S13 KA24DE crank angle sensor issues.

[FlatBlackIan]

Ok, so. My car is in time out right now after stranding me last night. She got to ride home on a flat bed.

Heres the skinny.

A few minutes after the engine reaches operating temperature, it will begin to misfire badly. Wideband reads full lean.

If I try to keep it running, the problem will get worse until the engine dies. Once the car is allowed to cool for 30 - 40 minutes, it will restart and idle normally for a short time. As engine bay temps go back up, the problem will re-appear.

Here is what I know. The crank refference signal drops out at operating temp. It fases in and out, causing the tach to bounce. As temps increase, the signal spends more time gone then there until the engine refuses to run.

With the engine idling at operating temp, and begining to show signs of signal degredation, I can bring things back to normal by pouring cold water over the base of the distributer. This narrows it down to a problem with the CAS.

Has anyone ever disassembled a failed distributer and attempted to fix it? Anyone else ever experienced this issue? I just ordered 2 more distributers, but I would like to attempt to fix this one in the mean time. I have a race in less than 3 weeks, so I need the car running and reliable.

Backround on the car.

1991 240SX stage rally car
KA24DE 12:1 compression
Link G2 standalone EMS

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%204/6250558064_0e3d9f81f5_b.jpg

[PureRush]

Wow I had a whole paragraph typed up and I accidentally closed the window. So basically the problem is not your distributor so dont replace it until after your car is fixed cause your timing is fine how it is. With an excessive amount of heat, any component will fail. Since you have a wideband, it gives us alot of crucial info. So heres the deal:

Our engines dont reach optimal operating temp after a few minutes. You think the engine is getting too hot but thats not the problem. The first few minutes after you start a cold engine I goes into what you call an Open Loop operation. This makes the engine run super rich for a few minutes until the computer completes its own check list. For this short period of time the ECU ignores the O2 Sensor, MAF Sensor, and Coolant Temp Sensor and runs the A/F Ratio Richer than normal. If you record the time from cold start till it starts misfiring, I bet you it will be at the same exact time as before.

After a certain amount of time and when the sensors have reached correct operating temp, Closed Loop starts and the ecu uses those three signals to determine the A/F Ratio. Your problem is that you have a malfunctioning sensor which is telling the ECU that your car is running rich when it's not. Its leaning out the A/F Ratio causing the combustion chamber to retain excessive heat which causes pre-detonation not a misfire. The source of your problem is the O2 sensor. It's either dirty or the built in heater circuit is broken. I wouldn't bother testing it with a Digital Multimeter, just go pick up a new sensor from your local auto parts store. Personally I would perform a compression test when the engines back to normal to see if it suffered any severe damage. Get back to me and let me know how it goes :)

[FlatBlackIan]

Wow I had a whole paragraph typed up and I accidentally closed the window. So basically the problem is not your distributor so dont replace it until after your car is fixed cause your timing is fine how it is. With an excessive amount of heat, any component will fail. Since you have a wideband, it gives us alot of crucial info. So heres the deal:

Our engines dont reach optimal operating temp after a few minutes. You think the engine is getting too hot but thats not the problem. The first few minutes after you start a cold engine I goes into what you call an Open Loop operation. This makes the engine run super rich for a few minutes until the computer completes its own check list. For this short period of time the ECU ignores the O2 Sensor, MAF Sensor, and Coolant Temp Sensor and runs the A/F Ratio Richer than normal. If you record the time from cold start till it starts misfiring, I bet you it will be at the same exact time as before.

After a certain amount of time and when the sensors have reached correct operating temp, Closed Loop starts and the ecu uses those three signals to determine the A/F Ratio. Your problem is that you have a malfunctioning sensor which is telling the ECU that your car is running rich when it's not. Its leaning out the A/F Ratio causing the combustion chamber to retain excessive heat which causes pre-detonation not a misfire. The source of your problem is the O2 sensor. It's either dirty or the built in heater circuit is broken. I wouldn't bother testing it with a Digital Multimeter, just go pick up a new sensor from your local auto parts store. Personally I would perform a compression test when the engines back to normal to see if it suffered any severe damage. Get back to me and let me know how it goes :)

I hate to be that guy lol, but reading pwns you today.

