FAQ: Series I SC Harmonic Balancer Diagnosis/Installation

Sorry I have been working crazy hours at work, and have not had time to get back.

Thanks for the input. I'm going to check out the electrical connector this afternoon, and plan to check the harness and ground a lot closer. I'm also leaning toward this is in the wiring somewhere...

Check or replace TPS. Could very well be the problem. But it should throw a code. Would a faulty temp sensor cause fuel trim to go one way or the other? I would initially suspect coil but that has been addressed. I think Albert is probably on the right path. Good luck, keep us posted.

And one other thing - the chafed parts of the wiring you found, recovering them might be/have been a mistake if they started corroding. The wire will continue to corrode inside the repair, which will of course cause problems. Kinda wonder if that's part of what you're experiencing.

Wow, has it really been 2 months? I guess It's time for an update...

I've checked pretty much every wire and connector under the hood, finding no breaks/cuts/questionable spots. Taking Albert's advice, I cut my previously repaired grounds off completely at the harness and re-connected with heat-shrink butt connecters and new ring terminals. The wire where I cut them off showed no sign of corrosion, although I know that doesn't necessarily mean it's not corroded.

While I was working yesterday, I had pretty much the whole harness loose from around the SC, so I got a wild hare and decided to go ahead and change the LIM gaskets. The write-up here is very informative and complete, so I had no problems. I did see where the stock gaskets had signs that there was some slight seepage from the water jacket, and see where the new design was much better than the old.

This morning, I was browsing some of the other threads on here, and two of them jumped out at me:

https://rivperformance.editboard.com/t8876-lost-delay#138574

https://rivperformance.editboard.com/t4839-hesitation-under-acceleration

The upshot of both of these posts is to use OE plug wires, which I hadn't (Right again albert! ) Went to the parts store this morning, bought a set of Delco plug wires, checked my plug gap again and installed the new wires. The car seems to be idling smoother already. I've got my fingers crossed!

Thanks to everyone for your help and suggestions.

What sometimes happens is a number of things give out at once, no surprise on a Riv over 100,000 miles. Car supposedly engineered for 150,000 miles or 10 years -- some components have to be mad durable to be sure to make it that far and others can be just barely good enough. That said, you are making good progress.

What I am thinking now:

1) I still suspect you've a hidden break in the wiring harness in or near that firewall connector, I'd especially check the wires in the corners of the connector. What you have to do is feel them and wiggle them to ascertain whether any of the conductors are broken inside the insulation. If they are not broken a wiggle won't hurt and if they are a wiggle may be the only way you will ever find out.

2) I know you don't wanna do it but at this mileage/age you really must get new throttle body and IAC (idle air control) gaskets, pull the throttle body and clean the passages. Unless you have already and i missed it. By the way, a spray-in cleaner or an on-car cleaning, even with a BG or other machine, does ***not*** count. You will be dismayed at the sheer amount of tar that builds up in the IAC and TB intake paths.

If it is any consolation, after you catch up on the 'long tail' (infrequent maintenance) items things will settle down a *lot.*

Forgot to mention that. I did have the TB off while I did the LIM, cleaned by hand (and my bore brushes) and reinstalled with a new gasket. It was FILTHY!!! Checked the IAC and reinstalled with a new generic o-ring. Cleaned the IAC passage also.

Rivillac wrote:

Forgot to mention that. I did have the TB off while I did the LIM, cleaned by hand (and my bore brushes) and reinstalled with a new gasket. It was FILTHY!!! Checked the IAC and reinstalled with a new generic o-ring. Cleaned the IAC passage also.

If the cross section of the IAC o-ring was too small or it was the wrong composition (I suspect black butyl won't work, it's too hot there, thats why they used the red silicone ones) you could have a problem (air leak).

Update....

Still having the problem. I did learn some new things:

I got an in-line spark tester, and tested all the cylinders. When the problem manifests itself, it is because the 3-6 (top, rearmost) coilpack barely fires between about 1800 and 3000 RPM. Below that, there is an obvious, visible (by the tester's light) random miss in that coilpack, and above that the engine does not miss. I have shuffled all 3 coilpacks to that position, and the problem stays in that position. The other two positions on the ICM fire smoothly and consistently regardless of which coilpack is there.

