Hello all, I picked up a bucket of a 6MT 3G TL for next to nothing and im hoping to coax it back to life and return it to daily duty.

The problem im having is when the car is under load, specifically under load above 2300 RPM or so, it bogs hard and sounds like it’s pinging as if it’s leaning out. i can get it to continue to rev past 3k if i lift up on the pedal a bit but under no circumstances will it go above 4k, even free revving.

My first thought was vacuum leaks, but spraying carburetor cleaner all over the engine bay has resulted in a rock solid idle.

There is also no check engine light, it’s possible i haven’t driven it far or long enough but i drove it for about 20 minutes continuously at speeds varying from 25-65mph and still no codes.

I did a resistance test on the APP, it seems to check out fine. I replaced the throttle body with a known good one, with no change. I replaced all 6 injectors with known good ones, no change. I replaced the MAP sensor, IAT sensor, and all relevant gaskets and O-Rings, with no change. I cleaned out the EGR valve and EGR passageway, with no change.

Im really at a loss for ideas here, again the car drives completely normally from idle to around 2,300rpm, at any amount of throttle from 0-100% throttle. from 2,300rpm to 3,500 rpm i have to reduce throttle position more and more to prevent it from bogging and pinging, until a little under 4k where even the smallest amount of throttle causes bogging and pinging.

I don’t want to keep throwing money at the car aimlessly so if anyone has experienced this before please advice as you can.

Also the car is completely stock minus an Injen CAI, is running 91 octane fuel, and does not smoke from the exhaust at all.

Thanks in advance!

 

How are the spark plugs?

 

Can’t believe i didn’t think to look, I just looked at them and they’re a little dark in color but more worryingly they’re autolite branded, i’ll replace with NGK oem plugs and report back.

 

Update: Replaced all 6 plugs with NGK laser iridium plugs and no change. still no DTM codes either.

 

^
Maybe clogged pre-cats or cat?

 

Thats my next best guess, it did throw a code before for the bank 1 downstream O2 sensor and i replaced it and the code hasn’t come back, but the car does have around 290k on it so it’s plausible the cats are clogged, the exhaust doesn’t smell like it though which is why i didn’t look into that further, but i guess i should now 🤷🏼‍♂️

 

This was exactly it. I removed the primary O2 sensor on the front cat and when shining a light inside i couldn’t see any honeycomb material, and then looking a little closer i could clearly see the secondary O2 sensor in there which meant the cat had blown apart. The quick fix was to temporarily chop out the secondary cat and tons of chunks of cat were sitting in front of the honeycomb of the secondary cat, clogging it and choking the engine. Car runs like a dream now.
Makes me wonder why the car didn’t have a P0420 or 430 code for the front cat being completely blown apart, will have to check live data on the O2 sensors and see what’s going on there.
Thanks everyone!