[88MX6LX]

Ok, my car wouldn't start before school today, so i went to school(I only had a 40 minute class), right when I got back home I tried to start my car again...didn't work.

I decided the first thing I should check is my plugs.

Cylinder 1: Plug covered in oil, gap ok.
Cylinder 2: Gap is about 1/4"
Cylinder 3: Plug covered in gas(I'd been cranking the engine for a while)
Cylinder 4: My plug has NO electrode.

I replaced the plugs and it is back to normal(well, back to normal for my car, which really isn't normal)

Anyway, how can a plug UNgap itself, and how the hell does an electrode break off?

I'm guessing I need a rebuild because of the cylinder 1 problem.

Not necessarily looking for help here, just want to hear some thoughts.

Brandon

 

[Guest]

detonation will blow the electrode of easily.

Sounds like the turbo is taking its toll on your engine.


**walks away humming**

 

[88MX6LX]

detonation will blow the electrode of easily.

Sounds like the turbo is taking its toll on your engine.


**walks away humming**

:lol: I knew I'd hear from you.

I thought detonation would be more obvious.

The weird thing is that the night before I drove home fine, and it just wouldn't start the next moring. :shrug:

 

[ZFreakMX6]

(this is kinda off topic...)....

Where in Omaha are you? I just moved from 168th&Q st area to Tyler, TX... I moved like 2 months ago...

I think it's time for an engine rebuild.

 

[Turbobink]

Are you using the correct plugs?

Correct heat range is important...

 

[88MX6LX]

I'm on 108th and West Center, that area.

I'm using NGK V-Powers

 

[Dex]

try going to a plug that is one step colder, ie miata plugs, and gap them smaller than stock, i think around .9 to 1.1 mm. I would worry about the electrode missing as well as the oil. What are you running for boost (how much psi) and what fuel are you using? did you retard your timing after you put on the turbo? Try using denso iridium plugs, for a miata gapped between .9 and 1.1 mm. I would make sure you are running higher octane fuel, even though the car is not mapped for it, bolting on the turbo will give quite a shock to the system, and retard your timing a couple of degrees.

 

[rebel2k4]

I knew the GT injectors wouldnt be enough fuel. Put back in the stock injectors, and get a 3:1 or 6:1 ratio disc for the FMU. You should have plenty of fuel then. Just make sure you get a walbro pump.

 

[magik8]

I'm thinking detonation as well. I've seen the missing-spark-plug-electrode trick happen on a 2nd gen PGT after a big spray of n2o. I would retard your timing (assuming you're still using the LX ECU and distributor) and run some higher octane gas. I'm afraid you probably damaged some internals though......hopefully not. I would do a compression/leakdown test ASAP.

 

[Dex]

I knew the GT injectors wouldnt be enough fuel. Put back in the stock injectors, and get a 3:1 or 6:1 ratio disc for the FMU. You should have plenty of fuel then. Just make sure you get a walbro pump.

The gt injectors should be able to get enough fuel in, the problem is the stock lx ecu has no way of controlling it. The stock lx injectors are only 220 cc injectors, a fmu with a 3:1 or 6:1 ratio is not going to give you enough fuel. To have everything work with the lx injectors you need about 120 psi of fuel pressure at the rail. I would love to see someone do it, but I think there would be other problems at that pressure.

I also agree with magik8, get a compression/leakdown test done asap, an electrode flying around in a cylinder could do some damage.

 

[rebel2k4]

120 psi?? For what pressure of boost? I would like to see how you came up with this.

Also, the GT injectors are apparently NOT working so something else has to be done. Mazda4life had plenty of fuel with an FMU.

 

[Dex]

go back and check that, mazda4life was running lean in 4th and 5th, with a 12:1 fmu, and better yet, I will do the math with you
The dx/lx/gt all have the same stock fuel pressure of 36.3 psi, they have the same fuel pressure regulator with boost reference. A fmu with a ratio of 3:1 will add 3 psi for fuel pressure, for every 1 psi of boost, stock boost of 7.3 psi will ballpark about a 21 psi increase in fuel pressure, plus 7 from the stock regulator. this wil give you 28, plus 36.3, will give you 64.3 psi at the rail. Mazda4life using a 12:1 fmu was leaning out, 12:1 would give you a rail pressure of 12*7= 84 psi plus the 7 from the stock regulator would give you 91 psi plus 36.3 stock is 127 or so psi. He was leaning out in 4th or 5th, because you can't get a pump that will create that pressure. You can get hi flow gph pumps, but they can't flow that at a hi pressure, so it won't work. If you could get that pressure (which is what you would need make the injectors spray higher than 220cc) i've figured it out b4, just gotta remember where if you need the math on that, than it probably would. However you cannot get a fuel pump capable of creating that pressure, so we need bigger injectors. The problem there is no way of correctly controlling them, just because it can flow more does it???