While you would be dead on with your diagnosis under normal circumstances. This situation is anything but normal. Trust me, I understand all the nuances of open/closed loop control, fuel trims, o2 switch time, and anything else to do with EFI, its my job. I am a mechanic, and I specialize in diagnostics. Thats why this situation miffed me so much that I spent half a day banging my head against the wall.

First things first, I dont have a MAFS. The Link G2 is a MAP based system. Technically its an MGP system because it moniters barrometric pressure as well as manifold pressure.

At the moment I am still in break in mode. The car runs in open loop all the time, relying on my base fuel and timing maps, with a little adjustment provided by ECT, and IAT.

When I said "a few minutes after reaching op temp" I mean I can drive 10 or so miles until the car reaches operating temp, then park and let it idle. Around the same time cooling fan kicks on (90c) the misfire will appear.

I can physically watch the crank refference on the computer begin to degrade. The Link uses the crank signal to determine when to fire the injectors, as well as calculate engine speed. The Cam signal is only used to determine which cycle the engine is on.

When the signal begins to phase in and out, the ECU fails to fire the fuel injectors. This is causing the misfire, and lean condition.

Using an infared thermometer, I checked cylinder head temps, block temps, manifold temps, as well as the temp of the distributer. Everything is normal, no hot spots, and the dizzy never got north of 100f. I should also mention that I am running E85, so cylinder head temps are actually lower then normal.

So my origanal question stands. Has anyone ever disassembled, or attempted repair on a Nissan opto 360 distributer? I have 2 more dizzy's on the way to me, but I would prefer to fix this one to have a backup to the backup.

[FlatBlackIan]

Well, its official. There are lots of similar parts inside of SOHC, DOHC, and S14 KA24DE distributers, but nothing directly crosses over.

S14 on the left, DOHC S13 in the middle, and SOHC S13 on the right.

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_12-40-11_69.jpg

Caps, rotors, and dust covers removed.

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_12-44-42_148.jpg

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_12-48-18_344.jpg

A close up of the 2 S13 units. The S14s internal coil ruled it out as a canidate early on. I continued to disassemble it for posterity.

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_12-48-26_45.jpg

Hall wheels, and optical sensors removed.

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-04-16_419.jpg

S14

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-04-26_997.jpg

DOHC S13

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-04-31_711.jpg

SOHC S13

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-04-37_676.jpg

The Hall wheels. They are all identical save 1 thing, the orientation of the inner ring of slots.

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-06-27_999.jpg

The sensors. All of the actual pickups are similar, most likely identical internally. Besided location of the wiring plug, the S13 sensors are nearly identcal. They share bolt spacing, and pickup style.

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-09-37_153.jpg

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-09-54_508.jpg

I attempted to disassemble the sensor itself, in hopes that I could swap pieces between the 2. Sadly, once assembled, they pack the whole thing with resin, and it becomes one piece.

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-49-10_828.jpg

http://i215.photobucket.com/albums/cc96/drnenappes/Rally%20Car%205/2012-06-08_13-49-19_640.jpg

I wonder if a person could just buy a new cam/crank sensor. Its easy enough to remove. Time to do some searching.

[PureRush]

Dude you could have included that you are a diagnostic specialist so I didn't have to go in depth smh. And you're wrong the Cam Sensor controls both FUEL and spark. Just replace the whole unit but if the problem persists check the wiring

[FlatBlackIan]

Dude you could have included that you are a diagnostic specialist so I didn't have to go in depth smh. And you're wrong the Cam Sensor controls both FUEL and spark. Just replace the whole unit but if the problem persists check the wiring

Sorry lol, I figured the mention at the end about running a Link G2 EMS would have made you aware that things weren't exactly stock.

Yes, you are correct about the crank refference also controling spark timing, but thats a moot point. The o2 sensor registered o2, so even if the fuel injectors were firing, but the coil was not, it would still read lean on the UEGO.

You can run injectors wide open, but if none of that fuel is ignited, then everything reads lean.

If it makes you feel any better, I have gone through the trouble of typing out big novels of text only to find out I am beating a dead horse, and the person wasn't as special ed as a lot of typical forum users lol.

In other news, when I tore it apart, it was pretty obvious that the hall wheel had been rubbing on the pickup for some reason. There didn't seen to be an abnormal amount of shaft play, but there was some. I am guessing this is why the problem was getting worse.

[mxexux]

...Excuse me if it has already been stated already, but....Why did you order 2 dizzy's that you can't use?

