RPM Activating Early

[iliasfyntanidis]

Hi there guys. I have a problem with my car.The RPM Limit activates lower that it should,at 7900rpm(8500 at my pclink)

This only happens with 4th gear and onwards,basically when i try to hit top speed.With 1st 2nd 3rd the rev limit activates at 8300,as it should.(Default setting 8500 rpm)

 

Here is a pull where i hit the rev limit twice,the second time went a little higher but nowhere close 8300.

Attached the pclink and 4th gear pull.Please forward the log at 8:17......

At the dyno(Dynapack)where 5th gear was used there wasn't a problem with the rpm limit.Kicked in where it should.

Have contacted the Link team but they said that it might be noise(i have an adapter harness on the stock wires)runout from the crank...etc.

Any insight from the community would help.

The car is a Mazda Miata 1.6lt  MK2 1999 model  rated at 180bhp fully N/A  built.

Regards

Lewis

 

https://www.dropbox.com/s/af83h9gn4sptede/Mazda%20Miata%20GearTech%20Ignition%20Map%20Advanced%2CCLL%2COil%20Pressure%20Limit%2COverrun.pclr?dl=0

 

https://www.dropbox.com/s/nimm9d0iqpy845x/4th%20Gear%20Pull.llg?dl=0

 

 

[Adamw]

You will notice the trigger error counter counts up in the two places where the RPM limit is activated.  The PC logging rate isnt always fast enough to capture a small quick spike in RPM but what happens is the trigger error causes a spike in RPM above the limiter value so the limiter is activated.  You will also notice in ECU statistic that max engine RPM is recorded as 9200.

So you have a trigger problem.  Start by doing a triggerscope at idle and say 5000RPM and attach them here.

[iliasfyntanidis]

I was looking at the logs and everything that has to do with spark/fuel cut crossed my mind.I had made the program my self aand i remember that i had set the GP RPM Limit 1 in regards to oil pressure.

I think that i have messed with the axis set up on oil pressure.

The interpolation between the last two values was a bit too agressive.Have changed that also,and tomorrow i will give it a try plus the scope.

Adam what do you think?The startuo lock out matches what i see at the log.....

[Adamw]

No, as stated above you have a trigger problem.  I agree your GP limiter is not set up well, but it is not activating in the log you attached.

The log clearly shows the cause of the cut is RPM limit, and the trigger error counts up at the same time.  

 

 

[iliasfyntanidis]

Here are the 2 Trigger Scopes.

https://www.dropbox.com/transfer/AAAAAE3Sy0xZgSqVKpFkbAvQPae8ZfJo5JAgf3PxbPRUW3dhKAKh4M8

[Adamw]

Can you change to the MX5 VVT trigger mode and see if that works.  You will need to check trigger offset again.  Your cam pattern is offset quite a way from the expected pattern and it looks like one of the important sync edges may be crossing.  The VVT trigger pattern looks pretty much the same except it allows more freedom on the camshaft position. 

[iliasfyntanidis]

Yes I can Adam. My trigger pattern at the moment is the usual, 2T-1 at the camshaft and 4T at the crank not equally spaced. 

Isn't that  we are seeing at the trigger scope that I have posted the correct pattern ? What exactly do you mean that my pattern is offset from the expected? 

[Adamw]

Both the MX5 OBD2 and the MX5 VVTi use the same trigger pattern - 4T on crank and 2+1 on the cam.  The position of your cam teeth in relation to the crank teeth are retarded (shifted to the left of the trigger scope) compared to where Link's internal documentation suggest they normally are on the OBD2 car.  I tested it on the bench and I also get trigger errors if I retarded the cam that far.  The VVT triggermode on the other hand didnot give me trigger errors when I moved the cam through the range yours is in.

[iliasfyntanidis]

Problem solved. I would like to keep the community up to date and to help everyone out, as I have received help from forum members and the guys running this forum,the problem was the timing belt slack. 

[iliasfyntanidis]

On 4/1/2020 at 11:21 AM, Adamw said:

Both the MX5 OBD2 and the MX5 VVTi use the same trigger pattern - 4T on crank and 2+1 on the cam.  The position of your cam teeth in relation to the crank teeth are retarded (shifted to the left of the trigger scope) compared to where Link's internal documentation suggest they normally are on the OBD2 car.  I tested it on the bench and I also get trigger errors if I retarded the cam that far.  The VVT triggermode on the other hand didnot give me trigger errors when I moved the cam through the range yours is in.

The problem has returned unfortunately.I had the belt tight enough and for a few days i did not have any trigger errors.Although there were times that with the belt with the right tension(loose) there where no trigger errors present,so i can not extract a safe conclusion ...It was wrong(tight) so i adjusted the tension on the normal specs.

I always get trigger errors,more than ever before and i can not figure out what is going on.Lately on a typical Sunday blast for the first 30 kms(250kms in total) the engine was throwing trigger errors.As the engine was getting hotter they disappeared.

