98 gst won't run worth crap.

[Firsts tuner]

Ok so here is the skinny. I just got this car after someone else gave up on it. It came to me with a bad turbo which I replace with a stock t25. The only aftermarket part on this car is a K@N air filter. The motor was just recently rebuilt (like 0 miles.) The idle is very poor (low) at best. I have found a couple vacume leaks which I have repaired. The only time the car seems to run right is when I rapidly press and release the the throttle multiple times and let off. In the brief moment when I release the pedal and the rpm's drop the engine smooths out and my short term fuel trim comes up. Unfortunately that's only momentarily. The fuel trim drops off to 0 and it's back to loping and running pathetic. As best as I can tell I have a severely lean condition that the computer is trying to compensate for by dumping obscene amounts of fuel? I have re placed the intake gasket, the tps, the maf sensor,
various relays, and even the ECM. ( btw its nice to have a complete running parts car). The timing is spot on, and the compression is 190 psi across all 4 cylinders, good fire on all plugs. I don't know what to try next. This is my first DSM and right now it will be my last unless I can get the thing going. Any help would be appreciated. I really like this little car. Other than the whole not running issue it's a cherry car, bone stock and pristine. Thanks guys, and sorry so long.

 

[Rsawd95dsm]

Give it a boost leak test And your O2 might be bad as well

 

[Rikolas]

Give it a boost leak test And your O2 might be bad as well

Big probability there are boost leaks.
Are you able to take a video of it? I'm a little confused on what exactly is going on.

 

[DSM1G90]

Well, if it's a rebuilt, things are pretty tight and it's gonna run low on idle unless you set up the BISS a bit.

 

[Firsts tuner]

After looking up Biss I checked it and it was 2 turns out. I don't think the o2 sensors are bad because they came off my other car that was running fine when I tore it apart. Addressing the boost leak: I actually just for curiosity sake bypassed the turbo all together. By that I mean I used parts from the other car to make basically a N/A intake. I plugged off the holes in the intake tube and installed a maf sensor. No help it runs exactly the same. I have a blue point scanner that reads limited live data. My short and long term fuel trims are at 0. The maf is reading within spec. As far as I can tell. The iat and ect are both reading accurately. I am going to try this weekend to rig up a boost leak test, and get a smoke machine from a friends shop. I have noticed there is no change when I unplug the maf. I thought there would be. I will try to get a video up of it running this weekend if I get a second to breathe. Thanks again

 

[GofaST4life]

Bad MAFT?

 

[Firsts tuner]

Oh yeah I forgot to ask. What are the relays mounted under the driver side dash. They are not the ones in the fuse box itself. If you were to lay in the driver side floor and look straight up there are 4 mounted in a white plastic holder. Closer to the door rather than the center console. It looks like I am missing the one in the lower right corner, but there is one installed in the parts car.

I assume MAFT is the maf translator?

Update: I am thinking I killed the maf sensor. It is still reading but in the early stages of messing with this car I was spraying maf cleaner through the air filter (which is apparently a big no no on Mitsubishi's). It would run better obviously because of the "fuel" being introduced through the charge pipe. You could actually rev it and it would make pretty good boost (14psi +- a couple). Of course after the cleaner burnt off the guts just fall out and the car will die. I did notice before that if I unplugged the maf the engine would idle better but as soon as you touched the gas pedal it would die. Now nothing changes wether or not the maf is plugged in. I shot a little video but I can't upload it from my iPad. I am planning on smoking the engine tomorrow to try to find any little gremlin vac leaks and go from there. Anybody got any other suggestions. I am also planning on new wires and plugs tomorrow. The current wires are Taylor, and the plugs are NGK. They're not the oem but according to the parts shop cross reference they are a suitable replacement. Thanks for the help. The rag stays out of the gas tank for at least one more day.

 

[Foreverthuggin0417]

It could be a lot of different things going on. If I were you I would start with maintenance of the car.
Plugs wires filters etc etc.
My car did something similar to yours but when I did maintenance it went away. It could also be a boost leak or maybe even fuel cut or something in the area to fuel. As in it starts but when you want to press the gas it dies? Make sure all sensors are in working order as well as relays. Hope you get it fixed man. Update us with what is going on. Hope this is of help.

 

[Firsts tuner]

So I got a smoke machine and it did have a couple really small leaks. Biss screw and maf sensor, both of which I fixed( no change). I did notice smoke inside the valve cover? Not sure what's about. I pulled most of the sensors off and going to try them out on a friends car tomorrow. I am kinda leaning towards the cas because I noticed that its actually two pieces bonded together and they are separated a little. The car is acting like everything is ok but as soon as it starts up everything shuts down. I haven't gotten any CEL's unless I unplug something. Btw the compression is 190psi even with the throttle plate close, and within 5 cranks. Just to make sure I am right in this assumption every thing will be working when you first start to self test then will settle into normal operating parameters? I have a spare ecu that I swapped in just to check but no change. Thanks again

Oh yeah it has a known good fuel pump, new fuel filter, new NGK iridium plugs, Taylor wires,fresh synthetic oil, puroilator oil filter, and pcv valve. I also washed the k&n filter and lightly oiled it before reinstall.

