Won't rev past 6285rpm!

[beachbuggy61]

Calling on the collective experience...

Can anyone please tell me why it won't rev past 6285rpm?

It acts like it is hitting a rev limiter but I can't find anything in my tune that has a limiter function set at these revs.

Please see the tune attached.

Thanks in anticipation.

Marc.

[DaveEFI]

IIRC, EDIS has a built in rev limiter. Not sure what revs it happens at, though.

[shadowplane676]

I believe there hasn't been anything actually found on the EDIS modules indicating they have a rev limiter. I have run 3 different v6 EDIS modules to 7200rpms. Might be worth digging up another module just in case.

Also, do you have a log of it when it is hitting this "limiter"?

[kjones6039]

Well, here goes another one of my unsolicited rants.............

It has been widely reported in the ms community, that various EDIS modules experience problems (generally) in excess of 6000 rpm.

My experience:

383 cu. in. sbc easily capable of ~7000 rpm
EDIS-8 module w/ timing controlled by ms2 Extra Code

This installation ran very well until the rpm exceeded ~6200 rpm. The shutdown was not only rev limiting, but absolutely violent! No amount of tuning, adjusting, etc. ever relieved the issue.

My fix was to very carefully place the EDIS-8 module into the trash can! I then installed a 4 coil driver board from JBPerformance and let ms drive the coils!

In the interest of fairness, EDIS is a very robust system and I would recommend it to anyone who would not be constrained by it's well documented limitations.

Bottom line............ I would not use EDIS on an installation that needed to regularly exceed 6000 rpm. MS is capable of everything EDIS offers and more!

Just one old guy's take on things of course.............

Ken

[beachbuggy61]

Hi,

Thanks for the thoughts Ken. It certainly sounds like my experience is backing up what you say.

You suggest placing it in the bin (that's what we call trash can here in Australa!)and replacing it with a board from JBPerformance. Is that an easy thing to do?

I'm not good at the electronics so do you think I should try another EDIS module first and see if that has the same issues? Might be an easier first step.

I have attached here a datalog that shows when it happens. Spark does what it is supposed to according to the spark table so it doesn't look like it's retarding to act as a limiter.

Given it can only really be fuel (plenty of fuel), mechanical (good valve gear set up right) or spark, so I'm thinking spark!

Thanks again,
Marc.

[billr]

What's going on with the MAT? I'm guessing your problem is related to that huge spike in MAT, with resultant drop in Gair and Gammae.

[kjones6039]

You suggest placing it in the bin (that's what we call trash can here in Australa!)

Thanks Marc! I'm always eager to learn another language!

replacing it with a board from JBPerformance. Is that an easy thing to do?

Jean's board only requires some basic soldering. If you are not comfortable with that, I suspect you probably know someone who could help you with the soldering. In addition to the board assembly, you will need to build a simple wiring harness to make the connection to your coils. You can take a look at the board along with the Assembly/Installation instrutions here: http://jbperf.com/quad_ign_inj/index.html In your case you will only need 2 out of the 4 drivers that are available. I think this is a particularly good choice for a user who might have only basic electronic skills.

do you think I should try another EDIS module first and see if that has the same issues?

I would not, but that will have to be your choice, of course. I suspect I will get flamed for this, but I doubt that the results will be much different, IMO.

I have attached here a datalog that shows when it happens.

At this point I have to echo billr's concern regarding your MAT! IMO (again!), I would find out what's going on there (and correct it) before proceeding!

Given it can only really be fuel (plenty of fuel), mechanical (good valve gear set up right) or spark, so I'm thinking spark!

Get the above corrected and then we can revisit this.

Hope this helps a little!

Ken

[beachbuggy61]

Thanks for the thoughts Ken and Bill.

I have not had a MAT sensor fitted but have just got one and will be fitting and calibrating this week. I've also got issue with CLT as I was running off head temp not oil temp which again should be rectified this week.

I will get those sorted and then re-look at the problem. Somehow though, I figure if it's the EDIS, then MAT and CLT aren't going to make much difference! They might help smooth out the tune but I can't see either of them stopping it revving.

Will let you know how I go.

Cheers, Marc.

[billr]

MAT wouldn't stop revving??? Look at 1174.821 secs, as it goes through 6093 rpm. MAT spikes so high (800+ C) that Gair, Gammae, and thus PW all get cut approximately in half. That much loss in fuel, assuming it was running more-or-less okay just previously, will certainly kill engine power and cause rev increase to cease. If you don't have a MAT sensor right now, just use a 1.8K ohm resistor in its place. That will give a "fixed" MAT at a reasonable value of about 35 C. As I recall, you have MAT correction set at 50%. I would put that at 100%, don't try and deviate from reality (the gas laws in physics) unless there is a good reason to do so. Since you don't even have MAT working, it is hard to imagine you have identified such a "good reason" yet...

[beachbuggy61]

Wow! Thanks Bill. Goes to show how much I don't know!

