Hey guys!

A couple of weeks ago my Blazer started having difficulty starting, so I did a tune up and took care of that. Now, a new problem has developed, the engine is much quieter than it used to be and I have absolutely no power over 3000 RPMs. I checked my tune-up to make sure I didn't mess something up and that all looks fine. I have almost 150K miles and have never changed the timing belt. I have all the power in the world at about 2750 RPMs, but when I get on the highway it is almost impossible to get from 85 to 90 because the kick down puts it right at 3500 RPMs.
A quick side note, I'm not ruling out the fact that it might be because my catalytic converter has been cracked in half for the last six months... but no emissions codes.
I'm also not ruling out vacuum leaks but have no idea why because last yr I replaced every gasket from the intake manifold up.
I really need this car to run because it takes me to college. I idle for about six to eight hours a week, this problem got really bad two weeks ago when I had to go schedule my classes, I was going to a movie with my friend afterwards. My friend stayed in the car while I went to see my counselor, so the car was running from 11:00 AM to 2:00 PM with most of it at idle.
Any ideas? It is probably something obvious, I can't help but neglect some of the stuff under the hood because I forget about all the little subsystems (just replaced the original PCV yesterday)
One more thing, there is a little soot that appears to be creeping up the inside of the throttle body from around the butterfly which I can't understand because this is a multiport EFI.

Thanks,

Thomas

Update: Just read that is has a chain regardless, should I change it?

 

Your timing chain would cause give you problems throughout the RPM range. You should still change it since it has had the original one for all those miles. Did you do a cap and rotor as well when you did the tune up? Before you look into the timing chain, Have you checked the condition of your distributor? If you idle so often, it could be that the PCM has adjusted to those sort of driving conditions, so when you lay into it, you feel that loss of power. Have you just tried driving around on the freeway for an hour or two and see if that affects the condition?

 

The reason for the soot is intake valves open before the piston reaches TDC so some of the burnt mixture comes back up into the intake. In the days of carbs, then TBI, the gas would wash the soot out of the intake. Now we have a giant air valve on top of the motor and no gas. (that's my theory anyhow...) As for your RPM restriction, the air filter is in good shape? I wonder what you mean about the converter being cracked in half, but if that's restricted/plugged it'll have the same effect.

 

During the tune up, I did a cap and button, then I looked at a plug to check for oil and all went well. It performs noticeably better if it warm it up, then turn it off and let it cool about half way back down then start it up again. I was quite a bit rougher on the spark wires than I wanted to be... But last time I had a problem in the ignition it was more than apparent by the violent vibration.

I did pull out the distributor a while ago when I changed all the gaskets, but there was no problem for six months so I assume I put it back in correctly.

What I meant about the catalytic converter being cracked in half is that the media inside is cracked, I have not taken it out to find any further information about that. It has been a while since I have changed the air filter (about 6-7K miles) so I'll definitely take a look at that.

Thanks for the quick replies.

Regards,

Thomas

 

Have you checked the fuel pressure?

Blazeme

 

Replace the cat. It's gotten clogged from the broken media and is causing the upper rpm power loss.

You do realize that you're not doing your engine any favors by the extended idling, right?

 

i would take the cat off or replace it. normally if the timing chain is stretched really bad you will hear it rattling. probably would be a good idea to change it though.

 

Fuel pressure was almost 60 PSI at idle and only fell to like 50 when I revved it up.
Air filter was dirty so I replaced it.
Tore off the intake today to look at the MAF, read a story on the net about someone with a similar problem having a bad MAF, it was pretty dirty and there was a bug stuck to it (absolutely no idea why, I buy the best filters I can afford) but everything looked intact. (F'ed up one of the pins a tiny bit but it still connects and doesn't throw a CEL)
Put it back together and test drove -> things were a whole lot worse, and now I think the cat is making a weird sound around 4K RPMs. Tops out at 60 MPH going up a hill and 40 up a steep hill.
Then my dad took of the distributor cap and my brand new Napa Premium cap already was carboned up! But the button looked okay. There was also a couple of degrees of slop in the distributor. Would a new distributor help? I don't know what my dad did to it, but it's a tiny bit better now. But still worse than when I began... I'll be driving my dad's cavalier to school tomorrow.
I am going to look at replacing the cat, I think I'll test by just ripping it out and welding a pipe in. I really need this thing to work because on my early days I'll need to borrow my mom's Silverado, and you all know if momma ain't happy, ain't nobody happy!

A quick side note, I had a ton of fun today because I removed the grille and the front bumper to re-paint parts of the core support! I wanted to keep tearing into it, but the sun was going down.

 

you might want to throw a timing light on it and see what its doing. if the timing is jumping around you'll see it with the light. i would take the cat off and put a piece of pipe in its place and see if that helps. the fuel pressure looks pretty good though. does it "diesel" when you turn it off after its warm?

 

Why do you let your truck idle pointlessly like that..you realize the letting it idle like that will significantly reduce engine life/part life?