stalls when warmed up

[Daveb]

94 GS with stock 1.8, runs fine cold and on the highway. C/I light goes off & on randomly, when light is off runs fine , but when hot and the light comes on, it stalls when you come to a stop. After it stalls, it starts hard (you gotta give it gas to start it and keep it running).

I only drive it in the summer and it did it last year for the first tank of gas and then ran fine the rest of the summer. I was thinking it might be the front O2 sensor (the rear one is new) but someone told me the O2 sensor wont make it stall.

I checked my air intake pipe (accordian) and it has a few little cracks but no holes, I dont think its leaking. I pulled a plug and they dont look to bad for 130,000 km (NGK iridiums) but I will put a new set tomorrow.

I do fing it starts harder than it used too, it used to fire up immediately but now it has to crank over a bit. Seems like if you crank a few turns, then stop, then crank again, it will fire immediately.

Even when your driving at 100 km (60 mph) and the light comes on it seems to still keep running normally.

I dont have a code reader but have access to reasonably cheap parts. A Sensor or a fuel problem ?

advice appreciated

[mazdags94]

Well, if it's temperature related, might suspect the coolant temperature sensor (CTS). The VAF, TPS, O2's, and CTS all help control your air/fuel mixture. If the 02's signal a lean mixture, they'll signal for more fuel (richer mixture) and vice versa. In theory, the O2 sensor could very well make your car run rough but I dont think it would be your problem.

I would check your coolant temp also to see if that's functioning correctly.

If your CEL is coming on, there's your starting point really. Pull those codes and go from there. You can pull them without a code reader. Just go to your DIAGNOSTIC box in the engine bay (near wiper motor) and jump the terminals marked TEN (test engine) and GRND (ground). Then, go into your car and turn the key to the ON position (don't start it). The CEL should start blinking. There will be a seires of long blinks and short blinks. Long blinks indicate the first number (in tens), short blinks indicate the second number. For example: if there are four long blinks, then three short blinks, that would be a code 43. You can use the search bar to research each code that comes up if you want or just look in the online manual. If the CEL is/was on, there should be data stored in it.

If there are cracks in your accordian intake, spray some carb/ choke cleaner on it while your car is running. If your Idle jumps then you have a leak.

[Daninski]

O2 sensors won't make it stall so don't worry about them. Try setting your TPS first then jumping TEN and gnd set your idle to 650 by adjusting the screw on the top of the TB. Basic initial setting is around three turns out. Turn it in untill your idle drops then out untill it's staedy at 650. Do this with the engine at operating temp. Once you remove the diagnostics jumper the idle will go up to 700 rpm.

[Daveb]

Wow,
thanks for the code reading advice, I ll get right on it.

[Daveb]

I managed to get the code, it keeps giving me code 16, EGR valve position sensor, connector or wiring. I think I found the EGR valve, what a horrible spot, think i ll have to get the car on a lift and see if I can check it out from underneath.

Thanks again for the help

[Mad Cow]

EGR sounds right, it only gets used when the engine is warm. But just to be sure, I would replace the coolant temp sensor too, it's only like $10, you'd be surprised how much of a difference it makes even if you think it's working properly.