How saving money can wreck an engine, OR: How I learned about ignition coils

I was requested to start a new topic on this, so here we are.

The patient is a Volvo S60R.  (Oh no here he goes again  ) Five cylinder 2.5l, 8.5:1 compression port injected, coil on plug engine running up to a measured 18psi of old school big turbo boost.  Volvo rang up Bosch and had them supply everything for engine control, because they're right across the water and they make solid components.  

I received the car with 185k miles and a stack of records.  While performing a wiring repair to the ignition coils, I noted that some coils were OE and some were aftermarket.

At a bit over 200k, it calmly started drinking water.   All that aside, after replacing the head gasket, having the head machined, and shimming the block (its a Volvo thing) it was repaired.

Then the #4 coil died while on  towing trip to pick up another Audi engine.  In a blizzard.  150 miles for three hours with a dead hole in subzero temps cracked the cylinder head to a remarkable degree.  I called up the local parts store and got a $65 coil and kept truckin' until Erie Vo-Vo could deliver me a replacement engine.  The coil was made by Delphi, not Bosch.  A coil's a coil, right?  And it looked just like the aftermarket coils already in place.  (Cue ominous music)

Erie Vo-Vo came through with a low mile late S60 T5 engine.  This is the same engine as the R, but with 2mm smaller bores, and 9:1 compression, but this is a common swap that doesn't need a retune as long as you use 93.  And the smaller bores make a stronger block, no need to shim.  Future proofing for possible turbo upgrades in the future, you see.

All was well and I could enjoy all the BOOOST again, right?  No.  Under heavy load, especially in the 3000-4000 range where the engine pulls sweetly, it wasn't pulling sweetly.  It was bucking and cutting out.  Kicking back, almost.  I noted that the issue went away with 100 octane, but at $8 a gallon and the nearest station 30 minutes away, not a permanent solution.

I babied it for a while and ruminated.  Then I remembered some things that I'd read on the msextra forums about LS coils discharging early if the dwell was set too long.  The coils would discharge to prevent overheating.  Delphi made LS coils, they made these coils, could they use the same circuitry?

An order was placed to iPD.  Tune up kit arrived with five genuine Volvo spark plugs (R and T5 used a weird long reach plug) and five Bosch coils in Volvo boxes.

Problem was eliminated. 

The Motronic must have been running longer dwell than the Delphi coils liked when under higher boost and more spark energy was needed, causing them to discharge early and cause engine wrecking detonation.  Not so much noticeable with the larger, lower compression engine, but with the smaller, lower grams of air per cycle, higher compression engine, it became quite apparent.

I'm convinced that the wrong coils were causing low level detonation that caused the original engine failure.  The PO was a retired gentleman who probably didn't drive the car nearly as hard as I did, so it only became an issue after I started driving it.

Bmw bosch pencil coils had a very high failure rate.  They made a switch to delphi coils on solenoid injection cars, both port & direct injection & eldor coils on piezoelectric injectors.  Never heard what the reasoning was but the eldor coils felt much heavier.

I think I know of the ones you speak. These are not tiny coils.

Huh... could have sworn that the coils were in Volvo boxes.  Neat packaging for the plugs, though!

The kicker was that, through iPD, the correct coils were $65 each.  But then I would have to wait for shipping (and it was my only winterable car and we just had a blizzard) and my credit card was spongy and bruised from the engine escapades, so I couldn't just buy a whole set at the moment. 

Going back through my garage journal, in the months leading up to all this, I'd bought a ton of parts for the Quantum in the middle of its high boost turbo engine build/swap. $450 crank seal/sensor here, $850 exhaust manifold there, "spare" S60R turbo that was a huge upgrade for Audi fives...  The Volvo sucked all the money away from that and I never really recovered momentum.

Ironically, now that I remember more deeply, the trip that netted me a spare Audi shortblock, a dead coil, and a cracked head, was mainly to acquire the ur-quattro downpipe that I needed to fit a turbo five in a B2 chassis car, but when he also offered an engine, I hitched up the trailer.

Not surprised. It's pretty well known in the E30 circles that fancy multi-prong spark plugs can cause all kinds of misfire/rough running issues. Just run the standard Bosch plugs and go.

I turned down buying one because of it. The guy called me back and said changing the plugs fixed it, but I figured if he didn't know that, what other maintenance was skimped on/done incorrectly. 

I lost the ring lands in #3 in my 850T when the spark went out under (lots of) boost.

That car was fun while it lasted.

In reply to ShawnG :

Ah yes... 850T used a distributor, right?

Audi turbo fives that used distributors used the same small Bosch cap.  Might even be the same part number.  At high boost with insufficient spark, the coil would fail to have enough voltage to fire.  It would, however, have enough energy to jump the small distance in the cap to the next cylinder, and fire the next cylinder WAY early.  In an Audi with Diesel-like pistons, this leads to an S shaped connecting rod.

Coil near plug was a Quantum mandatory thing, thus the need for a 60-2 tone ring and a computer that could do a five.  Bought two racks of coils from an LQ4, the next expense would have been an MS3Pro...

