armyman244

I gave my 400 a tune up today. Changed plugs, wire, distributor cap, and rotor button. All was done one plug, one wire and a time. So i couldnt mess it up. It sounds like i have a monster cam in it. and takes a year just to get to 45mph. I thought maybe it was the timing but no backfires just one heck of a rough idle. Ive moved a plug here and there on the cap with no change. Im at my wits end. It ran better before I changed a thing. HELP!!!!

Dx3

iTrader: (13)

Start with the simple problems... MAF plugged back in? Pull each plug and check for spark? Did you replace both rotors or just one? Doesn't the SC400 have 2?

Jonny

RedPhoenix

iTrader: (10)

sounds like the coil... check the wires and plugs to the coils.

armyman244

yep changed everything. Here are the steps i went through:

Changed driverside coil, cap, and rotor button. Started up the car to make sure it was right. And it was ran smooth as silk.

Changed all plugs and wires on driver side of motor. Cranked right up smooth as silk.

Changed passenger side coil, cap, rotor button. Started up ran like crap.

I went a head and changed the rest of the plugs and wires and went back to troubleshooting the the issue.

So i changed back to the old coil, cap and rotor on the passenger side to see if one of the new parts were bad. Car still ran like crap. This is the 4th tune up ive given the car so I do know what Im doing. I dont understand it. Ran fine before the tune up just a low idle and hesitation under acceleration, and poor gas mileage. Im at my wits end. This car has been dollaring me to death for a while now. Im thinking of just cutting my losses and getting rid of it, if I cant get it running like it should.

spooledx2

I had pretty much the same issues. What i found had happened was somehow the plug firing the coils had come apart. All the plugs and connectors become brittle with heat and age, while I was doing the starter changeover I must have accidentally unplugged the connector far enough that it wasn't making a good connection.

Here is a shot of the plug(it's the one with the blue wire going into it right above my finger). You might try unplugging it and looking at the connections if it is in fact still plugged in. After I traced it down to this and got it sorted out it ran like a champ again.



Best of luck.

V8Boy

check your camshaft distributor sensor. you have to 2 of them 1 for each set of cylinders this could definiletey be your problem. I did a complete tune - up and had the same exact problem u have.