94 Eclipse na questions

[Shamus]

I have a few questions about my 94 GS.
1. I put polly motor mounts on it and its now vibrating like craze. Undrivable in its current condition, at idle the dash is jumping about an inch. Is that normal? If not, what else could be causing the problem? Crank walk? (see next question) harmonic ballancer? or maybe the shaft ballancers????
2. Its a 94 but, from what I have read here, it may or may not have the 7 bolt engine, I've been researching this for weeks and can't figure it out. Any help on that would be appreciated. I know the oil pan trick but I can't really tell. Other than breaking down the motor, is there another way to tell? serial number on engine or something??
3. I have a real varying idle speed. It can change from around 2000 all the way down to 900. Usually it will idle the same the whole time I'm driving but then next time I drive it (after cooling down) it might idle completly diffrent.
There are a lot more but I am not far enough along to ask yet, I'll ask as I'm working.

 

[9!'clipseDOHC]

I have a few questions about my 94 GS.
1. I put polly motor mounts on it and its now vibrating like craze. Undrivable in its current condition, at idle the dash is jumping about an inch. Is that normal? If not, what else could be causing the problem? Crank walk? (see next question) harmonic ballancer? or maybe the shaft ballancers????
2. Its a 94 but, from what I have read here, it may or may not have the 7 bolt engine, I've been researching this for weeks and can't figure it out. Any help on that would be appreciated. I know the oil pan trick but I can't really tell. Other than breaking down the motor, is there another way to tell? serial number on engine or something??
3. I have a real varying idle speed. It can change from around 2000 all the way down to 900. Usually it will idle the same the whole time I'm driving but then next time I drive it (after cooling down) it might idle completly diffrent.
There are a lot more but I am not far enough along to ask yet, I'll ask as I'm working.

1. Poly mounts add a lot of vibrations. They are a lot stiffer then the stock rubber ones, which absorb a lot of the vibrations. However, refer to number 3.
2. 6 bolts were made from 89-92.5. Since you have a '94, if the engine is original then it's a seven bolt. Check the VIN number on your engine (located on the passenger's side of the block, just above the transmission bell housing, below the thermostat housing). If the VIN number matches the one on your dash, it's a 7 bolt.
3. This is pretty common on 1gs. It is usually due to dirty/leaking throttle body, bad BISS screw o-ring, or a Dead ISC. I'll post a few links for you on what to check out. Your idle surge, coupled with the poly mounts, is probably what is causing the majority of the vibrations you are experiencing at idle. I have poly mounts and a rock solid 750 idle and the vibrations are vary, vary minimal.

Here are some handy links:
http://www.vfaq.com/mods/BISS-1G.html
http://www.vfaq.com/mods/wayback/BradBauer/engine/tb.html
http://www.vfaq.com/mods/wayback/BradBauer/engine/surge.html
http://www.youtube.com/watch?v=l7R3gf7SiAo

Hope this helps!

 

[92AWDHX40]

Yep i got the polys too vibrations very minimal concerned at first but i love them.

 

[Shamus]

Very helpful. I opened the first link and it discusses the fact that an attiltude diffrence can mess up your BISS setting. My car was bought in El Paso TX at an attilitude of 1000ft above sea level and I live in Albuquerque which is 5100ft above sea level. I think that might be enough to require an adjustment. Thank you for your info and wisdom. I will start with these things and see how it goes. I will post after the weekend as to how much it helps. Thnaks again.

 

[9!'clipseDOHC]

Very helpful. I opened the first link and it discusses the fact that an attiltude diffrence can mess up your BISS setting. My car was bought in El Paso TX at an attilitude of 1000ft above sea level and I live in Albuquerque which is 5100ft above sea level. I think that might be enough to require an adjustment. Thank you for your info and wisdom. I will start with these things and see how it goes. I will post after the weekend as to how much it helps. Thnaks again.

You are very welcome. I live in El Paso and it's actually at about 3,500' above sea level. I really don't think its the elevation causing your problems. Like I sea the idle surge is very common on 1g's. Your car is 17 years old and my guess is that the throttle body has never been cleaned or rebuilt. O-rings, seals, and gaskets dry out and crack over time. Our throttle bodies have all three.

