GST doesn't *FEEL* like it's idling right. No codes thrown

[AMurderOfCrows]

Hi all

I am a new DSM owner (1997 Eclipse GS-T Sypder) and a bit of a worry wart, so please, bear with me.


Searched the forums for what i could to see if anyone else is having the issue, but since i'm not exactly a mechanic of any sort, i quickly realized that this was not going to work out too well for me...i just don't know the language.


Warning, this is pretty TL;DR



Problem Description:

The car doesn't have a "rough" idle, but occasionally feels like she is backfiring or misfiring via an out-of-sync vibration. it's very slight, and the only indication that anything is off is that she will occasionally "shake" or vibrate a tad bit more, out of the normal timing "feel". It's a lot more consistent when she's been driving for a few minutes, but for the most part, there is no 100% way to consistently get her to repeat the issue on command. Not with gas, or time, or anything.

Sometimes, this occasional vibration is accompanied by a very slight idle surge (though truth be told, i'm beginning to think that the idle surge was a different issuse, or non-issue. I think it only happened when the fan kicked on).

I'm used to cars having an idle surge (my old del sol had a nasty one), and i'm used to cars running super smooth (my mustang, my subarus). I've been told by two different people, one of them who runs an import shop and claims to know the engine VERY well, that this behaviour (the occasional slight vibration) is actually normal. the other one told me it was something called lope and that i shouldn't worry about it.


but, i do, and so i'm asking the help of the community to either make me stop worrying about it or to help me identify what it is.




Pre-Purchase condition:

Car had been sitting for around 3 months according to owner.
Has 131,XXX miles. Previous owner was 2nd owner, owned since 30,000 miles.
Primary drive was highway miles (the guy lived about 20-30 miles away from Portland, OR, where he worked)
No known history with timing belt.



Since buying it:

Taken to JiffyLube for a lot of services, including oil change, engine flush, coolant system flush, transmission service, etc. Car came in as a no read on oil (i failed to check the oil when bought. D'oh!).
JiffyLube tech under the bay popped his head out and asked how many miles were on the car....made it a point to let me know it was one of the cleanest looking undercarriages for a car of that many miles that he'd ever seen.


Car threw a CEL related to the EVAP circuit in the first week of ownership, right after the JiffyLube visit. Code was cleared and has not come back.

Previous owner claimed oil was seeping from the seal near the top of the case (?) where the plug wires go, and also from the oil cap. replaced the oil cap, no change at this point, but it was later fixed.

Anti-Lock light came on a few days after CEL was cleared. Believe this to be a wheel sensor going/gone out.

Purchased new battery, plugs, wires, and a fuel filter (didn't know it was in the gas tank at the time). Swapped battery, noticed corrosion on the battery terminals, so my buddy helped me clean them. Plugs and wires not changed till later.

Purchased a K&N Air filter. Old filter was not very dirty at all, but i wanted the piece of mind.

Power Steering/Alternator/A/C belt snapped while driving to store. Got her home and scheduled for service at a shop to replace timing belt, the belt that snapped, the water pump, and several seals. During this time, the coolant system was flushed again.

Car came back running VERY well, but still having the slight vibration issue occasionally, just much less frequent than before.

Changed plugs and plug wires. Noted new oil cap leaking.

Took back to shop. Showed the oil leak. Also tried to show them the vibration issue. I had to get one of the mechanics to sit in the car with me to feel what i was talking about. They suggested it might be a dirty injector, or perhaps an injector was dripping fuel directly, and suggested doing an injector clean might help. I paid for it, and when it was done they told me to "drive the hell out of it" and see if the issue continued. it did. While they had it, they found a plugged up PVC valve (?) and fixed/cleared it.


Idle still does the vibration thing. Taken to import shop, was told it was normal by someone claiming to "know the engine very well" and had one sitting in the middle of his shop. Went to a friend who owned a 3g and asked him about it, he also stated that it was normal and that i shouldn't worry about it. He was the first person to give it a name..."Lope"...and suggested that because the GS-T was a high performance engine, this was something i'd have to get used to. Friend adjusted the idle a little bit, and i'm thinking she's not running quite as well as she had before.


