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Schnell Gelb

Cranks but no start -Misfire

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2001 Boxster S 6 speed, 3.2L, 92,000 miles - engine recently rebuilt with many ,many new parts. Ran well.It passed Smog then a few weeks/hundred miles later started developing P0300 misfire codes for all 3 cylinders on Bank 1.

A few lifters were ticking and the engine barely ran , so I replaced all 24 lifters . Now it will not start and is over fueling. There is raw gas in the headers !

When I removed the Cams to replace the Lifters, I also found raw fuel in both headers. I assumed this was a symptom of Misfire caused by some collapsed lifters.

There is plenty of fuel flow at the Test Port.

The Crankshaft Position Sensor is new(for Smog Test)  & the tachometer bounces when I crank the engine.All the dash warning lights illuminate correctly during cranking so I 'guess' the Ignition switch is O.K.

The battery is new and tests perfectly.

The camshafts rotate when the engine is cranked(remove green plugs) .

The IMS sprocket was pinned to the shaft during the engine rebuild.

I haven't checked compression but when I rotate it by hand on the crankshaft bolt(to check timing) it seems normal.

All 6 coils and plugs are new and the car had these when it passed Smog recently.

The SAI system was fixed prior to the Smog Test.

I have not checked/replaced the camshaft position sensor. They seldom seem to fail.

When the Bank 1 camshafts were off the engine I confirmed the 'window' for the camshaft position sensor was not bent nor loose.

I can check to see if there is a complete blockage of the inlet system. I mention this because I did replace the Airbox with a CAI prior to the Smog Test and it ran well.

I have checked many times that I reconnected (after replacing the Lifters) all the connectors for the Variocam solenoids, O2 sensors, oil pressure sensor, camshaft sensor,crankshaft position sensor.

The car sat for around 2 months while I did the Lifter work. The Ignition key remained on the dash but not in the ignition switch throughout this period.

The car was in a garage so the immobilizer did not get wet and has never been wet.

The new  battery remained fully charged throughout. I did do the Initialization procedure when I tried to start it but only after building oil pressure(remove fuel pump fuse C4).

  * Is there some technique with Durametric during cranking to  help pinpoint the problem ? In the past, I have only used Durametric with the engine running.There are no codes yet because the engine will not start. There must be some Freeze Frame that would show a total failure of the Ignition system?

What am I missing ? DME checks?

Any helpful suggestions would be most gratefully received.

Thank you.

 

 

Edited by Schnell Gelb

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Danke schon !

All 6 injectors were rebuilt during the engine rebuild. I did buy a new one recently because I wanted to compare it with my rebuilt part. No difference. I fitted the new one anyway.It ran perfectly.

Nevertheless, your suggestion is a possibility to investigate. Thank you.

Edit : Wizard had a point regarding the Misfire.See below for flooding of cyl 1 with gasoline. Remedy is easy -6 new upgraded Bosch injectors. For once  , a simple job on the M96 !

Edited by Schnell Gelb

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A few things come to mind. They may not be coherent...

- Checked fuses C1-C4 and E1?

- coolant temp reading correct?

- have you tried e-gas calibration?

- have you checked for sparks when the engine doesn't fire up?

- retiming of bank 1...360 degrees offset of bank 2 was ensured?

- No special tricks in Durametric AFAIK during staring

- Perhaps worthwhile to check for compression in firing order

- Have you tried with no MAF?

- What's the MAF voltage reading with key ON engine OFF? (should be 1.1v or so)

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On 9/18/2017 at 11:16 AM, Ahsai said:

A few things come to mind. They may not be coherent...

- Checked fuses C1-C4 and E1? Yes , all good

- coolant temp reading correct?  Ambient temperature around 70 degrees F

- have you tried e-gas calibration?  Yes, did the 60+ seconds ignition on ,then 10+seconds off routine before cranking

- have you checked for sparks when the engine doesn't fire up? Yes , I made a special tool to do this with the spark plug still fitted in the engine and an old ,good coil+ a flashing spark plug tester.

