Metro 3-cyl General Info
 

Okay, motivation for starting this thread is a few things that have been bothering me lately. Any info anyone can provide is appreciated.

1...When I installed my vaccum gauge, krousdb thought my vaccum was reading too low. This could simply be a Suzuki vs. Honda issue, but I have noticed that vacuum will only hover in the 18 in. Hg. range on hot days when the engine is warmed up. Hayne's manual says 17-22 in normal, but I think it's referring to ALL engines (a generic portion of the manual). 16.5 in. Hg. seems to be the most common number.

2...A sticker under the hood states that the idle has been factory pre-set and sealed at 850 rpm. Lately it seems that the engine is really racing when it's first started up (I need a tach). It hasn't been cold, but humidity has been high due to some storm weather.

3...I probably should change my transmission fluid. The owner's manual calls for gear oil, but the viscosity level of gear oil is like 75w-90. This seems really "sticky" and I especially noticed it during the winter. In -20?C/-4?F the shifter felt like it was moving through glue. Is there lower viscosity gear oil I can safely use? What are some options?

1. These 3-pots have relatively high compression (199 psi is spec.), and the flip-side of that would be more vacuum, if I'm not mistaken.

2. Can't help much there. Firefly #1 consistently idled too low, and I was never able to fix it.

3. I followed the manual and stuck 75w-90 synth into FF#1. Made it worse (harder to shift, more likely to grind the 2nd gear syncro) - I figure the fluid had been changed by a previous owner to something lighter.

Did some learnin' since then and went with GM Syncromesh semi-synth. It's far lighter weight than the 75/90. I personally think the 75/90 recommendation is a typo/mistake.

See my comments on it at teamswift: https://www.teamswift.net/viewtopic.php?p=148643

Do you have any crunchy syncros on your car?

according to the ScanGauge:

MAP @ idle (845 RPM), temp @ 190 F

= 4.7-5.1 PSI

multiiply by 2.036 to get in./hg

1...So my vacuum should be higher? I can't find any bad hoses. I've been wondering about the head-gasket (partly because I want to change it for the experience...:p). I should do a full leak-down test, but the stupid tool is $70 :mad:.

3...The only time I've heard anything crunch was when I accidentally let the clutch partway out while I was shifting :o. I'll check out those comments. I have to be careful with teamswift...my computer locks after surfing for a few pages there...:confused:

So the ScanGauge is only reading 10.4 in. Hg.? That doesn't seem right at all...:confused: But is that air pressure instead of vacuum? I don't really understand a lot about this. :o

I'm no rocket scientist, but I'd say any pressure below ambient is what you'd call vacuum. (Probably more correctly: partial vacuum.)

Indeed, but I dun think your car is seeing any boost, :)

My factory manual doesn't give a value (just gives MAP sensor voltages). My Chilton says 18 in. hg at idle.

Can't say why the the SG is so far off that value.

18 in. hg is only in 20°C or higher weather though :mad: - no manual specified that.

I'm looking for info involving manifold pressure vs. vacuum. I think I've found something - I just have to read it.

Ok the vacuum is not going to be very high because it is a small motor and can't create a lot of vacuum besides only three cylinders are sucking on the intake not 6 or 8. My Geo didn't show a high vacuum until I went down a hill with engine braking and even then with crank ventilation it didn't get very high - emmissions probably prevent that - engine needs to keep burning fuel to run clean.
My idle under certain conditions was so low that you could feel each cylinder fire and I never had to adjust it up or down.
Transmission oil I never changed only added some Slick50 Gear lube to it but some good Spectro or Amsoil would be the best bet and if you are going to be in cooler northern areas all the time then a lighter weight should be ok. The syncro in second is the one that takes a lot of abuse and is usually the first to go and get crunchy. Make sure your clutch is not dragging too much and then allow some time for the engine to slow down between shifts or shift at a lower RPM from first to second to reduce the speed/rpm difference between gears. Downshifting from third to second is also tough on the syncro. Too slippery an oil will also have this effect in all gears - I.E. Synlube makes all my gears crunch a little if I shift too fast.

What's "high"? Some numbers would help!

Okay. Darin, I think your Blackfly's vacuum is fluctuating between 19 and 20 in Hg. Here's how I figure that.

A decrease in manifold vacuum means an increase in manifold pressure (acceleration).

14.7 psi = atmospheric pressure

30 in Hg = perfect vacuum (that's just for reference)

Your MAP sensor reported 4.7-5.1 psi. This should be manifold pressure. The pressure difference:

14.7 - 4.7 = 10 psi
14.7 - 5.1 = 9.6 psi

Should be vacuum.

10 * 2.036 = 20.36 in Hg
9.6 * 2.036 = 19.54 in Hg

At least I think this is correct. I haven't found info to absolutely confirm it. But if it is then mine is low in comparison.