Somehow, i can't accept that answer just yet. Took it into the shop once again for the wheel sensor, a brake exam (she squeaks a lot) and to try once more to figure out the idle thing.


This is where i'm at right now. I am not expecting them to know what the idle issue is when they call me.


Can anyone help me figure this out? I'm going to keep searching the posts to see if i can find anything else that describes my issue as well, but maybe someone here can recognize what i'm talking about....is "lope" even the right word for what i'm experiencing?

Thanks in advance.

 

[LiquidX]

I didn't see a boost leak test listed.

When your friend adjusted the idle, they did ground the diagnostic pin at the ECU right? If you don't then the IAC will be out of adjustment. Did you test the IAC coils per VFAQ instructions? Have you verified mechanical timing is correct? How do the plugs look color wise, any wetness on them?

"Lope" only happens when you have longer cam durations and overlap IIRC. Just because you have a 4g63 doesn't mean it's going to lope.

 

[AMurderOfCrows]

I didn't see a boost leak test listed.

When your friend adjusted the idle, they did ground the diagnostic pin at the ECU right? If you don't then the IAC will be out of adjustment. Did you test the IAC coils per VFAQ instructions? Have you verified mechanical timing is correct? How do the plugs look color wise, any wetness on them?

"Lope" only happens when you have longer cam durations and overlap IIRC. Just because you have a 4g63 doesn't mean it's going to lope.

Thanks for the quick reply.

all my friend did when he did the adjustment was change the position of a screw. i may not have the correct terminology, so i apologize if i described it incorrectly. Nothing more was done, and i did not test the IAC coils either. Actually, i don't even know that the IAC coils are...I can make my way around my mustang's 302 engine well enough, but i know zip about how the Eclipse's engine works.

No boost leak test was done. Need to go back and read more about that...my first read through didn't make it sound like it applied to me at all.

When the timing belt was replaced, the guy who did it was the resident expert in imports, and my friend at the local Baxter's suggested him to me by name. I have to assume that mechanic timing was correct. Issue occurred both before and after timing belt was changed.

The plugs looked pretty burnt/white tipped, not wet at all from memory. New plugs went in about 2 weeks ago. should we pull those plugs and check them as well?

Somehow, i had a feeling that "lope" wasn't the answer. I've never felt anything like this in an engine where the idle seems to be fine, but still has slight vibrations that are out of time and noticeable only when touching/sitting in the vehicle.



So, i'm guessing that i should

1) Boost leak check
2) Mechanical timing check
3) Whatever screw was turned, check it also
4) Verify IAC (?) and do an IAC coil check (?)
5) Check current plugs for their look/condition

 

[Abe'sGST]

do a boost leak test and also check your lines for any loose vacuum hoses...is your bov stock?

 

[AMurderOfCrows]

do a boost leak test and also check your lines for any loose vacuum hoses...is your bov stock?

alright, i'll read up on that boost leak. is this something the shop can perform relatively easily? it's there now and i might as well have them do it rather than take it in again after.

from what the previous owner told me, pretty much everything on the car was original and stock, except for the stereo, the tune-up parts (though i think the plug wires might have been OEM) and the front calipers for the brakes.

 

[Abe'sGST]

alright, i'll read up on that boost leak. is this something the shop can perform relatively easily? it's there now and i might as well have them do it rather than take it in again after.

from what the previous owner told me, pretty much everything on the car was original and stock, except for the stereo, the tune-up parts (though i think the plug wires might have been OEM) and the front calipers for the brakes.

you can do a boost leak yourself and save some $ but since it's in the shop now just tell them to do it can't be too much, not sure though....as far as the intake idling screw (i think that's name) i was told that it should never be messed with b/c it will never be adjusted back like it was, for some reason people tend to think that it is like the screw on the carburetors to adjust idle..does your bov recirculate back to your intake?

 

[AMurderOfCrows]

you can do a boost leak yourself and save some $ but since it's in the shop now just tell them to do it can't be too much, not sure though....as far as the intake idling screw (i think that's name) i was told that it should never be messed with b/c it will never be adjusted back like it was, for some reason people tend to think that it is like the screw on the carburetors to adjust idle..