- retiming of bank 1...360 degrees offset of bank 2 was ensured? I think Bank 2 timing may be the problem -see the Post following.If not I'll progress to the other issues you kindly mentioned below.

- No special tricks in Durametric AFAIK during staring

- Perhaps worthwhile to check for compression in firing order

- Have you tried with no MAF?

- What's the MAF voltage reading with key ON engine OFF? (should be 1.1v or so)

There are 5 conductors connected to the MAF .Identify them from Bentley Wiring Diagrams page : EWD-117-14

Here are the readings for all Key On ,Engine Off. You will need insulation piercing needles for this

WH/BU  - signal + 1.03v

RD/VT  - reference Volts 5.77v

BN/WH - Ground

RD/BU  - Supply volts  13.09

BU/GY - Temp Sensor at 70 degrees ambient 5v

 

 

 

 

Edited by Schnell Gelb

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In a Post much further down this page is a drawing explaining the problem. Hopefully it will save a lot of ambiguous words. The sketch needs better computer drawing skills than mine ! Feel free to improve them for other Forum members to understand & use..

Column 1 of the dwg  is the starting point for all M96 camshaft timing.

This Post refers to the 986 Boxster. There are some confusing differences with the 996 because of the backwards engine orientation there . I invite  the 996 guys to plagiarize this and re-write for their needs.

When we discuss problems with M96 timing we get confused with terminology ,orientation and engine positions. So why not use a picture?  

Just copy the dwg below and draw in your ‘notch’ positions when you remove the “green caps” Then it is much easier for the smart guys to help you. I am not in that group hence the clumsy sketches below.

If the dwgs confuse you ,I suggest you read more of the basic camshaft timing Instructions first. Sadly we lost Insite’s images with the hosting problem. So this may help ?

Basically it is all about camshaft notch positions at TDC. And specifically the confusingly similar right/wrong orientation of the2  Ex Cam notches.

These dwgs help with checking  a camshaft R&R with the engine still in the car. You CAN NOT see the camshaft notches directly because you can not get a direct line of sight. I have used a Smartphone on a selfie stick but such photos are useless unless you post alongside them all 4 positions. Nobody does this. Now you can- easily.

The Inlet camshaft single Notch is easy to observe in the car.  The difficulty is the Exhaust Cam notches.

There is one trick tool = LN9612 required to confirm the  position of the 2 asymmetric notches at the end of the exhaust camshaft. Do not try to eyeball this unless  the engine is out of the car IMHO. You need just the black ‘puck’ from the 9612  tool with the offset ‘rib’ across it’s diameter. It will only fit one way on the end of the EX cam. Go /No Go. Just note which way round  it fits and we’ll be able to confirm if you have reassembled your camshafts (in)correctly. Do not try to just use the cam retaining tool for this purpose unless you are an expert. I made that mistake several times and got lucky .More recently, my luck ran out……

I used the LN 9612 tool to make the dwgs below so it will be a good test to see if the experts can quickly diagnose my mistake.There is a photo in later posts of 9612.

Do all these observations without rotating the engine. We need all 4 quadrants completed at the same TDC position. Once you have done all 4, you can rotate 1 full turn of the engine(not the cams - they rotate only 180 for each 360 of the crank)and re-draw. But note this in your Post. All my dwgs  below are in the same ,locked TDC position.

 

 

Bank 2 is the problem. You need to observe and note the Inlet cam notch via the Access Plate in the Firewall. Maybe feel it from underneath ? See dwg for details.

The greater difficulty is the Exh. cam notches because of obstructing cross-member and other parts. You can’t get even close to a direct line of sight and no other tool except the puck will fit correctly. Yes, I tried !

Dwg shows the orientation on my “Cranks ,but no start” engine rebuild. Note the notches are deceptively vertical BUT the  important distinction is where the smaller segment of Bank 2 Ex cam is . Is it closest to the Cam Cover(outside of car) or the crankshaft(inside of car) ?

