this is part engine part tuning but i put it in here, but anyway. ok heres the timeline, my car was working perfectly fine after i installed a external dumped o2 housing, drove it a week, started having tranny problems, totally unrelated, so i got the tranny problems fixed (new tranny new clutch new flywheel), and i got my car back. broke in the tranny driving easy for a while , just today went WOT for the first time and the boost buildup was SEVERELY slow on a big16g fully ported with 34mm flapper, i had my boost controller set at 16PSI before the shop put tranny in, so i slam on the gas and in first gear by 6k RPMs im only at 10PSI, i redline it shift to 2nd, 2nd builds very slow again but gets higher and will redline at 22PSI !!! which is a lot higher then i had it set. I doubt the shop would touch it, but even if they did it would not be super slow buildup even if it was say set for 30PSI somehow.

so thats one major problem, now this im not sure if it is related or not sounds very wrong, i have a palm and tuning software from www.pocketlogger.com, i set it to log and took it for a run. ran 2 times up to top of 2nd gear, went back home. i checked out the log and here are the interesting stats...

highest RPM run
7068 RPM
23 Deg Timing
02 sensor 1, bank 1 (front o2) 0.04v 0%

highest 02 reading
2716 RPM
29 Deg Timing
02 bank 1, 0.18v 17%


im new to tuning and logging, but this run seemed weird also, this was just cruising. at this point the stats were:

4148 RPM
38 Deg Timing (WTF??)
02 bank 1, 0.00v 0%


can someone help me with this???

oh and also im not sure if this has anything to do with it cause i heard 2gs can run without the 2nd o2 sensor but mine has been broken for a while, the wire got cut somehow so its not reading anything on it and it gives me a CEL

check for boost leaks. Also the pressure line that goes to the turbine housing could be unplugged. If you have a leak it will cause slow spool .. and that line being unlplugged will cause you to just keep building boost forever. Just some things to check

i checked for boost leaks as good as i could without a boost leak tester, i will do that as soon as i can. i tightened all IC piping bolts, couplers, intake, etc.

also could you be more specific im not sure what line youre talking about, do you mean the line going from my MBC to my turbos wastegate actuator?

Your O2 sensor might be shot.. Going WOT, it doesn't matter because the car runs primarily off the MAF readings. No leaks and very slow boost, you may have a turbine wheel blade broken off or a HUGE boost leak somewhere...

well im getting perfect vaccum, 20-22. and yeah ive pretty much determined that my front o2 is dead. but what problems would that cause? would that matter for the boost problems?

O2 sensors go all the time... Usefull life can be anything from 10k to 50k, all depends on what brand you buy... As far as the boost spikes go, check your boost controller setup. Check your wastegate to make sure it's not siezed closed...

im wondering if this has anything to do with it....

CEL - P0125 Insufficient Coolant Temperature to enter Closed Loop.

Yes, its a good possibility that the coolant temp sensor is the problem.

also i just checked again and in the engine codes there was code P1400 but it had no description like they usually do, i looked it up and its this

P1400 Differential Pressure Feedback Electronic Sensor circuit Low Voltage


so does that coolant temp thing mean i need a new coolant temp sensor? and what about this other CEL?

Your ECU is probably pulling timing like a gardener pulls weeds..

it really doesnt look like that on the logger though, during WOT it just goes up with the RPMs and follows them down... im not sure what to do about all this crap. someone guide me! i am new to tuning...

Well, if your front O2 is dead, your ECU has no idea what is going on at this point. That code says that it can't go into closed loop mode, which means the ECU uses the O2 sensor to try and reach "Stoich". If the O2 is dead, your ECU in open loop, (which it is stuck in right now), will have no idea how to compensate for fuel and like stated before, "it is probably pulling timing like a gardener pulls weeds".

Get a new O2 sensor and make sure your car can go into closed loop mode.

In your other thread, you mentioned not having the first grounding strap on. Just so you know, when I had mine off, it threw the same code - P0125. Just something to check.

KeltonDSMer said:

Well, if your front O2 is dead, your ECU has no idea what is going on at this point. That code says that it can't go into closed loop mode, which means the ECU uses the O2 sensor to try and reach "Stoich". If the O2 is dead, your ECU in open loop, (which it is stuck in right now), will have no idea how to compensate for fuel and like stated before, "it is probably pulling timing like a gardener pulls weeds".

Get a new O2 sensor and make sure your car can go into closed loop mode.

Click to expand...

ok, tomorrow first thing im ordering a new one. should i also order a new coolant temperature sensor while im at it? does that code mean the sensor is bad or something else?

Coup D E'Tat said:

In your other thread, you mentioned not having the first grounding strap on. Just so you know, when I had mine off, it threw the same code - P0125. Just something to check.

Click to expand...

well ive had this code before i installed my downpipe today, and all these problems were happening before the DP install. just happened to have some help today so decided to put the DP and test pipe on but i think they are irrelevant to this problem. but even if the grounding strap did something, there is no spot on the pipe to screw it in, should i like clamp it on with a big hose clamp or something?

Welt a 1/4" bolt to the dp(weld the hex head to it) and now you can put the ground stap on and tighten with a nut. I hope you understand what I mean. Thats what I did and it worked great.

Weld, Im sorry for the incorrect spelling.

I bolted mine down with a fence strap (the ones that hold the actual fencing.)

Shit, I alway mix up closed and open loop. If the ECU code says it can't go into closed loop, it actually means it isn't using the O2 sensor at all. It is using the reading from the MAS and set fuel maps to determine how much gas to squirt. I would definately get a new O2 sensor and figure out why it won't let you go into closed loop.

I bet you are getting really crappy gas mileage, because cloesed loop operation at idle and cruise conditions strive for a Stoich ratio. Open loop is for acceleration conditions and uses a much richer AFR for safety and knock controll. Are you spewing lots of black smoke?

not really any visible smoke, and i just took off my cat too. it has been getting really bad gas milage though. i ordered a new sensor today, but would that cause turbo lag? only thing i can think of is its pushing so much fuel for safety that its bogging down my turbo but would it be that bad?

I had a dead o2 in my car same prob. But my car wasn't pulling timing it logged pretty good. I got a new 02 and my gas mileage improved drastically!

hellotbone said:

I had a dead o2 in my car same prob. But my car wasn't pulling timing it logged pretty good. I got a new 02 and my gas mileage improved drastically!

Click to expand...

what symptoms were your car showing cause of the dead o2? any similar to mine?

Well I made boost and logged ok for timing but had terrible gas mileage. Not really any running problems or codes other then P1500 idle circuit malfunction.

well guys heres the update, i think i figured it out. i got my new O2 sensor yesterday and i was under my car putting it in and i looked at my wastegate actuator and it has a big dent in it, its like the top was crushed down on one side a little. this would be causing boost problems right? it wasnt like this before i got my tranny put in which would explain why it worked before i brought it there and now spools slow, i think mitsubishi dented it when they put my tranny in. im gonna call them and tell them this morning and make them replace it cause thats BS.

also replacing my front o2 got rid of the P0125 CEL, and the 1400 still pops up but only occassionally i dont think it matters. and of course ill always have the one for the rear O2

o2 sensor replacement and wastegate actuator replacement fixed the problem.

just wanted to add this for anyone searching with similar probs