OK, I thought about the title a bit, but couldn't come up with anything that describes my issue better.
I have a 2004 6 S MTX that I purchased new that currently has about 85,000miles. Have always done my own maintenance, with the exception of a new clutch early on at 17k(made odd noises)in warranty and a new actuator for the ventilation mixing valve (for lack of a better name).
I'll get to the real problem in a minute, but first some valuable background info.
I must admit I drive a bit like a granny when it comes to shifting. The 6 never seemed to mind, even shifting early into 2nd at low RPM, it seemed to have descent torque and not complain. In the last year this has changed, shift too early and you are rewarded with a bit of whiplash as the engine seems to cut out and come back again. Wasn't too worried about it, would just rev at least to 2,500 prior to shift.
We decided to sell the 2004 to my daughters, and I would get another car to drive to work. I have to say, I wanted to get something smaller for them, but my wife insisted on something more substantial, in case they get into an accident.
As you can imagine, learning to drive stick in a 3.0L V6 that likes to give you whiplash when shifting at low RPM can be challenging. So, I had it on my to do list to look into this further.
Anyway, that accident thing that my wife was concerned about, happened
. Casey rear ended a Cadillac SUV (smaller one) and wedged the bumper up under. (See Attached Pics)
Double I was only carrying liability insurance on the car.
Regardless, there are not many projects that I shy away from. In fact, I had a similar accident (with a tree) when I was her age, and rebuilt the car soon after.
Post accident, I knew that the engine ran, had to get it on trailer. So my estimate was that I could fix for about $1k.. As my estimates go, that is code for $2k.
So, I've poured ~2k into parts (hood, bumper cover, radiator, condenser, headlights, hood latch, front valve cover, pass engine mount, air bags, seat belt, K&N cold air intake etc..). The last pic shows what it looks like now.
You may have noticed engine mount in that list. The top bolt on the passenger side engine mount broke, and the pass side of the engine was shifted to the rear about 2". After replacing the mount, I was able to jack up the engine and move it back into place. The valve cover seems troubling as well. One of the studs that holds that nice engine cover on got pushed and opened a small hole in the cover..
After getting the body into a drivable condition, I started checking out the engine. Initially when I started it, it ran a bit rough, in that the idle would hunt. I ended up finding a slice in a hose coming off the back of the intake, caused by an impact with the firewall. After that, idle is smooth.
The reason for the K&N is that the airbox got cracked up pretty good, and I couldn't see throwing too much money into a used one. I expected a different feel with the K&N, which wasn't optimal in trying to troubleshoot. Aside from the guttural sound you get from it, the engine seemed to bog down if you punched it quick.
As it stands right now. If you start it up cold, and road test, it exhibits similar symptoms from pre-accident (doesn't want to accelerate at low RPM. Once it warms up, the condition gets significantly worse. You could get it up to highway speed, but good luck if you want to pass someone.
After a lot of research on this forum, looking at the symptoms, I had myself convinced that my pre-cats were clogged and backpressure was causing my issues. Additionally I thought that the K&N was exacerbating the existing condition with the increased airflow.
Sunday I pulled the O2 sensors in front of both pre-cats. Running the engine with these ports open, led to good throttle response in the garage. Obviously also a fairly loud engine!!
So, convinced backpressure was the cause, I purchased a pressure gauge that screws into the O2 port.
Just tested both front and rear ports. At idle it doesn't even register a 1/2psi of pressure. Revving to 2500 gives similar results. Snapping the throttle, yields a gauge needle that jumps instantaneously to 6psi or so (hard to tell it moves so fast), then immediately back to near zero.
Was all geared up for the exhaust manifold / pre-cat replacement. But now I'm stumped. The limited view I got looking in through the front O2 port didn't reveal anything about the cat that looked odd to me, typical honeycomb.
Could a bad EGR or something cause this? I have access to a scanner (Torque Pro Android App), if there is anything specific I should check for. I haven't seen anything odd, but must admit I don't know exactly what I'm looking at.
