Hi everybody!

Like the title says the power below 3000 rpm seems quite low now to the extent that I actually feel a kick when it goes to the 3k when on WOT from cruising rpm. The upper rpms seem the pull normally, or mayby a little weaker, hard to tell. Also it seems that startup has gotten a little worse.
Couple of weeks ago everything was perfect and the car pulled smoothly thru the whole rev range with the nice little spike on 6000 rpm.

Do you guys have any idea what this could be? I have a remanned engine from Mazmart changed 3500 miles ago. At that same time I replaced the coils and plugs with proper ones. I replaced my wires 5000 miles ago. I got a new MAF around 1500 miles ago. Everything is properly secured, I double checked plugs and coils.

Please do help.

 

Now I noticed that all around the acceleration in below 3k rpm is really rough when the engine is cold. It gets little better when the engine is warm, but I still get low power and the "kick" when at 3k rpm.

 

Pure wild *** guess. How many miles on the CAT and have you taken it loose and peered inside with a flashlight? This doesn't fit the "norm" CAT failure scenerio, but might be worth a looksee.

 

Hmm. Interesting for sure.

Do you get a 'feeling' when it is under 3k? Like it's choking, sputtering, smooth, grainy, lugging, etc... 'Power loss' that low isn't commonly talked about. Compression is one of the few things where lower RPM usually makes it worse, but you haven't mentioned any of the other compression related issues.

Ignition is also usually very low or very high rpm. Makes me wonder if you have the wires in the right order?

Vacuum leak is another possibility. Any leak size is made more inconsequential as more air is demanded.

 

I have the original cat and the car has been driven 67.000 miles. I did what we have equal to the smog tests and all the readings were normal back 3.500 miles ago. I do get some sort of burning smell after spirited driving, though, that I only think could come from the pipes, but that has been there forever. You think it could be the cat even if the exhaust readings were very good?

When cold, it seems like it is sputtering a little bit and when warm it is smooth, but feels extremely weak. It seems like it is getting worse every day now. Idle is still silky smooth. When I crank I am not getting bird chirps, but mayby starting to get something that might lead into that. But coils? After 3.500 miles? Seems unlikely.

Wires are sure to be in right order. It ran really good and I made no changes to the car when it started to behave like this. I've also checked the leads many times to make sure the connections are good.

What can I do to know if I have a vacuum leak?

Thanks for your help guys. I am scared witless that my new engine will blow up on me.

 

Hey man...
I have an 04' 6spd, 2k miles on the new engine, 53k miles on the cat. For the last 3 weeks I've been getting the loss in power during low rpms w/throttle and the power would come back between 3k-4k rpms
After a lot of troubleshooting... I ended up looking at a failed cat.

First off...From my research I've found the most common cause for these particular symptoms is faulty SSV operation. Jon316G is the man to talk to about this... PM him or just as well you can find his DIY on troubleshooting the SSV (secondary shutter valve)
Mine checked out fine, but do this first, because it's more common that I would have thought.

If the SSV operation is okay for you, I would then be considering the cat...
I too was thinking this all along, but just wasn't convinced. Until...
I got on it a little bit driving home one night, and parked the car. Getting out I peaked under the car at the exhaust and the area around the o2 sensor was glowing red.
So i jacked up the car, unbolted the cat and took it down...
At first glance it didn't look too bad, but after shining a light into the honeycomb of it, I could see not all the holes were clear, then gave it a little shake and could hear a few small pieces moving around a little bit.
So I gutted it literally last night, and she's peppier than ever throughout the rpm range. There's no lag in the acceleration. It'll backfire (which i love... lol) and pops flames (which I love...rofl) and it's surprisingly easy to control as well.

 

Just remember if you are going to gut the cat do NOT breath in the dust.

That **** in there is very nasty.

As well you're going to like throw a check engine light.

 

Thanks for the very informative post! I will get on this immediately and report back.

Yeah, I have a habit of using a respirator in all things dusty. I do my fair share of renovation. You DO NOT want asbestos from brake dust or any of that carbon monoxide stuff in the cat into your lungs.

 

No prob... I know what it's like.
Yeah, the mask or a respirator is very necessary. Not only is it nasty stuff, but there's a lot of it... I wore a dust mask, then a bandana over that, and goggles. After maybe 60 miles of somewhat agressive driving without the cat it threw the CEL today. I hear sometimes people don't throw the CEL for a while, some get it sooner... Who knows. I'm just going to run the scan frequently and make sure there's nothing else going on.
I'm looking into high-flow cats and cat-back systems for later in the future. It doesn't sound bad as is, but could certainly sound better.
Again... Look into that SSV issue.
I'd check the cat 2nd. It's simple work, but on our 8yr old cars it's a little more grunt work than one would think to get those bolts loose...I'm sure that also depends on what climate you live in.
Let us know when you get somewhere.

