So the car ran great this morning. Went to a local car thing, parked it for an hour. Left to go across the street to eat, and now on the way home the car doesn't feel as powerful. It no longer rips the tires thru 2nd and third like it did before. Boost seems to break up above 10psi. Car dynod 475@19psi at the beginning of the month. Could being at 1/3rd of a tank cause this sort of breakup/lack of power? The aeromotive 340 stealth pump maxes out around 533hp. Im running 22 psi now which should be closer to 500.. could the fuel pump be running out of legs?

Setup: See sig

Things Ive tried: Added a ground to the coil pack bracket, swapped primary coil,

Just doesn't seem like its making the power it was this morning. At this point im tired of thinking about it so tomorrow ill put more fuel in the tank and swap the fuel pump for a bosch 044.

And of course as soon as I finished typing all of this my tuner yelled at me for running less than 1/2 a tank. So my guess is that's the problem.

 

I would check compression and maybe new plugs. You fuel pickup would have to suck to not work with even 1/4 tank.

 

Compression is good (via piston gauge). Ngk r7520-11 plugs have less than 1k miles on them. 1 has some cracking in the porcelain around the tip tho

 

Boost leak?

 

Builds boost ok. Just falls on its face. I'm leaning towards an ignition problem although my wideband says it goes lean when it happens. My head thinks if it was going that lean when it happens I would have grenaded the engine. Meth/water isn't THAT good if a savior.

 

its either fuel, ignition, or turbo/boost related.


the engine will lose power if you don't have the fuel to keep it going.

What AFR are you seeing when you have this problem?

 

I'm gunna venture to say that you have found the problem. Has your engine flooded out recently? If your plugs are fouled than obviously you'll have issues running.

While breaking in my last engine I ran 3oz/gal premix. My plugs got so fouled they would barely fire, my MTX-L read 16-18 afr. I was essentially dumping raw fuel out my exhaust because the plugs wouldnt fire.

At the very least I'd get rid of the one plug with cracked pocelain.

 

plugs.... "cracking in the porcelain "

you have detonation. detonation breaks porcelain.

of course the question is what was the cause.

more likely fuel rather than ignition. it might relate to an AI failure as well.

howard

 

I think I found the issue. The fuel hose that connects the pump to the supply tube in the tank had slipped down to the bottom and was most likely not supplying most if its fuel to the engine and just spraying it in the tank.

Haven't driven it yet but my guess is that's the problem.

 

Pics

 

Bingo.... I would still confirm compression, just to cover the bases.

 

compression is good. 40psi jumps on the piston for all faces. builds to 120. took it out, back to normal. now I just need to dial in the avc-r for solid 22psi at all times and change my sig to 500hp club

 

You almost blew your engine by scrimping on your fuel hose being too short and only having one clamp.


You are lucky.

 

Truth

 

It was most likely the water/meth injection that saved the motor. I didn't "scrimp" on the hose so to speak. Just miscalculated it. This car was reaaaaaaaly messed up before I bought it.

 

40 psi per face is lowlowlow.. Builds to 120? Did you not remove the Schrader valve?

 

that happens a lot in those pumps . also the wiring to the pump causes issues too .
make sure you got all that good and check the spark plugs

 

Either way you need new plugs...and not sure why your running 11's all around. you should def take care of that hose. Take this as an instance where you cheated death... could've really blown the motor like that. Time to fix the root problem and thats that whole line as a whole. Don't just re-tighten it.

 

He's holding the valve open manually. When you do this you just look for 3 even bursts they could be 40psi 60psi or 30psi, as long as they're even its good. Next you do the "build up pressure" which is the 120psi.

Sounds like he's one lucky bastard! Cracking porcelain is from detonation waving into the plug. I detonated 6 years ago on 3mm OEM seals and they somehow took it just like this instance. Sometimes Jesus blesses these engines...

 

One thing that sucks about aftermarket pumps is having to cut the metal pickup tube and mate it to the pump with pressure hose. My fuel setup looks the same but I made sure to run a hose long all the way up the neck with two clamps!

Good save and lucky bro!

 

still going on about this? its been repaired for a week :P. ive been building rx7s for 15 years, im not a complete newb. Plugs got replaced (just cant get them locally), fuel line got replaced with one thats probably 8" in length. the savior on this was the seals (its not a stock motor) mixed with the water/meth to limit the damage done. I have no doubt that 1 if not both housings won be reusable on the next rebuild, but thats a problem for another time.

as far as the compression tester, yes the schrader was still in the bottom of it hence the lower readings. i know when ive blown a motor, hell i know when ive weakened one.

 

Lmao a week ago your asking why your car dosent have the power it should b/c you had a 1/3 tank of gas! . This week your a master rotary builder who dosent know how to properly use a compression tester...

 

Last week I was tired and figured a post with ideas while I slept wouldn't hurt. Anywhere in my post suggest I'm a master rotary builder? 1/3 of a tank can starve fuel. Properly use a compression tester? Lets look at that statement for a second. If it was proper to use that style to begin with my guess is Mazda wouldn't have made the other style. You wouldn't have to remove anything for it to function properly. It's a tool that CAN be used for a base line. Not the ideal tool. If you don't have anything constructive to add to a post, don't reply. I added my fix so anyone else having an issue that uses the search function can read what I did for my repair. I built my car. Not a shop. Not my buddy. I did. Still runs after some detonation so I'd say I'm doing just fine.

 

You got lucky!

cracked the rear iron 3 weeks ago due to sucky stock fuel pump wiring (pump saw only 9v). engine had maybe 1000km since rebuilt, luckily no damage to stock 2mm FD seals. also plugs looked fine. lesson I learned..

measure fuel pressure with injectors out of the engine and 100% duty cycle at max boost (=fuel pressure) you want to run, if the fuel pressure remains stable, your good to go.

with the 9v at the pump (AEM 340 lph), pressure dropped over a bar when injectors got over 70% duty

 

Yup I did. I always re wire the pump to its own full 12v relay.