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Strange Idle

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pressf1forhelp

5+ Year Contributor
32
3
Nov 24, 2017
Oceanside, California
I know there's a ton of posts about this already, but none of them seem to have helped me.
1997 Eclipse GST 195,xxx k miles original engine
All of the engine bay is still stock except for the intake which is Dijon.

I just replaced the starter and now I'm having a slight idle surge and I also noticed that if I rev the engine the surge increases rpm a tad bit every time. While driving around my complex the car seemed to have an issue around 3k rpm and felt like the car was lacking power to be able to go any further accompanied by some lag getting to the 3k mark. I re checked all the vacuum lines and power connections and they seemed to be snug and none appeared to be damaged under the throttle body and around the evap canister. I also checked the ECT because I've had idle issues before due to the ECT not being snug enough. Is there something I could've knocked off while pulling and pushing the starter out of its clustered cage that I couldn't see way in there?

I did notice something a bit odd though. While I had the car running the second time idle was perfectly normal until I gave it gas. Also, I was under the hood while it was idling normally and knocked my arm into a black can looking device on the passengers side (edit) to the right of the fuse box and the idle went up 200 rpm. No check engine light during all of this. If I missed a post on something similar to this, my apologies and feel free to redirect me. Any help would be great!
 
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Can you post a picture of the black can thing you are asking about? The fuse box on all turbo 2G DSMs is on the passenger side, not driver side.
As for the idle surge, if your idle was perfect before doing this work, you most likely missed something, which is easy to do since these engine bays are so cluttered in wire loom. What all did you remove to get to the starter? I'd imagine at least the battery and upper intercooler pipe at a minimum. Did you happen to remove your throttle body at all?

If you are absolutely positive everything is connected as required, Maybe do a boost leak test with some soapy water and see if you get any bubbles.
 
Maybe just a fluke then. Should I mess with the TPS? I haven't had any idle issues like this before so I'm kinda not sure as to what I should be playin with. In the video I followed, are there any lines that I could've knocked into deep where the starter is? I spent a hour checking everything when this problem arose and I'm clueless to what has caused it.
 
Honestly, through my years of love/hate for these cars, I've noticed that a lot of times I'll set out to fix 1 or 2 problems, and then 20 more will pop up out of nowhere. The only thing I'd be really concerned with in the area of the starter, is the EGR solenoid. If you happened to bump one of the vacuum lines hard enough, you could have put a hole in it. Other than that, no real ideas. However, a bad line on the EGR would probably flip the CEL on with en EGR code. Since your CEL isn't on, it could just be a random boost leak not even associated to replacing your starter, but just choose a bad time to trigger the idle surge. The only vacuum lines down in that area are the EGR and the EVAP lines that sit under the battery (depending on model year, both 97 spyders I've owned had it under the battery).
 
Post a picture or 2 of your engine bay. I bet the intercooler piping isn't on the throttle body elbow very snug, or you have a vacuum line to the blow off valve that isn't connected. There is also a vacuum line from the valve cover that goes into the intake tube that could have been missed and not connected

My theory is that you have a vacuum leak coming from behind the mass air flow sensor. Most likely a breather tube hose from the valve cover to the intake. Double check the Dijon intake to make sure all of the little metal tubes on the side of it have a hose attached and the intake isnt sucking in air from an open hole infront of the turbo behind the mass air flow sensor. And that the blow off valve has the boost line attached to it from the intake manifold
 
Also check your cruise control vacuum assembly. Part if this is plastic. I have seem them get cracked from people putting there hands on them for support while working under the hood. If it's cracked it makes a vacuum leak & the cruise control stops working. Easy check is seeing if your cruise control works. If it crack it will not stay activated.
 
Also check your cruise control vacuum assembly. Part if this is plastic. I have seem them get cracked from people putting there hands on them for support while working under the hood. If it's cracked it makes a vacuum leak & the cruise control stops working. Easy check is seeing if your cruise control works. If it crack it will not stay activated.
I highly doubt that situation would cause continued idle surge. 1) although it has a vacuum operation, it is not connected to the engine's vacuum. 2) if broken, and won't stay active, there would be no vacuum pulling the cable and in turn pulling the throttle.

I agree what you said is good to check, but it shouldn't have any impact on engine operation.


If by chance, the module is damaged to a point where it is activating the cable without the OP using the system, that would create the extra rpms, and mimic surge.
 
So, a bit of development. I took everything apart for the third time and made sure all vacuum lines were connected and snug. I then proceeded to unplug and re plug all the sensors in the near area including any ones that were near the evap canister under the battery. Put everything back together and started the car. Idle surge no longer occurs while cold even when giving gas. Idle was perfect throughout this time, so when the car got to operating temp, I gave it gas and boom idle surge re appears. I've read all the posts that appeared while I was at work and none of them are the issue. The cruise control idea sounds interesting, but unlikely. It's not like I full force body slammed the darn thing. Just a bump or two while fiddling with the starter to get that @#@$!@#%#@# into its place.

I've uploaded photos of the engine bay as requested by one of the members. I'm fully aware that some of these hoses/lines look dated but never caused any trouble the past year. They also are not close to where I was working in the engine bay, so they haven't been touched. Yes I intend on replacing them in the very near future. Two of the photos are from my OBII reader. One is during perfect idle and the other is during the surge. Maybe someone can make use of the number differences. I'm starting to wonder if this is another ECT related idle issue. As I mentioned in an early post, I've had it happen twice due to one being bad and the other being the wrong part from pep boys.

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