The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support Morrison Fabrications
Please Support Fuel Injector Clinic

2G Help needed Running lean/only getting 5lbs boost

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

VivaLaOC

Proven Member
121
25
Mar 16, 2021
La Grande, Oregon
So since I've gotten the car in the past month and a half I've done maintenance and added a boost guage and MBC, fixed the oil pressure sensor and a few other things I can't think of off the top of my head. Anyhow, so when I'm driving and I'm in any gear I only get maximum 7lbs of boost normally only about 4 or 5. I checked the IC for oil in it and it had some in it, not a super significant amount but there was some on my finger when I pulled it out. I was getting the coolant temp code p0125 for a little while but that has stopped, and I also had a TPS code but that hasn't came back, but the other night I had a code for fuel trim bank 1 pop up and that was the first time for that one. I know it's because of an O2 sensor but would any of these things cause me to only get max 7lbs of boost? It's definitely running lean it idles normally at about 875-925 rpm but any help would be greatly appreciated so I can get the full potential from the car. Also, no I don't plan on running anything like 18lbs i just want a little bit over stock
 
How do you know It's lean? Did you use nylon line for the boost gauge? How is the boost controller hooked up and what kind is it?
 
Its been running low boost the entire time, also yes the boost guage is connected with nylon tubing its comparable to hospital iv tubing. I have a feeling that I'm hitting fuel cut because when I'm down on the throttle anything past I'd say 65%-70% and in boost on the normal and aftermarket boost guage its like I lose power but if I ease off its just fine. If I keep on it it'll buck, sorry for not responding sooner I've been busy all day and also I don't have the stuff to do a leak down test I don't have a compressor and neither does anyone I know in my town

Did you perform a boost leak test like as @luv2rallye & @eclipsyco recommended? Did it run low boost when you first purchased (pre mbc) or were guage and controller done at same time? How did you hook up mbc?
I also capped off the normal boost controller and connected the MBC correctly from what I saw online
 
Its been running low boost the entire time, also yes the boost guage is connected with nylon tubing its comparable to hospital iv tubing. I have a feeling that I'm hitting fuel cut because when I'm down on the throttle anything past I'd say 65%-70% and in boost on the normal and aftermarket boost guage its like I lose power but if I ease off its just fine. If I keep on it it'll buck, sorry for not responding sooner I've been busy all day and also I don't have the stuff to do a leak down test I don't have a compressor and neither does anyone I know in my town


I also capped off the normal boost controller and connected the MBC correctly from what I saw online
Im either hitting fuel cut for some reason, or i have a really bad boost leak
 
Did you perform a boost leak test? You are not hitting fuel cut. Fuel cut isn't subtle. It's violent. If you aren't sure you haven't hit it. Boost leak would surely make a car run poorly but it would not run lean.
How do you know it's running lean? Tell us what you know and have tested.
 
BTW I asked that nylon line question because that stuff sucks. The ferrules leak. This likely isn't your problem. Either way I suggest getting a hose barb fitting and running rubber line all the way from the boost source ot the gauge.
 
Did you perform a boost leak test? You are not hitting fuel cut. Fuel cut isn't subtle. It's violent. If you aren't sure you haven't hit it. Boost leak would surely make a car run poorly but it would not run lean.
How do you know it's running lean? Tell us what you know and have tested.
Im getting pretty poor mpg, I'm guessing my o2 sensor is going out (fuel trim bank 1 code) and, I feel like it isn't getting the performance it should be which are signs of running lean. But then again I honestly am not 100% sure because I'm pretty new to this car in particular
 
Did you perform a boost leak test? You are not hitting fuel cut. Fuel cut isn't subtle. It's violent. If you aren't sure you haven't hit it. Boost leak would surely make a car run poorly but it would not run lean.
How do you know it's running lean? Tell us what you know and have tested.
Also, likei said when I'm on the throttle/in boost and I keep on it it cuts out and bucks but if I let out slow while its cutting out it won't buck it'll just spool the turbo, when I say cut out I mean it just doesn't keep building speed, it's like it loses power
 
Do you have any way to log what’s going on? It’s going to be hard to really pinpoint where and how much needs work with out some sort of logger.
 
Take a look at your knock sensor. Sounds like its pulling timing and also has a boost leak. Do a BLT and do a visual on that sensor. Its on the block under the intake manifold.
Have you confirmed base timing is set at 5* BTDC?
All of these things should be checked off.
 
You need to do a boost leak test. I know you’ve said you don’t have access to a compressor. You can buy a craftsman pancake at Lowe’s for $99. I know this unfortunately increases the cost of your test but you will get plenty of use out of it!
There isn't a Lowe's around here but ill look on the classifieds/marketplace for one 2nd hand that way it's cheaper.
 
Im getting pretty poor mpg, I'm guessing my o2 sensor is going out (fuel trim bank 1 code) and, I feel like it isn't getting the performance it should be which are signs of running lean. But then again I honestly am not 100% sure because I'm pretty new to this car in particular
No. That's clearly not objective. Tell us what you KNOW, not what you are guessing. Poor performance is not necessarily a sign of being lean. Could also be rich. Neither of which you know without testing instead of guessing. Please back up and give us a full run down. It is very difficult to help you if some things aren't know for sure. Tell us what you've done and please find a way to boost leak check. You will find problems and fix problems much easier if you have a method.
 
Ok let's be objective. What have you actually tested and what maintenance did you do?
I did an oil change, spark plugs (gapped correctly), replaced alt-wp belt, (cause it broke) pretty much all fluid changes, I've checked over pretty much every bushing and part of the suspension, I installed the boost guage, MBC, replaced vacuum lines from turbo and wastegate, air filter, bought a FPR (haven't installed yet), bought a 255lph fuel pump (also not installed) and I replaced the oil filter when I did the oil change, and also I've checked the turbo over and there's no shaft play whatsoever, also front tires are new, brake fluid is full and fine PS too, I replaced the valve cover gasket and checked the timing belt and there isn't and leaks whatsoever either

Edit: I also checked the SMIC for oil build up and there wasn't a significant amount.
 
