Valve job or misdiagnosis?

[serotta50]

Here is my dilemna, 95 legacy lsi wgn, 186k, running great until 1 wk ago. Check engine light comes on solid. Take to reputable independent Subaru shop. Here is what they come up with: pulled codes, p0303 & p0304 misfouire, determined bad ignition coil for cylinder 3&4, replaced coil pack. I pick up the car, drive it 20 minutes and check engine light comes on again, this time flashing then solid.

Take back to shop, they determine, possible valve sticking in cyl 3 & 4...would require engine disassembly for further diagnosis. The shop said if I keep driving it I could end up damaging the catalytic converter, which means more $$$$.

 

ANy suggestions appreciated. I have no idea of what this might cost and if it is worth it for year car and mileage. btw, the car is running fine, except the check engine light still on. I want to keep the car, but if fixing is cost prohibitive, then I'll have to get another.

 

Thanks for any input.

[frag]

My unexpert opinion is you should keep away from this «reputable» shop.

1) They diagnosed a bad coil which turned out was not the problem.

2) You dont need to disassemble an engine to diagnose a sticking or burnt valve.

3) It seems very unlikely that valves would start sticking or failing in two opposed cylinders at exactly the same time.

My .02$

[porcupine73]

Sometimes but not always ngk spark plugs with oem plug wires takes care of this issue. Soobs can be picky about these items, esp around that era.

[stevetone]

...I want to keep the car, but if fixing is cost prohibitive, then I'll have to get another...

s50, Just my two cents,

 

Let's say it costs $1,000 to fix (probably not, but humor me). I figure if you don't fix it, you could probably sell it for a grand, maybe $1,500. My '95 Lsi wagon is worth about $2,500-$3,000, with fewer miles and a recent timing belt project.

 

So, where can you find a replacement car for $2,500 (the $1,000 you would have spent plus the $1,500 sales proceeds)? Let's say it costs you another $2,000 over the course of a year (unlikely). Where can you find a car for $4,500 that you can trust AND does not have the potential to cost you the same amount (or more) in maintenance?

 

If you don't like the car, get another. But the cheapest car to own is almost always the one you're currently driving. And don't knock it for periodic maintenance--they all need it.

 

Steve

[porcupine73]

Sometimes they get so carboned up the valves can't close completely.

[nipper]

You dont need to dissassemble the engine to diagnose bad valves.

 

Too many people have never been taught, or have forgotten or rely too much on computers.

 

Get yourself a cheap vacuum gauge. This will tell you the health of the engine, along with a compression test.

 

 

http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm

 

nipper

[OB99W]

[...]pulled codes, p0303 & p0304 misfouire, determined bad ignition coil for cylinder 3&4, replaced coil pack.[...]

When misfire in cylinders #3 and #4 suddenly develops simultaneously, its cause is likely to be ignition-related. However, the coil for those two cylinders isn't the only thing they have in common. The ignition system is a "wasted spark" type, which effectively puts plugs and wires for opposing cylinders in series. That means that when # 3 is firing, the spark current still has to travel through #4's plug and wire, and vice-versa. Therefore, an increase in wire or plug resistance at either #3 or #4 can affect the firing of both cylinders.

 

When were the plugs or ignition wires last replaced? If either wasn't done recently, consider replacing one or both. As porcupine73 mentioned, NGK plugs and OEM (Subaru) ignition wires are good choices. (In fact, even if the wires were changed recently, but OEM ones weren't used, they may still be the cause of the problem.) If you'll be doing the work yourself, I'd suggest starting with the wires, since they're relatively easy to replace.

[serotta50]

thanks for all the info guys. Only piece I forgot to mention was that the mechanic did put ngk plugs in and test drove, light still on. I'm wondering if maybe I put oem wires on, will that make a difference.

 

Anyone's opinion, is this car ok to drive around with cel on like this?

[OB99W]

[...]the mechanic did put ngk plugs in and test drove, light still on. I'm wondering if maybe I put oem wires on, will that make a difference.

Given that the coil and plugs were already replaced (and assuming that the coil pack was new, or used but known to be good), it would probably be prudent to consider replacing the wires, especially if they haven't been changed in many thousands of miles.

 

Another possibility is a failing igniter (or even the ECU ), but that's much less common than the ignition wires.

 

 

Anyone's opinion, is this car ok to drive around with cel on like this?

I wouldn't drive it any more than necessary -- the shop you took it to may not have the best diagnostician, but they're right that enough misfiring could put the catalytic converter at risk.

[biglittledog]

Try replacing the wires with OEM Subie ones. A little dollop of dielectric grease while installing too! We've had the misfire CEL light on two different cars that were both fixed with new wire sets. They seem to be picky cars and don't like aftermarket sets. High powered ignition system.

It sounds like the shop replaced the coil pack and plugs but not what's in between...not so smart.

Good Luck!

[nipper]

Try replacing the wires with OEM Subie ones. A little dollop of dielectric grease while installing too! We've had the misfire CEL light on two different cars that were both fixed with new wire sets. They seem to be picky cars and don't like aftermarket sets. High powered ignition system.

It sounds like the shop replaced the coil pack and plugs but not what's in between...not so smart.

Good Luck!

 

Either picky or spoiled, but always use OE wires with sooby.

 

nipper

[serotta50]

Well, Nipper was right, put on oem wires, disconnect battery to put out the cel light. I've driven my baby over 100 miles and, NO CEL!

 

Nipper just saved me a great deal of $$$. I was about the go to another garage for a valve job.

THANKS GUYS!

[serotta50]

Well, I spoke too soon, stinkin cel light comes on yesterday AGAIN! I thought the new wires were the culprit. I'm tired of messing with it, will probably sell and buy old pickup truck.

[nipper]

Buy a 20.00 vacum gauge first and see what it does.

 

Also check the engines grounds.

 

What this DOES tell me is that its probabaly not valves. Get the vac gauge just to be sure.

 

nipper

[stevetone]

Well, I spoke too soon, stinkin cel light comes on yesterday AGAIN! I thought the new wires were the culprit. I'm tired of messing with it, will probably sell and buy old pickup truck.

 

Geez, 3 weeks of an issue and out the door...Good luck with an old pickup truck.