I also went to the pull-a-part and got another ICM, and when installed, performs exactly the same way. I know that this could theoretically be because I got another bad ICM, but I now have three of them, and all 3 perform exactly the same way on the car.

Once again this points to the electrical system. While I was shuffling coilpacks, I had the bracket off and cleaned the head and bolts for the ground, and reinstalled them with dielectric grease. I also took the alternator off for access and checked the ICM/Crank/Cam harness over again. I checked the wires back to the firewall connector again, did the "wiggle test" with no results.

I should also say that I found a service manual set on ebay, it should be here today. I hope this will help me trace the wires a little better.

I feel I am getting closer, but it's so frustrating! I want to get this taken care of because the car is comfortable and nice to drive. I really think once I get this sorted out, it will really be a great car!

It occurs to me that I need to update the list of things I have changed

already, since the first list is now incomplete:

*New plugs and wires
*New coilpacks and ICM
*New fuel pump/module
*Fuel filter
*New Crankshaft Positon Sensor
*New Camshaft Position Sensor
*New ICM, cleaned ground contact surfaces, repaired ground wires
*New Coolant Temp Sensor
*MAF cleaner through the MAF sensor
*Checked MAF sensor against a known good one
*Check TPS against a known good one
*Removed IAC, checked IAC against known good one
*Cleaned IAC passage
*Replaced LIM gaskets
*Cleaned throttlebody, reinstalled with new gasket
*Replaced all vacuum connectors
*Checked for vacuum/air leaks
*Checked EGR valve


So if nothing else, I'm getting caught up on my maintenance!

EDIT: Added temp sensor to list

How old is your battery? You know, under the back seat? Checked it lately?

I was thinking about your problem - Riv battery needs minimum 450 CCAs for the car to function right. By design it will start and run with a relatively weak battery but the weak battery pulls system voltage levels down. The sensors work via voltage level signals. If the voltage is low many if not most of the sensors won't work right - this might be why you have the persistent problems that look like the ICM, PCM, or various sensors.

As for the "wiggle test" in wiring also need to find bent or corroded pins. The hint would be a connector that is hard to reach but might have been unplugged to get to something else, like to swap a transmission or some such. Another hint would be a connector on which the weatherstripping/rubber gaskets are torn or missing.

I would double check the connectors on the plug wires that go to the 3-6 coilpack, and also check the 3 and 6 (especially 6) plug itself. Might want to use shop air to blow debris out of the plug wells before removing them.

Based on where we've got to so far, there's probably something simple and non-obvious we have not checked yet. Got to think about this one.

I had a problem a couple years ago that looked like a bad ICM but turned out to be bad ignition switch. Not the keyway, the electrical part. They only last so many years until the contacts carbon up, it's a typical high mileage/age replacement item. I can't say the problem looked like one coilpack because I used NOID lights and the problem moved around. I had another problem around 8 years ago with the 3-6 coilpack (set a code) and it turned out to be the line to the 6 plug failed and when it did somehow it took out the pack.

Albertj

Hmmm....

I have checked the voltage (12.9 static), but have not load tested it. I had noticed that the battery punch tabs hadn't been punched out when I was checking voltage, so I have no idea when it was replaced.

As I think this process over, it occurs to me that the battery could be very old but not show its age so much because it is in such a protected position. This is a mistake on my part. I should know better because my job is so focused on "Don't assume, CHECK".

I will be getting the load tester out within the hour.

Rivillac wrote:

Hmmm....

I have checked the voltage (12.9 static), but have not load tested it. I had noticed that the battery punch tabs hadn't been punched out when I was checking voltage, so I have no idea when it was replaced.

As I think this process over, it occurs to me that the battery could be very old but not show its age so much because it is in such a protected position. This is a mistake on my part. I should know better because my job is so focused on "Don't assume, CHECK".

I will be getting the load tester out within the hour.

