"05 LGT - Lacks Significant Power - No CEL!

My chief complaint is lack of power. It started lacking power around 4000 RPM, but still drove. Now the problem has escalated so that I have almost no power until I reach operating temp, then it will drive with greatly restricted power.

 

The car is completely stock and well maintained (minus the following). The only two known issues I have are: 1) a likely bad purge control solenoid valve (P0459, hard to start after fueling, but not bad enough to get a CEL); and 2) the infamous oil consumption problem most likely from blow by.

 

I have no CEL!!!! What the heck is wrong?

 

So far I think I've ruled out the fuel pump/filter and regulator. The fuel pressure checks out. Its around 36PSI with vacuum to the regulator and about 45 PSI with no vacuum to the regulator.

 

I did a quick vacuum test. At idle, it is at 17 in Hg. When I snap the throttle it drops to 7 in Hg, then it goes to 21 in Hg and returns to 17 in Hg quickly.

 

The engine does seem to be reaching operating temp quickly. I haven't measured it yet, but the the cats seem to be getting a bit hotter then they should too.

 

I am considering that I may have a plugged exhaust. Maybe years of oil consumption finally ruined the cats? I will run some checks for that tomorrow.

 

I could definitely use some help diagnosing. Does anyone have any ideas? Any input is appreciated.

Before I finished reading, I thought clogged cat(s).

^ yup, id replace that catted up pipe with something "less restrictive", and check for blockage in the down pipe.

^^^What he said. A friend of mine had a Mazda MX6 GT years ago and it did exactly the same thing and what had happened was the front cat had self destructed and all of the pieces blew into the back converter. It took a while for all of the pieces to jigsaw their way together to completely seal up the pipe and meanwhile it kept getting slower and slower and less and less power until finally it would idle fine and would barely pull itself.

 

He of course did NOT tell me about the slow progression of power loss, just told me when it would barely pull itself. Dropped the DP off of it and heard crap rattling around in there. Unfortunately, the system was rusted too so when we went to pull it off, it basically broke and we had to replace the converters anyway but it was full of busted up media.

 

Start it up, put your hand over the rear pipes and see how much pressure is coming out at idle. Then have someone push on the accelerator up to about 2000 r.p.m. and see how much pressure is coming out. It should blow your hands away from the tips pretty easily if it's unrestricted. If not, time to drop your UP, DP and CBE and see what's going on. If you still have the catted UP, GET IT THE HELL OFF OF THERE, and put on a straight through pipe of whatever flavor you prefer. That alone could be the issue because that so-called "pre-converter" (turbo destroyer) could be plugged and the rest of the system OK although if the first is fouled by oil, then most likely the rest would be too.

 

Also, check your PCV and see if it's stuck and clean the hell out of it. Maybe that will help with the oil consumption and subsequently, the cat life.

I took it to the dealership to confirm that that the cats were the problem. They called me back and said that I had two bad cats, but the guy on the phone couldn't give any further info than that. He also said that I needed a valve job and he wanted to know if they should start work. To which I asked, "What evidence do you have that shows I need a valve job?" (I know that my valves are fine by the way.) He admitted that they did nothing the check the condition of my valves! Maybe he should have said, "Bad valve can cause cats to fail so we should check the condition of your valves."

 

I still plan on investigating theory that this was caused by oil blowby.

 

I'm going going to put in an up pipe and if i still have some restriction, I'll do something about the other two cats. I would just do it all, but I don't have the money.

 

Does anyone know if you can get anything for old stock up pipes at the scrap yard?

The advisor really didn't explain things very well at all. It isn't a valve job, but rather a valve adjustment. Still doesn't explain why they suggested it though. For rough idle and a timing related CEL, sure, but not for a consumption issue.

You know what? I just removed some of my mean spirited words about the misinformed adviser. Although I stand firm that the advice that I was given wasn't very good, there is no need for name calling.

 

Danteneon: Thanks for the input. You're probably right. I didn't think of that. It would make sense for them the recommend that given that my car is at the mileage for that. I had it done a few thousand miles ago, but they didn't know.

 

As an update: The car has been sitting to prevent damage. I bought an Invidia up pipe and down pipe. The car has scheduled for a dyno tune after I install the parts. This is definitely the most appealing and inexpensive fix. I'll can't wait to see the difference it makes.

You know what? I just removed some of my mean spirited words about the misinformed adviser. Although I stand firm that the advice that I was given wasn't very good, there is no need for name calling.

 

Danteneon: Thanks for the input. You're probably right. I didn't think of that. It would make sense for them the recommend that given that my car is at the mileage for that. I had it done a few thousand miles ago, but they didn't know.

 

As an update: The car has been sitting to prevent damage. I bought an Invidia up pipe and down pipe. The car has scheduled for a dyno tune after I install the parts. This is definitely the most appealing and inexpensive fix. I'll can't wait to see the difference it makes.

 

You'll love it.

 

On the stock tune I always found the car to be very lacking motor wise. Going stage 2 helped open the car up. Top end of the revs still lack but you'll have more power till about 5K that will make the car seem a lot livelier.