I have 04 evo8 rs. Running speed density. Sheepy manifold, I’d 1000 injectors, 9 turbo, o2 dump, 3.5 intercooler, 2.5 inch ic piping, cams, 3” turbo back exhaust. Open source tune making just over 400whp. So my issue is when I start the car it cranks over fine and starts right up hits about 2000rpms for about a few seconds then drops down to like 400 and shutter like it’s going to stall. (Afr goes to like 19ish) catches it’s self does this a few times (total of maybe 30secs I can make it stop faster it it give it a little gas) and then it levels out at 14.7-15.2. Trying to diagnose the issue without having to take it to the tuners. It runs and idles fine after that 900rpms where my idle is set on my tune

 

When did the issue start happening?

 

it just recently started happening. I hadn’t driven the car for a few months as I was doing some regular matanience stuff. Nothing that would affect the tune. And I had just had my son. So there wasn’t always time to work on it. It had been tuned and running fine prior to working on it. I had all new tires put on, new alternator, new wheel hub assembly fronts, new spark plugs, all drivetrain fluids changed oil and coolant. And new battery. None of which should have affected my tune.

 

If you had a weak electrical system, they might have had to compensate for that in the tune.

 

I understand that but the car was tuned prior to the issues with the alternator going. As I said the car had sat for a few months and my battery died and I believe the regulator went in my alternator because it when I started it overcharging so I replaced both. Again it could have been possible it was poor before but I doubt that was the issue. It had been tuned 2 twice in a year and a half because of clutch failing after new modifications. And neither time did it have this issue.

 

Are you on E85? I know my car and others hate first starts if it's cold.

 

no I’m am tuned on 93

 

Check for boost leaks just as a first step, set biss screw. Then I would assume the tune needs adjusted.

 

You live in Cali and have hard E starts?

You need a better tuner.

 

So this is how it’s acting on cold start up. I replaced iac with used working iac and symptoms remain the same.

 

Based on AFR reading doesn't it run too low on gas if you just started the car? My goes 9-11 AFR

 

Yea it seems to be running lean at start up but once it warms up the idle is stable at 900rpm afrs settle to between 14.7-15.2. It feels like a slight miss when the afrs go lean and then it stabilizes. It’s only an issue at start up. Driving and wot throttle afrs are fine and there is no miss. So I’m confused as to why it’s doing it. If it was bad or clogged injector or fuel pump it would happen consistently it’s only an issue at start up

 

Well you can check pressure in fuel pump by adding extra gauge (only for test time), fuel tank if its not full of dirt but I would try to modify AFR on start to get some more fuel and then check it again. If you are able to manage your ECU you can do a "dump" of your current map and then come back to it if needed

 

i don’t have access to manage ecu. It done at a tuner shop. It didn’t seem to have the issue prior and I had a fuel pressure gauge on it at one point it it looked to be accurate. Around and the pressure went up as u gave it throttle. Done a boost test leak fixed ones o found loose lower coupler and map sensor o ring. And the throttle body bleeder flapper o ring. It’s tuned on 26 pounds it gets to 26 but it seems to taper fairly quickly as I’m not super experienced in doing it not sure if it should bleed off that quickly or not. I have checked the pump and replaced the sock filter on my 255 to see if the filter was clogged still the same result