Silverhorn

Hey guys,

So I've been reading a lot of posts about engine stalling on the 8's but I can't find a thread that seems to be the same issue as mine. I've read up about the solenoid, but that doesn't sound like my issue as it runs fine while stopped and at idle. Its while decelerating that I have an issue, not while at idle. Sorry if this issue is somewhere, but I've looked quite a lot through the forums, and haven't found anything that was close enough to help.

I have a 2005 6spd. I've recently started to experience an issue with my engine stalling. This happens when I push in the clutch with the RPM's above ~3k while driving. Basically while travelling approximately 65mph in 6th, and I push the clutch in, the RPM's drop quickly, straight to zero. It immediately starts right back up if I let the clutch back out. The electronics on the car never turn off, just the engine (they don't turn off or flash). I just get the warning lights on the dash that also appear when you have the key in but the car not running (Check engine and battery light). At first I thought this was an issue with the battery since this started to happen originally when I had a bad battery, and got it replaced, and it stopped happening for a while (may have been unrelated). I've added a substantial amount of electronics to the car over the past few years so even though this was unlikely I thought I'd check it out. I still have the stock 100A alternator, but I've upgraded the battery and installed a voltmeter to try to eliminate that as a source of the issue (it stays a solid 12-13 volts throughout the stall). I also installed new + and - clamps on the battery since the stock ones were corroded and the design is WTF?

I've installed a K&N ram air intake along with the Revi CAI about 6 months ago, but this issue started a few winters ago with what I thought was a bad battery. As best I can remember this issue was happening before the intake change. I did clean the mass air sensor when making the swap, it was quite dirty but the issue was present before and after.

If I let the car decelerate in gear until it gets under 3K rpm then the engine won't stall when I put in the clutch. It doesn't seem to make much of a difference if I have the A/C, lighting kits, or radio with sub/amp/cap, on or off when I push in the clutch. With the A/C off it does seem to last slightly (maybe) longer before it stalls.

One of my friends thinks that the issue is the idle air sensor. Does this sound reasonable? Any other ideas?

RIWWP

iTrader: (2)

Vacuum leak, O2 sensor failure, ESS fouled, ESS profile needs resetting, MAF dirty, compression loss, and/or that K&N intake (it's known to cause idle problems).

You confirmed voltage, so stop worrying about the battery.

Something is disrupting your AFRs while returning to idle, or is having trouble with the ignition/fuel signal at idle, or your engine is failing.

The best way to go about this is to get access to the OBD2 live data. Do you have something for this?

Silverhorn

Thanks for the reply!

I have cleaned the MAF sensor. But both the O2 Sensor and the MAF would affect the car while running normally correct? So they wouldn't be isolated to this issue, it would be noticable under all driving conditions? The car performs great around town. Its only exiting from, or coasting in nuetral on/off the highway that I have problems. The issue did exist before the intake was installed, so I don't feel that that is the issue.

I'll try to look into the rest of these over the next week. Working more that I would like the next two weeks, but I'll try to get them.

I know the local shop really well, so I borrow their OBD2 tool whenever I have a code. But to get the live data is that a different tool?

RIWWP

iTrader: (2)

Not necessarily. As an analogy, think about any other car's analog speedometer and needle. How hard is it to see what speed you are going at 20mph? 40mph? 60mph? You can see it with a fair degree of accuracy. How about at 5mph? Not so much, as most 10mph marks are a faction of a distance from 0, far smaller gap than between any other 10mph mark.

It's similar. The MAF and O2 sensor voltage to converted values aren't linear, but a curve, so especially for the MAF, at low flow rates it doesn't take more than a tiny hair of a variance for problems to show up.

You may not think that your intake is causing any problems, but I can tell you that it's certainly not helping. You might end up fixing the original problem, only to continue to still have that problem or another similar one caused by that intake, leading you to chasing your tail. Weapon R is the only brand name intake with a worse reputation on here. You have proven power loss and idle instability at a minimum with that intake. The stock intake is better in every way to that one. Only Racing Beat, AEM, and Mazdaspeed are superior in power to the OEM, and the OEM still provides better filtration.

