Engine mis-fire/ shutter / skip

[19svx94]

i have solved my problem and i do feel stupid, my air filter had become soaked due to the massive puddles that i was driving through the other day and my intake sucked the filter up causing the mas air to read wrong, i also took my intake manifold off and cleaned my bypass air control solenoid valve, this fixed the idle problem, the only bad thing that happened was while i was in the process of redoing all of my vacuum lines because they were all brittle i broke the infamous black solenoind that is on the passenger side, i had one on my parts car and while i was trying to take the "plastic" vaccum hose off of that i broke that one to, so until i have time to go to subaru and get another one i have just bypassed the solenoid.

[Dessertrunner]

Do the US cars have EGR value and does anyone have experiance with them causing problem with the running of the engine.
Tony

[svxcuseme]

Yes, we have an EGR valve. No problems with mine. sorry

[svxcuseme]

Well I replaced the coil boots with new ones from another set of spark plug wires... they are a little longer, much tighter, and seal much better. No luck.

My problem is getting worse. Now it's missing like crazy once the car gets warmed up. When the car is cold no noticeable miss. At this point I'm leaning back towards a bad coil.

My wife had this issue on her car. Car ran fine until warmed up and then started shuttering like crazy. Turned out to be the primary coil. Anyone want to weigh in on this. I think I'll pull all the coils from the spare car and replace the 3 on the PS, drive it to see if it was one of those, then replace the 3 on the DS if necessary.

Would you guys agree that the symptoms are pointing to a bad coil?

[Trevor]

Originally Posted by svxcuseme

Well I replaced the coil boots with new ones from another set of spark plug wires... they are a little longer, much tighter, and seal much better. No luck.

My problem is getting worse. Now it's missing like crazy once the car gets warmed up. When the car is cold no noticeable miss. At this point I'm leaning back towards a bad coil.

My wife had this issue on her car. Car ran fine until warmed up and then started shuttering like crazy. Turned out to be the primary coil. Anyone want to weigh in on this. I think I'll pull all the coils from the spare car and replace the 3 on the PS, drive it to see if it was one of those, then replace the 3 on the DS if necessary.

Would you guys agree that the symptoms are pointing to a bad coil?

Yes, heat often shows up faults within fine wire components.

[svxcuseme]

Well. After all this it turns out I had a couple issues. First, spark leak. More importantly, I had at least two coils slowly going bad. I replaced all 3 on the PS and sure enough, runs like a top. Originally I had only replaced one coil at a time, replacing the old one, then putting it back in when the replaced one had no noticeable effect. Great idea for diagnosing one bad coil. Not so great when it's more then one. Hindsight!

So the, "Big SVX Mystery", as Ricochet likes to say is no longer a mystery. It's a coil slowly going out.

I'll replace all coils with new ones then move on to the next SVX issue. Wait a minute! I've fixed everything now! Whew hew! (knock on wood).

Thanks for all the suggestions and responses. I've been trying to resolve this issue since got the car in August last year. Success!!!!!!!

[Ricochet]

$80 times 6 is a lot of money though
Is there any way to test a coil pack for this problem?

[Trevor]

Originally Posted by Ricochet

$80 times 6 is a lot of money though
Is there any way to test a coil pack for this problem?

It is very difficult to test the coils out of the car as there is a diode in circuit which prevents proper continuity testing. What is more your problem involves heat and you would have to heat up the coil while testing. It can be done, but there are complications.

(Edit P.S. If you have a multi meter capable of measuring down to 0.25 mA and know how to use it, I can tell you how to make tests which would be worthwhile.)

Purchase one new coil and make substitution tests one by one, making sure the engine gets fully up to temperature and you have the conditions when the problem was obvious.

N.B. That said refer to the previous post, as with more than one coil faulty this method is not fool proof. However this is still your best bet.

[Beav]

I agree that it sucks. Are the spark boots available separately from the coils? For the past few months I've been the only Isuzu OE tech for several hundred miles in any direction. I've been po'd to find that they don't make the boots available without the coils. I guess that in their defense they aren't the only OE that operates that way but it still isn't right. A coil that any OE pays less than a buck for with a boot that they pay less than 10 cents for selling for $80-$130 ea. just isn't right.

p.s. coils rarely go bad, secondary problems are almost always bad plugs or leakage.

[svxcuseme]

I stripped the boots off a set of standard spark plug wires. You know, the boots that are 3-4 inches log. Cut them down, then fitted them over the coil. Works great. The rubber insulation is thicker, hole diameter smaller, and you can cut them to a length more suitable.

Right, coils rarely go bad but they do. And sometimes in pairs.

Ricochet, you could start by replacing just the boot to see if it is a spark leak issue. Here's what mine look like with the standard spark plug boot cut down some. I grabbed these off a junkyard car, but you could buy a cheapo new set of wires and just use the boot.

[Beav]

I forgot that the SVX has extremely short boots, most COP applications have 3"+ boots.

Always, always, always use silicone grease when installing the coils back onto the plugs, to do otherwise is asking for problems.

Also, never remove platinum or iridium pugs for the heck of it. Numerous OEMs have issued TSBs regarding this issue. The threads are specially coated and are 'one-trick-ponies'. Trust me, it sucks on most engines to remove a spark plug and have the threads come out of the head. To have it happen on a horizontal engine is really inconvenient. Besides, the platinum or iridium tip coatings are so thin that merely adjusting the gap would scrape enough off to render them to no better than a 69cent spark plug.

[Trevor]

[QUOTE=Beav

Also, never remove platinum or iridium pugs for the heck of it.[/QUOTE]

Beav I have always thought along these lines. It wound be worthwhile if you expanded on this subject for the good of all, with some "ONLY when to remove and why."

Thanks, Trevor.

[svx_commuter]

Originally Posted by Trevor

(Edit P.S. If you have a multi meter capable of measuring down to 0.25 mA and know how to use it, I can tell you how to make tests which would be worthwhile.)

I am up for this Trevor so let me know how to do it.

My car has developed this problem in the past two weeks and is getting worse and is heat affected and is bad at low rpm's under load as in going up hills. I have 5 extra coils and I would like to know how to check them before I start to swap them. I really can't afford to buy new ones. So any help would be great.

Take care too,
John

[Beav]

More and more OEMs are realizing a problem and issuing TSBs regarding stripped sprak plug threads. Many are now stating that if the threads are stripped a new cyinder head should be installed vs. repairing with inserts - e.g. Heli-coil, et al.

Before the conspiracy theorists jump on this realize that these same OEMs are paying warranty time and parts when it occurs during coverage. CAVEAT: only remove plugs when the engine is cold. Stripped threads generally only occur when plugs are removed hot or when cross-threaded.

Also, I cannot emphasize enough to use silicone grease. Most coil replacements are made when only a spark leak has developed. Check plugs and boots closely. Small black trails on plugs that could be confused as rubber boot deposits are actually carbon trails and could have been avoided by using a bit of silicone grease with the last install. Dark black, powdery marks on the boots or coils indicate a spark leak, as does light gray spots on the boots.

[svx_commuter]

Hi Beav,

Are you saying to put the silicone grease on the inside and outside of the rubber boot? If I pull off all the coils and clean off the boots and apply silicone will it correct the voltage leaking problem or has damage already been done to the boot? I am going to pull mine and take a closer look.

The other thing I have been wondering about is water spray. I have seen a tech use a misting spray bottle to find a coil pack leak on top of the 2.2L engine. He just sprayed a little mist on the pack and the glow showed up, cracked pack. Do you know if that will work on the SVX coils? Should work as long as distilled water is not used, right?

Thanks and take care too,
John