Wtf slow car no power

[VtecvrsTurbo]

I did a boost leak test....it held for 20 seconds, I did a compression test, about 170 across the board. Changed my plugs, fuel filter. Dammit what is left? I want a fast car to be fast and I'm sick of the dsm. It seems to boost fine, but it just doesn't move. Sometimes when I get on it, it stutters and pops.

p.s. Don't tell me to make sure my plugs are gapped correctly. I had adequate knowledge of dsms.

 

[bmwisthekey]

what boost level are u running when its sputtering and popping on ya, and how much did your pressurize your system when doing the boost leak test how much was regulated air was pumped in , how high did u take it on the boost gauge. i was gonna ask about spark plug gap but saw what u wrote

 

[95talon_in_ma]

You say "Sometimes". Is it intermittent like it will happen 15 times one day, then not for a week? Or is it every day but at different times? Just want to safely rule out things like it only happens when it's humid out, which tends to be electrical. Or it only happens when I fill up at this one gas station. Which by the way if you always use the same gas station, run your tank dry and use a different brand (93 only of course...) It's happened in the past. Cumberland farms got in trouble years ago for having too much water in their gas...

You didn't mention timing but I assume you already checked it.

Other than that it reminds of this prank I pulled on someone years ago that pissed me off. We put pin pong balls in the gas tank. It would idle fine, but after a long hard acceleration the balls would get sucked down to the pickup and choke it. The car would stall, but the balls would float again and it would start right back up. He would start going down the road and eventually the same thing happened. We let him suffer for a week before someone told him.
Probably not the problem, but really funny...

If you have a pyro gauge, you could tell if it was leaning out, which would solidify it as a fuel problem. Which leads me to ask if the injectors were checked? or pulled and cleaned? if it wasn't leaning out then maybe do an ohm check on the wires. I have seen defective ones brand new. Most of the rest of the ignition is do or die, it either works or not.

Is the car a "tic" off or is it a real dog? Did it start doing it all at once?
I'll have to read your list of mods again...

Latr, Duane

 

[95talon_in_ma]

Just curious, in your pic your BOV was venting to the atmosphere.
I'm no expert but going by what was posted a gazillion times, it sounds like that could lead to problems. Is it still setup that way?

 

[VtecvrsTurbo]

No im not venting anymore(that was for the beach ) It does it everyday 3/5 times I get on it. If I let off then punch it again sometimes it goes. The timing? I checked the teeth on the gears and the white lines line up. I always run 93 octane from sunoco. The guy that had the car before me run 87 octane since it was new. Talon 95 mabye you should just look at my car. Oh ya when it does it its slower the a hummer. (real bad)

 

[donmagicjuan]

You mention in your mod list that you have a B&M FPR. You haven't by chance raised your fuel pressure above stock, have you?

 

[VtecvrsTurbo]

I had it above stock, but I put it down a while ago.

 

[donmagicjuan]

I had it above stock, but I put it down a while ago.

Good. With your current mods, you don't stand anything to gain by running higher than stock fuel pressure, and it will cause your car to run overly rich without proper tuning. If you can honestly rule that out as the problem (you're positive that it's returned to stock pressure), then I'll move on. What boost is your MBC set to? I'm assuming you have an appropriate aftermarket boost gage.

 

[VtecvrsTurbo]

I have a turbo xs mbc with a faze boost Gage. I get 1psi of spike. But even if I'm at 1/4 or 1/2 throttle it still does it. I running 15psi. I read in one of the posts that it could be my lifters(they knock loud) because the knock sensor with pick it up and change the timing. Is this a possibility? WTF

 

[donmagicjuan]

What you're referring to is called "phantom knock", and it can be caused by a number of things in the engine bay. Unfortunately, this problem is somewhat difficult to diagnose without a datalogger to capture various engine parameters. The knock sensor detects a specific frequency that correlates to the noise produced by detonation in the combustion chamber. Vibrations from other (often faulty) components can excite the knock sensor when they occur at this specified frequency, resulting in a false knock signal sent to the ECU. The ECU reacts by retarding the ignition timing, which normally reduces the knock at the cost of some extra horsepower. In the case of phantom knock, however, the signal sent by the knock sensor is abnormally high, so the ECU pulls a LOT of timing and kills the power output.

I'm not saying this is necessarily what you're witnessing, as we don't have a timing curve to look at, but it is a possibility. Since you've already ruled out a boost leak and poor compression, and if you plan on modding the car in the future, I would recommend picking up a datalogger. It not only will tell you what's going on in your engine, but it will make it much easier for other people to help you out as well.