egprelude

I can barely see the gauge but is the the Vacuum pressure in the normal range. Is it pulling less vacuum at idle then it was before the problem?

hockey1989

I'm new to an s2k, but i did have an evo 9 with a very similar problem to this and mine turned out to be a crank positioning sensor. especially when heated the sensor acted up more. also a cam angle sensor may be checked. i understand that these are pretty difficult to check unfortunately but just an idea. good luck

Gators2kt

Sorry, out of town right now. I'll try and take a better video of the gauges when I get back. The vacuum is the same at idle unless It's running rough.

Gators2kt

So I took a video but YouTube is being dumb. The vacuum and fuel pressure are reading normal. The issue is definitely temperature related. I realized that the times i thought the engine was "cold" it wasn't completely cooled from the last run. Everytime I first start the car from letting it sit overnight or a long period, the car runs fine. There are times that the car will act up on the first trip, but most of the time if I run it and let it sit, as soon as I start it the next time, it runs like garbage.

I wrapped my downpipe with some DEI thermal wrap to try and keep the temps down a little. I also cleaned the IAC valve and the issue has gotten slightly better. The car doesn't "buck" as much now, it still isn't smooth at all but the A/F are a little lower when I give it gas, around 15s now... Still way too lean though. I'll post again with some pics when I get a chance.

jh4db536

I think something is wrong with your tune (iat or coolant temp compensations), however, you have a useful tool available to you that you should be using or learn to use:

use your aem ems and laptop to datalog the instance of the car when its running like rubbish. Download your calibration file too. Those logs will tell us a lot more than any video can capture. You will not be getting CELs with that ems

We have plenty of etuners on this forum who will probably be happy to give it a look for free and possibly offer solutions.

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Gators2kt

I ordered the cable that I need to log the EMS. Should be here next week or the following. I'll put up some of the garbage runs so people can take a look.

jh4db536

What cable do you need? It didn't come with one? The ems series 2 could use any usb cable...it uses the same one as my printer and scanner it works fine

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Gators2kt

Well, the actual unit is mounted with the plugs pointing upward. There was a 9 pin serial cable already attached so I assumed it was that. If I have time to swing by my brothers today, I'll try and unmount the EMS. Sorry, I am a little incompetent, I don't usually mess with electrical or tuning unless it's easy... Mechanical stuff is fine but the tuning is over my head right now. I haven't even looked at the actual EMS unit in over 4 years.

Gators2kt

Also, I forgot to mention that the EMS was tuned with high and low boost maps. I have a toggle switch on my a pillar by the gauges to change between the maps. It doesn't matter which setting I'm running they both run the same.

pettyboy69

Has the weather by chance changed a lot recently where you are from? Because if humidity, temperature, or density altitude change a decent amount it could throw the car into a different part of the map when it is at full operating temperature since when it is cold, it is on a different cold startup map because you said it doesn't do it until its warm right? Also could be a sensor I have had cars that would run fine when cold but the second they warmed up they would start having issues and it was very often something electrical like distributor, coolant temp sensor, crank sensor ect. good luck hope that helps