You said you found some evidence of the sensor wheel rubbing the pick-up. Looks like its worth replacing. Try the junk yard if you need it quick.

[PureRush]

I just noticed that your distributors are all Hall style. When I took my cap off mine it was a magnetic pickup. I have a 91 kade

[FlatBlackIan]

...Excuse me if it has already been stated already, but....Why did you order 2 dizzy's that you can't use?

You said you found some evidence of the sensor wheel rubbing the pick-up. Looks like its worth replacing. Try the junk yard if you need it quick.

No, those 2 were just stuff I had laying around. The car used to have an SOHC in it, and one of my spare motors came out of an S14. Trust me, you dont want to see my spares pile. Rally is destructive, I have a full rolling shell backup, another full set of suspension including all control arms and subframes, 2 extra diffs, 2 spare sets of axles, 3 drive shafts, 12 extra wheels, 3 starters, 2 alternators, water pump, 2 radiators, and shelves full of misc other stuff.

I ordered up 2 S13 DOHC distributers. One to use, and one as a spare.

I just noticed that your distributors are all Hall style. When I took my cap off mine it was a magnetic pickup. I have a 91 kade

Strange, I have never seen that before, are you sure? Nissan has used an optical 360 degree trigger setup on most everything from the mid 80s all the way through to the late 90s, and on some vehicles all the way into the 00s. I can't think of a single Nissan that uses a reluctor trigger setup from that era. Even my 1986 hardbody with the Z24 uses a optical setup. The SR, KA, VG, GA, and VHs all used nearly identical optical setups weather they are direct spark, or distributer. The RB, and CA are the only motors Im not sure on, but I would bet they use the same system. The only things I know for sure use reluctor are the QR and VQ, because the are flywheel based, and I have had to replace way too many of them.

[AdamR]

The wheels and sensor aren't a hall type, they are optical.
Does the Link ecu have any issues with the optical shutter wheel?
I am using a MegaSquirt and had to change the wheel because the CPU couldn't handle the 360 slits in the wheel.
With that wheel, there is a way to wire the board to trick it into thinking the inner slits are a crank signal and the outer slit is a crank signal. So did you add at crank wheel to your car or are you running it that way?

[silver350z05rb]

awsome info.............but my head just exploded with all your awsome info and pics!!!!!

[FlatBlackIan]

The wheels and sensor aren't a hall type, they are optical.
Does the Link ecu have any issues with the optical shutter wheel?
I am using a MegaSquirt and had to change the wheel because the CPU couldn't handle the 360 slits in the wheel.
With that wheel, there is a way to wire the board to trick it into thinking the inner slits are a crank signal and the outer slit is a crank signal. So did you add at crank wheel to your car or are you running it that way?

The way I have the Link is set up, it uses the wide slot on the on the inner ring to provide engine position, (cam signal) and the outer slots for rotational refference. So the ECU knows the engine is running, even in the gaps between the other slots.

It was working great, right up until it wasn't.

[PureRush]

The wheels and sensor aren't a hall type, they are optical.
Does the Link ecu have any issues with the optical shutter wheel?
I am using a MegaSquirt and had to change the wheel because the CPU couldn't handle the 360 slits in the wheel.
With that wheel, there is a way to wire the board to trick it into thinking the inner slits are a crank signal and the outer slit is a crank signal. So did you add at crank wheel to your car or are you running it that way?

Hall type potentiometers are optical lol

[Walperstyle]

From the few of us at KA-T . org. Thanks for posting this information. Its nice for people to compile what they find. I've noticed some odd differences as well, but nothing in this area.

Thanks.

[FlatBlackIan]

Hall type potentiometers are optical lol

Well.......

A reluctor based pickup is a Hall effect sensor, and its not optical.

The system Nissan uses is optical, but its also sort of a hall system, but only in the broadest sense. A varying voltage is created by the optical sensor, but its not created by changes in a magnetic field. It would be difficult to differentiate between the two on the electrical level, but the Hall Effect is a technical name for the reaction of a ,now named, Hall Effect sensor to changes in magnetic field.

This could get very sticky very fast, as its a complicated, and boring subject, so lets just agree that we were, and are, all wrong.

I repeatedly called it a Hall system, but I may or may not have eaten a retard sandwich or two over the last few days.

[abcdefg123]

I need a step by step kindergarten picture version of how to wire the " crank position sensor trigger?" Megasquirt