96 Riv S/C Stuttering/Misfiring

Didn't read that far back LOLOLOL

When I get the money Ima swap the spark plugs the previous owner bought bosch platinums i believe..

Does overdrive put a very large amount of load on the motor? I can drive it in 3rd for about 2 hours b4 it goes to stuttering but if i let it go into overdrive it can happen withing 5 minutes...

Yes OD puts quite a load on the engine, especially when going uphill. And GET THOSE BOSCH PILES OF GARBAGE OUT OF THAT ENGINE!!!!! Bosch Platinum plugs are absolute junk........

You know I thought I heard someone say bosch platinums were junk just wasnt sure, somebody suggested a/c delcos

Abaddon wrote:

Yes OD puts quite a load on the engine, especially when going uphill. And GET THOSE BOSCH PILES OF GARBAGE OUT OF THAT ENGINE!!!!! Bosch Platinum plugs are absolute junk........

I've used Bosch Platinums, my experience has been they are great new but after a while the metal ablates off the center electrode, turning it into an insulator of sorts, and they don't run so well. I had that happen in both a Subaru (with the boxer 2.2) and a Volvo (with the inline 2.3L NA 4-banger). I did not try them in my Riv. I used different bosch plugs in my Audi with very good results, the Platinum +2 and Platinum +4, they both seemed to work fine. Not sure why, maybe different running voltage level, who knows. And besides, Abaddon's in a much better position to comment, I think he sees more cars than many if not most of us.

If anyone cares... I understand the issue is that the Bosch Platinums are not the best for a waste-spark ignition like we have on the Riv, in which the ignition fires the plugs 2x per revolution. For some reason this burns out the Bosch Plat center electrodes. I have been able to probe the center electrode on a used Bosch Plat from my Volvo and Subaru with a straight pin. Effectively, that means the gap grew and the way those plugs are made (ceramic insulator around a thin wire for the center electrode) I was hosed... I understand that this erosion problem for some reason isn't a problem with coil-on-plug ignition system. My Audi had coil-on-plug. Subaru was waste-spark. Volvo was conventional distributor with electronic (no points) ignition.

I have solved hundreds of misfires that were caused by Bosch Platinum plugs. In fact, about a month ago, my buddy called me sayin his truck was runnin like balls. He just had the plugs replaced a week ago with Bosch Platinums (He lives 45 mins away, so he has me diagnose it when he's in the area, and has a mechanic he knows fix it). He brought the truck by.....#4 cyl was a dead miss (if any of you have had the pleasure of working on a Jimmy 4.3L, you know that #4 plug SUCKS to get to). Anyway, I got the plug out, and the center electrode had already fell out, burned, whatever. Point being, I don't know a single person that has used the Bosch Platinums and had success as far as longevity goes. Albert is dead on......as soon as that electrode goes down into the ceramic, the plug starts misfiring horribly.

trumbo, I wouldn't be surprised at all if those plugs were your problem (if that's what's in the car now). I recommend the factory plugs, or AutoLite. Either the 605 coppers or 605 platinums.

I think I figured it out... for those of you with physics backgrounds, check me on this -- what's probably happening with the Bosch plats is the metal is ablating off the center electrode and turning into a plasma. All plugs do this, it's why they wear, however on the Bosch plugs there is just a lot less metal to vaporize because the metal conductor (anode) is so small. So on a standard plug there is many times more metal at the interface between anode and cathode across the air gap... the plug gap will creep but not as fast. If the *rate* of metal ablation is the same on all plugs as measured by the ablated mass, then the Bosch plugs will blate much faster because the area from which metal can turn into a plasma is much less.

A platinum button like Autolite uses would last much longer if only due to the basic physics of the conversion of metal into plasma, I suspect. At the gap setting distance there is much more metal mass to blast away so it takes longer for the gap to creep from ablation than on the Bosch plats.

I also suspect that in a waste spark system more metal ablates per unit of real time no matter what plug you use because for any useful real time interval the plug fires twice as much.

Hmmmm....

Thoughts?

