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Reluctors, programming and all sorts of fun

BillBoost37

BillBoost37

New member
Here's a little story and some info about my 2000 Regal.

On Dec 17,2010 and 173K miles the trans started acting up. I drained the fluid and refilled with a quart of Lucas and 4 or so quarts of dex 3. It was quickly jumping 1k rpms and slamming back to where it should have been. That stopped within a hundred miles of doing the fluid. Being me, I kept driving the car and had all the trans parts sitting around waiting to be put together and go into the car. In the spring, cleaning up for the meet.... I took a little time with some of the guys and put together the transmission into one of my old cases from the Bonneville. Built as follows
Reused Intense input shaft
New precision stock converter
fresh clutches in all along with new steels and added some 2nd and 3rd plates to take up extra slack.
Reused hardened 4th hub
Reused valve body from Intense build
2.93 (stock gearing) with new V8 chains
New reluctor (gee...go figure huh?)

During the summer the right axle went bad, so I tossed just that in, delaying the trans swap as I planned to change the rear engine cover gasket while the trans came out. Kept on driving. Sometimes I needed to press and depress the Perfomance button to get the trans to go into converter lockup. This symptom then stopped happening. Saw an input speed sensor reclutor welded to the drive gear. This is the one thing that kept failing on me. It gained my interest, kept me thinking about it.

Now we are about to November and the trans begins acting up with the rpm jump fairly often, causing me to think....it's time. Being me, I keep on driving and driving. Passenger axle is bad (GSP, cheap chinese), I picked up another. A front wheel bearing, right side outer tie rod and that pesky rear engine cover are bad. I pulled the trans out of the threaded cooler line 97 case it was in and put it into a 2000 case with click style lines like my car has, while it was apart the ISS and drive gear got welded together. No more worries from that part ever again. December 29th I drove the car with new transmission in the trunk to Dan's for the swap.

Official mileage at time of swap 193,750 still had 4th gear and was overall running pretty good. Max helped out and we swapped the trans, wheel bearing, rear engine cover, oil, coolant, (tried the oil pan..the engine sealant goop is really strong lol) and when I test drove it..the rpms were jumps a bit and there was clearly something wrong with how it was shifting. By the time I limped home it was apparent that it probably was max adapt shift.

Over the next couple days I tried programming 3.29's (in case I grabbed the wrong gears) and a few other things. I noticed the speedo was off by 5-10mph no matter what I tried for gearing. Changed pulses per mile to determine a 34 tooth reluctor was on the differential. This would have been a leftover from the spoofs Intense put into a car to fool it about having 3.29 gearing. All stock HD diffs come with a 30 tooth count. Tried programming around the issue, talked to one buddy having some TCC issues and he mentioned he had 3.29's and 34tooth as well as having programming that worked for it. I took a try at that, looked it over and no luck. Removed the axle and diff cover, swapped the reluctor, programmed the 2.93 (stock) ratio back in and.... MAGIC. There must be some tables that we can't see that get effected by the reluctor. Having the wrong reluctor and knowing it, trying to program around it was unsuccessful. The correct reluctor is all that was needed.
 


Being on vacation I have barely found the highway.

No one tell Maffy, but it's time for me to actually diagnose the car. The hiccups are still present and as bad as ever. My thoughts are TPS/MAF at this point.
 
Kinda feeling like I'm chatting with myself. Which is cool, I'm talkative and most probably don't have much more to suggest than I'm already trying.

Tonight. Scanned the car. TPS and MAF are perfect when the hiccups are recorded. No signs of dropout or problems. TPS went 0-100 nice and slow w/o glitch or issue. I am thinking that if either were an issue, it should show. Anyone seen one be bad w/o showing on a scan?

When I initially got the car, I had to pass emissions a half hour after connecting the battery. So a few codes were told to be quiet. Figured maybe that was causing a problem (although it was fine for 6 months prior). Flashed to stock tune. No change

The trans really wasn't showing any gear change on the scans, which changed my thinking to .... pcm, crank sensor. Programmed up a spare pcm and swapped it in. No change.

Ok, I'm not crawling under the car tonight. Because it's mine, that's the only reason. I tried a crank learn aka case. No change

Tomorrow I'm heading in after a crank sensor and or ICM.

