This car was cheap, but used to run great. I noticed it missing when cold, but acceleration would get it running smooth. Now it runs ruff all the time. I replaced the plugs to no avail. I found a vacume leak that seemed to have been rigged before. The hose collapses (probably because it is just a heater hose) and causes variations in idle when disconected or pinched, but doesn't seem to smooth out the engine any.
A friend said it might be the coil-pac. Auto Zone said it might be an injector. I thought it was the plug wires, but allas, it doesn't have any. If someone could help me with this car, we can then get my 96 Chevy pick-up running better... what fun these polution free computerized vehicles are.

 

There are many possibilities, but lets start with the basics:

Have you replaced your fuel filter?

EGR valve maybe clogged or defective.

Have you checked your timing?

 

Thanks Mark,

The way the engine is running is as if a cylinder is not firing. It kinda sounds like a lawnmower. It doesn't backfire or frontfire and it doesn't seem to want more fuel (hesitation or stalling). The check engine light is not on. Can you actually check the EGR valve somehow and where is it? What do you think about the coil-pac possibility?

Bart

 

If it were a coil pack, I would think it would throw a misfire check engine code.

When was the last time the fuel filter was changed? You never answered me.

 

Thanks again Mark,

As far as I know, the fuel filter is original or 225,000 miles old. I'll replace the fuel filter and get back to you or this sight. I sure appreciate the input.

It may be a while, as the car is only needed once or twice a month when I leave my Kenworth at the shop... 45 miles from home.

Bart

 

2.5 "U" ..........or 2.3 Quad4??????............The Quad 4's are noted for coil tower issues.........Just wondering........At 200,000 + have you run a compression test????

 

I replaced the Fuel filter. No Change. I removed the new plugs for inspection and found #3 real wet, so I replaced the boots for the plugs. No Change.

Is a coil tower the same as a coil pack? #3 was obviously not poppin'. No compression test has been done as I do not have a compression tester in my back yard (ha,ha... back yard mechanic as I am).

What should I do next?

 

Based on what you have said since post #1, you really need to see if you get spark at that cylinder and if you have good enough compression to fall within at least 20% of the other 3. If you don't have an extra plug, swap with another cylinder and recheck the wetness of each plug, to see if that bad cylinder is also wet on the 'new' plug.

 

If it's a 2.5 "U" the coil packs will be bolted to the ign module on the back side of the engine............If"n it's a 2.3 "Quad 4".........to access ignition components, you'd have to remove 4 bolts from the top cover. Unplug the module and invert the top cover to expose the plugs coils module and plug boots...........The large plastic piece that encompasses the coils is the coil tower..............Whatcha got?????

 

It's a quad 4. I was wondering how to check for spark? So I turn the tower over and crank it over... is that what your sayin'?

 

Do you have a spark plug wire you can pull off the tip of the sparkplug?

 

You'd have to use a set of wires to test for spark getting to the plugs .......If it's a Quad 4 I'd almost bet the farm the coil tower is bad.........Acts like a bad distributer cap sending spark to the wrong place and not the plug that needs it
I believe you can rent/borrow a compression tester from AutoZone.........and I would do that just to put my mind at ease .........Q4's are 16 valve engines
so anything IS possible.........but I'd be betting on the coil tower

 

Before I leave to get that compression tester, I wonder if this tower vs pack thing is one in the same? Mounted on the underside of the Quad 4 cover (plastic peice that holds the plug boots with the four bolts holding it down) is a black box. That black box has a reqular type elec conection with about 8 regular color coded wires. Is that box the coil pac mounted on the coil tower?

 

I think you're looking at the ignition module............If you were to unbolt the coil tower from the cover..........you'd see 2 coil packs neatly tucked away inside

 

I have the new coil pack/ 2 coils in my hand. Auto Zone tested the ignition modual for me and yes that is what I thought was a coil pack. We will soon see if these 2 coils fix my problem. I will let you know shortly.

 

........And that is NOT the problem. No Change except for the $70 missing from my wallet. I'm still stuck... what will a compression test show me? (Auto Zone didn't have one available)

What should I do next? (BTW Ecman51, the 'new' plug was wet too)

 

Hold on a sec...........Did you replace the COIL TOWER???........The big plastic piece the coils fit in???..........or the coils themselve?????......One cyl misfire is probably NOT a coil prob as when a coil fails you generally lose TWO cyls..........The TOWER can give you a ONE cyl miss.....

 

[QUOTE=Barton2562;1215998(BTW Ecman51, the 'new' plug was wet too)[/QUOTE]

So now we know we have dead cylinder (as opposed to a bad plug). Either insufficient spark, or the compression is bad.

When you get a compression gauge, make sure you get the complete kit where you get the fitting at the end that fits your plug size. Mine has a screw on/off adapter for fitting a couple plug sizes.

 

To ECman51;

I did a compression test as you suggested. I'm calling cyc #1 at the passenger side. #1=205 lbs/sqin, #2=195, #3 (the wet one)=185 and #4=185. I'm just guessing, but that all sounds good enough to me.

So...

To wrench47;

Yes, I did just replace the coil packs in the white tower part. Should I go get the tower too. I might as well make it all new, huh. Or is there a way to test it? I'm going out there to take it apart... hope you or somebody is around for suggestions before I get ansy and go buy one.

 

Thanks to everyone for the help, but expecially wrench47. It was the TOWER itself. I would have never thought that all by myself. Thanks guys!

 

Hope Wrench comes by to see your accolades.

Regarding the compression readings: Wow are THEY up there. No wonder why Pontiacs are fast cars.