Help!!
I have a 2004 6 S MTX that I purchased new that currently has about 85,000miles. Have always done my own maintenance, with the exception of a new clutch early on at 17k(made odd noises)in warranty and a new actuator for the ventilation mixing valve (for lack of a better name).
I'll get to the real problem in a minute, but first some valuable background info.
I must admit I drive a bit like a granny when it comes to shifting. The 6 never seemed to mind, even shifting early into 2nd at low RPM, it seemed to have descent torque and not complain. In the last year this has changed, shift too early and you are rewarded with a bit of whiplash as the engine seems to cut out and come back again. Wasn't too worried about it, would just rev at least to 2,500 prior to shift.
We decided to sell the 2004 to my daughters, and I would get another car to drive to work. I have to say, I wanted to get something smaller for them, but my wife insisted on something more substantial, in case they get into an accident.
As you can imagine, learning to drive stick in a 3.0L V6 that likes to give you whiplash when shifting at low RPM can be challenging. So, I had it on my to do list to look into this further.
Anyway, that accident thing that my wife was concerned about, happened
. Casey rear ended a Cadillac SUV (smaller one) and wedged the bumper up under. (See Attached Pics)Double
I was only carrying liability insurance on the car.Regardless, there are not many projects that I shy away from. In fact, I had a similar accident (with a tree) when I was her age, and rebuilt the car soon after.
Post accident, I knew that the engine ran, had to get it on trailer. So my estimate was that I could fix for about $1k.. As my estimates go, that is code for $2k.
So, I've poured ~2k into parts (hood, bumper cover, radiator, condenser, headlights, hood latch, front valve cover, pass engine mount, air bags, seat belt, K&N cold air intake etc..). The last pic shows what it looks like now.
You may have noticed engine mount in that list. The top bolt on the passenger side engine mount broke, and the pass side of the engine was shifted to the rear about 2". After replacing the mount, I was able to jack up the engine and move it back into place. The valve cover seems troubling as well. One of the studs that holds that nice engine cover on got pushed and opened a small hole in the cover..
After getting the body into a drivable condition, I started checking out the engine. Initially when I started it, it ran a bit rough, in that the idle would hunt. I ended up finding a slice in a hose coming off the back of the intake, caused by an impact with the firewall. After that, idle is smooth.
The reason for the K&N is that the airbox got cracked up pretty good, and I couldn't see throwing too much money into a used one. I expected a different feel with the K&N, which wasn't optimal in trying to troubleshoot. Aside from the guttural sound you get from it, the engine seemed to bog down if you punched it quick.
As it stands right now. If you start it up cold, and road test, it exhibits similar symptoms from pre-accident (doesn't want to accelerate at low RPM. Once it warms up, the condition gets significantly worse. You could get it up to highway speed, but good luck if you want to pass someone.
After a lot of research on this forum, looking at the symptoms, I had myself convinced that my pre-cats were clogged and backpressure was causing my issues. Additionally I thought that the K&N was exacerbating the existing condition with the increased airflow.
Sunday I pulled the O2 sensors in front of both pre-cats. Running the engine with these ports open, led to good throttle response in the garage. Obviously also a fairly loud engine!!
So, convinced backpressure was the cause, I purchased a pressure gauge that screws into the O2 port.
Just tested both front and rear ports. At idle it doesn't even register a 1/2psi of pressure. Revving to 2500 gives similar results. Snapping the throttle, yields a gauge needle that jumps instantaneously to 6psi or so (hard to tell it moves so fast), then immediately back to near zero.
Was all geared up for the exhaust manifold / pre-cat replacement. But now I'm stumped. The limited view I got looking in through the front O2 port didn't reveal anything about the cat that looked odd to me, typical honeycomb.
Could a bad EGR or something cause this? I have access to a scanner (Torque Pro Android App), if there is anything specific I should check for. I haven't seen anything odd, but must admit I don't know exactly what I'm looking at.
Help!!
