Tuning adjustment for performance mods.

Do you think changing the fuel pressure (adjustable FPR) would be an easier way to get the mixture you want?

Possibly - I've already raised the fuel pressure to 3bar - going too much more will put the injector duty cycle on the high end of the spectrum, I believe. I don't know what the effective range of these injectors is, but I doubt it's as versatile as the Bosch injectors of the past decade.
 
I've already raised the fuel pressure to 3bar - going too much more will put the injector duty cycle on the high end of the spectrum, I believe.

If the system is running closed loop, higher pressure will result in lower duty cycle (higher pressure => heavier flow while the injectors are open => shorter squirts needed for the same total fuel amount).

If you are running very lean it would not be closed loop, so there should not be any change in duty cycle.

This is my understanding, anyway.
 
Horse before the cart?

Not to be off topic but would it not be prudent to dial in the cam timing and engine timing, then play with the lean/rich conditon?
 
I'm not concerned about the cam timing. Based on Matt's post, I'm likely a couple of degrees advanced. Ignition timing is fine * 12ºBTDC, and car runs extremely well, AFR's in the 14's, into the low 13's high 12's under heavy load.

The lean condition is solely with the Mazda AFM, so I just removed it for the time being.
 
85 RX7 AFM came today...

...this is the direct ND version of our Bosch AFM, EXCEPT it has larger flow capacity (2.75" outlet)

X19mazda85AFM0002.jpg


X19mazda85AFM0001.jpg


tried a couple of clicks looser to compensate for the greater air flow, but that still gave AFR's in the high 13's under load/WOT, so I went 7 clicks & readjusted the pump cut-off.

X19mazda85AFM0004.jpg


at this setting, I used the CO adjust (CC to lean, C to enrich) to bring the AFR to 14.5-15.2 at idle/cruise, and confirmed that the 02 sweeps .2 -.8v. Under heavy load/WOT, AFR's drop to high 12's, so I may lean it out a click.

X19mazda85AFM0003.jpg


fitted a 2.75" x6" K&N filter I had left over from my last Volvo setup. Need to get a 4" version.

What's frustrating, is that I started the tuning as dusk was approaching, and as soon as I turn the lights on, the load pulls the idle down, & messes with the AFR's :wall: Basically, If I don't keep the idle over 1k rpm, the charging system is an issue.
 
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Looks like I have the charging issue under control- I pulled the alt cover & cleaned the feed wire eyelet & applied a little low temp electric grease to the terminals. Now the voltage doesn't drop appreciably (or the idle) when the lights or cooling fan are on.

Got the 85 Mazda RX7 AFM set up (7 clicks loose, f/p cutoff pin moved) to give AFR's in the high 11's low 12's * WOT, feels very nice.

Another issue I've noticed since I added the heated O2 sensor is that it's too lean during warmup - no problem if you're moving, but at idle it was kinda lean.

So, I installed an ECT from a LH2.4 Volvo system ( 0280130032 ) 1346030, which operates over a similar range, but doesn't drop resistance so fast in the warm up range. The stock ECT is under 500ohms by 150ºF. This one doesn't go under 440ohms * 190ºF (stock drops to 200ohms * 190ºF), so it's keeping the system a tad richer.

EDIT: hmm.. just checked the graph for this sensor,

1346030ECT.jpg

EDIT: stock ECT graph (026) same values indicated as the 032 (?)
Picture3.png

and my findings are not in keeping with it. Either the engine is colder than the gauge indicates (ran til cooling fan cycled, checked resistance value of sensor = 440ohms), or my test was erroneous. However, it is still higher resistance when checked against the stocker at similar temps.

Now the AFR's drop into the 13's under mid throttle, instead of staying in the mid to low 14's, definitely feels better, and still idles in the 14-14.7 range.
 
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Not to be off topic but would it not be prudent to dial in the cam timing and engine timing, then play with the lean/rich conditon?

My Miller's-Mule adjustable timing gear arrived late Jan, so it'll soon be time to get the X1/9 out of the winter wraps & start playing with it! Need to do the strut plates, strut mounts, & stainless coolant reservoir as well!
 
