420A 420a Turbo Idle problem

[Brad Bell]

I bought a 1999 420a turbo eclipse about a month ago, I've solved some minor problems with it but this is an issue that makes me too scared to drive it until it's fixed. The idle is very odd, if you take a look at the video. Whenever i give it some gas either rev it high or low the car starts to choke up and drop way under 1000rpm. This problem also happens when I steer the wheel and happens extremely when the car is in gear and the clutch is used. Hopefully it's just a minor problem but please people help me out. Thanks!! (near the end of the video is when you'll notice the idle problem.)

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[Brad Bell]

Also there is a begi fuel pressure regulator installed but i'm not quite sure if it's setup right. Not sure fuel might be the issue.

 

[Wrathofwalrus]

Cant watch vid.

 

[Brad Bell]

Alright here we go,

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[j3st3r]

sounds like a bad injector or a pulg or wire going bad

 

[tec_41]

Have you checked for vacuum leaks? Hear any hissing under the hood? I'd also check your base fuel pressure...should be 45-50psi at idle.

 

[Brad Bell]

I pulled the plugs on it and they're completely covered with carbon build up, extremely black. There's an electronic fuel pressure gauge installed but it's not working for some reason, so i'll need to fix that in order to check pressure. I'm thinking the engine just isn't getting enough air, I'm going to try running it without the inter cooler piping hooked up, just straight into the manifold.

 

[tec_41]

Unless you've got some wicked blockage, airflow due to restrictive IC piping would be a longshot. I once left a rag in my IC piping and it took me forever to figure that problem out...but You would notice a huge loss of power while driving, not just a rough idle. But if you want to pop one off and just see how it runs, won't hurt.

You should be able to do a fuel pressure test without the gauge working. I believe 96-99 420a's have a schroeder valve for testing on the end of the fuel rail. Just rent a testing kit from your local AutoZone if you can

What plugs are you running? Most will agree that a turbo 420a should use NGK BKR-7E gapped to .028-.030.

Also, do you know your tuning setup? Is it just a basic FMU/High pressure fuel pump combo?

 

[Brad Bell]

Alright I changed spark plugs over to the ngk BKR-7E, checked the wires and the problem still occurs. I also tried running it with no IC pipping and that didn't solve it either. Im also still getting a lot of carbon build up, after 5 minutes of running with the new plugs, I checked and they were covered, and the tail pipe spews black soot everywhere like a diesel (exaggerating). So it's fuel problem Im thinking, too much fuel or too little fuel. May need a filter change. Also the guy that owned the car before me decided to use regular fuel instead of premium octane like your supposed to, not sure if that's a problem. Alright finally, I couldn't find a schroeder valve on the the rail, would it be the right or left side? On the left side is a line going to the regulator and the right side looks to be the line coming from the tank. Thanks everyone for helping, really appreciate it.

 

[mzdspdsm]

Youre running too high on fuel. Try setting the fuel pressure at a lower setting. Try at 35 then work its way up. Make sure the vacuum line is unplugged when you adjust it and the hose is plugged while adjusting it. Make sure the regulator is connected correctly too. If you have a boost activated fmu remove it and leave the fpr by itself. Usually when the boost activated fmu go bad they tend to do exactly that. Try checking the fmu first. Remove and just leave it with the fpr at idle if it stabalizes then u need to fix it or replace it. If nothing changes then follow the fpr adjustment

 

[tec_41]

^^Yeah, odds are that fuel pressure is just way too high. The FMU going bad is definitely something to take into consideration once you get the base fuel pressure set correctly.

It would make sense, especially if your plugs are carboning up that quickly. It might also be worth the time to verify your fuel setup. With a regular FMU and high pressure fuel pump you still need to be running stock injectors. With an adjustable FPR you can tinker with bigger injectors, but if you only want to run 6-8psi stock injectors are what you'll want. Untuned with larger injectors could cause what you're describing, too.

 

[Brad Bell]

Alright I'm gonna go with adjusting it, which way would reduce pressure? I would think tightening it would do it. And do you run the car with the vacuum line off aswell?

 

[mzdspdsm]

Reduce pressure by umscrewing te stud that goes into the regulator. Do it while the vaccum line is unplugged from the regulator to make sure its set correctly. Lower it to like 25 and work your way up.vaccum line shoukd be off only to set the pressure at idle then plug it back on.