Rough idle at cold start

Worbit

Worbit

Gold Member
Greenie N00B Member
Greenie Member
Ok MSO, I need your help. I had my engine replaced about two months ago and ever since then I have had a really rough idle during a cold start, so rough that the engine almost feels like it's going to stall. Once the engine is warm though it evens out and drives fine. I've upgraded/gapped the plugs to .026 and did the spring stretch mod and it still does this. The guy who installed my engine (fuck that guy) kept pointing the finger at the mods/my tuner saying that's the issue. My tuner claims this is normal but I know it's not since my car never sounded/felt like this with the old motor. What else could possibly be causing this? Bad injector seals maybe? I'm at a total loss as to what to do now.

***EDIT*** DATA LOGS HAVE BEEN UPLOADED

Mods are in the signature....

Cold start on old engine:


Cold start on current engine:
 

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So wouldn't the injector seals cause an issue even after the engine is warmed up? Sorry if that's a noob question, I've never dived this deep into engine mods before so this is all new to me and I've read so many threads between here and MSF that my head could spin.

I went ahead and ordered the CS injector seals and figured I might as well do the EGR delete while I was at it so I ordered that kit from DMS. Blowing my engine has become a VERY expensive rebuild process :(
 
I am not saying 100% its the seals but could be. Also the seals could make a seal as the car warms up and things expand.

Double check all the work that was done. Make sure the vtcs box is hooked up right and has the little rubber seal for the mani. Maybe sure the arm is working correctly. Do a boost leak test to look for leaks. Injector harness. So much u will have to look at but boost leak test should put u in the right direction.
 
Mods don't show in sig, but it sounds awesome! Sounds like VTCS delete to me.
 
Pretty good chance your vtcs was hooked back up wrong or not at all.

I've got a PNP Mani with vtcs delete and sounds almost exactly like this. Just check the box on the mani and trace all the lines. Probably a missed connection.
 
The VTCS was checked out and everything looked good. Installed the CS injector seals and it still does this stutter on cold starts. Once the car is warm, its a champ. I'm also getting KR around 5700rpms now :(
 
Interesting thought, but when my EGR was clogged, it ran like shit when cold, was slow to start too.
 
maybe that's the common culprit here, my EGR valve and tube have been completely removed.
 
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I would rarely (maybe once a month) get a random misfire code if I didn't let the coolant warm up past 100 degrees before taking off (no wot, just cruising through the subdivision).

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nekret said:
I would rarely (maybe once a month) get a random misfire code if I didn't let the coolant warm up past 100 degrees before taking off (no wot, just cruising through the subdivision).

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These cars dont like running cold. My car will shudder and buckle on shifts below 100 ect.
 
Worbit said:
The VTCS was checked out and everything looked good. Installed the CS injector seals and it still does this stutter on cold starts. Once the car is warm, its a champ. I'm also getting KR around 5700rpms now :(
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Hey if you don’t mind me asking did you ever find your issue?im having a random misfire on cold start up and I get p0300 code.I have done everything possible that I have been told and I’m curious what you did?if you can please let me know and thank you
 
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