*facepalm* yeah, that screw thing is no good. ugh. surely there has to be a way to find the proper position for that thing.

 

[Abe'sGST]

*facepalm* yeah, that screw thing is no good. ugh. surely there has to be a way to find the proper position for that thing.

i was told that the only way to fix it back to the way it came from the factory is by getting a new intake manifold

 

[AMurderOfCrows]

i was told that the only way to fix it back to the way it came from the factory is by getting a new intake manifold

i don't understand why they'd make a screw for something that shouldn't be adjusted.

this doesn't seem right somehow.

 

[Abe'sGST]

i don't understand why they'd make a screw for something that shouldn't be adjusted.

this doesn't seem right somehow.

i know what your saying, it doesn't make sense (i asked my instructor back in college and he said that he doesn't know why they put it there but they do, and that people seem to think of it like the screw on carburetors but they are not), also at my work every technician knows that they shouldn't be adjusted. If the cars idle isn't right look elsewhere b/c i can guarantee that screw didn't turn itself and is the cause of the cars idle sudden change. i mean if you mess with it, the car will run okay, but that screw will not go back like it came from the factory

 

[LiquidX]

i was told that the only way to fix it back to the way it came from the factory is by getting a new intake manifold

Bad info and its wrong. The BISS is on the throttle body anyway.

Ground the diagnostic pin at the ECU, set the BISS so your RPM is at 750.

Make sure the shop does a proper boost leak test using soapy water, testing to at least 20psi, and starting with the TB and then to the turbo inlet.

It's better if you do it yourself so you know what is wrong and what is replaced properly. Injector seals, couplers, pipe, vacuum lined, EGR gasket, throttle body shaft seals are common leak points.

 

[Abe'sGST]

Bad info and its wrong. The BISS is on the throttle body anyway.

Ground the diagnostic pin at the ECU, set the BISS so your RPM is at 750.

Make sure the shop does a proper boost leak test using soapy water, testing to at least 20psi, and starting with the TB and then to the turbo inlet.

It's better if you do it yourself so you know what is wrong and what is replaced properly. Injector seals, couplers, pipe, vacuum lined, EGR gasket, throttle body shaft seals are common leak points.

yea i meant the throttle body, sorry...and I'm just stating what we are told at our shop, idk if its GM that set that rule or our shop but we can not adjust the BISS in under any circumstances, especially during warranty work

 

[LiquidX]

That seems extremely odd. Even a new TB would require adjusting the BISS. Besides there would be no one under a 10 year warranty with a DSM any more.

 

[Aproductions]

Not to jack the thread here but

Ground the diagnostic pin at the ECU, set the BISS so your RPM is at 750.

do the 2g's have this pin too? I couldn't find it on vfaq in the ecu layout.


and this is the dumbest thing I ever heard on this site BTW.

i was told that the only way to fix it back to the way it came from the factory is by getting a new intake manifold

 

[LiquidX]

Here is the VFAQ on the procedure. 2G BISS Adjustment

You'll ground the proper pin by hand unless you have the proper scan tool or use ECMLink.

 

[Abe'sGST]

That seems extremely odd. Even a new TB would require adjusting the BISS. Besides there would be no one under a 10 year warranty with a DSM any more.

I Know, i'm talking about the cars that come to our shop, it's a chevrolet delarership so there all mostly GM vehicles. Like i said idk if its a GM rule or our shop's but if the car's idling is off we cannot mess with the BISS

 

[LiquidX]

Then what the Hell are you supposed to do? A dealership that doesn't fix a highvor low idle is terrible. Maybe new cars are set up differently, I don't know, but just from that, what else is done wrong over there?

Also note that this is a DSM forum and not a GM forum ok? Be sure the information you post is going to be correct unlike what you mentioned earlier.

 

[Abe'sGST]

Like i mentioned earlier that if the car's idle isn't right, we look to fix the problem elsewhere than going into adjusting the BISS, b/c that screw doesn't turn itself and cause a car's idling to suddenly be off...people adjust the BISS to "fix" the idle but they are not fixing what's really causing it..