Yes ,this is mind numbingly geekish but it will save you if you check this before you fit the Cam covers but after the Tensioners are refitted.

I hope this helps. Feel free to improve for others to benefit. Did you spot the mistake btw?

 

Here is a link to some useful photos from Nutrod for those unfamiliar:

http://www.nutrod.com/Nutrod/Pics/Pages/Install_Head_4-6.html

There is a great Thread by Insite on the 986 Forum but Photobucket dumped all his photos !

http://986forum.com/forums/performance-technical-chat/26418-diy-setting-cam-timing-m96.html

 

 

 

 

 

Edited by Schnell Gelb

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Yup, bank 1 and bank 2 should be offset by 360 degrees crank angle and you should only be able to fit the cam lock tool to ONE of the banks  at a time. Looks like you could have fit the tool in bth banks above (barring slight misaligment).

 

To further convince yourself, I suggest you remove all the spark plugs and check compression of each cylinder one by one following the firing order. If your timing is correct, you should get compression of each cylinder in the correct order. With your existing timing, I believe you won't (two opposing cylinders will compress simultaneously).

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Ahsai,

Thank you for responding so helpfully and promptly. I'll get right on it.

I have already confirmed that all 4 cams rotate when the engine is turned over - hey you never know !

I do want to emphasize that the tool LN or Baum 9612 is the key to verifying the correct orientation of the Exhaust Cam notches with the engine in the Boxster. Using other tools particularly the flat "E" shape retainers can be  misleading. They are virtualy impossible to fit with the engine in the car anyway.The smaller "C" shaped tool is also inadequate.

This is the best link I could find to help others identify Porsche tool # 9612 among all the other Baum tools.

http://www.ewktool.com/porsche-986-996-engine-timing-camshaft tool

Click on the thumbnail photos until you find the tool.You need to extract and use just the black "puck" with the offset rib . It is the perfect go/no-go gauge for M96 Cam setting with the engine in the car.

I recall you recommending a TDC compression whistle some time ago.Since I work alone, that may be helpful.Innovative Products # 7894 may work well.

One challenging issue is the procedure for correcting the timing problem. The convention is to rotate until Bank 1 cam notches are  correctly oriented and then to remove the Bank 2 cam cover to rotate it's cams to the proper position. The problem is that Bank 2 is more difficult to work on because of the a/c compressor obstructing the chain Tensioner and other obstructions.

I may try to lock at TDC with Bank 2 correct so I can work on the easier Bank 1 side.

To do that correctly it will be essential to use the  cheat chart  below to verify all 4 notch notch positions are correct. And use the whistle before replacing the cam cover !

Thanks again and I hope the extra details help others.

Edited by Schnell Gelb

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Yes, that whistle works very well. If the problem is truly the 360 degrees offset, correct either bank should work.

 

Btw, I thought you got your missing variocam solenoid spring fixed sometime ago and everything worked well afterwards? What happened?

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You are correct .The engine ran beautifully after Porschetech 3 kindly supplied the missing spring.It sailed through the Smog Test.Then the ticking and misfire began.And the misfire deteriorated to the point the engine barely ran .So I was thinking that collapsed lifters that may have been the cause of the Misfire . I discovered  several new INA lifters had collapsed and could not be restored by pumping when immersed in oil. So I replaced them all.Yes, all 24 ,both sides.

I wish I knew what else happened.

Below is a photo of the puck from 9612 and the Cam Notch orientation chart.

Edited by Schnell Gelb

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9612.jpg.thumb.JPG.1bd0a2bcf55a0900cf33c11ec031d43f.JPG

Below is a comparison chart of the Camshaft notch /Timing issue .

The Chart  has 3 columns and 2 rows.

The top row is the Intake Cam notch position at TDC for Bank 1  and Bank 2. Note the "C" shape and its orientation -normal or mirror image.

The bottom row shows the corresponding  Exhaust Cam notches for Bank 1 & 2. The Exh Cam has a pair of OFFSET notches.These create to unequal segments.

The left hand column is the usual starting point for checking cam timing.