 

[19awd93]

check the transistor..they are notorious for going bad

 

[Jesse2012]

Do you have any cel codes? It sounds like something a cam or crank angle sensor, or possibly knock sensor could cause. Also use bpr6es plugs, not those iridium ones

 

[Firsts tuner]

The iridiums were all I could find at the time. I cheked all the sensors I could on a buddy's car and his did fine. Maf cas coil and ignition controller module. I am kinda starting to lean towards the possibility of a bad fPR. The only reason I am saying that is even after I have just tried to start the car and I know there is fuel at the rail, when I unhook the fuel line gas just trickles out. I would have thought it would spray with residual pressure. I am building an adaptor to go inline so I can check exact what it is putting out.

Oh and there are no check engine lights. Other than the ones I caused by unplugging stuff.

So I checked the fuel pressure and after I got the regulator to move( been sitting empty for a while) the fuel pressure is rock steady at 45-50 psi. I did stumble on a post about knock sensors while educating myself and found something about black ooze from the sensor. Well I ran out to the garage to check it and sure enough it is covered in the stuff. Enough in fact that it has formed a drop. Needless to say I am going to get a replacement tomorrow. Someone suggested that replacements can be over sensitive and recommended putting a nylon washer on it when installing. Any thoughts? Seems like Advance sell oem just re boxed. I really hope this fixes this thing I can't afford much more beer for the garage.

 

[Firsts tuner]

To hell with it. First thing tomorrow morning I am going to put full coverage on the damn thing then wait a week or so, then set fire to it. I give up, there is no saving this pos. I have tried everything I can think of and it is pissing on my head.

Ok sorry dsm gods I was just venting. Here is where I am at now. I can get the engine to startup. It sounds good and strong and is pulling about 20hg of vacuum. However the idle starts to dip really low and vacuum drops drops to ten or so and the needle bounces. Then as always it dies. So to paraphrase here it starts great then drops off the face of the earth. Could a huge hole in the evap system cause it to do this when the solenoid gets activated? I swear I have swapped out just about every relay in this car except for the one down by the boost control solenoid. What is that anyway? I have new wires and a new knock sensor coming in tomorrow is there anything else I should try? Should I cap off all the emissions crap? Also I have the stock computer and one from the exact same year car but it is a 5 speed are these interchangeable? I have swapped them and there is no difference. Lastly I am jumping the car from my jeep because I don't have a battery for the eclipse. The alternator is good but should I just put a battery in it and clamp it down to see if anything changes?

 

[Firsts tuner]

So here's an interesting new development. I can unplug just about anything on this car and it won't throw a cel. So basically I figured out that if I take everything I have learned in the last 16 years or so since I have been driving and wrenching and flip it completely ass backwards then I might have somewhat of a start to figure out how to work on DSM's. have I basically got the general idea. I unhooked just about every relay under the radio and the car continued to run. Poorly as always but it continued to run and no cel. Any I sight would be welcomed at this point.

 

[dsmvenge]

Does the battery light come on really dim

 

[Firsts tuner]

No it's on pretty steady right now. That's only because I removed the alternator belt I think. I pulled it just to take the crank pulley off to get a look at the crank sensor. Before that the light only came on for the self test at start up then went off.what would it mean if it did?

 

[dsmvenge]

All your injectors firing

 

[Firsts tuner]

I have checked the injectors. First I ohmed them out, then I used an electronic tester to fire them off with fuel pressure applied and watched for a pressure drop when each one was activated and they all work as advertised. I also checked the wires for each using a noid light. They all seem fine. On another subject though I forgot my password and had to reset it when the computer asked me the random security question " Who makes the Eclipse?" it wouldn't take Satan as an answer. Weird huh?

 

[dsmvenge]

Im gonna say either your cam angle sensor or your temp sensor

 

[Firsts tuner]

Swapped both. Installed on another car and it ran fine.

 

[Firsts tuner]

I am going to try that temp sensor again. Now that I think about it I don't remember if I swapped it or not. It seems to be reading accurately though. I am going to get the knock sensor though. Wish me luck

 

[Firsts tuner]

Ok after messing with it for about 3 hours I think I have it narrowed down. If I unplug the MAF sensor the car runs great. I have been checking every sensor that has anything to do with the MAF and it all comes back to it. I have ohmed out the wires going to the computer from the MAF and there are no opens. I am going to check for shorts then move on. I have a MAF on order. They said it will be 170 and has a lifetime warranty. That's at O'Riely auto. Anyone have any other suggestions on a place to get one? Thanks all.

 

[delta448]

You really should put a battery in it, the alternator needs it in order to function properly.

Stock 2G MAS

 

[Firsts tuner]

I did. It is no different with or without. I can get it to run now but only with the MAF sensor unplugged. I ohmed out everything and it comes back fine but when I check for a short to ground I am getting a short at the thicker gauge red wire. I forget the number but that's it I think. I do have a guy willing to swap me a MAF sensor for a known good one. Gonna try that before I go ripping wiring harnesses apart.

 

[delta448]

It will have the same problem. The thicker red wire on pin 4 of the MAS plug is the +12V power sourced from the MPI relay. Fix the short.