Some questions

1) are you adjusting idle with the throttle plate? Isn't that wrong and there is a bypass for adjusting idle? But I'm a carb guy. :)

2) are you not using the heater connection on a heated O2 sensor? I would make sure to connect the heater, makes a big difference.

3) the car pulling better while warming up is the same in my car. I attribute that to the intake tract still being cool, creating a denser charge and more power. If my car always ran like it does when warming up, I would be a happy man.

I think your mixture tuning sounds really good.
 
1) I no longer have a bypass, I bored out the intake for a larger throttle plate from a Volvo 850.

2) Yes, I did hook up the 02 heater

3) Initially, it ran too lean during warmup, then it was OK after I switched to the Volvo coolant temp sensor & wired the 02 heater element.
 
Installed the MM adjustable cam gear this afternoon.

I must have not had crank exactly at the TDC marker when I installed the the stock gear after the shaved head install...

X19_0713.jpg


X19_0712.jpg


...it's clearly around 1/2 a tooth retarded, don't know why I didn't see that.

Installed the MM gear in the same position

X19_0466.jpg


now I can advance the cam a smidgeon to get the timing back.

Also installed the new CO strut mounts & MP doubler plates in the rear - I'll do the fronts tomorrow. Only downside to the plate is that it's raised the car at least 1/2" in the back.. The old mounts were actually still fine in terms of the bonding, the inner flange had just folded down. Probably could have just straightened it & used the doubler plate only, but it's all good.
 
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Advanced the cam..

IMG_8704.jpg


.... basically eyballing the amount to bring it back just ahead of neutral, as described by Matt.

I tried advancing a tad more (than shown), and it became increasingly more difficult to start - excessive crank time, so I moved it back a smidgeon at a time, until it 'felt' right.
 
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TonyK's post here, and Rob's video of his 1600 build on the road got me thinking about my cam timing :D

MWB 35/75 cam spec

X19_0070.jpg


2014 initial cam setting - BVH, Block decked, MWB shaved cam box. MM adjustable cam gear.

True TDC confirmed back when engine was built.
X19_0545.jpg


From my build pic, looks like cam pulley is centered in valley with pointer in alignment, cam centered in gear.
X19_0714.jpg


moved here
X19_0715.jpg


Once running, I set the cam timing back to 'neutral' according to this post (Sept 2014) Not sure what I meant by that other than cam is not advanced based on dimples.

Since then, I've converted to LH2.4 & have appropriate base timing of 12ºBTDC.

Started thinking about making adjustments having now driven the car on extended runs. Pulls very strong from 1200 - 4500, then goes pretty flat.

Posted other thoughts regarding timing/setup in my melted piston thread, this seems a better place to discuss it.
 
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Hey Hussein,

I used my adjustable cam pulley to compensate for both the block and head being machined. If you do nothing, your cam will be retarded, because the distance between the cam axis and the crank axis has been reduced, effectively lengthening the belt. I used a large degree wheel on the crank and a dial gauge on a shim bucket to dial in the cam timing.

It doesn't take much adjustment to get your cam back in sync with the crank, but it definitely makes a difference to performance.

Hope you get it to pull beyond 4,500rpm.

Cheers,

Rob
 
Hey Hussein,

I used my adjustable cam pulley to compensate for both the block and head being machined. If you do nothing, your cam will be retarded, because the distance between the cam axis and the crank axis has been reduced, effectively lengthening the belt. I used a large degree wheel on the crank and a dial gauge on a shim bucket to dial in the cam timing.

It doesn't take much adjustment to get your cam back in sync with the crank, but it definitely makes a difference to performance.

Hope you get it to pull beyond 4,500rpm.

Cheers,

Rob

Hi Rob

You used a dial indicator on the cam bucket to measure lift? I'll have to show the spec sheet to my speed shop guy, I don't know how to read it to set up & mark neutral on #1 @ TDC.
 
