question for demon

[selfinfliction]

i seen on your website you said you recommend taking out the secondaries if you have a 3L, it also says you will have a few drivability issues.... what kind of issues would something like cause other than a loss of torque on the bottom end?

[NorCalCoug]

CEL if you don't do it right. :)

[PuckPuck]

Originally posted by: NorCalCoug
CEL if you don't do it right. :)


interesting.... does anyone know the "right" way to do it?

[selfinfliction]

:::::::::::::::::::::::::::::::::::::::from demon's website::::::::::::::::::::::::::::::::::::::::::: :::

DemonSVT's
CDW-27 & Duratec Information Archives
Intake Manifold Runner Control (IMRC) FAQ My SVT Page


If you build a 3L Duratec should you take out the secondaries?


Yes & No

Yes - I recommend you remove them on a 3L because the low end torque is much greater then the 2.5L This way you gain the multiple flow benefits of them not being there.

No - You do not have to nor should if you can’t stand some minor drivability issues.



No - An ATX should probably never remove them because you can not pick your own gears.

No - It's not the best idea without a chip tuned for them being removed because you can not add extra timing & fuel. That is crucial to tuning and removing most of the issues.



If you take the butterflies out of the LIM should you still leave the IMRC box connected so the computer thinks you still have them?


Yes - You should leave the IMRC boxed installed and rigged with a return spring.

Yes - The PCM has to have the IMRC attached because it looks for the reference signal and the pass through signal from the IMRC. If it is not found/returned it then goes into SEVERE limp mode. This overrides everything including a chip. Flat line timing and ultra rich fuel trim.



A chip would be required to be specially programmed to have the IMRC removed.

To date I am the only person to have done this properly and datalogged that the changes actually occured. You can program the code to tell the PCM to advance the timing but without solving several code issues it just won't increase timing. Tuning without datalogging is just shooting in the dark.



Does that mean you will get the early timing bump and fuel bump?


No - You will not get any Timing or Fuel bump before the IMRC point programmed in the PCM.
SVT is 3400rpm & stock is 3800rpm at WOT - other times both vary but by 4100rpm they are always open



Are there any drawbacks to rigging a return spring?

Yes & No



No - When used with a return spring and the normal IMRC point it would wear just like normal. That unfortunately is mainly dictated by HEAT.



Yes - When used with a chip that lowers the IMRC point it is open longer. To gain full timing benefits the IMRC point would have to be lowered to 2000 rpm or below. That increases wear exponentially.

This brings us back to that “specially” programmed chip I mentioned earlier.





Is there any other way besides buying an expensive chip?



You can get some early timing & fuel ramp up with the P1518 CEL. That means no return spring.

It's not what I would recommend but it does work and I did it for quite a while when I had my Superchip. (“having” the chip was a BIG reason as to why I did it though!)



What does this way gain?



Your timing increase below the stock IMRC point is based on the PCM tuning.

Also your “early ramp up” starts about 2500-2800 rpm.



If you have a stock PCM your gains will be marginal. (from 5-8 to 13-16 degrees)

If you have a SVT PCM your gains will be slightly better. (from 10-12 to 19-22 degrees)

If you already have a chip your gains could be okay.

My Superchip gave me timing of 25-30 degrees when run with the P1518 CEL. That was a very noticeable difference.

When using this method you will want to monitor your CEL codes every few days to make sure you don't trip any Hard codes (like Lean or Rich for instance)



Does this apply to every year Duratec?



This applies to all 96+ 2.5L Duratecs. (95 uses a vacuum IMRC with reverse operation and is OBD-I ~ They'll have to fend for themselves)

Back

[Blackcoog]

Right way of doing it would be to have a chip burned so you can add the correct timing when you pull them out and some way to fool the IMRC or disable it with the chip. Last time I asked ADC they suggested against doing it. It has only caused problems and negligible gains.

[DemonSVT]

Originally posted by: Blackcoog Last time I asked ADC they suggested against doing it. It has only caused problems and negligible gains.
Spoken exactly like a tuner that doesn't want to hassle with returned chips for drivability complaints.
I don't really blame them either since they can't tune drivability on a dyno much less a mail order chip.


I strongly disagree with the negligible gains part though. Even if the power gains from 4000rpm on up are just a handful that's a small part of why you would be doing this mod. Their statement is being very short-sighted.
No intermittent IMRC flutter, No IMRC closing the plates every time you leave WOT, No stagnant air in the secondary ports, Less sludge build up on the secondary valves, et cetera.


It's definitely not for everybody or more likely even most people, but I wouldn't have mine any other way.

[FastCougar]

I spoke with Keyser about this and he said that there are soo many factors that this one component interface with that Jerry with SCT ... one of the Ford Engineers that helped develop the EEC-V IIRC charges $500 extra to remove them from older Cobra 4.6L engine reburns because the changes are that extensive! Leave them in!

[ilovemycar]

i know mine are not completely removed but i have had mine pinned for almost a year now and i don't mind at all. my car is a daily driver and yes i can see a small loss in torque when flooring it in ist at like 1500rpm's, but it does not bother me. i think it has been more benficial to me than anything else.

[selfinfliction]

sounds like that idea was shot down from the possible extra costs to have the chip reburnt :S

[Instigator]

i had ADC remove the secondaries on my chip

[selfinfliction]

was that a new chip or a reburnt one? i actually guess i should just call them to see what kind of price i can get on mine if i decide to do that

[PuckPuck]

so let me get this straight.... my car is right now running in SEVERE limp mode....

I don't have secondaries... heck I don't even have the box (i gave it to Leo Capaldi's son a long time ago).... I do plan on getting a simulator installed, which will simulate the return signals to the PCM. We tested an actual working cougar first to determine what the signals are at open/close... now I just need to get the electrical guru to finish the simulator.....

once I connect the simulator, are you saying i should be expecting 12-15% gains?!?!? that seems pretty big... and if that's the case i'll find ways to get the simulator finished earlier... and if it works this might be something for everyone... albeit not optimal as the PCM will still think that it's there and adjust accordingly based on MAF/TPS/engine load (or whatever the PCM uses to control IMRC), but I should end up getting out of LIMP mode, and most importantly get more power....

I guess i'll be going back to the dyno shop for a re-tune, as i'm also assuming, once the simulator is in, my current tune, which was done wihtout IMRC, will be off given that the engine will going back to normal timing and a/f ratios.....

[Instigator]

mine was new, i have a turbo so i never wanted them in there