jalchin

I am a little baffled at what is happening with my 2000 Trans Am M6. Gas mileage is still good at 22-24mpg average but the SES light will come on for a couple days and then turn itself off for a couple days. It usually turns on after a long decel from the toll road up to a redlight (70mph). Sometimes the engine almost shuts off at the signal, the rpm drops to about 200 then it picks back up and idles. This turns the SES light on. Also, it idles rough now and the shifter handle shakes a lot. The car does not have a miss at any rpm other than idle. It has started detonating (on 93 octane) at WOT around 5000 rpm when I tested it so I let off. It NEVER used to do this.

Where do I start? We pulled the codes and all I had was a "cat efficiency" code. I don't think a bad cat will make an engine idle rough.

I have some Mopar fogging foam and I think I am going to try that today and clean the MAF. Any other ideas?

Thanks!

omarrakeen

iTrader: (2)

what makes you think a bad cat cant do that?! it can def do that! its preventing the flow of your exhaust. time for LTs and ory

mhorn0817

exactly what he said, lol, dont ya get the shakes when you "backed up"? lol if the computer is telling ya something is wrong, you might as well start there, plus a good excuse for an upgrade

WS SIK6

iTrader: (1)

Ive had this exact same problem in the past, you might want to check your spark plug wires make sure theyre hookep up properly(tight) onto your coil packs and spark plugs

ds98formula

iTrader: (3)

London decal problems rough idle and almost dying. I would defently suspect the cats run them at free way speeds at night then pull over and look I bet they are glowing

jalchin

Well I did the MCCC and just did the test ride to burn it off after letting it sit for 3 hours. I must say it runs a LOT better and idles smoother. It also doesn't try to die after decel to a stop with the clutch in. I did find a loose PCV valve hose that needs to be replaced but that's tomorrow. I am going to go ahead and install the truck fixed orifice pcv valve as well.

ds98formula

iTrader: (3)

Hope that fixes it for you but I would still check out the cats with a night time run

jalchin

It's getting a "cat-mod" right now and new O2's. At 70,000 miles I don't feel that is a waste of money if it helps. I'll need sims now or is it cheaper to tune it out of the PCM?

ds98formula

iTrader: (3)

Look in to a tune they will delete the codes at the same time. Lots of people say a bolt on tune is not worth it but it helped my milage out and smoothed out my rough idle. Frost on here does mail order tunes pretty cheap search his name

yellowdawg

whats MCC. why you f body guys have to make up fake names is beyond me..

ds98formula

iTrader: (3)

And why people come in a thread and offer nothing to the thread but garbage is beyond me.

jalchin

Well, do spacers work for the rear O2's? I don't really want to do a tune since I am selling the car.

ds98formula

iTrader: (3)

It will probably be cheapest to just get a mail order tune for around 100 then to buy sims. Not sure what spacers you mean