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View Full Version : Rough idle, low RPM, and general plea for help



torrentprime
09-12-2004, 10:50 PM
Hey all,
I haven't asked for opinions on this yet cause I always feel like if I knew more about my car I could diagnose it myself (translation: I hate to expose myself for an automotive newbie), but I want to get some answers/questions for this that will hopefully lead to a plan before too much longer.
Only mod is a GFB blow off valve (pretty sure the Perrin isn't affecting anything)
I have had a problem with low idle and what felt like acceleration problems almost since I got it last Oct. Nothing I could point to really, especially since I didnt have another EVO to compare it to, but the car didn't have the power I thought it should have.
I installed the GFP BOV and things got worse. Idle was down around 800. While
a) going slow (driving in a parking lot, for example)
b) with A/C on
taking my foot off the gas would see the idle dip to 2 or 300 and the car threaten to stall. The A/C has a HUGE effect, both on the sound and shake of my car and the lower RPM during idle. I actually find myself turning it off when I have to, say, park or manuever over speed bumps, etc.
I first assumed I had not set the pressure for BOV correctly, and turned it slightly towards negative, and it helped. For a little while. Then, I took the car in for the first major tuneup at Mitsu. After their 3 billion-point inspection and tuning it runs worse than ever.
I again checked the BOV (got some info from the people here) and found i hadn't set it as low as I should have, and moved more towards negative. Slight change, but still bad. The idle is still real low, the car threatens to stall (and sometimes does) in low-speed, 1st gear situations.

Related: when the car is even slightly cold (and sometimes even when hot) and I slowly accelerate, depending on how much gas I give, the car shudders HORRIBLY, loud and painful. Had passengers say, "WTF was that?"

I don't expect y'all to be able to diagnose based on these symptoms, but I don't know how to approach the problem. I mentioned it to Mitsu during the maintenance, and got one of those "no problems seen; what do you mean, try letting it warm up more, no warranty work required" answers. I would like to take it to someone who knows what it SHOULD run like and can help me decide if I need some work, maybe a chance to upgrade new parts, maybe it really is warranty work that I need to make them do, something! I dont know enough to tell Mitsu that there is a problem they need to fix. Right now, they can hold me off by saying there isn't even a problem.

anyway, this was waaay too long, so: Help is appreciated. Any other info I can send along, I will do so.
Thanks all,
-D.

Black_EVO
09-12-2004, 11:00 PM
I have had the idle drop to 300 sometimes with the AC on in parking lot situations. I have never had the car stall though. I figure it is somewhat normal because my SVT does the same thing. Both of my cars ar unfortunately still stock.

garrick70
09-12-2004, 11:17 PM
I just had Works install my GFB BOV last Friday. I have not had any issuew with driveability at all. It was set to they're recommended settings. Give them a call. I know they would be more than willing to help you get it set up correctly.

JanSolo
09-12-2004, 11:18 PM
Try turning the BOV to completely recirculate and see what happens.

torrentprime
09-13-2004, 12:49 AM
Thanks. I'll give it a try tomorrow (well, right now actually) and let you know how it goes.

FWIW:One thing I don't think I made clear; the really bad shudders in 1st gear pre-dated the BOV install.

nebolic
09-13-2004, 06:48 AM
hey torrentprime,

the problem isn't with the car, I don't want to come off sounding like its all user error, but my Evo does the same thing. With the A/C on, it robs the Evo of all power, it freaking drives like a lancer ES. Anyhow, the idle at 800rpm is sorta normal, my car idles at 800 rpm, kinda fluctuates sometimes, but idling at 800rpm is normal.

Now about the shuddering, you're just releasing too much of the clutch and the clutch isn't grabbing hold that is why you are experiencing the shudder in 1st gear. I have the same problem sometimes when I first drive it in the mornings.

I know that you've probably driven manual cars before and you're pretty good at it, but the Evo really needs some time to learning in driving it. (Also the shudder probably happens too when you back out in Reverse gear?)

Anyhow, my solution to your problem is that you release less of the clutch. Most people think that giving more gas will help the launch of the car, but i think it helps more if you modulate the clutch. Not claiming that I'm an expert on driving manual but if your releasing the clutch with your whole left foot (maybe you might know what I mean), trying letting go of the clutch with the flex of your ankle, usually when you feel tension on your ankle is the sweet spot for the clutch and hold it there for a tad second. Hope that helps, otherwise my only advice is that you let one of us take a look at it, drive our Evo (I'll let you drive mine cause i'll be in San Jose this weekend) and compare to see if you have any difference. If that still doesn't work, I'd take it to WORKS RAllY and have those good folks over there take a look at it. Let me know if you want to test drive mine to see if you can reproduce the same result.

