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Tofuball's '94 XFi; It's all about city MPG
Topic Started: Mar 12 2011, 08:59 AM (39,448 Views)
nerys
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Grr

Tofuball time for a REALITY check for your brain.

you got a RUST FREE under 100k miles XFI with NEARLY NEW compression figures for $1700

are you freaking kidding me? are you nuts? is there something wrong with you? :-)

that is what we call a grand slam steal.

WOW what a find ! you could turn around and sell that on ebay RIGHT NOW and probable get $5k for it depending on where you are.

in a few months you could get more for that car than it cost NEW (about $6550 which was the sticker price on my 94xfi's documents)

Now you appear to have had some bad luck afterwards but there was positively NO way you could predict that would happen. ANYONE who could afford $1700 would have been NUTS not to take that deal so don't feel bad.

44-45mpg is bad 48mpg is horrible. I AVERAGE 47-48mpg combined in the WINTER with my 94 xfi and I Have a bad tranny and bad clutch.

Check your EGR mine has had to be cleaned twice in one year already. SOMETHING in hinky its definately not your engine core sounds like that is darned near perfect.

did you vin confirm XFI? has the engine or tranny been replaced? (maybe they had to replace and did not get XFI engine or tranny??)

you should be getting close to 45-50mpg even in WORST winter city driving conditions with an XFI if you don't hammer it. Even on E10.

something is hinky. I am confident you will NAIL it.

one problem with your megasquirt problem. any improvements you see will be an UNKNOWN. the reason is simply. will the improvement be from adding the megasquirt OR from replacing some "defective" part ? very curious.

describe your driving? what conditions do you operate the car in tank to tank. level? hilly? drive it like an F1? like grandma? lots of short trips? a few long trips? stop and go or largely "steady state" ??

MAN what a sweet deal :-)
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Tofuball
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Strange Mechanic

Don't worry, I'll get a baseline first. I've got my ideas :P

It's definitely an XFi, numbers match and I even checked the camshaft, it's definitely got pointer lobes then the stocker. ECU seems XFi, I'll be able to tell when I pull it (I think it should say "FE" on it) donno bout the trans.

Sometimes I drive F1, sometimes normal, sometimes hypermiler. Same MPG no matter what, city or highway.

Thanks for the encouragement :)
Edited by Tofuball, Mar 15 2011, 09:43 PM.
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mcmancuso
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was that off a 85-88 turbo sprint mk1? that would be a different design as the head is different, you want a mk2/3 (89-94) T3 intake...
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Woodie
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mcmancuso has it, that's a MK1 intake, you have a MK 2 engine. Problem is, they never sold the MK2 turbo in the States. You need to be buying from someone in Canada.
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Tofuball
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Strange Mechanic

Do you know if I need the whole intake (Upper, Lower, TB) or if the lower intake manifold will go MKI to MKII? (Unlikely I know)
Edited by Tofuball, Mar 16 2011, 06:09 AM.
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bogs
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Duct tape heals all wounds

Ugh, I feel your pain Tofu .
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Tofuball
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Strange Mechanic

Allright, I've got the correct manifold\rail headed my way. I'll clean this other one up and try to sell it.
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nerys
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Grr

if your seeing no difference in FE the way you drive then you VERY MUCH have a problem that needs to be fixed before you experiment :-) (otherwise you won't know WHAT Is giving you an improvement the experiment or correcting an existing flaw)

I get VERY different FE results if I drive differently.
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Tofuball
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Strange Mechanic

Believe me, I'm aware. I saw this problem on another car I owned and it was a bad O2 sensor. I can't find a list of expected sensor outputs so I'm just going to test things for shorts and the like after I install my wideband if I am still having an issue.

But I do have vac flutter. And I'm willing to bet that is truely at the core of my issue. However, compression\leakdown tests are PERFECT with no valve leakage at all. Carb cleaner wont change the idle (external vac leak) so now I suspect an internal vac leak - PCV or (I suspect) the idle valve. Why do I think it's the idle valve? Because there is no flutter when I bypass it ;)

Maybe I'll break it open and check for leaks.

