First of all, no DTC codes at all.
The vehicle starts and idles fine. Upon startup there's a loud sucking noise coming from the airbox before the filter, which I know is normal because of the IAC during cold startup. At any point in neutral or park, cold or hot, the engine sounds fantastic, has great throttle response and revs up nice all the way to the limiter. I've replaced all the plugs, wires, and coils. I did a compression test when the plugs were out and it came out to 167-175 for all cylinders. Every plug looked fantastic, nice tan color, no fouling. Beautiful.
If I start driving right away immediately after I start the vehicle, it accelerates through the gears and shifts smooth with what I would call normal acceleration. Feels like it should and if I could get it to stay that way, I'd be happy. However, after a couple of blocks, (or if I let the engine idle for a couple minutes before driving) the acceleration becomes very poor. There is a more hollow muffled sounding sucking noise (not even sure it's air, but that's the best way I can describe it.) During the poor acceleration. It seems to shift though the gears still, it just takes forever to get up to a speed to get the gears to shift. I'm actually not sure if it's even starting out in the proper gear. It doesn't slip during this, it's just like pressing the gas and it accelerates super slowly, there's no high rpm's as you would see in slipping.
If I press the accelerator maybe 2/3 of the way down so that it drops down a gear, the engine revs higher, the hollow sound goes away and it sounds more like it should. It accelerates much better, but I'm still not sure it's as good as it should be.
If I floor it so it drops down another gear, engine RPM's go way higher, but zero acceleration (transmission is slipping) with a loud rattling like marbles in a tin can. This rattling is worse the more the car is driven (or warms up I guess).
originally, I suspected the cat, but I'm not sure why it would be okay for the first couple blocks before it warms up. Also, in neutral, the engine sounds awesome with great response. Because of this, I"m beginning to think it's not a plugged cat. Even if it was clogging up after coming to temperature, it would be bad at idle too, I'm thinking. I'm also ruling out fuel delivery as it revs up great and very responsive. I haven't checked the rail pressure.
If I stop the vehicle and let it sit for a few minutes, then start it up and drive again, again it's good for a couple blocks and then starts doing the same thing again.
Would doing a transmission fluid and filter change (not flush) fix this? I'm thinking that there's some kind of restriction someplace that clears as the transmission fluid drains and then clogs up soon after starting the vehicle again. The fluid level is correct and the fluid isn't black, but it isn't red either. I'm confused because it seems so great for the first couple of blocks and when it starts having low power, it's not slipping until you floor it, it just bogs down under normal acceleration. If it's the PC solenoid, why does it take a couple blocks to see the problem?
Another question. Will pulling the front O2 sensor allow enough air through the port to allow me to diagnose the catalytic converter? I don't really feel like disconnecting the whole pipe or manifold before the catalytic converter.
I plan to clean the MAF sensor, but looking at the readings on my OBD tool, the numbers don't seem out of line and there is no DTC and the engine seems to be running fine.
Any help would be truly appreciated. Thanks in advance.
have the same problem?
Thursday, July 11th, 2019 AT 2:38 PM