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2G Cuts out when trying to boost. Help!

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Joey2k21

Probationary Member
9
4
Jun 21, 2021
Greenbush, Maine
Hey everyone! Let's start with this. 1998 Eclipse GSX.

This recent winter (the day before Christmas), I was going out to do some shopping, and my car had been acting up recently at the time when it rained. This day, it was downpouring. I finished my shopping and left; the car bogged out and died, so I parked. I couldn't get it to start again, so I had it towed home. I let the car sit as I got busy with work and honestly had little interest in working in the snow (I live in Maine).

Every once in a while I would try to start it, but this ended up with a crank-no-start every single time. Then one day I got tired of it and missed my car. So I started ordering parts. Only going off a mis-fire code and a map sensor code, I ended up getting a MAF sensor, plug wires, and coils. This ended up making the car start but still run terribly. After those things, I bought a new fuel filter and cam sensor, cleaned out the fuel lines, cleaned out the injectors, and put new injector seals in. This made it run much better. It will start up fine and idle with little to no problems, but driving it is a different story.

It will drive, but when I come into around three-quarter boost, it cuts (video attached). When that happened, I was looking some stuff up and saw someone with an ECU problem. I pulled mine out and looked at it. The protective film on top didn't look so hot, so I was thinking about getting it refurbished. The whole time the car sat, it rusted out my flex pipe. Hoping that back pressure could be a problem, I replaced it today. Still no luck.

The only code I have now is P1105 (Fuel Pressure Up Solenoid). I'm now at the point of getting a MAP sensor and a solenoid. If that doesn't do anything, I'm going to get my ECU refurbished, and if THAT doesn't work, I'll do the timing (after checking it). In the video that is attached, the car is only reaching around 4000 RPM. I've obviously skipped a step or two.

But I'm ready to fix this thing now. Any help will be deeply appreciated. I think I have listed everything that I have done to the car since this whole thing happened. I'm sorry for how the story jumps around so much; it's a lot to write up. Thank you in advance for any replies and any ideas to help!

Video:
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I'd start with new plugs or if they've been replaced check out the gap and how they look. I'd also just check the basics like intercooler piping, exhaust leaks before the turbo. Check fuel pressure and make sure you don't have any vacuum leaks. Thats about all I can think of at the moment that you haven't mentioned.
 
Is there a specific way to check fuel pressure? Can’t seem to find a Schrader valve anywhere. I’ll check out the other stuff as soon as I have time.
 
A boost leak test should be your next step. Also check your intake snorkel (pre-turbo) for any disconnected lines (i.e. BOV, crank case breather, EGR/charcoal canister) where it could be pulling in unmetered air causing lean conditions.
 
Is there a specific way to check fuel pressure? Can’t seem to find a Schrader valve anywhere. I’ll check out the other stuff as soon as I have time.

You have to pull the bolt out of the top of the fuel filter and install an adaptor. If you rent the large fuel system tester from autozone it has the adapter in it. Otherwise you can buy a banjo bolt adaptor like this one and gauge off of it. You'll have to rig up some sort of line to get the gauge inside the car so you can watch it as you are driving.

 
Is the Fuel Pressure Solenoid Valve the same between the 420a and the 4g63t? Or different parts?

You have to pull the bolt out of the top of the fuel filter and install an adaptor. If you rent the large fuel system tester from autozone it has the adapter in it. Otherwise you can buy a banjo bolt adaptor like this one and gauge off of it. You'll have to rig up some sort of line to get the gauge inside the car so you can watch it as you are driving.

Awesome, thank you!
 
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