spitting and sputtering

[humesrichard]

I have a 97 grand prix it run great.....when its cold but as soon as it warms up it takes a while it will start to miss here and there then a few minutes of that and you press the gas down it will spit and sputter and the tach will jump to 0 then to 3 grand. when I got it we put a new pcm in it, new fuel pump,new fuel pump relay and a new iac. I just put a mass air flow senser on it because it through a code on it. now it doesn't through any codes. I was hoping for a miss fire code are something but nothing a have a scanner it seems to be showing fine. I'm leaning toward the crankshaft senser any other input would be nice. I know the the Ignition Control Module could be a possibility any thoughts

[dsmuts]

Have you ever tuned it up? Changed the plugs and wires? Fuel filter? air filter?

[humesrichard]

yeah never changed the spark plugs but it doesn't sound like spark plugs but should eventually change them another fact is that the tach jumps when to ignition is on but the engine not running. It did it first time a got it then i changed the tps sense then it stopped for a while now its doing it again

[dsmuts]

Could be the crank sensor then. They are fairly cheap and easy to replace.

[BlackGT97]

my tach still jumps when the ignition is on and car off. But I have none of your symptoms. did u replace the fuel filter? It may be plugged also.

[humesrichard]

yeah did that a while ago as for the tach jumping thing now sure what is causing it my a short or something if i unplug one of the sensor like the camshaft sensor or the crank sensor it stops.

[BlackGT97]

Is it possible it may be a clogged catalytic converter?

[Rico]

yeah did that a while ago as for the tach jumping thing now sure what is causing it my a short or something if i unplug one of the sensor like the camshaft sensor or the crank sensor it stops.

If tach stops bouncing when CKP or CMP is unplugged then there may be a problem with battery voltage or the ignition switch.

Check the battery voltage with the key in the "on" position and make sure you have a steady 12.5 volts.

[humesrichard]

no, mine has holes every where, it could cause the engine to run bad but not anything electrical like that. I would like to take the cat off but i would like to tune it so it dosnt through codes for the second o2. I find out if the tach jumping things is one of the sensors shortly I ll change everything if i have to. not knowing what it is going on is driving me crazy. hopefully its the crankshaft sensor cause the next thing it could possibly be is the ignition control module and that is not cheap

[humesrichard]

the ignition switch may not be bad to check out, the key can come out and we sometimes don't even need a key to start it it you dont put in the lock position might need a new switch

[bmx6454]

i doubt that its the ignition, cause as long as it starts, i dont think it would cause other problems like that. if u unplug the cps/ckp, and it stops, then mabye its a good idea to check those first?

[humesrichard]

will here is the update changed the crank sensor and its still doing the same thing so I guess it has to be the ignition control module I hope. it does something new now it runs fine till it warms up then if i shut it off it will not start like its not getting gas or spark. I know its getting gas sounds like it is the ignition control module. wonder why its not giving any codes.

[Rico]

Diagnostic trouble codes for CKP, CMP and ICM are fool of poop. You have to just throw parts at it until it starts working...cheapest first of course.

[BillBoost37]

Often I'd say heat related is ICM
Sporadic/intermittent is typically crank sensor.