Ruled out:
Transmission
PCM
Crank learn

Remaining to be ruled out
MAF
TPS
Crank sensor
ICM
Wiring

If anyone has suggestions...I'm listening.
 
Try driving with a disconnected MAF to see if you still get thew RPM hickups?

Also, pretty rare, but PCM might be bad.
 
BillBoost37 said:
Tonight. Scanned the car. TPS and MAF are perfect when the hiccups are recorded. ................ Programmed up a spare pcm and swapped it in. No change.
Click to expand...

Thanks for the ideas bud. I covered the pcm already. Funny little tidbit. I pulled the pcm out of the airbox, noted the service ID number and a sticker that said Regal PCM. Thought..maybe it's a reman. Then looked at the programmed one and ....it was the same service number and had the same sticker that said Regal PCM.

Crank sensor tonight...maybe a maf, but there's just no fluctuation in it.
 


MAF = try SD mode
TPS = unlikely to cause this
Crank sensor = likely (but a pain)
ICM = unlikely, usually these fail completely, or just completely fail in one way, not intermittently
Wiring = Not much that can cause this except for an issue in the ICM harness, or the 3x wire going from the icm to pcm.
 
Scott... thanks for the suggestions.

Crank is 15min.. :th_king-normal: and going to be swapped tonight. Maf.. yeah SD is easy enough.
 
You are not talking to yourself Bill. I am following this. Just nothing to contribute at the moment.
 
Starting to wonder here...

swapped crank sensor, no change
Swapped ICM and coils, no change
swapped pcm, no change
swapped trans, no change
ran with maf unhooked, no change (maybe slightly more pissy, tough call)

Looks like I have map, cam and tps sensors left.

I told the car if it kept this crap up...I was going to disassemble it.
 
BillBoost37 said:
Starting to wonder here...

swapped crank sensor, no change
Swapped ICM and coils, no change
swapped pcm, no change
swapped trans, no change
ran with maf unhooked, no change (maybe slightly more pissy, tough call)

Looks like I have map, cam and tps sensors left.

I told the car if it kept this crap up...I was going to disassemble it.
Click to expand...

Hi Bill,

I hope you've been doing well other than your car. Figure I could add a few thoughts. When you say hiccup, could you describe the symtom a little more? As you may know, sensors can sometimes get skewed and the PCM wouldn't detect a problem (set a code) unless they really got way off. For sensors that failed internally through an open or short will usually bring on the CEL. Even a broken or shorted wire would bring on the CEL. That's why I mentioned about a sensor being skewed and not possibly setting off the light.

For all of the sensors that you mentioned for cases where the PCM may not detect a problem, I connect a 4 channel Picoscope to it and confirms them one way or the other. Scan tools or not the best for looking at raw data from a sensor since the values are read from the PCM. And the scan tool is usually too slow to pick up intermittent problems from a sensor. The scan tool could read values between a fault condition.

If you don't have a scope, the next best thing is to use a voltmeter with a min/max feature which could capture dropouts such as from the TPS. The MAP sensor could also be checked this way. The MAF sensor puts out a variable frequency relating to the amount of air being pulled in. Most meters today, at least the midrange ones have a feature which allows you to measure frequency or at least the duty cycle of the waveform. But again, the best method to confirm all of these sensors is with a scope. I hope this gives you a few ideas to help in checking out your vehicle.

After a little thought, your hiccup sounds like it may be an ignition misfire. Does you scanner have a feature to look at the misfire counters? Maybe a bad plug wire.

Terry
 
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Terry,

Thanks for the info. I should have a scope, but wouldn't use it 99% of the time in what I do and I won't admit that I work on too many cars. Typically it's my car that becomes the headache and all the others are straight forward.

The hiccup has changed and given me more info to go on.
Originally it would happen on the highway typically in fourth gear at steady rpm of about 2k. I'd feel a small quick pulse in the car, similar to running over a difference in pavement. Except without the suspension travel. At that same time the tach would quickly jump approximately 1k rpm and return down to 2k as if nothing had occurred. Usually happening once or twice in say a 20 mile drive. Infrequently it would happen 15 or so times in a row, this was very infrequent though. A few times I saw the behavior in 1st, 2nd or 3rd gears as well.