I did an oil change, spark plugs (gapped correctly), replaced alt-wp belt, (cause it broke) pretty much all fluid changes, I've checked over pretty much every bushing and part of the suspension, I installed the boost guage, MBC, replaced vacuum lines from turbo and wastegate, air filter, bought a FPR (haven't installed yet), bought a 255lph fuel pump (also not installed) and I replaced the oil filter when I did the oil change, and also I've checked the turbo over and there's no shaft play whatsoever, also front tires are new, brake fluid is full and fine PS too, I replaced the valve cover gasket and checked the timing belt and there isn't and leaks whatsoever either

Edit: I also checked the SMIC for oil build up and there wasn't a significant amount.
You may have multiple issues but why Paul has been asking you how you know if it's lean and if you did a boost leak test is because what you described sounds one of typical symptoms of boost leak and/or too rich condition. Boost leak is one of the most critical issues of cars with MAF setup.
 
No. That's clearly not objective. Tell us what you KNOW, not what you are guessing. Poor performance is not necessarily a sign of being lean. Could also be rich. Neither of which you know without testing instead of guessing. Please back up and give us a full run down. It is very difficult to help you if some things aren't know for sure. Tell us what you've done and please find a way to boost leak check. You will find problems and fix problems much easier if you have

You may have multiple issues but why Paul has been asking you how you know if it's lean and if you did a boost leak test is because what you described sounds one of typical symptoms of boost leak and/or too rich condition. Boost leak is one of the most critical issues of cars with MAF setup.
Okay, ill try and get a BLT done asap
 
You may have multiple issues but why Paul has been asking you how you know if it's lean and if you did a boost leak test is because what you described sounds one of typical symptoms of boost leak and/or too rich condition. Boost leak is one of the most critical issues of cars with MAF setup.
Bingo. Teach a man to fish basically. Also we don't know what you have already tested and or corrected with maintenance. So we don't know where to point you other than the usual suspects that are very very common. Still just a shot in the dark unless you've done something you can measure or make a statement about from some observation. Ie the spark plugs are black or worn. There is an obvious tear in a hose coupler. Measured values on any number of sensors are xyz based on a data log or something. Things like this.
The point of all my bluntness is to get you to not only take a good look but to not guess at things. Some tests are so simple and quick we suggest them just to quickly rule out certain things. Others take time and sometimes equipment. However usually a simple obd scanner and a multimeter and most importantly, a factory service manual, will help diagnose many many things accurately the first time. 1g cars require a different way to get obd data but still easily done. Help us help you.
 
I did an oil change, spark plugs (gapped correctly), replaced alt-wp belt, (cause it broke) pretty much all fluid changes, I've checked over pretty much every bushing and part of the suspension, I installed the boost guage, MBC, replaced vacuum lines from turbo and wastegate, air filter, bought a FPR (haven't installed yet), bought a 255lph fuel pump (also not installed) and I replaced the oil filter when I did the oil change, and also I've checked the turbo over and there's no shaft play whatsoever, also front tires are new, brake fluid is full and fine PS too, I replaced the valve cover gasket and checked the timing belt and there isn't and leaks whatsoever either

Edit: I also checked the SMIC for oil build up and there wasn't a significant amount.
What plugs and what gap? Did yiu change wires too?
 
Not to clog up this thread but a wideband o2 sensor wouldn't be a bad thing to have either. I run one in both my cars both as a safety measure and for logging purposes :D

Also also I'd consider running an electronic boost gauge rather than an analog one. Again, I have one in both of my cars. You also don't have to mess around with vacuum tubing and potentially poking holes in stuff or the line pinching
 
I can neither confirm or deny this ROFL ......good catch.
I only usually play with 1g's.
 
Bingo. Teach a man to fish basically. Also we don't know what you have already tested and or corrected with maintenance. So we don't know where to point you other than the usual suspects that are very very common. Still just a shot in the dark unless you've done something you can measure or make a statement about from some observation. Ie the spark plugs are black or worn. There is an obvious tear in a hose coupler. Measured values on any number of sensors are xyz based on a data log or something. Things like this.
The point of all my bluntness is to get you to not only take a good look but to not guess at things. Some tests are so simple and quick we suggest them just to quickly rule out certain things. Others take time and sometimes equipment. However usually a simple obd scanner and a multimeter and most importantly, a factory service manual, will help diagnose many many things accurately the first time. 1g cars require a different way to get obd data but still easily done. Help us help you.
Its a 2g and I have an OBD2 Scanner, ill get all my live data and post photos tomorrow
 
Bingo. Teach a man to fish basically. Also we don't know what you have already tested and or corrected with maintenance. So we don't know where to point you other than the usual suspects that are very very common. Still just a shot in the dark unless you've done something you can measure or make a statement about from some observation. Ie the spark plugs are black or worn. There is an obvious tear in a hose coupler. Measured values on any number of sensors are xyz based on a data log or something. Things like this.
The point of all my bluntness is to get you to not only take a good look but to not guess at things. Some tests are so simple and quick we suggest them just to quickly rule out certain things. Others take time and sometimes equipment. However usually a simple obd scanner and a multimeter and most importantly, a factory service manual, will help diagnose many many things accurately the first time. 1g cars require a different way to get obd data but still easily done. Help us help you.
7bpres or however you spell it. But where's the most common spot for a leak on a 2g?
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top