She will drive slow but when I get on her all she wants to do is shake

[03GPScottyd]

Left for 6wks on business trip. Wife started the car and let run while I was gone. When I got back there's something wrong.

If I feather the clutch the car will drive normally and get up to speeds of 75+. If I step on the gas to get there quicker the damn thing wants to sputter and rock. Engine won't die but I cant get on it or it starts shaking. Starts every time and had 2 fillups since I've been back now.

What do you think? Fuel Filter, Plugs and wires, no codes are being thrown currently, but I did try to stomp on the gas once and as it was shaking the check engine light came on and then when I let off the gas it disappeared.

[Bio248]

clogged cat is my guess.

[hourang]

plugs and wires check first. the check engine was probably a misfire.

[nault31]

Did you have a code reader look for stored codes? (even though the check engine light is off)
I believe the clogged cat or exhaust theory because you never know about animals quickly stuffing crap in there when the car is sitting, even if it was started almost every day.

[03GPScottyd]

Went to AutoZone today at lunch, no codes are being thrown. Plan on disconnecting the MAP to see if it's that and then I'm going to the muffler shop to check on the CAT. I hope it's the CAT, because I want a new high flow dp from ZZP.

[whiney]

Unhook it off the manifold and see if the problem goes away.

[hourang]

Went to AutoZone today at lunch, no codes are being thrown. Plan on disconnecting the MAP to see if it's that and then I'm going to the muffler shop to check on the CAT. I hope it's the CAT, because I want a new high flow dp from ZZP.

misfires dont really store codes from what i remember. or it could be that the cheap scanners cant retrieve the misfire codes or im just an idiot?

[FoSHO99]

It will store a code if it misfires repeatedly. When you stepped on it, it likely flashed because of misfires like described above. The codes are P0300 for misfires detected, then P0301 for misfire on cyl#1, P0302 misfire cyl#2 and so on.

It wouldn't hurt to replace fuel filter, check wires/plugs and check the tailpipe with it idling to see if there is decent exhaust pressure coming out.

You do not want to unplug the MAP sensor, you want to unplug the MAF sensor on top of the throttle body and see if there is a change.

[03GPScottyd]

Clogged CAT...fowled EGR valve....

[Bio248]

hm..weird.

[FoSHO99]

I saw a clogged cat on a impala nvsrides/JJ bought from a salvage auction. The dealer labeled it as major computer problems, but after he pulled the engine cover off, there was a hole in the n/a upper intake above the egr. Cat was clogged so bad it came through the egr and burnt a hole through the manifold. New uim, gutted cat and car ran great.