Car Won't Idle

[ohlegend]

Ok, so before I fixed my boost/vac leak, I was able to idle the car for 30 seconds. If I unplugged the MAF, It would idle between 800-1000 and it would not cut out.
I found a huge leak at my intake manifold, replaced the gasket and mounted everything back on the car. (All vac lines and connectors are connected). Now, I turn on the car and it will run for 20 seconds or less and die. I did another vacuum test and it did not leak. So I have come to the conclusion the it could be one of the following things:
ECU
Not enough spark
Low Fuel pressure (bad FPR)

If I give it some gas it lags for a bit, backfires and then revs up.

Any ideas? Am I on the right track?

I have new battery terminals and another ECU on the way. - FYI

 

[ohlegend]

I am swapping out the o2 housing with a tubular style and putting in a new o2 sensor. I am going to try to run the car with no downpipe on to see if it will idle

Does it sound like a exhaust problem?

I installed the new o2 housing and started up the car, it idled for a while and then started backfiring and struggled to run. The downstream o2 sensor is not getting a signal because I do not have the exhaust hooked up to it. Would this cause the car to stall out if the downstream o2 is not getting a signal?

 

[ohlegend]

Any help here would be appreciated

 

[gofast63]

Any help here would be appreciated

before you buy a o2 sensor.

1) is it a wideband o2 sensor?????? If so, test it.
2) if not its always good to have one.

 

[lasershark]

Do you know if it has the stock injectors? Maybe the previous owners swapped them out with no tuning

 

[ohlegend]

No they are stock GSX injectors. I have a 3" downpipe and a 3" catback coming. I bought new O2 sensors for the up and down stream ports. This car sat in long grass for 2 years. If this doesn't fix it, it has to be a fuel issue then?

 

[gofast63]

No they are stock GSX injectors. I have a 3" downpipe and a 3" catback coming. I bought new O2 sensors for the up and down stream ports. This car sat in long grass for 2 years. If this doesn't fix it, it has to be a fuel issue then?

well your computer takes the reading from the o2 sensor to determine what amount of fuel is needed. Of course it takes other sensor reads into account as well.

 

[SNYD3R91]

would a maf from a galant or 3000gt n/t work on my gsx?

 

[thejollyrancher]

The first time you changed the maf did you change to a known working maf? Your situation sounds identical to mine which was a maf issue. Check the wiring and log the maf Hz value. I know for my 1g it should read around 30Hz at idle. If your maf is showing wacky numbers and isn't more Or less linear, that would be your issue.

 

[1G Eclipse94928]

No they are stock GSX injectors. I have a 3" downpipe and a 3" catback coming. I bought new O2 sensors for the up and down stream ports. This car sat in long grass for 2 years. If this doesn't fix it, it has to be a fuel issue then?

Dude, your using gsx injectors with no tuning, and you put in a walbro 255 without a FPR..... Put in stock injectors, you cant just throw in bigger injectors without tuning,...

Before you go buy any parts please read up A LOT MORE. Or get a local tuner/dsm expert to help you with your build, If you had all your mods on your profile updated and everything else we could help you better.

would a maf from a galant or 3000gt n/t work on my gsx?

Dude don't thread jack, and use google not someone elses thread.
Dont be so lazy, first result on google tells you the answer, its NO
http://www.dsmtuners.com/forums/newbie-forum/370992-mitsubishi-mafs.html

 

[ohlegend]

oh crap. What is the difference between GST and GSX injectors?

I thought they were both 450cc?