Today I played with the cam timing a little. Advanced the cam from the base centered setting a little less than 1/2 tooth, about 1/8". Idle and tip in feel a little 'cleaner' not much difference up top. What I did find is that my tach is very inaccurate. With the pulse relay I had to use with the wasted spark setup, the tach just doesn't respond properly, I hooked up a spare Volvo tach, and free revving the the motor, when the Volvo tach shows 5K, the Fiat one only shows 4K, 6K, around 4.5K.. and is sluggish to respond. So, part of my problem is not so much lack of power up top, it's the tach wildly unreporting actual rpm(!)

I'll try an alternate relay setup tomorrow. Worst case, I'll have to fit an different tach.

I'm wondering if anyone has a reference list of rpm/road speed for the 5 speed trans.
 
Today I played with the cam timing a little. Advanced the cam from the base centered setting a little less than 1/2 tooth, about 1/8". Idle and tip in feel a little 'cleaner' not much difference up top. What I did find is that my tach is very inaccurate. With the pulse relay I had to use with the wasted spark setup, the tach just doesn't respond properly, I hooked up a spare Volvo tach, and free revving the the motor, when the Volvo tach shows 5K, the Fiat one only shows 4K, 6K, around 4.5K.. and is sluggish to respond. So, part of my problem is not so much lack of power up top, it's the tach wildly unreporting actual rpm(!)

I'll try an alternate relay setup tomorrow. Worst case, I'll have to fit an different tach.

I'm wondering if anyone has a reference list of rpm/road speed for the 5 speed trans.

See if you can get ahold of a higher end automotive multimeter, say one from Fluke for example. The one I borrow from my mechanic buddy has an inductive pickup for the tachometer function. The tach on my car reads high also, about 100-125 rpm higher than actual. Can't say if that % error is constant or variable---next time I borrow it I should check at several RPM points above idle, such as 2500, 3500, etc.
 
Put put in a standard relay (with contact removed) between coil + (85) and powerstage pulse/coil/tach feed (86). Seems good now. The added conditioning circuit suggested does not work with our tach.

CAF9BBDB-557A-457A-A06A-C1D55B34A295_zpsuijpgdpy.jpg


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Revised the timing map today to make it a little less conservative than before.

X19_LH24_00133.png


Made another with further advanced timing in small increments, to try if I get no knock with the first revision. Stock curve is 26º - 30º by 3500rpm. Car used to pull much harder up top with the Volvo mapping, but that also killed my head gaskets, so baby steps to get it back to the sweet spot.

X19timingRev2_6_17_zpsxhz6iege.png
 
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Other concerns.... I've noticed that the fuel pressure recorded at the rail drops when the engine is hot & ambient temps are high the pressure dropped to 30psi. With LH2.4, base regulated pressure to the rail is 3bar/44psi, and typically should drop about 5-7psi (.4-.5bar) at idle with vacuum connected (high vacuum). I'm concerned of course, as if this condition is present while moving, and not just from idle heat soak, then I will definitely have a lean condition up top.

I replaced the rail gauge first, as I wasn't sure about the quality. I can't hook up my mechanical test gauge as my adaptor for the Volvo schraeder fitting is kaput :( No change. I'm going to have to install a 5 bar pressure sender (VDO 360-009) on the end of the rail & hook up a 5bar Volvo (oil pressure) gauge I just happen to have, to see what's happening under load / high rpm.

I've read a bunch of threads on line running the gamut from rail temp can't possibly be an issue, fuel temp doesn't effect flow/ volume, etc, to massive gains to be had with fuel cooling system ($$$) :D

Since I can raise my regulated pressure (adjustable VW/Audi pod), I've done that - I set the base pressure to 44psi when the engine was fully heated, so now it drops to about 36psi at idle, hot. Since that worked, I think I can safely rule out pump volume & regulator as potential causes.

C4C281C4-1A55-469B-BDF9-BC5081D76808_zpsjny3tr9x.jpg
 
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And with those changes, how does it feel different from before? Any logging for the AFR?

Is the Volvo knock sensor system very aggressive in knocking back timing? Would it be better to use a normally aspirated system like VW's that they used on the 9A twincam or similar? I would think a system tuned for a NA engine would be less aggressive in knocking back the timing and more willing to move it back up. Just a thought.

Could it be the placement of your knock sensors or is that a non issue as its looking for a particular frequency? Lots I don't know about knock sensing systems...but willing to learn.
 
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