Lock the engine at TDC with the Bank 1 Intake cam notch at 3 p.m. , with the single notch facing away from the crankshaft/toward the Cam cover/outside of the car. This is shown at the top row of the left hand column. The diagramatic representation looks like the letter "C".

Now look at the Row beneath this , the bottom row is the orientation of the  Exhaust cam notches. Look at the bottom left dwg for Bank 1  -this is located close to the water pump area. It is viewed  facing toward the rear of the car with the water pump on your right side. Note the smallest part of the crescent is adjacent to the Cam cover. The larger part of the segment is adjacent to the cylinder head. This cam cover/crankshaft orientation is noted on all the dwgs for clarity.Verify with  Porsche tool # 9612-not eyeball.

The center column shows the orientation of the Intake and exhaust cam notches on Bank 2 of the problematic "crank, but no start engine". Note the Ex cam notches  are  NOT a mirror image of Bank 1. This is my current situation verified by using Porsche tool  9612.

The right hand column is a speculative, alternative (correct??) orientation .

Which is the correct column? Jake Raby should use this as a Final Exam question for his M96/M97 engine rebuild class - oh how I wish I could attend it !

BTW , if you have a FSM the relevant Section/pages are 15-51 for the Inlet Notch 1-3 Bank 1, for 4-6 Bank 2 it is 15-23 & 15-69 .

I think the "cranks but no-start " clue is in the center column, bottom row. It should be like the right hand column,bottom row.

One other clue is the engine is stiff to rotate near TDC even with plugs removed (bent  valves on the exhaust side of Bank 2?)

I am hoping for a simpler explanation.

How can one cam be 180 cam degrees out and the other 3 perfect ?

 

Boxster Timing Problem_20170924.jpg

This is the 'puck' from 9612 below.The rib is marked in green for clarity.

9612.jpg.thumb.JPG.1bd0a2bcf55a0900cf33c11ec031d43f.JPG

Edited by Schnell Gelb

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If your timing was correct, you start at column 1 reading, rotate the crank 360, you should see column 2 on bank 2.

 

However,  since your columns 1&2 were taken at the SAME TDC without crank rotation, you have the classic problem of failing to turn the crank 360 before timing (and installing the cams) on the second bank. The engine will run on 3 cylinders only.

 

This issue should not have caused valves damage though but I'm not sure why the engine is stiff when it's close to TDC (with the spark plugs removed).

Edited by Ahsai

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BTW, super easy to verify CORRECT TIMING with any TDC tool. Start with TDC for cyl #1 (like your 1st column). It's actually TDC overlap (as opposed to compression) for cyl #1.

 

Put a TDC tool in cyl #3. Rotate crank 120 degree, cyl #3 should be at TDC (compression).

Then put the TDC tool in cyl #5, rotate crank 120 degree, cyl #5 should be at TDC (compression).

Repeat the above for cyl #1, #6, #2, #4.

 

Firing order 1-6-2-4-3-5

 

With your current TIMING, I expect #1&#4 to hit TDC compression simultaneously. Similarly for #2&#5, #3&#6.

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Thank you Ahsai !

To help others follow I have separated the reply into distinct parts.

" per the factory shop manual, we want to be at TDC compression when we time bank 1 (cylinders 1-3) and TDC exhaust when we time bank 2 (cylinders 4-6)."Insite.

So we need to confirm the piston stage/compression/overlap in #1 .The tools required are mentioned in Posts above and alternative methods below.Best to double/triple check otherwise ....
 

Below is a link that shows the cylinder numbering - so you know which  place to  put the TDC tool into ! Note the helpful comment by Loren comparing the M96 as fitted to the 996 vs the 986. We are discussing Boxster 986 here.Look for the color chart buried in a few Posts in this Thread below.See the April 12 post by Domiac to find the color chart.This is important because you must make the distinction between "TDC Compression" aka TDC firing = top of compression stroke and all intake and exhaust valves for that cylinder are completely closed and tht spark plug has just fired.  TDC overlap (aka TDC Exhaust) is when all the valves are slightly open .Specifically, the 2 exhaust valves of that cylinder are almost closed and the 2 inlet valves are just beginning to open. There is one complete revolution of the crankshaft between the two events.