 

[rebel2k4]

Well I would have a hard time believing that the stock pump even moved any fuel above 60-70 psi. It's a very weak pump. me and a friend worked it out to be somewhere around 70-100 lph if my memory serves correct. Raising pressure does nothing if the pump can't move the fuel. An FMU would work better with a walbro pump IMO.

Apparently he was leaning out with the GT injectors so back to the drawing board huh? I say get a real pump, stock injectors, FMU, and a 5th or 6th injector. That will do the trick.

 

[Dex]

This is what I figure. New pump w/rewire for 14 volts, fmu with 2:1 ratio, and 5th injector. From the beginning this is what I figured anyone would need to do this with any sort of reliabilty and performance in mind. So it would seem that we agree

 

[Guest]

Forgive me for not being knowledgeable on this subject, but how would running 120 psi to an injector rated to flow at 220cc's change the flow rate?

I understand that the fuel would flow out of it in a hard fast stream, but I doubt it would drasticly increase the fuel coming out. An example of this in the real world is trying to get more water out of a small hose by increasing the water pressure.

Physics isn't really my thing, so I could just not be understanding though.

 

[Dex]

From where I understand it (and I could go looking for the posts if you want) You can add pressure to the injector, and it will force more fuel through, there is a formula somewhere out there to aprroximate how much psi you need for what kinda of flow, but generally the injectors will get maxed out fairly quickly. It doesn't neccessarily change the flow rate, it just forces more fuel through the injector

 

[88MX6LX]

Ok guys, all of you think detonation. My car drove fine the night before and the next moring it wouldn't start. Can I detonate by cranking the engine??? that doens't sound right.

I run 92 octane usually, I have 91 in my most recent tank. By the way, 92 is the highest here.

The boost I'm running is in my sig, 11-13ish, however, again, I wasn't boosting that high for a mile or two before I got home the night before it wouldn't start.

I am going to retard my timing, as soon as I figure out which way to turn the disty, I'm guessin left:shrug:

 

[Guest]

From where I understand it (and I could go looking for the posts if you want) You can add pressure to the injector, and it will force more fuel through, there is a formula somewhere out there to aprroximate how much psi you need for what kinda of flow, but generally the injectors will get maxed out fairly quickly. It doesn't neccessarily change the flow rate, it just forces more fuel through the injector

Well, on a hose theres a point where no matter how high the pressure gets it just won't flow anymore, and the fluid backs up.

I thought that at 220cc the injectors were already running at 100% duty cycle.

Forcing the injectors to spray more fuel seems to be the same as installing injectors that actually flow better. So you would still have the crappy idle and such.

Why stress your small injectors out? I don't see guys who make big power out of engines (4G63 and FE-DOHC guys) running on pitiful small injectors with tons of pressure. I see them running large injectors with around 60 psi of fuel.

Originally posted by 88MX6LX

I am going to retard my timing, as soon as I figure out which way to turn the disty, I'm guessin left

Get yourself a timing light.....

 

[dougiefresh]

It doesn't neccessarily change the flow rate, it just forces more fuel through the injector

Wouldn't that be changing your flow rate (flow rate = rate of flow)?

 

[Dex]

Well, on a hose theres a point where no matter how high the pressure gets it just won't flow anymore, and the fluid backs up.

I thought that at 220cc the injectors were already running at 100% duty cycle.

yes, at a given (controlled) pressure level, as to keep the measurements between all injectors the same. However up the fuel pressure, and you change amount of fuel going out of the injector.

At 100% duty cycle, if you increase the pressure, you will flow more fuel, however there is a point where you max out the injectors, I don't think that the manufacturers build these cars running at the limit, its harder on the parts, so its safe to say that you can push past for a little while.

Forcing the injectors to spray more fuel seems to be the same as installing injectors that actually flow better. So you would still have the crappy idle and such.

Why stress your small injectors out? I don't see guys who make big power out of engines (4G63 and FE-DOHC guys) running on pitiful small injectors with tons of pressure. I see them running large injectors with around 60 psi of fuel.

Yes, however they have a way of controlling those injectors, with standalone fuel computers etc, we do not, so we need to get fuel in through mechanical means, or someone needs to figure out how to do it electrically (zombie please lol). Until then I say wire the pump for it gets higher voltage, run a 2:1 ratio on a fmu with the stock 220cc injectors, and a 5th injector

quote:Originally posted by Dex
It doesn't neccessarily change the flow rate, it just forces more fuel through the injector



Wouldn't that be changing your flow rate (flow rate = rate of flow)?

No, because the rate of flow that a injector is measured at is in a controlled situation, with normal fuel pressures, say 30 psi. The second you change that the injector flows more, however it is still measured as a 220 cc injector. Just because there is a number associated with the injector, does not mean that is its limit.