Yes, live data is different. You can buy more expensive tools, but there are better options.

Many of us use a bluetooth or wifi OBD2 adapter and connect our smartphones or tablet to that, and then use an appropriate app.

We can pull lots of information, but here is a random youtube video of the kind of live data feedback I'm referring to:

I personally use a bluetooth dongle and Torque (Android based).

There are a variety of behaviors of sensor outputs that we can use to help diagnose problems. If you get something like this, then you can pull codes and diagnose issues on any vehicle you have, friends and family, etc... without having to find a shop that will do it for free or pay a diagnostics fee again.

It's one of those insanely useful tools that I don't understand why every car owner doesn't have one.

Silverhorn

Thanks, that looks helpful. I'll see if I can get that going. It seems that the ones I can find are Android compatible. Do they make an Apple compatible version?

Got the vacuum gauge installed yesterday. Results are as follows.

At idle of 900-1k gauge reads 5psi vacuum
In neutral with minimal throttle (approx 3k rpms) reads 0psi
Under load with RPMs at 3k reads 0 psi
Coasting in gear returns to 5psi vacuum

Trusting the numbers of JDM

He's getting:
14.5 inch of mercury [0 °C] = 7.121 pound/square inch

He says spec is:
min --- 16 inch of mercury [0 °C] = 7.858 pound/square inch
max ----19 inch of mercury [0 °C] = 9.331 pound/square inch

His numbers were low, mine significantly lower. This would suggest substantial vacuum leak?

Is there anything I'm missing here?

RIWWP

iTrader: (2)

Sounds like it.

Most people aren't actually using vacuum gauges, so I'm more used to a vacuum leak being identified as too-low MAF value at idle (which should be ~5.5g/s) and positive short term fuel trim.

Silverhorn

Ok I'll do vacuum testing, I also found an OBDII tool for Idevices... They apparently aren't very reliable and are substantially more expensive, THANKS APPLE for being special.

alnielsen

iTrader: (4)

It has something to do with Apple not paying for the rights to Bluetooth technology, if I remember correctly.

RIWWP

iTrader: (2)

An easy way to thank them... Buy an Android?

Silverhorn

Seriously thinking of buying an android tablet to mount in my car.... but I already have a touchscreen pioneer... so its seems a waste. Would love it if my pioneer could handle that OBDII bluetooth data...

RIWWP

iTrader: (2)

This is what I do. I can take the tablet with me when I leave the car, no theft risk, can use it freely like any other tablet. Mount was $30 I think. The bracket gets anchored through the seat rail bolt. Restricts the seat movement some, but not a problem unless you almost always have a passenger.

Silverhorn

That's perfect for a mount! Where did you find that beauty? I hate window mounts for anything larger than 2". They are always falling off here. Hot > Cold > Hot > Freaking hot > Freezing cold.... I can't ever win that game...

RIWWP

iTrader: (2)

I bought 2, one in my wife's car too. Works really well. A bit of vibration, but that can be mitigated with proper positioning to cushion an edge against something.

Silverhorn

What is this? And can it be contributing to my leaking problem? I've found that its attached past the butterfly... on bottom, used to run up front, don't know what it did then either... Its been either connected or capped (never open)....

AZ_Copperhead

I have a 2004 RX-8 base model, and I'm actually having a similar issue as Silverhorn. I do have a check engine light that comes on and shuts off intermittently (every other day). If I have the RPM over 3k and coast, it shuts off. All electronics remain on but the lights come on as if I hadn't started the car. Also, if i'm sitting in idle, the car will drop RPM down and sound as if it's shutting off and then will kick back up to 1k. When the light's off, there are no problems at all and the car runs like a dream.

engine code shows rich fuel mix on port 1. I've replaced the 02 sensor and cleaned injectors. Not sure what else to do. I'm a newbie do-it-yourself mechanic *basically, I do my own brake an doil changes* and not certain how to figure out what's causing this.