If you are showing 12.9 static you'll probly pass a load test. No-load shoud be 12.7 v or so +/- 0.7 v or so. And you're looking for 450 CCAs or better. So --g'luck, hope I'm wrong and the battery is fine.

By the way - yeah the battery *will not* show age due to location. I am on my 3rd battery. The first was replaced by the dealer when I bought the car (that replacement was probably unnecessary) and I replaced it 8-9 years later when it finally fell below 450 CCA. When the car hit 5 years old I asked the dealer to load test it at each annual inspection. My guess is your batt's OK but not showing 870 CCAs to the load tester either.

While you are in there check out condition of cables and might as well clean to contacts?!?

We may have hit the bulls-eye here...

Static voltage is still right around 12.7-12.8, but under load (100 amp) the CCA starts around 400, and continues to fall. The battery is an Interstate, and based on the picture of the race car on the battery, looks to be as much as 4 years old.

Looks like I'm going to be in the market for a new battery.

I don't think a bad battery will cause a specific misfire like you are seeing. If you have enough power to start the engine it's not likely your problem.

Replace the #3 and #6 spark plugs again. These ignition systems are very sensitive to a slight crack in the plug. Also try misting the spark plug wires with water (from a plant sprayer, not a hose) to hunt for arcing/shorts. You wouldn't be the first person to have cracked a spark plug in that hard to reach back corner during installation.

deekster_caddy wrote:

I don't think a bad battery will cause a specific misfire like you are seeing. If you have enough power to start the engine it's not likely your problem.

Replace the #3 and #6 spark plugs again. These ignition systems are very sensitive to a slight crack in the plug. Also try misting the spark plug wires with water (from a plant sprayer, not a hose) to hunt for arcing/shorts. You wouldn't be the first person to have cracked a spark plug in that hard to reach back corner during installation.

Thanks for weighting in Deekster - I think we both may be onto something here.

The Riv will *start* with nearly no CCAs (around 50-75 CA's ?!?) as long as it's temperate out and the car is in otherwise good shape, especially with synthetic oil in the sump.

AND you are right I also agree that a bad battery won't cause a specific misfire. The plugs are cracked or some wires are wacked. Given the "waste spark" system either the 3 or 6 plug/wire, or both, could have a problem. I am guessing 6.

As for finding the arcing - have to do it in the very dark so that the deep blue (almost UV) of the Riv's coronas can be seen.

As for that battery, too bad you only got 4 years before CCAs fell below spec. On "seconds" Interstate only warrants 400 - 450 CCAs, it could be if the battery was bought in a pinch by the PO or a used car lot they tossed one such in. Maybe... I mean, prolly not but it has happened. Regular Group 79 battery should punch out 750CCA or more, and the new ones I see are usually rated 880CCA/1000CA. After 7 years my Delco Freedom (original to the car) still produced 500+ CCAs.

So it sounds like we may be almost to the bottom of the mystery. Caught up on deferred maintenance and it's down to a cracked plug or bum wire. Or 2.

Albertj

Didn't the OP say that he replaced all plugs, wires, and coils - TWICE?

Question for the OP: what was the condition of your plugs' electrodes when you pulled them?

AA wrote:

Didn't the OP say that he replaced all plugs, wires, and coils - TWICE?

Question for the OP: what was the condition of your plugs' electrodes when you pulled them?

I replaced the plugs, wires and coils originally, and then upgraded to Delco wires from what I had initially used. So, plugs and coils once, and wires twice.

I don't recall what my plugs looked like off the top of my head, but they didn't set off any alarms. In fact, I think may have hung on to them as spares, I'll check tomorrow. I didn't think they were that old, I just changed them as a matter of course since I was doing the coils and wires anyway.

I just looked at my old plugs again. No deforming of the electrode, a solid tan over the whole ceramic part, no melting or burning of the tip. As I remembered, I wouldn't be opposed to using them again.

I'll probably put the car up on ramps later and check the #6. I pulled the #3 this morning and found nothing objectionable there. It looks like it has been firing normally. Of course if there's a small fracture, it might not be visible to the naked eye. Kind of points to #6.