I can see what you mean. The ECU would've thought I was trying to operate in a furnace. No wonder it would cut the fuel. I wouldn't want to be spraying E85 around in a furnace either!

I've got the MAT sensor so now just have to get a fitting welded into the intake pipe so it can measure the MAT properly, so I won't go the resistor path, I'll wait til I get the fitting calibrated and installed then see how I go.

I wasn't aware of the MAT correction being set at 50%. I will find that and set it to 100% as you suggest. I'm also a firm believer in the laws of physics.

Thanks so much for your advice.

Marc.

[DaveEFI]

Hope that does sort the problem - and if EDIS does or does not have a rev limit built in.

[beachbuggy61]

So do I Dave, so do I!!

From the research I've done it does seem that 6200rpm is a common limit, but there are some that say they've had success to 7500rpm, so I remain ever hopefull.

Guess I'll find out soon enough...

[DaveEFI]

It wouldn't be too much trouble to feed an EDIS unit from a JimStim and check if it has a rev limit. I'm just curious as if it has it's higher than my RV8 will rev to anyway.

[jsmcortina]

I know I _claimed_ to have observed an EDIS rev limit on my EDIS8 Rover V8 install. However, I remain unconvinced about whether it was real or other issues. I have long-since switched to direct coil control.

James

[kjones6039]

I have long-since switched to direct coil control.

The best thing I ever did, for certain!! IMHO, it just takes one more component out of the equation, in terms of trouble shooting etc.

Ken

[DaveEFI]

Could you clarify, Ken? You're taking the EDIS ECU out of the equation - but adding in four coil drivers. And EDIS is said by everyone to be ultra reliable.

Go on - sell me why I should change from EDIS to direct drive from MS.

[beachbuggy61]

It's taken a little while (why does there have to be other things to do when all you want to do is play with the bug!!) but I've now had my MS2 rebuilt so that it now runs the coils directly.

A nervous time for a guy with fingers like Fred Flintstone but I've got the wiring right now and it fires and runs well. In the garage at least!

Easter tomorrow so a road trip and tune is in order.

Let's see if I can crack 6,300rpm now!

MAT is now installed and reading right too

Wish me luck!

Cheers, Marc.

[kjones6039]

Could you clarify, Ken? You're taking the EDIS ECU out of the equation - but adding in four coil drivers. And EDIS is said by everyone to be ultra reliable.

Go on - sell me why I should change from EDIS to direct drive from MS.

Dave,

My apologies for losing track of this thread.

And EDIS is said by everyone to be ultra reliable.

And I agree! I have stated in any number of my own posts that EDIS is a robust and reliable system. My post above (among many others) was merely to point out the experience that I personally have had with EDIS8 regarding my inability to rev past approximately 6200 rpm. That was the one and only reason I dumped my own EDIS system!

You're taking the EDIS ECU out of the equation - but adding in four coil drivers.

Correct! I retained the EDIS crank sensor in the exact same position and routed the sensor to the VR input on the MS. Then I added a 4 coil driver board to the output of the MS to drive the same EDIS coils. Just a side note: driver board = ~$52 shipped ------ I'm betting an EDIS is a lot more than that!

sell me why I should change from EDIS to direct drive from MS

I am not trying to sell anyone on this system. I am merely sharing my experience with both setups. In my case, directly driving the coils via MS eliminated one more piece of hardware from my system, coupled with the ability to turn my sbc up to ~7000 rpm anytime I want.

All-in-all....... I would opt for the direct driven coils every time!!

Ken

[panabax]

It wouldn't be too much trouble to feed an EDIS unit from a JimStim and check if it has a rev limit. I'm just curious as if it has it's higher than my RV8 will rev to anyway.

I know this is an old post, but I ran up against this issue in my 65 Mustang. I converted to EDIS using the EDIS module and a Megajolt. It would cut out just past 6000 rpm every time. I ended up replacing the Maegajolt and EDIS module with a Microsquirt which I am using to drive the EDIS coil packs directly in wasted spark mode. The car now revs as high as I dare rev it.

However, I also took the time to do some post mordem diagnostics on the EDIS module. I hooked it up on the bench with my megajolt and a StimJim simulator. I hooked the Megajolt tach signal to my oscilloscope. I got a steady tach reading right up to about 2.24 ms, then it would go flat. On the Stim Jim, you could see that the ignition circuits went dead as well. At 2.24 ms, the rpm is 6250. That explains why some EDIS 8 units can't rev past 6,300 rpm. Also of note, the tach signal and ignition circuits did not start firing again until the engine speed, as simulated by the Stim Jim, got down to about 2,800 rpm.

The EDIS module I was testing was part number F4SF-12K072-AA 4G27B. I don't remember what I pulled it out of. I have this exact same setup (EDIS-8 and Megajolt) in a Bronco with a supercharged 351 and it runs great. Of course, it never revs past (or even to) 6000 rpm.

Baxter