Please can anyone help me? I have a 98 V6 3800 engine, it has aprx 164,000 miles on it, I have owned it almost 2 years and have had very little trouble out of it, but for the past several months, it has been shutting off at random, does not matter if you are sitting still or driving at various different speeds, when this first started happening, I did get a service engine light and discovered that the EGR valve was going bad, so I replaced that, it kept doing this, I replaced 2 fuel filters, again it kept doing this, I replaced 1 of the coil packs and the ignition control modular and it still does it, I have put denatured alcohol in the tank, thinking that I had bad gas, it still does this. It is driving me up the walls. I can go several days and it will run fine, then I can be driving at different speeds or just sitting at a stop sign or stop light and it will cut off, when it does this, some times I can turn it over and it will immediately crank, other times I have to sit a couple of minutes and it will crank right away or it takes several times to crank. we are going to replace the other 2 coil packs this weekend and hope it will stop. This car does not spit or sputter it just dies and 2 different mechanics had it at their shops and of course it would not shut off on them and since there is no service engine light on I don't think it would matter anyway. Anybody got any other suggestions as to what might be causing this, I have full power when I do get it cranked, but when it shuts off, the motor turns over but it's like it is not getting any fire. HELP.

Vicki

 

I would lean towards Crankshaft Positioning Sensor,or Knock Sensor.That is if you have checked the fuel pressure to rule out a bad fuel pump.I doubt its the coil packs.A Bad CPS would do exactly what you decribe.There is also a chance the CPS plugs are dirty.If you can find the exact one unplug it,Put some dielectric grease on it and plug it in.

 

Thanks will try that, looking at the service manual, I have 2 of these plugs on this model, it says I have to disconnect the battery cable in order to replace and set to torqe in guide lines of manual, I don't need to do this just to put some grease on them do I ?

 

i assume its running rough? what code is it throwing? have autozone scan it, they will do it for free and should give you a specific code.

If its running rough and cutting out, it may be the maf sensor too.

 

No, it is not running rough, or even idling rough, this is what is so frustrating about this, car has full power, does not spit or sputter or skip, runs very smooth, just shuts off at random.

 

Knock or CPS sensor.

 

ok, b4 we got to ck anything on this, I drove it a couple of blocks today, it did just fine, came home put it in the garage, went to crank it a couple of hours later and nothing, all it does is turn over, will not fire at all, same as it was doing when it would just shut off, but this time it will not crank at all, I waited an hour and a half and went back outside to try it again, still will not crank, still think it is the krank or CPS sensor? do they just quit like that after acting up for so long ?

 

Hmmz.Almost sounds like you have a loose ground wire or something.For it not to have power at all sounds like a main ground wire loose.Check all the wires on the starter and your battery terms.You might have 2 issues.Does the car lose power (dead) when it shuts off on you normally?If the car flat out dies with no interior lights and then wont start its a lose wire.if it has power but just spins over and over its a CPS or Knock sensor.If it does both you have 2 issues.Definatly get it checked over by someone you can trust.

 

also to answer the second half of your questions .Yes they can just go all together.But I am still not clear if you mean you have lights and power while this is happening.

 

ya it definatly sounds like somthing electrical to me my car was behaveing similararly and it turned out that the wire prvideing power to my computer was bad so it woudl shut off when driving and then it would crank over but not start untill i fixed the wire now it works great