top by the thermostat housing. The CTS is a common failure on high mileage GM vehicles. I have seen them read 100+*F on a 40* day, prior to a cold start. What happens there is the cold engine needs more fuel, but the ECM thinks the engine is already 120*F and it does not get it. This causes the engine to hesitate and stumble. Then as the engine temperature increases, the problem goes away.

jagone

Fast, the problems started before the mods. The mods were a result of me chasing the problem. I will try the CTS, that is one of the things I haven't tried. Does the CTS or the fan switch provide the guage its signal? The temp guage seems to be acting correctly.

On the tech board someone said the base timing may be retarded, and I will check that too, but the way you explained how the CTS operates on startup sounds like that may be my fix.

jagone

Wasn't the CTS. Still have to check timing.

UnderCover89TBI

iTrader: (25)

sometimes the connector on the coolant temp. sensor fails causing the vehicle to malfunction like the CTS is malfunctioning, no check engine light on or anything?

jagone

Nope, never a check engine light.