 

Personally, I would recommend looking at the cat condition first as it is MUCH easier to get to than the SSV (just three header bolts vs removing thermostat, airpump, and battery)

Of course you can try to check ssv operation by hand and by looking at it while someone revs the engine as well.

Good Luck!

My money is on the cat, however

 

I wasnt suggesting he romove/clean the SSV. But to "inspect the operation" of the SSV and it's related components. This can all be done with a new white shirt on, without ever getting on the ground, or jacking up the car for that matter.
The cat just to visually inspect, you need to look inside it. This requires jacking up the car, and wrestling 3 seized up bolts while laying down under the car.

I'm not sure what I would put my money on, even though I had the same exact symptoms and it was the cat in my case...

The SSV opens up at 3250rpms when under a LOAD... So no you can't have someone just rev it up while you watch it...
However the fact that there is power loss up to 3k rpms, would make sense if the SSV was stuck open. This is because it's supposed to be CLOSED up to that point, then power comes back just after 3k rpms, which is the point at which the SSV is supposed to be OPEN....
Makes sense for the valve to be open right?

The cat is clearly a suspect, and probably should be checked. I'm merely mentioning what I would do first based on the fact that it makes more sense to be the SSV, and honestly easier to do a quick inspection.
The cat is harder, but simpler.
A failed cat can have various effects, although these very particular symptoms are uncommon for a failed cat.
A stuck open SSV, will have the exact same symptoms as he's experiencing.

I wouldn't suggest completely removing the SSV before checking the cat.

 

yes ... you are right ... personal fail ...

The valve should open once you get to 6k or so ... but I agree that a test by pushing it with your finger when the car is off is probably a better idea.

 

Groundhog day...

 

After a lot of studying and loads of scratches on my hands later, I managed to test the function of the SSV by hand and it moves very easily, nothing to signal a problem. Should I still do the vacuum check to it with a pump as well? There is so little room to work with that I am a little worried I might damage the vacuum hose, as I'll need pliers to get it off. Also getting it back in with a good seal might prove difficult.
It'd have to be stuck open for me, though, right? Moves freely so that cannot be the case, am I right?

I tried to check my cat once myself and ended almost stripping the bolts. I drive my car all summer, all winter so it experiences temperatures between -35 to +35 celcius. The bolts had become one with the flange.
I am calling a local garage today about checking it ASAP.

Thanks again for paying attention, guys!

 

The garage I called told me that it would be easy to see if the cat is okay by doing exhaust tests and seeing if the readings are correct. Is this right? I know that a truly failed cat will show with the carbon dioxide and other numbers thru the roof, but can our cat's be sort of "stuffed" without it showing in the "smog tests"?

 

The diaphragm inside the actuator might (possibly) be damaged. Meaning the SSV itself would move freely but air would just pass right through when the solenoid opened to activate it.

Running a new vacuum line is kind of a pain in the *** but easily doable in a days time. If you get the engine nice and hot the line should come off freely.

 

Not necessarily ... we have two cats, one before the o2, one after. If only the front one is fubared, the readings should still check out.

 

What he meant to say is we have two 02 sensors one before the cat one after. however the rear 02 just measures temps, the front is a wide band and measure A/F.

Unless you meant something else...

 

Sorry for the poor communication.

What the shop is most likely doing is old school emissions test for OBD1 vehicles.

That is testing emissions in the tailpipe using auxiliary equipment.

What I am saying is that the front cat can be completely shot and you can still pass the test due to the rear cat.

OP, have the shop do a visual inspection of the cat ... i.e. take it off and look at the honeycomb with a flashlight

also pics!

 

Do you mean the rear of the cat, or the resonator, or maybe even the mufflers?

If the front is plugged up then you most likely will pass due to the restricted airflow.

 

See picture:




I dunno how else to explain it

 

Someone has been playing too much draw something me guesses

 

Have you had any joy Kilpa? I was having the same problem between 3-5000rpm but dont wanna spend £££'s on a new cat! plus takin the original off is proving to be a right s**tbag!

 

Gotcha... I figured that's what you were talking about just wasn't sure.

 

Well, my logic told me that since my problem is below 3000 rpm and the ssv valve isn't STUCK OPEN, the problem must be with primary intake or catalyst. Only restriction within the primary intake would be the air filter so I vacuumed it to clean most of dirt. It isn't too old, but we have gotten a lot of dust on the roads recently as the roads were littered with sand during winter. I have to say that the situation is atleast 50% better!

It is clear that there still is some restriction, though. Thanks for clearing the cat issue stinksause! That was my understanding as well, but as the garage manager was telling me otherwise with great conviction and I hadn't taken a look of one myself, I folded. I will make sure some garage does the checking now.