EDIT: I'm thinking that my lower vacuum probably has more to do with engine age/mileage than with any possible problems. I've been considering a rebuild for some time. Perhaps by next year...

Oh sorry Yeah gauge is not here so . . . mine was marked in Green for highest then yellow and red for lowest I seem to recall mid 20's for down hill in the Rambler flat head 6 idle at the green yellow line which was I think around 20-22 inches 26 for a high - If I could find it I could remember it better. Tried to accelerate in the 15 inch range. When I used it in the Geo it was always so low it wasn't worth using it - engine was always lugging to reduce pumping losses. I remember when I went downhill in the Geo with it the vacuum did NOT get very high - EGR and PVC were working. Maybe 23 or 24 for a high down hill in the Geo.

Yeah, mine is typically in the 5 in. Hg or less range while I'm accelerating. The engine is small and needs a lot of air to get the vehicle moving. I'm thinking that the G10 is pretty sensitive to wear and tear over time. They keep running, but they sacrifice efficiency.

I think we all need photos of our tail pipes!

If I get into the basement later today I will see if it is there. Would be interesting to see what the Scion xB is sucking for air...don't know were a vacuum line is however the engine has a cover over it.

The transmission/gear oil discussion kind of peaked my curiosity so I've done a little research.

Apparently gear oils and engine oils are actually the same viscosities, but are given different measurements by the SAE to differentiate their uses:

Quoted from: https://www.wearcheck.com/literature/techdoc/WZA007.htm (stupid layout on the website, but good info)

A pdf on Redline's website confirmed this by helpfully stating the gear and engine viscosities. 75W90 gear oil is similar to 15W40 motor oil, but the GM/Penzoil Synchromesh is actually closer to 5W30 motor oil viscosity.

Here are some fluid comparisons:

Legend:
Pour Point: Pourability at temperature (°C)
Viscosity Index: The higher the number, the less change in viscosity throughout temperature range
cSt @ 40: Kinematic viscosity in centistokes at 40°C
cSt @ 100: Kinematic viscosity in centistokes at 100°C

Short bit on kinematic viscosity:

Quoted from: https://www.synthetic-oil-tech.com/d....weight_oil.htm

Penzoil 75w90 GL-4 (basically what the Metro manual calls for, but it's not the correct stuff!)
https://www.pzlqs.com/Tech/Pdsheet/Do...E75W90GL-4.PDF
Pour Point: -42
Viscosity Index: 149
cSt @ 40: 108
cSt @ 100: 15.3

Penzoil Synchromesh (apparently this is the GM synchromesh)
https://www.pzlqs.com/Tech/Pdsheet/Do...omeshFluid.PDF
Pour Point: -50
Viscosity Index: 208
cSt @ 40: 41.6
cSt @ 100: 9.08

Amsoil Synchromesh 5W-30
https://www.amsoil.com/StoreFront/mtf.aspx
Pour Point: -45
Viscosity Index: 194
cSt @ 40: 47.1
cSt @ 100: 9.6

Royal Purple Synchromax
https://www.royalpurple.com/prodsa/scmax.html
Pour Point: -51 (their PDF states -40...???)
Viscosity Index: 196
cSt @ 40: 35.3
cSt @ 100: 7.7

Redline MTL (70W80 gear or 5W30 engine)
https://www.redlineoil.com/pdf/6.pdf (pdf for a number of Redline transmission fluids)
Pour Point: -50
Viscosity Index: 183
cSt @ 40: 56.2
cSt @ 100: 10.6

Mobil 1 5W-30 Synthetic (engine oil - just threw it in to see the difference)
https://www.mobil1.com/USA-English/Lu...bil1_5W-30.asp
Pour Point: -54
Viscosity Index: 169
cSt @ 40: 64.8
cSt @ 100: 11.3

EDIT: The characteristics of some of these MTFs is very close to some 0W30 motor oils. Looks like krousdb's method may be perfect...???

https://www.amsoil.com/storefront/tso.aspx

Additional reference point: I've been running a vacume gauge on my 89 Civic. I typically see about 22 at idle. On deceleration I will see about 26. On accel, I typically try to stay 13-15, although at 60mph, it takes about 13-14 to stay at speed. I know it's not a 3 cylinder, but the number's are fresh, since I currently have the gauge hooked up.

I should check vacuum on my Aunt's 1.3L 4-cyl Metro. I wonder if it would read a fair bit higher than the 3-cyl?

If we consider MetroMPG's Blackfly as the "standard" or "best" at 19-20 in. Hg then it could be that most larger engines will read 22.