Or trade it to a squirrel for a stash of nuts. You can never have too many nuts, esp 10mm and 12mm.
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mwebb
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FOG

the front 02 sensor must cycle from
150 to 850mv
and
850 to 150mv

each , change in 100 ms or less at 2k rpm hot , this one is bad

Posted Image

blue trace is MAP sensor signal , shows vacuum per cylinder

to begin what you are about to begin
you need a scope

this one shows Misfire in cylinder 2 as the 02 sensor sees it
and yes
the 02 sensor does show misfire , if the system is misfiring , even a little bit
Posted Image
in this image red trace is MAP , black is the 02 sensor

don't have a scope ?
buy one
yesterday

you do not know how much you need it until after you use it

got an engine breathing problem ?
Posted Image
you can not test for it without a scope
Edited by mwebb, Mar 16 2011, 11:40 PM.
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nerys
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Grr

you need to build a toot or something on HOW to use a scope. I have that recording nano scope but not even a slight clue what to do with it :-)
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Tofuball
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Strange Mechanic

I sold my huge desk scope in 2007 :/
However, I do have an MT2400 :) It's OK for really basic stuff.


---

I had an idea last night, but it seems someone already did something similar:
http://www.jagclub.ru/plasm_plug.html

or

http://www.freepatentsonline.com/6289868.html

Plasma injection :)

---

Also I was thinking about the spray patterns on these injectors - and if they would be improved by vastly increasing the fuel pressure (to lower the boiling point) and running the fuel through a thermostatically controlled "preheater" to encourage rapid evaporation upon injection.

The only issue is that the heat aspect is a fire hazard no matter how you look at it.

My original plan was a thick copper pipe wrapped around the exhaust all the way to to the fuel rail and a super high pressure pump. The newer plan is basically like a mini-water heater that has it's own second high-pressure pump. I don't think I'll ever implement this due to safety concerns.

---

A third thing I was thinking of was constant propane injection (CPI?)
I use my propane equipment to inject a constant, very light flow of propane into the intake. This allows the spark off of even extremely lean mixtures of gasoline, and can possibly "fix" a lot of unpleasant lean burn conditions, allowing me to run leaner across the entire map (even at idle!). It would not use much propane at all, think of it as a pilot light.

The system could be made very small, and run on a regular refillable hand-held propane canister kept anywhere safe on the vehicle. Using modern propane safety methods, this implementation would be much safer then my fuel "pre-heater" idea.

Downside: it would mess with my EGT and WBO2 readings, but I would learn to compensate. It would also make it harder to calculate MPG (because I couldn't only count the gas any more, I'd have to count propane as well and I don't have a meter on it other then "It feels half full now")

Now the whole propane thing would be next to useless if we could just have smaller fuel droplets, and that would come if we could have some half-decent injectors!!
Edited by Tofuball, Mar 20 2011, 08:56 PM.
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Tofuball
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Strange Mechanic

Been busy fixing other people's cars. MSIIv3 complete, adapter complete, got my WBO2 wiring harness mostly repaired. Measured and cut grooves for the head, and disassembled and threw the MKI manifold in the parts cleaner (I figure I'll clean it up, paint it to look really nice, and sell it)

Grooved head and indexed plug:

Posted Image

The whole time I was cutting those grooves I was thinking "JASON YOU IDIOT YOU'RE RUINING A PERFECTLY GOOD HEAD WHAT IS WRONG WITH YOU STOP!!"
Edited by Tofuball, Mar 17 2011, 02:21 PM.
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bogs
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Duct tape heals all wounds

Tofuball
Mar 17 2011, 02:18 PM
The whole time I was cutting those grooves I was thinking "JASON YOU IDIOT YOU'RE RUINING A PERFECTLY GOOD HEAD WHAT IS WRONG WITH YOU STOP!!"
....and then your better half of the brain kicked in and thought "hmm......a few more might make it more symmetrical....." :lol
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Tofuball
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Strange Mechanic

OK, anyone have any ideas why it "flutters" or is this an acceptable amount of flutter?



I've always thought this was normal, esp cuz we only have 3 cyls, and it's got a tiny intake manifold. I've had two friends tell me it's not normal and one tell me it is. And everyone so far on this forum has said it should be rock solid. I've never seen a vac gauge rock solid on ANY car without a restrictor on it.

BTW: The gauge is what is making that noise.
Edited by Tofuball, Mar 18 2011, 07:58 PM.
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