Shaky Idle....Whats going on?

[fldcar]

Hi everyone,

I'm having a problem with my 92 Svx, it has 91,000 miles. Get ready this is a long one.........

The car runs decent, and I stress decent, not good, when its cold but as it warms up and the idle settles it starts to idle extremely rough (enough to shake the car violently) and it sounds like it is missing (the car has an exhaust leak and you can hear it missing) also at the muffler tips instead of the normal SVX deep growl i'm hearing a more popping/huffing sound, like its not running on all 6 cylinders.

When you switch on the A/C the idle goes way down (like to 300 rpm) and just fluctuates up and down really rapidly as if someone is inside the car gassing it and letting off and gassing it and letting off over and over again quite quickly. Sometimes it will even stall.

When you rev it up (A/C off) it kinda of stumbles up and even if your holding the throttle steady at say 3 thousand rpm it still idles badly as if someone is gassing it and letting off continuously even though you are holding the pedal steady.

When you rev it up and hold it at the 4-5rpm range its more smooth but when you listen to the leaky exhaust gasket it sounds like a snowmobile, like a 2 stroke engine, with the random popping/missing sound even though the engine sounds smooth the exhaust definetly indicates that the engine is missing.

I have pulled the plugs and checked for spark all there, everything is checking out ok. The CEL is not on, but does work. I have swapped TPS off my good working SVX, replaced the idle air control valve and selenoid, MAF is fine, knock sensor is ok, coolant temp sensor checked out alright. All vacuum lines are intact and in place, Air filter is fine......What could possibly be causing this? Am I overlooking something very simple? When at idle it is shaking hardcore, enough to rattle a can of pop right off of the roof.

Everything is pointing to a spark problem to me but i've checked it all out and the coil packs all have spark and the plugs seem ok.....

I'm at a loss, I really want to get this thing up and running but i'm completely stumped on this....any help would be GREATLY appreciated.

Thanks in advance
~Tim

[dwd1985]

I am having this exact problem at the moment, and the solution is relatively easy to fix: Bad Spark plug coils. The SVX uses a coil-on-wire system, so you will need to diagnose which coil is bad. with the engine idling, unplug each feul injector 1 at a time. If you unplug a good one, the engine will die down a bit, and when you plug it back it, it should return to its previous power. You will know the bad coil(s) because when you unplug it, nothing will change in terms of engine power. I have 2 bad coils, and my new ones should be here on Monday. Everyone reccomends replacing all 6 at once, but I am only replacing my bad ones..

[fldcar]

Hi, I guess I forgot to say that I pulled the coils one at a time and put a plug into them fired up the car and checked for spark and they all have it, could it be possibe that one or more of the coils is still bad?

This is driving me nuts...
~Tim

[dwd1985]

According to your signature, you have several other SVXi. IMHO, you should pull all of the coils from a known to be good SVX, and switch them to the one running badly. See if this helps.

[fldcar]

Sounds like a plan, i'll switch them out today and see what happens.

Thanks
~Tim

[fldcar]

Well I went and got new NGK plugs and headed out to swap the coils and change plugs.

I changed all the plugs and then swaped over good coils onto the car. Started it up with absolutely no difference :-(

Upon further investigation, all the drivers side cylinder bank plugs looked ok when I took them out, the passenger side's plugs were completely black and one of them was wet with what smelled to be gas when I pulled it out. I think the problems lies somewhere within the passenger sides fuel/spark delivery system. When I started the car after the plug change and after it warmed up...I started to unplug the fuel injectors, when I unplugged any of the 3 injectors on the drivers side the engine idle got even worse. When I unplugged any of the 3 fuel injectors on the passengers side there was no change at all, at one point I had all 3 of them unplugged on the pass side and it ran exactly the same, just sitting there shaking and missing as it has been and when I plugged them back in the same thing...nothing changed.

I think the injectors are working though, because I listend to them all and heard a ticking sound comming from each which I believe is normal right? I just dont understand why there was no difference when I unplugged the pass side ones, especisally if they seem to sound like they are working.....

Any ideas? I've never had a problem like this on any of my soobs.......its kinda frustrating