Of course, this could also point to the possibility of small and large engines reading lower and "mid-size" engines reading higher. Perhaps 4-cyl engines are more efficient overall. It's possible that the 3-cyls pumping losses may reduce it's actual efficiency percentage.

But, I'm just rambling hypotheticals.

Well, while your rambling, I had one other consideration. My car has new ring's and a competely rebuilt head, so it might be a little higher just because it's tighter?

I think you're right. That's why I considered wear-and-tear into my 202,500 km engine compared to MetroMPG's <5,000 km engine (What are you at, Darin?).

I'm certain an engine rebuild would increase FE fairly dramatically.

EDIT:

Make that < 10,000 km. Man, that's not even broke in yet!

It's about 8300 kms... Piling the miles on...

I need to find out injector size so Yoshi can program the MID. As I said, TeamSwift keeps locking my system and it's ticking me off.

MetroMPG, anyone, please help? Please? :o

What browser are you using that's crashing over there?

Both IE6 and Netscape 7. I think it actually has something to do with the server in my workplace. Possibly Norton's remote scanning or something. Teamswift is the only site it happens on and only after I surf through 4 to 5 pages. It's weird.

I'd do it at home, but my computer is in pieces at the moment (and I'm sick of computers by the end of the day) and my wife and kids are always on theirs...:p

Looking through my last SuperMID Revisited post, I said I had found a number of 272 cc/min on Teamswift. However, on my latest visit before my latest lock up I found out that the 272 cc/min is either not correct or only for Swift GTs.

I don't know. I'm confused about the whole thing. :confused:

OK, tell me exactly what you need to know, and I'll look for it or post a question. I think all the 1.0 and 1.3 motors are TBI, not multi-port. I'm not sure if that changes things for you.

Keep in mind I also know nothing about injectors...

Me neither :(, all I know is that Yoshi asked this question:

So I just need to know how many cc/min the stock 3-cylinder TBI injector spits out.

I was thinking that I should see if any of the Suzuki/Pontiac/Chevy parts people would know as well. They may have it in their computers. I'll phone or visit some dealerships later today.

Wait a minute...I just found a site with the formula for converting cc/min to gal/hr and it suddenly clicked that you listed your liters/hr in your warm-up time experiment.

0.5 Lph was your warmed up flow and the initial start flow was 1.5 Lph, so this calculates to:

500cc/h = 8.3333 cc/min at idle.
1500cc/h = 25 cc/min initial start.

These values seem very small. So how do they calculate/measure fuel injector size? Maybe it's what the injector is capable of flowing. More to figure out...:cool:

EDIT: Interesting...I just punched 65 hp and 1 injector into the calculator here: https://www.rceng.com/technical.htm and it gave me a cc/min rating of 272...coincidence???

Sorry I miss the importance of the 272 in the coincidence :confused:

EDIT: OK, I see it's the number you found at teamswift previously.

Then again, our cars make 55 hp peak, not 65, so that calc may be off.

Also, doesn't nn cc/min depend on RPM and load?

I wonder if Dan has anything to offer. I didn't pay much attention to the injector discussion he was having with Ben, when they were calibrating their MIDs.

Oh, 272 cc/min was a number I found on Teamswift, but some guys were saying it was wrong and others were saying it was just for the GT.

I assume it would depend on load, but I figure that this must be the maximum rating - perhaps at wide open throttle. Ben was saying that the VX injectors were 190 cc/min or something like that.

EDIT: oops...55 hp, right. I don't know why I always say 65. I guess I'm hoping for more?

EDIT2: Injectors are rated at 100% duty cycle, but only operated at 80% maximum.

Displacement x RPMmax /2 = CFPM (make sure you get the CC/Cubic Inches right) then calculate the fuel needed for that air flow rate to obtain the fuel flow rate at the air/fuel mixture ratio. Or figure the rate you could burn fuel at at max speed with maybe 45mpg at 90mph = 2 gph then convert the units to cc/minute.

Okay, great help from https://www.docinjector.com/

Not much on their site or their eBay store, but I emailed them and they responded really quickly.

Apparently the injector size is a huge 400 cc/min (39 lb/hr)! I guess it makes sense considering that it is one injector feeding three cylinders = 133.33 cc/min/cylinder (13 lb/hr/cyl).

Oh Yeah it is a throttle body injector in the Geo - maybe a turbonator would work and acetone too!

I guess to figure out the CC of gasoline you need the weight or volume of air to gas ratio I guess it is by weight 14 to 1 ratio?

So are you going to shift to the GM Sychromesh fluid? I can somewhat relate to the question about using gear oil in the Swift. If Honda has me putting in engine oil, I would think the Swift would definitely need a similar viscosity.

Actually I'm considering 0W20 since the winters are so cold around here. krousdb doesn't seem to be having any trouble with it in his Honda's and I'm running a Japanese drivetrain as well...