Of course, the car is still cool this morning, and still running well. I'm going to wait until it starts acting up, do a clean cut and check the #3 again.

Just asking for opinions here, if I have two different brands of platinum spark plugs, would it be a problem to use my old ones as test pieces to check for plug issues?

Still waiting on my FSM with bated breath...

Your description seems normal. Sometimes I reuse mine in that condition. I see no problem with mixing brands for testing, but use a consistent set for the final install.

Just an update.

I pulled #6 yesterday and eyeballed it. Nothing obviously wrong with it, but the ceramic didn't seem as dark as the other plugs I've looked at. Could be from the lack of firing. I swapped #6 with #1 so (a) that particular plug is easier to get to if it is still a problem, and (b) to see if it moves the issue to the 1-4 coilpack.

I haven't had a chance to get out and drive it much yet, but I should either this afternoon or tomorrow.

Also, I noticed the O2 sensor wire was physically touching the #6 wire, so i zip-tied it up out of the way. I doubt there's any electrical interference there, but it seemed like a better idea than letting them touch.

I finally got a chance to go drive the car today. Same story, when it gets good and hot the miss begins again. It is still missing on the 3-6 coilpack.

When I got home, I rolled it up on ramps to check the #6 wire again. When I grabbed it, it was slick with oil. I checked the plug itself, and the outside ceramic also had a sheen of oil on it. Poking around a little more, I figured out that my rear valve cover gasket is leaking. The plug I swapped to the #1 was a little slimy when I removed it, but I assumed it was from the dielectric grease I used to install the wires, so I just wiped it off and put fresh grease on it.

So my thinking is this:
-My initial problem began after I ran some Seafoam through the oil system and changed the oil, which may have affected the gasket.
-The problem is very much associated with the temperature of the engine, i.e. the oil begins to leak, runs out on to the spark plug.
-I haven't been getting any further SES codes that would indicate a short/break in the electrical system.

My theory is that the oil is shorting out the plug and that is the source of the miss. Either way, it looks like I need to do the valve cover gasket. I just wish I had known this when I did the LIM gasket. I'm sure the valve cover would have been much eaiser to do then.

Did the rear valve cover today, and cleaned the back of the engine. Seemd to drive well for about 30 minutes. Hopefully this solves it!

*sigh*

Still at it. I believe I hit at least half the problem though, becuase it didn't start to miss until I drove nearly 40 miles.

It's still the 3-6 coilpack. I took two of my old plugs and wires, and plugged them into the 3-6, grounded them to the alternator bracket, and I'm still seeing a lack of spark between 1800-3000 rpm. It's still isolated to the position of the 3-6 coilpack, no matter which pack is on those contacts. It also happens on both plugs, regardless if one (or both) is plugged in or not.

So, (since i'm STILL waiting for my FSMs) I have a question. Is it possible that having an oil-shorted plug on #6 killed my ICM but not the coilpack? After all, that coilpack seems to work well at the other positions. Without my books, that's where my (poor) logic leads me.

I'm probably just going to park it until my books get here.

Sorry for being a PITA, but I'd appreciate your thoughts.

Rivillac wrote:

*sigh*

Still at it. I believe I hit at least half the problem though, becuase it didn't start to miss until I drove nearly 40 miles.

It's still the 3-6 coilpack. I took two of my old plugs and wires, and plugged them into the 3-6, grounded them to the alternator bracket, and I'm still seeing a lack of spark between 1800-3000 rpm. It's still isolated to the position of the 3-6 coilpack, no matter which pack is on those contacts. It also happens on both plugs, regardless if one (or both) is plugged in or not.

So, (since i'm STILL waiting for my FSMs) I have a question. Is it possible that having an oil-shorted plug on #6 killed my ICM but not the coilpack? After all, that coilpack seems to work well at the other positions. Without my books, that's where my (poor) logic leads me.

I'm probably just going to park it until my books get here.

Sorry for being a PITA, but I'd appreciate your thoughts.

I think you are probably right, IIRC there is a power transistor or scr that fires each coil and if so then you probably nailed it.