Recently replaced both my head gaskets because one of them blew and the car was running like a champ and pulling like a raped ape. Lately it's been down on power-and I mean a lot of power. If I'm driving-no matter what the speed-and I put it to the boards, it downshifts only once and the rpm's climb really, really slowly. It acts like it's not getting enough fuel or air. Not throwing any codes, and no lights on the dash. Where should I start? Thanks

 

Sounds like a clogged cat (if its not stumbling).
Or fouled plugs (if it is stumbling).

 

That's the first thing I thought of but there is only one problem...I replaced my cat with a 3" cutout a year ago. And it's not stumbling either...

 

doh, thats very odd.. I guess a checklist is the next best thing here, a really long list of questions

But first could you throw your sig up with some car info? (Mods/a4/m6/stalled/gears etc)

-Has the fuel filter been changed lately?
-Pull a plug an check to see if its lean/rich/other
-Throw a scanner on and check:
-Voltage
-Throttle TPS voltage is reading correctly
-MAF
-Temps OK?
-Do the headers start to glow?
-Hows it do on hills?

 

It won't let me put in a signature (I get an error that says something about the admin must add it to the whitelist???) but here is my car and mods:

1994 Polo Green Z28 A4: T-Tops, Vortech Intake Elbow, FIPK 57 Series Intake, Meziere EWP, 3" Cutout, !CAT, AC Delete.

Haven't checked the fuel filter and I know it hasn't been changed for a while. I'll check plugs and scan tomorrow if possible. Temps are fine. Manifolds are fine. Don't really have any hills to speak of so I can't tell you anything there. But I notice whenever it shifts up it bogs a bit (I can tell easily because of the cutout).

 

I had a similar situation in the past with a 97 Z.It wasnt this severe but I checked and cleaned my air filter which was extremely dirty and it seemed to have helped alot. Something else to look at is the bellow going to intake.Since you just had the gaskets replaced and these parts were taken off something could have gotten in the hose and is causing the restriction.

 

Yeah, I'll have to check everything from the filter to the throttle body. But could something as simple as that cause such a decrease in performance? It doesn't seem sensible...

 

Perhaps a plastic bag got sucked up and is caught on the air filter I've had some darn clogged filters in the past, but nothing bringing the car to its knees so to speak. Ensure that the elbow is on right too (and isn't torn). Once you rule out breathing, id check for fuel pressure asap.

 

Well, the K&N intake along with the elbow makes for a tight fit. The elbow is aluminum so I'd have had to try pretty hard to tear it but the elbow is aligned slightly to the left of the throttle body intake, just maybe a 1/4" tops but there are no leaks. It's hard to explain but the elbow isn't matched perfectly to the throttle body. That wouldn't have anything to do with it...

 

I dont think the elbow being over just a little would affect it.Im in agreement with the previous message.Fuel pressure would be my next step by checking that fuel filter. Here is something else to think about. You said earlier that you have a new cat.Just because something is new doesnt mean it works right.Anything mechanical can be defective. All this to say before I started ripping the motor apart, I would double check this.

 

They key is, was it progressive or did this suddenly just start being a dog?

 

My elbow had a massive crack in the air silencer for a long time before I noticed it. And it still ran pretty damn good. (Didnt idle too well but it still had power) I dont think the air elbow would have this much of a diff.

 

I replaced my cat with a cutout, not a new cat... I think that's what I said. But yeah, I'm gonna check the fuel filter and fuel pressure and plugs tomorrow.

 

After I replaced the head gaskets, it ran better than it ever did. I can't say for 100% but I'd say that it wasn't just all of a sudden. Once it started getting really cold outside it started acting up.

 

Here's something else that might tie in with this problem. I didn't think that it had anything to do with my car running like a dog but after all these posts about fuel and air problems it makes me wonder. It's a real dog to start too. It sounds like the starter, but sometimes it will almost start, like a few pistons fire but then nothing. Kinda ties in with not enough fuel pressure or not enough air. Could the source of hard starting and it running like crap be the same thing?