Interesting, this is the first time I've heard of stock replacement Delphi coils for non-GM engines having this issue with the stock ECU. When I saw this mentioned in the other thread, I thought you had bodged a set of LS coils into a Volvo with the stock ECU, or otherwise put together a set of parts the manufacturers never expected to ever be combined.

In reply to Pete. (l33t FS) :

Distributor ignition but I believe the failure was due to the platinum spark plugs that were in it (and me being an idiot).

I was playing silly buggers on a back road with a guy in a modified 280ZX Turbo. I don't know what he had done to it but I had the ARD Tuning orange tune in my PCM. I could out run a lot of fairly fast cars. He was VERY fast.

I put my foot in it hard and when it came up to full boost (14lbs IIRC) there was a rather abrupt cough that I hadn't felt before. Nothing bad happened after that and I stopped being an idiot and drove home.

I found out that some guys were having issues with the increased boost causing the plugs to not fire. The fix was good old copper core plugs, gapped to .028 so that's what I did.

Ran fine for a week or so after that until I was merging on the highway on my way to work. I gave it the business and there was a loud pop and a bunch of blue smoke. Car ran ok on boost but awful off boost.

I limped it to work and put the compression tester on it. Nothing in the third hole.

I figure the little cough caused some damage and then the last little run down the onramp put the nail in the coffin.

Poor thing. I really had fun in a clapped out, scratched up Volvo station wagon.

In reply to MadScientistMatt :

Heh, yeah... Learning experience.

Ever since then, in my professional life I insist on OE coils for anything European.  One time I was doing coils on a newer direct injected Mercedes and was given a box full of aftermarket.  OE not available for a week so it's this or nothing, I was told.

I threw my justified grumpiness into gear, revved up my outrage engine, and was all ready to pop the clutch, and then I opened a box and saw that Standard had simply reboxed Mercedes coils.  Still in Mercedes parts bags, stuffed in the Standard boxes.  That was a win for sure, aside from having all those gripe-hormones still flowing in my veins with no more target for them 

Definitely an odd one. Only coils I have seen have protection mode issues have been the ls ones and the non oe ones being worse. 

In reply to Paul_VR6 (Forum Supporter) :

I can't find the thread on Swedespeed via Google, and the ads on that forum are so intense that I can't log in anymore without a flagrant system error.  But everyone insisted it had to be something else.  My service manager, a similarly experienced tech, insisted that it had to be something else.  No codes, no fuel trim weirdnesses, and Volvo doesn't give knock retard PIDs so I couldn't be sure that it was even knock... but it felt just like when I stabbed a 12A distributor in 90 degrees out and I had 192 degrees of trailing advance...

But it's also interesting that the people who remote tune these cars require that you have new Bosch coils before they start work.  Which was going to be my next step if this didn't work.

My Nissan NAPS-Z power 720 pick up would eat ignition rotors if you used anything but OEM plug wires.

We always assumed the resistance was just different enough that it burnt the rotor.

Pete. (l33t FS) said:

In reply to Paul_VR6 (Forum Supporter) :

I can't find the thread on Swedespeed via Google, and the ads on that forum are so intense that I can't log in anymore without a flagrant system error.  But everyone insisted it had to be something else.  My service manager, a similarly experienced tech, insisted that it had to be something else.  No codes, no fuel trim weirdnesses, and Volvo doesn't give knock retard PIDs so I couldn't be sure that it was even knock... but it felt just like when I stabbed a 12A distributor in 90 degrees out and I had 192 degrees of trailing advance...

 

But it's also interesting that the people who remote tune these cars require that you have new Bosch coils before they start work.  Which was going to be my next step if this didn't work.

The tuners know! I do the same with fuel injectors, if I don't get a brand and supplier, hard no. 

This is some crazy stuff...

And from one of the sub-points above, I really wish I understood how different spark plugs could behave as differently as they seem to sometimes do.

In reply to Jesse Ransom :

I think heat range plays a role, not all heat ranges seem to cross over from one manufacturer to another.  This gets critical when you go off the deep end of the usage bell curve, in either direction.  Use what it was engineered around, even on Mopars that used Champions 

I'm also not a fan of platinums where they aren't called for, and if they still make those godawful Platinum +4s, they should stop already because they don't seem to work right in anything   Very tiny center electrode that relied on surface discharge effects that worked great in theory but in practice they loved to flash over the porcelain once they had any miles on them.

Volvo used a weird long reach plug in the R and the other engines that used its head.   They revised the water jackets so they could one up the M3 for Autobahn performance (250km/h? This does 260 )  and the threads had to be longer.  I always had got plugs "for the application" from NGK, before this incident, but you had to be careful because the base 2.5t used a short plug and parts guys didn't always pay attention.  The catalogs listed S60R as a different model and the right plugs wouldn't come up if you looked for S60.

All this happened 110-80k miles ago, start to finish, incidentally.  We're at 347k now.  No salt and pepper on the plugs this time when I changed them last winter... with another set of OE plugs.