Hey...

Got my EVO8 last week and have since properly broke it in to 600 miles. I'm at 1000 miles now and noticed an acceleration "quirk". When accelerating from about 3000 RPM, the cars seems to pull harder at one-half or 3/4 throttle than if I "floor" it. At WOT it seems to back off a little, and the turbo spool whistle isn't as loud either. This is my first turbo car, so I don't know if something like this is normal.

Don't get me wrong, I still love the car - but I'm just overly concerned of any problems. The only problem I've had so far is the drivers-armrest "felt" has come unglued and is peeling away. The dealer has offered to look at it as soon as possible. Should I mentioned the turbo item too???

The last 1000 miles have been pure motoring joy! For the price, this could be the perfect car . No complaints, really.

Thanks...

Evo2003.5

 

You need to let me drive it... I'll tell you if it's normal.

Doesn't seem normal... none of the turbo cars I've owned or driven have exibited this behavior.

My car should be here tomorrow... we'll have to get together and take some dual-evo pix.

 

Remember that once you go over 3500 rpm the boost goes down from 19 psi to 16psi. That might be the power loss that you are experiencing

 

Where are you located? What is the octane rating of the fuel you are using. One thing it sounds like to me is your ecu pulling back the timing at WOT.

 

Get a boost gauge.

Like Scooby said, may be your ECU falling back due to knock.

 

Hes got it right. I experience this in my WRX often.

 

Hi,

Fun huh! Try trial and error from different RPM's to ensure you are getting the turbo spooled up. Take it up to say 4,000 then WOT, then work from there. You should see a quicker response. A turbo engine requires a little more attention to RPM and boost than a N/A engine. A boost gauge will help.

Speedlimit........

 

Yes, I feel the same thing in mine. Here's what I posted in another thread:

"What I'm noticing is that if you put your foot in it early (< 3000rpms) you in a way, flood the engine. It pulls a LOT more when you are in the throttle only about 1/4 to 1/2 until the turbo is fully spooled and then above 4500rpm, put it down more.

That problem probably has a LOT to do with the intake and the exhaust being so restrictive. I'd bet that the problem goes away with an upgrade system on both ends. "

I'd like to hear some feedback from people who have driven 4g63's prior to this one, such as Claudius to tell us if this is normal. I feel, like I said above, that it has a lot to do with the restrictive intake/exhaust.

 

It might be like how I was told my Subaru ECU works. There's closed-loop operation and open-loop operation when it comes to fuel delivery. I hope I don't get it backwards because it's been a while since I've talked about this but...

Closed-loop is how you normally run. The ECU monitors the AF ratio before the cat and constantaly adjusts the fuel delivery to give stoich readings. As long as you're just gently pushing on the throttle or not at WOT the ECU assumes you're not looking for gobs of power and operates in this region. This gives you good emissions and fuel economy and stuff.

In open-loop mode the ECU delivers fuel based on a load/rpm map it has stored in it. The ECU goes open-loop when you stab at the throttle (so it's checking the TPS on the TB) or at WOT. It's assuming you're asking for all your power right away in those cases, which is probably true.

Maybe the engine is actually better at accelerating under closed-loop conditions rather than open-loop? I don't know, but that could be one explanation for some of this.

You also might need to take into account how "open" the throttle plate really is at 1/4, 1/2, 3/4 throttle. I belive it's not a linear progression since the throttle plate is circular and rotating to obstruct the TB. I think that at like 3/4 throttle the Tb is a lot more "open" than you might think.

 

hey

iodine23 is right on. my wrx wagon was much faster at part throttle than WOT. it is a part of having a japanese car made to work on our crappy gas. it is the safest way for them to make the engine work with so much variation i gas quality around the nation.

hopefully shiv and other tuners will find a way around this as they have on the wrx. i never found it a huge issue, just kinda annoying.

josh

 

Actually, I can answer this one, and I even know the correct answer.

The intake is too large. Sort of. I drive a, ahem, different 2.0-litre turbo, but I've driven two different versions of it. The first one had a large-diameter intake pipe, and suffered from the "problem" that you noticed. The second one had a smaller diameter pipe, and no problem with WOT.

However, the power characteristics of the two motors changed because of this. The first one made huge amounts of power from 5000-7800rpm, and would continue to make power after that point if there wasn't a rev-limiter. The second motor made huge amounts of low-end torque - but had absolutely nothing after 6800rpm. It would still spin to the 7500rpm red-line, but there was absolutely no point. I never hit the rev-limiter on that engine.

And these are factory cars. What MMC has stuck with is the ability for the car to produce gobs of power at the top end, especially if you put some higher-flowing air filters in and open up the exhaust a bit. It just means you can't WOT at lower rpms. Once you get used to it it will become second nature not to WOT, and overall, you get a stronger setup from the start.

Cheers,

Paul Hansen

 

My 2G Eclipse had a similar problem. If you WOT to early, the turbo would stumble and the car would hesisate jerking back in forth until you let off the throttle. Many theories, like a loose Knock sensor, to type of oil, to intake mods, to cleaning your combustion chambers were discussed with no real winner. But if you immidiately floored it again, it would work beautifully. I believe it has something to do with the fact that running leaner provides more horsepower at the risk of detonation so finding that balance is up the the driver. The computer should never run it lean enough to risk detonation unless the boost is too high for the stock fuel pump, but the computer can flood the engine when it knows a lot more air is entering which is not optimal for producing power.

I have also found that WOT too early also is bad on my S2000. It definitly is an acquired feel, but it pulls a lot harder if you give it 60% or so at first, then ease it to 100%.

smanders

 

Ahhhh, the quality is already shining through. Hope its covered under warranty.

 

Hmm.. odd .. I don't have my EVO yet , but have never experienced this in my 99 GSX, or in any of the other 1G or 2G DSM's I've driven.


Wait Wait ..

I have experienced this back in the day when my carb really need a rebuild badly tho !

 

Thanks to all for the advice! I'm going to get a boost guage soon so I can monitor the situation. As far as gas goes in this area (Jedinite can back me up on this) 91 Octane is the norm for "Premium" with 92 found here-and-there at BP/Amoco. It's too bad we don't have many Sunocos with the Super 94, maybe one in the Metro that I know of. Would an additive help, like for Autocross, etc. (like the 104+ Octane booster)? My Civic Si loved the extra octane, and didn't chug so much at start-out with full-accesory load, A/C, 100-degree weather, etc. I did try the A/C in the EVO yesterday, and it's great! You can cruise along, and you can't feel the compressor kick on, or any power loss!

If the fuel mapping uses a protective closed-loop at WOT, I can certainly live with it. 3/4 to 7/8 throttle even in 5th gear on the highway smokes a majority of the driving public, so I'm happy.

I'll keep folks posted on the armrest deal - I just need to get stop by the dealer when I find the time.


Evo2003.5