Nebo

torrentprime
09-13-2004, 09:21 AM
hey torrentprime,
the problem isn't with the car, I don't want to come off sounding like its all user error,
No, don't apologize, that's EXACTLY what I wanted someone to tell me. If it's just me getting used to a high performance car, than great; I can learn what i need to learn to make it happen.
My last car was an '99 GSX, so I thought I had a feel for this type of car a little, but the clutch is (obviously) giving me problems.
I'll work on what you mentioned today and give things a try.
thanks

nebolic
09-13-2004, 09:43 AM
cool, glad you didn't take it the wrong way. Let me know if you want to meet up this weekend, I'll be more than happy to let you test out my car. I have the same BOV on their so only minor differences between your car and mine. Hope that solves your problem.

Nebo

BluEvo
09-13-2004, 10:32 AM
I have the same problem sometimes when I first drive it in the mornings.
...Also the shudder probably happens too when you back out in Reverse gear?
i thought i was trippin. yeah i get the shudder in 1st and reverse when i leave to work in the morning, but never again through out the day.
strange shit! same remedy here, clutch in a bit more.

torrentprime
09-13-2004, 12:39 PM
Let me know if you want to meet up this weekend, I'll be more than happy to let you test out my car. I have the same BOV on their so only minor differences between your car and mine. Nebo

Definitely like to meet this weekend. Is there a meet of some kind I haven't seen the post for? If not, we can hook up at InnOut or whatever and do some testing for user error. LOL

JanSolo
09-13-2004, 01:22 PM
There is a monday night meet tonight over on the Starbucks on Wolfe in Cupertino Village.

nebolic
09-13-2004, 01:39 PM
no special meeting that i know of for this weekend, but like u said we can always hook up at in n out.

Nebo

Let me know.

EvolvedDSM
09-13-2004, 01:55 PM
Regarding the idle: If it's sitting a little lower than you'd like, you can adjust the BISS screw on the throttle body (number 4 in the diagram).

http://www.columbusdsm.com/forum/files/tb1_780.jpg

I can never remember which way to turn it. I think clockwise lowers and counter-clockwise raises idle. You may still have an underlying problem (a small leak somewhere), but this should help your EVO be more liveable until it gets tracked down.

torrentprime
09-15-2004, 05:23 PM
hey all--wanted to give results to your suggestions.
* Adjusted the BOV to full recirculate--almost. One of the hoses isn't quite long enough to reach so it slides the BOV to one click short of full recirc. But it is still much further closed than before.
* As best I can, tried to modify my shifting technique to allow a little more time on the clutch. I think i was operating under the impression that "the longer your foot is on the clutch, the faster you wear it out" and so I was trying to shift very quickly, even in very low speed driving.

Much better. I definitely have smoother shifting, and I can avoid the shudder thing almost entirely.

I think I need some basic lessons too in getting a feel for what RPM to want to shift at for driving, whether take-off speed or commute traffic. I read the discussion on double-clutching, and while I know DC isn't needed per se, the discussion help fix in my mind that I need to understand better what RPMs I should go for when shifting, especially downshifting.

So much to learn...

nebolic
09-15-2004, 05:39 PM
:) cool glad to hear that you got your shudder in first gear fixed. if you have time, you could probably take a ride in any ones car and sort of watch how and when the shift, that might give you a better idea on how you would like to drive as there is no one "correct" way. Everyone has a different style.

nebo

nebolic
09-15-2004, 05:40 PM
Oh also about the clutch thing, "the longer you're on the clutch". I think it pertains more to the distance, say like your moving 200ft and your foot is still on the clutch, yes you'll wear the clutch out, but when you are first starting off in first gear, staying on the clutch for that tad second longer shouldn't affect it too much, also besides the fact that the factory clutch is designed to slip.

Nebo

torrentprime
09-15-2004, 06:14 PM
Thanks.
Yeah, need to pay more attention to shifting. Definitely want to hook up w/you this weekend sometime (and anyone else too of course). What days r u around? I work right by InnOut at McCarthy so I am there on Friday's anyway...

nebolic
09-15-2004, 06:18 PM
i'll be in town starting friday 9/17/04 ill be staying in cupertino, so its like 15 mins to in n out at mcarthy. Give me a call and we can meet up if you like.

cell 408-421-0231

Nebo

warpspeed
09-15-2004, 06:29 PM
Actually stepping on the clutch pedal doesn't ruin the clutch. It is mainly the throw out bearing. If you guys think about it, when you step on the clutch pedal the clutch is disengage so how can it ruin the clutch? :wink:

nebolic
09-15-2004, 06:37 PM
i think he meant riding the clutch, like not releasing it all the way.

Nebo

warpspeed
09-15-2004, 06:42 PM
* As best I can, tried to modify my shifting technique to allow a little more time on the clutch. I think i was operating under the impression that "the longer your foot is on the clutch, the faster you wear it out"

He wrote this and so like he said he was under the impression. Which is wrong. :wink:

nebolic
09-15-2004, 07:04 PM
:) lol

Nebo

torrentprime
09-15-2004, 10:48 PM
Ok, not quite sure how to answer the above exchange. LOL
Yes, Nebo you're right, I meant riding the clutch and not just using it more.