duratec downgraded to 3-cyl

[ralph]

Got these from a friend with a cosworth:  

• resting voltage V_Initial_New = 0.36v
• resting throttle site Throttle_Site_Initial_New = 0.0
• peak voltage V_Final_New = 3.5v
• peak throttle site Throttle_Site_Final_New = 14.2

...since I can actually reach this voltage range with my setup, going to try that and see what happens.  The 9M4 is certainly hot off the presses -- vacuum of experience/opinions on it so far...

 

[ralph]

...something more like .42v at .07 seems to work!...I'm guessing there are actual target numbers for the 9M4, but only Mr. MBE knows for sure...

 

Idle's a little rough, but throttle is more responsive off the line, and holy crap those horns howl...my new favorite sound. 

 

will do some fine tuning with an anemometer and might play around with the voltage some more.  

 

Pretty stoked to have this thing back on the road; just need to salvage my chainsaw surgery on the bonnet somehow...

[KnifeySpoony]

Congrats. Once you hear that sound it's hard to go back... 

[ralph]

Still struggling with idle, will crank the TPS past site 0.0 and see if that helps, and will tune the barrels via bleed screws.  Also, my tach appears to have lost its marbles: registers ~400rpm at idle (which may not be too far off -- definitely too low still), but sweeping up through the revs, it never really gets much past 1100 or so...

 

no word yet from CC on what the idle voltage should be on the 9m4 with rbtb...wonder if i got the wrong map...

[KnifeySpoony]

My guess is the idle issue is a map issue. The barrels should be pretty well sync'd from factory, but then again, you had your other issue so all bets are off I guess. How is it behaving at idle? Does it run/pull fine elsewhere?

 

 Re: tach - that should be an easy fix. Will need to set the dipswitches on the back of the tach to appropriate setting. Search this forum to find the switch settings. 

[ralph]

Idle is low-rpm and rough (not quite as rough as when cyl#1 was dead).  As far as sync goes, I'll use a flow meter before I start fiddling with bleed screws, and, as you observed, they do seem aligned well within the pairs (I could see the balance screw working loose and making things interesting between the 1,2 pair and the 3,4 pair, but, based on the drill blank used to measure the 6mm, 1=2 and 3=4).

 

Pull's great once I'm up around what I'm guessing is 2krpm, revs great from what I think is 1krpm -- in general it's way more responsive and doesn't bog the way the plenum setup did.  Also seems like less finesse/precision is required in what you do with the throttle when letting out the clutch in first (peeve of mine with the stock setup).

 

Glad to hear the tach is an easy fix, just a little annoyed (though not surprised) that this sounds like something that should have been specified in non-existent instructions.  I have not heard that the tach would need to be adjusted, and the 9m4 (per SBD) has exactly the same pinout as the 9a4, so I'm not sure what's different...sending different voltage to the tach?...this spooks me a bit.  

[KnifeySpoony]

I'd be curious to see/hear a vid of it idling. Is it rough as in uneven/stumbling etc? Excessive vibration? Or just "sounds" rough. With the ITBs you will def get a harsher sound at idle. 

 

The tach issue is just based on how the tach pulses are meant to be coded/read by the tune. Mine was off from new as well for my RBTB tune. Let me know if you can't find the dipswitch info.

[ralph]

If I read the related threads correctly, I need to flip some dip-switches in my tach to get it to agree with the ECU (1,2,8 should be on...implying there's something with the crank/pulley ratio (i.e. 2 pulses, not 4)).  Thing is, everything else I read about the tach suggests I may have a different tach (see pic, no wrench-free nuts to detach evident).

[KnifeySpoony]

the dipswitches are inside the grommet through with big cable exits

[ralph]

Ah, so in theory, with a mirror, I could set the dipswitches without removing the tach....still not sure how to remove it....not seeing those 'thumb nuts' others are talking about. 

 

Notwithstanding the tach being on crack and the idle being low/rough, I've managed a couple spirited blats in the SC mtns, and find that a slight nudge of the throttle at a stop will keep the low idle from being a problem.  I drive with a shoeless right foot, so I can finesse it with my small toes without too much trouble.  

 

For anyone following the idle metrics, I'm at .45v/site=1.7, and it's still acting like it's at 500rpm.  I might try going a bit past 6mm on the idle screw and try to get a voltage at site 0.0 that works.  I'm assuming that you want idle at 0.0 for the rest of the map to make sense. 

 

All that said, this engine now pulls like a slingshot once revs are north of 1.5k or so, and it has no trouble eating as much gas as you can feed it (plenum setup bogged a bit).  Passing folks is a breeze, and I feel a vague whiff of contrition knowing my exhaust pipe is aimed at the driver I'm passing -- sorry, not sorry...

[KnifeySpoony]

The entire "ribbed" ring is the "nut" that holds the gauge up against the dash. Just rotate it and it will unscrew.

 

Based on a tickle of the throttle solving your idle, I would adjust your TPS in the appropriate direction to mimic that at idle throttle position, rather than actually opening up the barrels more at idle. 

 

Have you run it to redline at WOT? The sound from the intake is really something else.