-I just looked at my order, it says GST/GSX/TSI

 

[ohlegend]

OK, since my last post I have replaced the PTU, Replaced both O2 sensors, replaced the coil packs, Put on a new T25 turbo, 3" downpipe, and 3 " exhaust. I am still having the same issue. The cars starts strong then fades out. I am going to do a vacuum test this weekend. I also have to replace the o-rings on 2 of my injectors. I also put on a full hard pipe kit - so there is no boost leak (everything is tight)

 

[dakang]

Have you tried to give it gas just to keep it running. by that i mean, stay in the car in give it some gas right before it cuts off and keep doing it. my car right now does something similar. it was worse before i blocked off the FIAV. Usually about 5-15 minutes depending on how cold it is out here, then it levels out and runs fine until i shut it off and start again then its the same problem whether or not its at operating temp. I read in another thread that it could possibly be an ECU and ISC problem(bad ISC messed up ECU). if you have a spare or a buddies i would check that out. i just havent done anything since i plan on getting link in a couple of weeks and will have them repair if needed.

 

[ohlegend]

I also have my FIAV blocked off and I am running my spare ECU. If I rev it cylinders 1 & 4 get super hot and usually the car will die after I rev it. It revs up, but on the way down the RPMs drop low and the car dies.

 

[dakang]

check out this link. they talk about it a bit here. but from what i understand you can keep frying an ECU with a bad ISC. By the way, mine does the very exact same thing before i get it to go. what i do is give it a quick push of the pedal and let the rpms drop back down to where it almost dies then give it a another tap and keep doing that. i cant keep it throttled since it sputters and drops down till it "catches" but once it does it runs fine. the amount of time varies and it runs rough till it "catches" a good idle.
http://www.dsmtuners.com/forums/tuning-engine-management/269343-bad-isc-destroying-ecu.html

 

[ohlegend]

i put in the new ECU after i blocked off the IAC.

 

[dakang]

oh thats a different ball game then. thought you only had the FIAV blocked. guess you cant fry an ECU with something that isnt there .

 

[untouchablecc]

Dude, your using gsx injectors with no tuning, and you put in a walbro 255 without a FPR..... Put in stock injectors, you cant just throw in bigger injectors without tuning,...

Before you go buy any parts please read up A LOT MORE. Or get a local tuner/dsm expert to help you with your build, If you had all your mods on your profile updated and everything else we could help you better.



Dude don't thread jack, and use google not someone elses thread.
Dont be so lazy, first result on google tells you the answer, its NO
http://www.dsmtuners.com/forums/newbie-forum/370992-mitsubishi-mafs.html

What do you guys mean by GSX injectors? I thought all manual transmission dsms came with 440s and autos came with 390s or something like that. That shouldn't matter.

Also I dunno why everyone says you can't run a walbro 255 without a fpr. I did it for years in my car. It never over ran the stock regulator. I smoothed out my fuel and airflow in dsmlink and drove it everyday like that on a full build. Another buddy of mine didnt even have dsmlink in his 1g and daily drove it for 5 years with a walbro 255 and no fpr.

Anyways it sounds like your runnin right as heck. Do you have any boost leaks at all or have performed a boost leak test?

 

[ohlegend]

I know I dont have any boost leaks. I might have a vac leak (I am testing this weekend). I will also do a boost leak test. I have new spark plugs coming too.

This guy is having the same problem I am :
[ame=http://www.youtube.com/watch?v=ncdfZWy4WwM]Weird idle 2G DSM - YouTube[/ame]

 

[ohlegend]

I unplugged mt MAF and the car would idle.
??? I dont know what is going on.

When I give it gas, I get a woosh out of the BOV. It appears it is holding no boost. I have checked all of the IC pipes and all couplers with soapy water. The set screw on the bov is almost all the way in.
I cannot feel any air coming out of the intake manifold or throttle body. Now it doesnt matter if I plug in the MAF or not.

 

[gofast63]

I unplugged mt MAF and the car would idle.
??? I dont know what is going on.

When I give it gas, I get a woosh out of the BOV. It appears it is holding no boost. I have checked all of the IC pipes and all couplers with soapy water. The set screw on the bov is almost all the way in.
I cannot feel any air coming out of the intake manifold or throttle body. Now it doesnt matter if I plug in the MAF or not.

Post a video of what's going on.