If the chosen cylinder is at TDC  and you need to know if it is compression or overlap you can refer to the chart or try using a leakdown tester on that cylinder. In theory TDC compression allows very little/no air to pass .

TDC Overlap would allow air leakage through both the intake and exhaust systems because all the valves of that cylinder  are slightly open. If you try the leakdown tester -  compare Cyl #1 with Cyl # 4. When #1 is TDC compression, 4 is TDC overlap(slight leakage) .When Cyl 1 is TDC Overlap, # 4 is TDC compression.The color chart shows this clearly for our 6 cylinder engine.

This dwg below shows the chains and cams for a 5 chain engine.The 3 chain is similar. It helps explain Ahsai's point about setting the timing and avoiding being 180 out.

image.gif.ffe32b690edae35a2249f39f4097eb46.gif

 

 

Edited by Schnell Gelb

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I added the MAF voltage readings in bold type to Ahsai's basic troubleshooting questions in the appropriate Post higher up the page,

Doing the Maf test is a good opportunity to remove it,clean it, check that you have the latest part number for your Model Year - yes it varies by year !

Mine is # 986 280 218 055.

Some discussions elsewhere mention ECU Doctors found an advantage in using the 996 # if your car is modified.

 

 

Edited by Schnell Gelb

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Here is the simple dwg of the Cam notch positions with the crankshaft rotated 360 from the basic timing starting point shown in a previous Post in this thread.

Boxster Bank Two Camshaft Timing.pdf

It seems I do not have a timing problem according to the cam notches in the PDF attached..

The next task is to verify with the various TDC tests on each piston position.I'll report how useful the leakdown tester is in distinguishing between TDC Compression and TDC Overlap.I'll do this at the weekend.

Edited by Schnell Gelb

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Way too technical for me, but a superb reference document for those with the necessary patience and dexterity .... and one of the reasons why RennTech stands head and shoulders above others.

 

The best of luck.

 

 

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Thank you for your encouragement. I prefer the open source ,collaborative approach and am grateful for the support of this Forum and particularly Ahsai & JFP.

The tiny details may seem trivial to some readers - until they also need them ! For our International audience, the diagrams, photos & drawings are even more important.

I admire you using a foreign language Forum for your Porsche . Is there a German equivalent to Renntech?

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Actually, I'm an Englishman living in Germany and, with my extremely limited knowledge of technical German, I'd probably end up with 4 cylinders on one bank and 2 on the other :-)

Edited by wizard

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I figured out my mistake.

When fitting the 4-6 cams on Bank 2 , I did rotate the crankshaft 360 degrees after setting Bank1 . BUT....then I fitted the cams exactly like Bank 1 with the Intake cam notch facing outward(toward the Camshaft  Cover).Arrrgh ! It should have faced inward toward the crankshaft.

I deleted a previous drawing in this Thread and will post a simpler cheat sheet over the weekend.

I won't publish until the engine is running.

I now have to dismantle Bank 2 - again .It is the worst of the 2 sides to do. But it seems I need the practice ! I sure won't forget this brutal lesson .

 

Edited by Schnell Gelb

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9 hours ago, Schnell Gelb said:

I figured out my mistake.

When fitting the 4-6 cams on Bank 2 , I did rotate the crankshaft 360 degrees after setting Bank1 . BUT....then I fitted the cams exactly like Bank 1 with the Intake cam notch facing outward(toward the Camshaft  Cover).Arrrgh ! It should have faced inward toward the crankshaft.

I deleted a previous drawing in this Thread and will post a simpler cheat sheet over the weekend.

I won't publish until the engine is running.

I now have to dismantle Bank 2 - again .It is the worst of the 2 sides to do. But it seems I need the practice ! I sure won't forget this brutal lesson .