 

[Shamus]

So I pulled my car apart yesterday. My throttle body wasnt too dirty but I cleaned it any way. It was missing a nut on the bottom right and the gasket was broken there so that was causing some air to be sucked in I'm sure. I couldn't find the ISC that is shown on the video though. What I think is the ISC is located on the bottom of the throttle body and it has a large plug going to it. But I pulled the three screws off and it looks very diffrent than the video. I put new NGK plugs and wires on it. Replaced the leaky valve cover gasket and the BISS screw gasket. Also blocked off the EGR valve. I should have it back together in a little bit, I'll post how its running.

 

[brownfinger]

There are only 3 screws holding the ISC to the TB. I think you took the ISC apart while leaving it attached to the TB, as opposed to removing the ISC from the TB. There are two different types of ISC. The newer type is black and looks like the one in the video. The older type is lighter-colored and has screws holding the cover on. You should try to pick up a different one from the classifieds or a yard. Every DSMer should have 5 or 10 of those things laying around. They're $300 new, $25 used.

 

[9!'clipseDOHC]

I put new NGK plugs and wires on it. Replaced the leaky valve cover gasket and the BISS screw gasket. Also blocked off the EGR valve. I should have it back together in a little bit, I'll post how its running.

Good call on the plugs, wires, gaskets, and EGR. Sounds like you are making progress!

There are only 3 screws holding the ISC to the TB. I think you took the ISC apart while leaving it attached to the TB, as opposed to removing the ISC from the TB. There are two different types of ISC. The newer type is black and looks like the one in the video. The older type is lighter-colored and has screws holding the cover on. You should try to pick up a different one from the classifieds or a yard. Every DSMer should have 5 or 10 of those things laying around. They're $300 new, $25 used.

There are actually only 2 screws/bolts holding the ISC to the throttle body. You are right though, the OP probably took the cap off the old style ISC.

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This is the old style, leave those three screws on and just remove the 2 bolts on the side.

You can either buy a 15-20 year old used one which may or may not work or, if you have the money, get a brand new Mitsubishi revised "black" ISC for $137 shipped from these guys: http://www.dsmisc.com/dsmweb-dw/index.html.

 

[92nolatist]

There is also another thing that MIGHT cause an idle issue. Its called the FIAV- Fast Idle Air Valve, located on the throttle body which has coolant running into it. It has a bi-metallic spring, like on a thermostat and allows more air to run through it, around the throttle plate, when the engine is cold causing a higher idle; when the car warms up, the spring is SUPPOSED to close (because of warm coolant retracting/expanding the spring) blocking off some of the air which in turn drops your idle down to 750/800 rpm. But when this valve stops working properly, it causes idle surge.

Mine idle did the same thing; i tried replacing the ECU, ISC, adjusting the BISS and nothing worked so I did the FIAV Bypass mod. Except my plunger didnt want to turn in so I had to fab up a bypass plate out of muffler sheet metal. Worked like a champ-cold idle up to 1500 rpm then down to a solid 800 rpm.

Bypass plate (still allows ISC to be used):
EXTREME PSI : Your #1 Source for In Stock Performance Parts

Now, with your car being 17 years old, the FIAV might not be working as properly as it once did so here is a link that can help you out in fixing this:

http://www.dsmtuners.com/forums/articles-intake-exhaust/391977-free-fiav-block.html

Note: this mod is somewhat time consuming and requires some patience (at least for me it did), so do it only if you are comfortable enough.

Good luck,
Dave

 

[9!'clipseDOHC]

I've tried the FIAV bypass plate and the FAIV/ISC block off plate in the past and while it can help, nothing beats having a working FIAV/ISC as far as idle goes.

 

[92nolatist]

Oh, I agree with you 100% but you cant expect too much out of a 20year old car now, can you?
Of course unless you have this RARE ass dsm that everything in it works

 

[9!'clipseDOHC]

Oh, I agree with you 100% but you cant expect too much out of a 20year old car now, can you?
Of course unless you have this RARE ass dsm that everything in it works

Or you have had the same 20 year old DSM for the past 8 years and you've fixed EVERYTHING that didn't work

 

[Shamus]

Well, I did every thing I mentioned and no luck. Still shaking like crazy. Even changed back to rubber mounts every where except the top mount. Buming. Any more suggestions? Only thing I can imagine to do is put the top mount back to rubber. The idle is good and solid at about 750 just shaking a lot. It does a little better at 2000 plus but I can't imagine driving it the way it is, its violent.

 

[Gs Dewd]

Check the front and rear mounts. (the one at the front near bumper and one near the firewall). If you put them in backwards (as in fliped around on there mounting spot/ not front at rear a rear at front) it will vibrate due to the mount contacting the frame.