It makes total sense to me Albert. Let's "dumb it down" a hair though.......

When that tiny little electrode in the Bosch Plats wears away, it wears down into the ceramic. Once it wears down so far, the spark finds the nearest piece of metal it can find and arcs to it. This may be the block, which causes the misfire. On the AutoLite Plats, that electrode is much larger, and the spark has a much greater area to hit......even if one edge of the electrode wears away, the next nearest place to arc is, let's just say, the other side of the electrode. This is why the electrode on "worn" plugs appears dome shaped after awhile. But even then, the spark still has a place to go (the center).

Those Bosch Plats were just a bad idea IMO. In my car, I actually prefer the standard copper plugs. Sure they wear out faster, but I'm yet to have a misfire caused by one.....

Yeah thats the next thing im going to do is swap out the spark plugs I pulled one out a week or so ago and the ceramic piece looked nearly flat..

Okay it was the spark plugs, they were brand new but the owner over tightened them 3/6 cracked when I removed them and they looked like the spark was arcing to the threads on the spark plug correct me if im wrong its what Im assuming is on the side of the plug pictured here...


now the threads on them contained some oil, the top 3 threads were dried oil obviously from the heat im wondering if that could be causing the spark to miss?
Other Side of Plug...

those plugs look "blown by" hence the soot on the insulator (the part you are holding in the pictures) I guess when they were overtightented something happened to the seal not sure how.

the riv plugs have no washers and fit just so with tapered seats. I suspect the only thing that saves some folks is that the block is cast iron not aluminum alloy -- or we'd see a lot more stripped threads...

were the back 3 and front 3 plugs identical (iridium) type? Please tell.

They were all NGK Platinums.. what are the chances that the new ones get blown by? I just tightened them with 1 hand with the ratchet didnt really try to overtighten them, the previous owners a macho man and he tightened the shit outta them..

Also should the boot on the plug wires completely cover the whole white portion of the plug? I tried to adjust them where they atleast covered the lines on the ceramic, theyre longer then the old plugs..

Cool beans dude. Glad ya got it figured out

The new ones i just put in are all iridium they said it was wat came stock so I took em

trumbo71 wrote:

The new ones i just put in are all iridium they said it was wat came stock so I took em

Yep. Those are the stockers.....

Well Ive replaced the wires, PVC Valve and now the spark plugs next thing on my list is the EGR Valve, now that I've fixed the misfire I've noticed more when I've speed up to 50+ if i decellerate quickly to almost a stop or to a stop the car stutters and almost wants to stall, could that be the EGR getting stuck wide open or transmission related? Someone also suggested the MAF

trumbo71 wrote:

Well Ive replaced the wires, PVC Valve and now the spark plugs next thing on my list is the EGR Valve, now that I've fixed the misfire I've noticed more when I've speed up to 50+ if i decellerate quickly to almost a stop or to a stop the car stutters and almost wants to stall, could that be the EGR getting stuck wide open or transmission related? Someone also suggested the MAF

it sounds like you might be simply catching up on deferred maintenance.

Yeah the cars at 160k and I dont think the person who owned it before the guy I bought it off of was any better at doing regular maintenance then him... cause whoever last changed the serpentine seriously bent up the oil pan...

trumbo71 wrote:

Yeah the cars at 160k and I dont think the person who owned it before the guy I bought it off of was any better at doing regular maintenance then him... cause whoever last changed the serpentine seriously bent up the oil pan...

You might want to look at the high mileage section where we tried to outline what's in high mileage maintenance.

Too bad about your oil pan, it'll leak like a new puppy (not housebroken) til you replace it...

I've been keeping an eye on her the past month or so and suprisingly leaks less then a 98 corolla at about 200k does, I'm wondering if the pan being pressed in and lessening the volume in its capacity and pushing the oil up creating practically an overfill would cause any problems?

Yeah, my op is bent too. Found it when I did her first oil change....I was pissed. But, it doesn't leak, and 4-1/2 quarts is right at the top of the hash marks on the dipstick. Out of sight, out of mind I suppose