 

 

Don't be hard on yourself, this is not that uncommon a mistake for someone doing this for the first time.  Fecal matter occurs, just be happy you have not caused bigger problems. :beer:

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Thanks JFP.

To make matters worse - I have done this xact job succesfully several times. The excuse was - I was working late at night while distracted with unrelated issues.

Whoever  said this job with the engine in the car was "like building a ship in a bottle" - was a wise man.

I could have R&Rd the engine and times many times ......

Yes, you can physically do this job in situ but access and visibility handicaps create many other issues.

One other problem recently mentioned elsewhere is using slightly too much (+incorrect type) sealant on the cam covers. The surplus gets squeezed out inside the cover. There it can easily block the oil-return passageways. If you are 'lucky' the blockage is so severe it blows out the green plugs as a warning. If the blockage is only partial you may get oil starvation issues, the cam cover will be half full of oil,will leak, the spark plug tube seals will leak .........  Interesting hidden problem that could be difficult to diagnose ? Any related experiences ?

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Using too much sealant is a common DIY problem on these engines.  Along with blowing out the cam plugs, we have seen oiling issues that were traced to a spaghetti like clog of the main oil pickup in the sump from the excess sealant that breaks off.  As others have noted, first the mating surfaces must be scrupulously clean, and then only the bare minimum (a couple of MM) of sealant applied.  Unfortunately, trying to work on these surfaces while lying on your back with oil dripping in your face, and while you can't even properly see the surfaces, leads to a multitude of issues.

 

Along with blocking oil passages, when too much sealant is applied, subsequent repairs become problematic because the covers are not just sealed, they are cemented in place.  When that happens, people end up breaking the cam covers trying to get them off.  Then they discover that you cannot just substitute another cover because the cover and cylinder head is machined as a unit.  Now you are in the market for an entirely new cylinder head assembly, which is both a major pain as well as a major expense. 

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13 hours ago, Schnell Gelb said:

When fitting the 4-6 cams on Bank 2 , I did rotate the crankshaft 360 degrees after setting Bank1 . BUT....then I fitted the cams exactly like Bank 1 with the Intake cam notch facing outward(toward the Camshaft  Cover).Arrrgh ! It should have faced inward toward the crankshaft.

 

Sounds like it. BTW, TDC whistle is a great sanity check to avoid this (and the 360 offest) mistake. I did the whistle test before sealing the cam covers when I rebuilt my engine even though I was 99.99% sure I timed everything correctly.

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      Hope this helps save you the hour or so of searching in your 986 Tiptronic for the CPS.  Remove that O2 sensor harness first and you'll save a bunch of time and frustration!
       
    • By bourski22
      My 2005 Cayenne (190k miles) had been misfiring and running rough. I’ve replaced the plugs and coils, which cleared numerous misfire codes. It starts and idles fine, but at around 3500 rpm, it labors to shift, chokes or runs rough, and occasionally dies completely.  Durametic gives codes p0335-p0337.  So, my question is, does anyone have detailed instructions (a video link would be awesome!) for replacing a CPS?  I have the service manual instructions, but have to admit they aren’t very instructive and the pictures are really “uninspired”.  I ordered a new CPS from Amazon, but sure can’t find anything under the hood that looks like it.  Help!
    • By logray
      I'm troubleshooting an issue with random rough running values below 2.0, infrequent and random hot re-start idle stumble (difficulty holding 680rpm momentarily), and stalls once or twice after hot and idling.
      I've already located the specs for the crank sender and ohmed mine out at 839 at 50F, which I understand is within spec of 800-1000 ohms, however closer to the "tired side" as I've read people with new sensors have read closer to 950 ohms. I plan to artificially heat the sensor and re-test.
      I'm hoping it's not an issue with the DMF, but want to also rule out the cam senders as well. I think I will replace the crank position sensor regardless, since it is a $100 or so part and easy to get to.
      I can't find any specs on what the cam position sensors should ohm out at or which pins to test.
      Thanks in advance if someone has those specs.
      (no codes of course). ;)
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