Cascade Crew

kurfbird · Posted: Tue Jul 17, 2007 10:14 am Post subject: Firebird 92 3.1 Engine Problem

Okay this is hard to describe but I will do my best. My 3.1 normallly has a higher exhuast noise upper range just like a 6 cyl. Just recently it now sounds like a v8. Lower and a puffing noise coming out of the exhaust. A slight miss.

It actually sounds like a 305 or a 350 and some lifter noise. I pulled the plugs last night and they are clean and burning normally and replaced them slightly worn.

Check timing was 6 degrees book calls for 10 I am going to adjust tonight.

I am going to check fuel pump pressure for normaly operation. and see if any bleed down.

New or new with in the last year.

Spark plugs
wires
cap Rotor
Ignition Module
Ignition Coil
New Timing chain and two new injectors (the injectors and chain were bad)
New Cat and muffler.

Here is what I am thinking it might be.

1. Bad Cam
2. Bad lifters
3. Burnt Valves

IS they anything else that I need to look at.

And am i on the right track.

Also I can pick up a 3.1 for 200.00 would that be the way to go instead of puylling this one apart.

blue89 · Posted: Tue Jul 17, 2007 11:00 am Post subject:

Could be a clogged cat or exhaust. If you pull the o2 sensor does it blast air out? You can also take it to an exhaust shop for a free cat check.

Sellmanb · Member Joined: 30 Nov 2004 Posts: 727 Location: Tigard, OR

So it runs OK at low RPMs then? Does it seem to be lacking more power than usual at higher RPMs?

Or is this just by ear it sounds like something's off, just doesnt feel like it?

Does it throw a code?

kurfbird · Posted: Tue Jul 17, 2007 11:55 am Post subject: Cats and Muffler

Both the cat and muffler are new replaced last year less than 16,00o miles.

O2 was replaced last year. But I will pull it out and check. Does not seem to be lacking power just seems to have a low rumble. ANd puffs and a slight miss.

Its like you drive your car then noticed that it sounds different. ALso has valve / lifter noise.

91RSVert · Posted: Tue Jul 17, 2007 12:09 pm Post subject:

If you suspect valve problems, it should show up in a compression check. As well as a vac guage test.

kurfbird · Posted: Tue Jul 17, 2007 12:15 pm Post subject: That something I can test

I can easly do a vaccum check today prior to doing the timing.

No codes

kurfbird · Posted: Tue Jul 17, 2007 5:19 pm Post subject: okay the results

I did a compresson test so survey says.

Okay here is the compresson test

1 75 Sad

2. 145
3. 150
4. 140
5. 150
6. 145

SO I guess number 1 is my culprit. I squirted oil with no improvement.

Tested fuel pressure held for over 5 minutes
tested timing adjusted to spec.
Vaccum showed no sticker valve. Go figure

Now what to do I can get a 3.1 engine for 200.00 and just remove and replace my old one. Give me some insight. It can be a bad valves. Bad rings Bad lifters or Bad cam. Question is what is the easest and cheapest way to go.

Giv em some insight

Sellmanb · Member Joined: 30 Nov 2004 Posts: 727 Location: Tigard, OR

Bad valves, rings, hole through the piston and gasket are the only real possiblities.

I seriously doubt if it's the head gasket (it normally affects another cylinder as well, but not unheard of...), if it were rings the compression would have changed w/ oil in the cylinder, so really you're looking at either a hole right through the piston or a chipped valve. More than likely, a chipped valve.

For 200 dollars, if it's a long block and all you have to do is swap your intake on, I'd do that. You'll save yourself money just in gaskets and having the heads machined, as well as time.

kurfbird · Posted: Tue Jul 17, 2007 6:38 pm Post subject: Thaanks

this is 1 3.1 so it already has intake (everything) I just need to drop it right in. Has injectors everything.

Thanks that what I was thinking

91RSVert · Posted: Wed Jul 18, 2007 3:55 am Post subject:

Could go with a RWD 3.4 as well, but its more work. 20hp and 15tq?

kurfbird · Posted: Wed Jul 18, 2007 6:44 am Post subject: staying with the 3.1

I am staying with the 3.1 need it as my daily driver

91RSVert · Posted: Wed Jul 18, 2007 6:53 am Post subject:

3.4 is a commen replacement for 2.8/3.1. All you have to do is swap oil pan, timing cover/accessorys, and intake. The block n heads are direct replacement and bolt right up. I had a 3.4 in my car for over 2 years tell it blew camshaft.

2.8 is a 2.8
3.1 is stroked 2.8
3.4 is bored n stroked 2.8

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2328

91RSVert · Posted: Wed Jul 18, 2007 6:59 am Post subject:

kurfbird · Posted: Wed Jul 18, 2007 7:14 am Post subject: Valves etc

Valves vaccum was normal with in spec range.

I am going to apply air to the poston tonight. 1 TDC and see what happens. Will keep you up dated.

blue89 · Posted: Wed Jul 18, 2007 8:56 am Post subject:

Did you happen to check compression? If you have good manifold vacuum then the cam/lifters should be good right?

91RSVert · Posted: Wed Jul 18, 2007 9:06 am Post subject:

blue89 · Posted: Wed Jul 18, 2007 9:17 am Post subject:

Said he checked vacuum and then was going to blow air into the chambers? I'm confused

:confusion cleared. i think work boredom is spreading to lack of brain activity....

kurfbird · Posted: Wed Jul 18, 2007 9:34 am Post subject: Apply air

Going to TDC number 1 that the bad cyl. Apply air with my air compressor and see where the its leaking from. Intake exhuast or crankcase.

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