Without ever really diagnosing, I blamed it on probably an input clutch piston seal and called it a transmission issue. I built a complete transmission from other parts and swapped it into the car. Had the incorrect reluctor on the diff from an old spoof for 3.29's and once that was corrected all seemed good with the trans for a moment. Then I realized the problem hadn't left and was occuring more often. More often being a good thing in my eyes. Intermittants are tough to find.

Using HPT I scanned, saw where the rpm spiked once on the scan and dropped down about 500 rpm suddenly in another area (as you say..scanners can be slow). MAF and TPS appeared steady and not moving during the spike. Being that I have tested spare parts laying around,

I programmed up a new pcm and gave it a try. No change
I then thought about how flakey out crank sensors are and swapped it out, no change
Off the wall, but maybe an ICM, swapped it and the coils, no change
During a test drive, pulled over, killed it and unplugged the maf. Car fired up nicely and now appears to not be spiking up, only dropping down. Pulled over again and cycled the ignition. At this point the SES pops on for the MAF being unplugged and I test one more time. Still dropping rpm although it seems more often and only drops, not spikes. In more gears at more speeds. Typically though it appears to be in the throttle, where it would be most apparent. Plugged maf back in and about the same behavior.

HPT would display misfires etc current and history. It's not seeing any according to the pcm. Typically if I have a mis on a car, it's seconds to spot it with the scanner.

Tonight the plan is...back to basics: Aiming to look over the plug wires, swap a tps and probably the maf as well. Thinking I may as well swap out the map, but there's no logical reason that I can think of.
 
Had stuff come up last night. Nice thing is I think the desktop pc will stay running for more than an hour now.

Anyhow, to the white piece of dog turd. Checked misfires and found 2/5 coil to be bad. Apparently swapped a questionable one in the previous night. Fixed that and test drove.. no change to original issue. Swapped the TPS, no change. Pulled a plug. Still gapped at .060" copper core NGK TR55. Electrode slightly erroded. I'm seeing some occasional misfires and that probably explains when the rpm dip, which wasn't happening in the last trans. Still getting some upward rpm hiccups as well.

Going to toss some plugs into it and scan again for misfires. Probably pull the connector off the trans and look for backed out pins. There's no data to support what is happening and it's tough to believe that a new trans is suffering the same issue as the 194K mile one. Especially when parts of this trans have been run by me w/o issues in other cars. Problem has to be on the vehicle/engine.
 
Bill, I'll stop by tomorrow with a MAF. Text me tomorrow (won't be at work) and I'll make sure to grab it for you. We can try some things.
 
Weekend update for you guys.

I swapped the 2/5 coil as it was misfiring horribly after trying speed density (aka unplugging maf). Things got better, however Friday was still rough going with the car. I hoped that the issue had manifested itself and finally come out of intermittancy all the way. Instead of looking at the car, I diagnosed the neighbors wireless router as being dead and drank a lot of margaritas. Saturday did a trans swap on a GT and before heading out to pick up dinner, swapped the 3/6 (misfiring) coil. Since then I haven't had it act up once.

To me this means that either the 1/4 coil (which I haven't changed) was ever so slightly bad causing things to be messed up or something magically got a better connection, reseated itself or I'm having a couple of lucky days. Time will tell.

Overall it makes little sense.
 


Drive to work this morning was hiccup/problem free again. Talked to a mechanic buddy who lived GM for over 10 years. Asked if he's ever seen a spike in rpm from one bad coil, without registering misfire, and not retarding the rpm for a second like a misfire would. He said he had, it's not common.

If that's what happened here...I gotta say. That's a new one for me as well and a definate lesson on something that makes little sense. Going to keep on driving to see if it will ever do it again. Meanwhile..the shifts are stout and the car as always pulls nicely. Might be time to tune the little white Regal.
 
Wanted to conclude after some true time to prove things out.

Not one single issue since the 1/4 coil came off the car and the 2/5 and 3/6 good ones were put back on. Tossed a Gen V with 3.6 on the motor and it's all good, needs a tune though.

It appears that the "hiccup" was all caused by a bad coil. Never showed misfires. Really odd.
 
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