I have switched the trigger set up to MX5 VVTi trigger pattern and have adjusted the base timing again.Is there anything else that i should do with the trigger 2 VVT(cam type)on the settings?I dont have an adjustable camshaft type neither anything plugged in the ecu so what should i do....There are plenty of  options such as Inlet LH/RH and Exhaust LH/RH..Should i manipulate the offset in either way to have it centered ?

Have not driven the car since the trigger pattern change.

[Adamw]

All vvt settings should be turned off since you don’t have vvt.

[iliasfyntanidis]

Thanks Adam. Will test it on the road and get back. 

How does the VVTi trigger pattern compensates(everything is set to zero) ?I did a trigger scope and got the exact crank and cam patterns as the OBD2 pattern that I had. 

[Adamw]

The triggerscope will not change, this is just showing you the signals that the ecu is receiving from the crank and cam.

The VVT trigger mode since it is designed for an engine where the camshaft can move in relation to the crank, uses a more complex "sync test" which allows a larger margin on where the ecu expects the cam teeth to be.

On the non-vvt trigger mode the cam teeth are expected to be near the factory location and only allow a smaller deviation from the expected factory position.   Your cam teeth are not in the normal factory position.

[iliasfyntanidis]

Today with the different trigger pattern I got trigger error, upon acceleration. 

Should I change the crankshaft and camshaft sensors and the coil on plugs? 

Is it worth try? I am asking, I don't know if the trigger error has to do only with camshaft and camshaft sync. 

[Adamw]

Get us some triggerscopes at higher RPM, say do one at 5000.  Attach your latest tune also.

[iliasfyntanidis]

Adam this my latest map.

https://www.dropbox.com/s/eqn0d312fkv05uu/Mazda Miata GearTech Ignition Map Advanced%2CCLL%2COil Pressure Limit%2COverrun High Resolution 2 VVTi.pclr?dl=0

https://www.dropbox.com/s/viqob7jfvrqce6s/Trigger Scope 5500rpm 2.jpg?dl=0

 

[Adamw]

Ok, I can see why it is not happy, one of the cam teeth edges is sitting right on top of the crank edge that the ecu uses to sync.  Something a bit weird with the position of your cam teeth compared to our internal records and all pics I can find online.  Has this engine been apart?  What do they have for teeth on the cam - are the teeth part of the camshaft or are they on a disk that can be moved?  

Here's a pic from the FSM, notice the cam teeth are nicely sitting in an un-toothed area on the crank:

 

Compare to yours, the raising edge on the cam is very close to a rising edge on the crank:

 

One thing I would like you to try - switch back to the "OBD2" trigger mode, but change trigger 2 to rising instead of falling.  

[iliasfyntanidis]

Hi Adam. Yes the engine had a full rebuild. The reason for the edges of cam and crank teeth falling one each other is because it has different camshafts, so I had to time them using the lift at top dead center method. 

I have seen the original trigger pattern. 

Yesterday in a long ride with various WOTs I had plenty of trigger errors. As soon as the engine got really warm, so the belt slack eliminated the engine pulled all its gears to 8300 rpm. 

I will try what you have suggested me and if this doesn't work I will rotate the outer portion of the adjustable camshafts gear in the other direction to fit the magnets(teeth) centered in relation to the crankshaft teeth. 

May I ask if I keep the VVTi pattern and switch trigger 2 to rising what will happen? 

Thanks for the help. 

[Adamw]

24 minutes ago, iliasfyntanidis said:

May I ask if I keep the VVTi pattern and switch trigger 2 to rising what will happen? 

The VVT trigger mode already uses rising on the trig 2 but you can try falling as well if you wish.  I cant actually test it on the bench as my simulator doesnt give me enough movement of the cam signal to generate a pattern that matches yours.  But from the testing I could do, it appeared that the OBD2 mode with cam set to rising was the option that I think will give the biggest margin from edges that could cause an error.  

[Rossobianconero]

if you keep having this problem I will say that switching the trigger wheel to something that allowe you to run the engine without cam sensor, could be a good option. Just run semisecuential injection, as you already run wastespark like the stock engine. 

[iliasfyntanidis]

@Rossobianconero thanks for the input!

Well today i adjusted the intake adjustable camshaft gear.The Trigger Scope it's much better.The magnets are almost centered between the crank teeth.Even with a ruller the difference is obvious.

https://www.dropbox.com/s/fqgpjxn22lsaiea/Trigger Scope Adjusted Trigger VVTi.jpg?dl=0

https://www.dropbox.com/s/ghn65t1365ky317/Trigger Scope Adjusted Trigger VVTi 2.jpg?dl=0

This one is from an old Trigger Scope.

https://www.dropbox.com/s/viqob7jfvrqce6s/Trigger Scope 5500rpm 2.jpg?dl=0

Have not driven the car but i feel that the problem is solved,finally.As soon as i hit the road i will report back just for the record.

[iliasfyntanidis]

Runs like a champ,again!