[ralph]

re: tach removal...duh!...yeah, that's super easy -- my dip switches are: 1,2,8 on (which sounds right from what I've read)

re: TPS, will try that, but doesn't increasing site position mess with the overall map?...doesn't it expect something close to "0.0" at idle?

re: redline, dunno...tach is still on drugs...haven't hit the rev limiter, so there's that; I definitely like the noise this thing makes now, and more so the response/pull (laggy/weak with the plenum)

 

...if I can't fix the tach thing with dip switches, I'm probably going to have to get the ECU reflashed, which is beyond annoying at this point.  

[KnifeySpoony]

Yep if your dips are correct, but it's still misreading, it may be something with the tune - however you could try other dip settings to compensate? During my initial build/shakedown I was able to reflash multiple times myself until all issues got sorted. No sure if you're sending it out for updates or doing it yourself. 

 

I'm not sure about the throttle site - I never paid attention to it. I just set the idle voltage to 4.62 per my setup instructions. Not sure with your different ECU.

 

[ralph]

CC responded and advised that I just drop the first two dip switches on the tach (to reduce PPR) -- seems a bit ham-handed, but I'll give it a go -- also, still no explanation for why this particular variable would change from 9a4 to 9m4 (which are supposed to be able to run with equivalent configs -- begs the question as to exactly what config I was shipped).   Hopefully this sorts the tach.

 

As for TPS/mapping, turns out, I'm the first customer to use a 9m4 with RBTB, and since their R&D is essentially customer funded, there we are:  tabula rasa.  The working theories don't make sense to me (i.e. if the voltage *should* start high and descend as throttle opens, how I'm I able to drive this thing with WOT approaching redline and have the engine basically going gangbusters?).  It is certainly starting to look like the 9m4 they shipped has a bogus config, but as to what the right one is...that seems a very open question.

 

Again the symptoms are:  very low idle even well past site 0 (2.9) on the TPS, and engine won't stay running when cold, plus a bit of backfiring when backing off the throttle quickly (to me that reads: too rich, but maybe it's normal rbtb behavior?).

Edited December 4, 2023 by ralph

[MV8]

Delete. I see tps swing is also reversed on knifey's.

Edited December 4, 2023 by MV8

[ralph]

tach: all dip switches off except #8,  and the tach seems to behave (down to .5ppr vs 2ppr)

 

idle: cold idle is still not a thing at all, but the engine warmed up will idle stably at .50v/2.9site  (which seems pretty off, imo)

 

 

[KnifeySpoony]

Any additional support from CC/MBE? 

[ralph]

From CC, no, just kind of a shrug so far. 

 

From SBD, I got a similar kind of non-answer restating that for RBTB the voltage is inverted by S/W; for absence of doubt, when you talk about your setup being at 4.62v, is that the voltage value from Easimap, or from a multimeter on the actual TPS leads themselves?...If the latter, I'm going to have a good laugh and go the probe route in future calibration attempts.  SBD also told me to follow the instructions that came with the ECU...what instructions? (not laughing)

 

To your earlier suggestion about just turning the TPS until the engine behaves, I suppose there are two problems with that:  as noted before, mapping should correlate with TPS site position (so if I roll that too high at idle, I'm fairly certain this will screw up my mapping...it does backfire a lot like it's on the rich side), but the other that occurred to me after snapping my stock TPS is that if the site position is too high, I may run the risk of exceeding the rotation limit of the TPS barrel with the pedal to the floor, which would not be a good thing -- floored WOT and the TPS barrel snaps?...no thanks.

 

I'm starting to wonder if maybe I've been overcorrecting this the entire time, making the engine run way too rich, and buggering up the mapping with way too high a site position.  My assumption was if I want higher rpm at idle, I need higher voltage (as read by Easimap, which shows voltage ascending as throttle opens).  I'll keep fiddling with it and report back here once I get it working properly...

 

 

[ralph]

CC confirms idle should be site=0.0, so I've cranked the TPS too far.  They also said the dip switch gymnastics on the tach is normal, but I still don't see why/how.

 

Working theory is that the imbalance of airflow between the barrel sets (1/2 was 2x 3/4) was a bigger factor in causing rough idle than TPS position.  I'll focus on dialing that in better and drop my TPS voltage down to whatever gets me just barely at site=0.0. (I think this was around 0.42v as read by Easimap).  I have an inquiry into CC to confirm that TPS voltage ascending as reported by Easimap is indeed normal, and the concern about the voltage path being inverted is actually spurious.  For anyone on thread who has fiddled with roller barrels, I'd love to hear confirmation as to TPS voltage start point and direction as measured via Easimap vs. multimeter probes on the TPS itself.  

 

 

[KnifeySpoony]

The voltage can be measured either at the back of the TPS connector or through easimap. When I first built my car I did not have easimap and set the 4.62V via multimeter at TPS. I have since adjusted it multiple times via easimap, which is infinitely easier. I have never measured back to back from plug to easimap to see how close the numbers correlate. I forget what voltage it is at WOT.

Edited December 8, 2023 by KnifeySpoony