Hello, I need some help diagnosing this issue:

First time it ever happened:

Yesterday after I've driven my car around for a bit that day, while I was pulling into my parking spot, I put the car in neutral and the tach drops below 1k rpm and acts like it's going to stall. So I give it some gas, raise the rpms, and the needle keeps dropping below 1k. It would stop short of stalling, but it'll get really "rough" and shakes as it's not getting enough gas/air.

So today, i get in for the cold start:
1. clutch in 2. key turn, the car starts up, tach goes up and then drops all the way down to zero and engine stops, the only way I can keep the engine running is by consistently giving it some gas, then it evens out at a little above 1k and it feels like a normal neutral. I then try to drive, put the car into gear, then back into neutral, and it does the tach drops below 1k again, and almost stalls..etc.

Any ideas what's going on?

Car has not power mods. I've never had this issue before ever for the 2003 Evo. It's got gas.

Recent history, I was out of the country for 2 weeks, the car's tank was full. I come back and have already driven on the same tank for a week without any issues until yesterday and today. Please help me out!

Is it battery, spark plugs? I dont think it's electrical b/c radio all electronics works, lights aren't dim, and the car starts up as I mentioned. thanks.

 

I would check for a vacuum hose that came off (check the EGR valve right below your throttle body). Could be a bad boost leak too. Those damn MAF setups are finicky

 

I'm no pro but a similar situation happened to a friend of mine and his Honda, his mechanic diagnosied it to be timing, and fixed it temporairly then some other problems came up. Just my 2 cents, sorry couldn't help much.

 

could it be O2 sensor?

 

+1 on egr

 

Another thing you can try is diconnecting your battery to reset your ecu. O2 might be the problem, but I would check the obvious things first (ecu reset, vacuum lines, boost leaks).

 

it also might be the iac valve

 

I'll do the ecu reset now, but I've checked all the clamps and lines, they all seem to be in order. Can someone take a picture of the Evo EGR for me, i see a picture of other cars' EGR on google pics, but I just need to pin point it on the evo. thanks.

 

it was so bad, the car simply shuts off and couldnt' even idle unless you keep a foot on the gas, so I took it to a local auto shop today. The guy cleaned the inlet of the throttle flap, readjusted to allow more fuel/air, and it now idles at 850 rpm warm and 1100 rpm cold. The real test will be a cold start.

he said that I'll have to just replace or clean the Idle Air Control valve. It sounds right to me, but man, my car's got less than 90k on it and I can't believe that valve and the throttle will get that much gunk on it to have an effect like this. Yellowrocket pin pointed it, what do you think, have you had to replace or clean yours?

 

The egr valve is on the driver side right where your intake manifold bends towards the engine in the center. It looks like a mini wastegate with two vacuum lines comming out of it.

As far as the idler motor being the issue, I suppose that is a possibility, but I would check the egr first.

 

I had the same problem, and it turned out to be a vaccum leak..fixed it and no problems. Could be your BOV...I have an atmospheric BOV and most people will agree, the Evo dispises VTA BOV's... I used to have a rough idle and and a stall problem, similar to what your describing. Got the HKS idle stablizer and viola..problem solved. I disconnected the battery to reset the computer and all seems to be well.

I'd check for a vaccum leak first if your still running the stock BOV.

 

ECU reset fixed it for me.

 

Acted up again, cleaned MAF reset ECU now its fine.

 

+ iac

 

This is a common problem go with what they have said and most likely it will fix it. All the info is accurate.