shaking again

[mrcoffee]

Gentlepeople,

(Car type: '94 S-10 Blazer, V6, 92000 miles)

About six months ago, the engine on my Blazer began shaking very noticably. The whole car would rock when I was at idle or at low acceleration. I took it in and got a lot of additional work done on it (got a new fuel injector, but that was to solve a hard-start issue), but the guy at the mechanic said that I had a cracked "upper plenum gasket" and that was causing the problems (cost me about $15). Well, he did his magic and the car worked fine.

Now it's today, and my car is exhibiting the same shaky behavior. The mechanic previously said that I had 6 of these gaskets, so do you all think it's possible that I have another cracked gasket? If so, would you know if that's a simple thing for me to check for and to fix? I'm so tired of pouring money into this car every single month, so if I can fix this myself, that would be AWESOME).

You guys rock. Thanks for your help.
Tucker

[dmbrisket 51]

well lets start with, when was the last time a full tuneup was done? cap wires plugs roter pcv valve etc etc, and which v 6 the 2.8 or 4.3?

[mrcoffee]

Originally Posted by dmbrisket 51

well lets start with, when was the last time a full tuneup was done? cap wires plugs roter pcv valve etc etc, and which v 6 the 2.8 or 4.3?

Can't say for sure as to when the last tune up was...I believe it was the summer of '03, so a little under 2 years ago. And it's a 4.3 L. Sorry for the omission.

[BlazerLT]

Originally Posted by mrcoffee

Can't say for sure as to when the last tune up was...I believe it was the summer of '03, so a little under 2 years ago. And it's a 4.3 L. Sorry for the omission.

What was done during the tuneup?

What was replaced?

[mrcoffee]

Originally Posted by BlazerLT

What was done during the tuneup?

What was replaced?

To be honest, it was so long ago that I can't remember. I don't think any belts or spark plugs were changed; I think it was more of flushing/changing fluids, filters, etc...nothing too hardware intensive. I know that doesn't help much.

However, I have noticed that the engine begins feeling "unbalanced" after it's gotten hot (i.e. not when it's cold). Hopefully that helps.

[BlazerLT]

Welp, you need to do the usual tuneup stuff.

Cap & Rotor
Plugs (AC Delco only)
Air Filter
Fuel filter
PCV valve

Also, you should remove the vortec name plate on the top of the engine and remove the round IMTV valve underneath it and check for your CPI injector leaking.

[mrcoffee]

Originally Posted by BlazerLT

Welp, you need to do the usual tuneup stuff.

Cap & Rotor
Plugs (AC Delco only)
Air Filter
Fuel filter
PCV valve

I took my car to a mechanic and had him check it out and give it a tune up. He checked it out and said that everything (plugs, wires, cables, etc.) looked good...a little old, but in good condition.

But I've noticed, at least when I'm idling, that the car tends to have moments of shivers (i.e. sudden vibrations that also cause my display to dim momentarily). So I thought this might be an electrical problem. Sure enough, my battery died yesterday (this after driving it for about 10 minutes, turning off the engine to run inside for a minute, and then coming back to find that nothing would start). I got a jump, but after a minute while I let my car idle to charge the battery, the engine shut off. I don't think it's my idle level, because I just got a new IAC about 6 months ago.

I took my battery in to have it tested, and it passed with flying colors. So I'm thinking I may have an alternator problem. What do you guys think? Do you think that a bad alternator would play a part in causing my "vibrational problems"?

Thanks!

[BlazerLT]

Charge the battery outside of the vehicle.

Test the charging system with a voltmeter.

[mrcoffee]

Before I go out to buy a voltmeter and a battery charger, please tell me if this adresses what you are thinking: since I had the battery tested this morning and then placed it back in my car, it has started fine. I sat in the car, revved the engine, and she didn't die on me (though I'm afraid to take it on the road).

The guage on the dash reads that the battery is at 14 volts, which would indicate to me that maybe there's not a charging problem (it reads this way even when the car shivers and the dash lights dim). So do you still think the charging system may have a problem?

[BlazerLT]

Just get a voltmeter and test the coltage with the engine off and with the engine running.

[mrcoffee]

I did the voltmeter test: the battery read 12.7 volts with the engine off, 14.4 with the engine on (I also got the same reading after I turned on the headlights, A/C, radio, etc.). The alternator also read 14.4 V. I think that sounds normal. I did notice that, when the car "shivered" the battery readout would drop about 0.5 V and then return to 14.4, but I don't know if that's significant.

Any ideas?

Thanks!

[BlazerLT]

You didn't notice having the defrost on when this happened did ya?

[rlith]

Silly question, but have you looked at the motor mounts?

[mrcoffee]

I had a friend of mine who's a mechanic take a quick look at it and he says my engine is definitely mis-firing, but doesn't think there's anything wrong with the battery, alternator, or cables. He did take one of my spark plugs out and showed me that it was a bit gunked up and corroded, so he thinks this may be part of the problem. He also thinks that I need to take a look at my distributor cap.

So, do you all think this sounds reasonable? Thanks.

[BlazerLT]

Yip, I would invest your money into a full tuneup including:

Cap & Rotor
AC Delco Plugs
PCV Valve
Plug Wires
Air Filter
Fuel Filter

Also, check your fuel pressure, you might have a leaky injector if your truck is a Vin W CPI Vortec.