High rough idle

[teamo2t]

Hey my car has been sitting for about a year while I slowly worked on it. We changed head gasket and oil pump and removed balance shafts. ANy way we just got it started and i will not run right. It will not idle where it is supposed to. we checked for boost leaks and I have a minor one at the throttle body. It stays revved at between 2-3k. I have DSMlink and checked the codes. It says malfunction of temp sensor and barometric pressure sensor. Could the sensors be my problem? Please let me know. Also I have poor vaccum when the car first starts (between 5 and 10) could the problem be boost leaks?

Thanks everyone.

profile is up to date but most has been recently installed

 

[teamo2t]

By the way, I just installed 880 CC inj and 190 walboro with DSMlink. I obviously have not had time to tune. Are the rough settings that come with the chip sufficient to drive on while I break in a new clutch?

 

[98mitsuGSX-SD]

Correct your current DTC's and see if that resolves your high idle issue. The temp sensor might have something to do with it. Since the engine is unable to determine the current temp and adjust the idle accordingly. BUT that is total hearsay so don't take my word on that!

 

[timot]

if your getting a temp sensor code that means your ecu is noting an incorrect or out of range reading from the temp sensor. That sensor is about 7 bucks replace it an see what happens

 

[teamo2t]

Will do... By the way, I took the car to the shop even though I swore never to trust anyone with the car because I know the shady things that happen at SOME shops... Any way, would you believe the guy called me from the shop SCARED saying I can't touch than car because you have too much after market garbage. I said what??? And he said you have that SUPERCHARGER and other things... I replied thank you please don't touch my car. It is a factory turbo. He stayed very confused...

Any way, thanks for the info. I will change the sensor and let you know.

 

[laserspeeddemon]

I find it funny that you posted a possible solution in your orginal post. Let us know if you still have the problem.

 

[teamo2t]

I always made fun of people who posted "hey I have a code of ______ do you think that is my problem..." BUT I posted this trying to find some hope in my circumstance. There is so much knowledge on this forum, I was hoping for someone to say hey I had this problem to and it is the sensor... Any way.

I was trying to find a place to purchase the intake temp sensor and barometric pressure sensor online. Does any one know where I can find it? If not I will have to take off of work to go to the Mitsu Dealership. I searched google with no luck. Also I once knew of a website to find pics and diagrams for all the sensors on the DSM. Can someone point me to a site where I can get instructions and precautions for installing the sensors?

 

[teamo2t]

Okay. I have been searching this site and it seems that the intake temp and pressure sensors are incorporated into the MAS. Is that correct? If so I have a spare 2g I can put in just to check.

How long will it take for the code to correct in the ECU? Do I need to reset the computer (disconnect battery)?

 

[MountainDew]

I believe the barometric sensor is CAS related. I did a 1G CAS swap and reading on RRE, you wire in a volume control knob to "adjust" the barometric pressure. This only happened when I got the CAS.

When I reset the ECU, my CEL never came back.. which is weird because I had 4 codes before.

 

[oldman]

I believe the barometric sensor is CAS related. I did a 1G CAS swap and reading on RRE, you wire in a volume control knob to "adjust" the barometric pressure. This only happened when I got the CAS.

Negative, both the intake temperature and barometric sensor are part of your MAF sensor, you need a new maf or it's not plugged in, reason why you're idling high.

Okay. I have been searching this site and it seems that the intake temp and pressure sensors are incorporated into the MAS. Is that correct? If so I have a spare 2g I can put in just to check.

Bingo.

How long will it take for the code to correct in the ECU? Do I need to reset the computer (disconnect battery)?

It only takes about 30 seconds to reset the ECU but you can use DSMLink to clear the DTC's after you check the mas plug and/or swap in a replacement 2G mas.

 

[MountainDew]

Negative, both the intake temperature and barometric sensor are part of your MAF sensor, you need a new maf or it's not plugged in, reason why you're idling high.

http://www.magnusmotorsports.com/tech/1gina2g.pdf

Towards the bottom at troubleshooting, talks about adding resistance to the barometric pressure to help fix misfire/idle/CEL.

Not trying to prove you wrong or anything, just trying to verify. Maybe this is completely unrelated to his problem.

 

[oldman]

http://www.magnusmotorsports.com/tech/1gina2g.pdf

Towards the bottom at troubleshooting, talks about adding resistance to the barometric pressure to help fix misfire/idle/CEL.

Not trying to prove you wrong or anything, just trying to verify. Maybe this is completely unrelated to his problem.

That is a method to trick ECU and prevent the "random mis-fire" code often associated with using a 1G CAS in a 95'-96' during a 6 bolt swap, it does this by intercepting and manipulating the barometric sensor signal (pin# 85), pin#85 (barometric sensor) is connected to the MAS, nothing to do the CAS.

If the method was to manipulate the O2 sensor signal instead, would you still assume that your O2 sensor is part of your CAS as well?

 

[oldman]

Ok I think I know where our confusion is, the part of your post that I was disputing was "I believe the barometric sensor is CAS related", I was not disputing the fact that you can prevent the misfire code by manipulating the barometric signal. When I said "you need a new maf or it's not plugged in, reason why you're idling high.", I was referring to OP, not "you". Hope that cleared it up.

 

[teamo2t]

I picked up the car last night. The check engine codes were gone and the shop said that it seems like I may have some bent valves. This is possible because when we changed the head gasket we failed to make sure the timing belt was tense enough. It did skip a couple teeth. I was hoping everything was okay. I forgot all about it until this mess.

When the car is near idle vacuum is at about 5 I know that is WAY too low! Could that cause the DTC that came up or do I have more problems? Any way I will be checking compression tonight. If it is too low then off goes the head AGAIN! I have about 5 miles on the head gasket I assume I should change it for a new one any way because the head was torqued down. Is that correct? I have ARP studs so can I use them again?

 

[oldman]

When the car is near idle vacuum is at about 5 I know that is WAY too low! Could that cause the DTC that came up or do I have more problems? Any way I will be checking compression tonight.

No, I suspect the mas was either not plugged in tightly OR it was disconnected at one time or another and the code just needed to be cleared. If it comes back on, check the mas plug again. You can also log intake temp and baro on Link to verified they're now functioning properly.

If it is too low then off goes the head AGAIN! I have about 5 miles on the head gasket I assume I should change it for a new one any way because the head was torqued down. Is that correct? I have ARP studs so can I use them again?

Which HG did you use? If it's the stock composite, I would just get another.

 

[teamo2t]

I got a cosmetic multi layer steel HG gasket. Save me some money and tell me its okay to reuse!

 

[oldman]

I got a cosmetic multi layer steel HG gasket. Save me some money and tell me its okay to reuse!

Yes you can re-use it as long as there are no visual damages. The real question is, did you resurface the head and make sure that the block was perfect before you installed the MLS last time around?

 

[MountainDew]

Yes you can re-use it as long as there are no visual damages. The real question is, did you resurface the head and make sure that the block was perfect before you installed the MLS last time around?

This isn't stressed enough. In most cases your block may need to be surfaced as well for proper sealant.

 

[teamo2t]

I had to get teh head resurfaced (which was done) and the block was good so I will re use it then! Sweet!

Any way, I think I found my problem... compression on cylinder number 1 was... uhhh... ZERO! That is right! Nothing. The rest were between 155 and 160. I forget what the service limits are but I know 0 is a bit too low. So I will be pulling the head this weekend and trying to get this thing running in a a week or two. Thanks everyone.

I still haven't heard about my tuning question. Are the rough settings from DSM link enough to run with while I break in my clutch? I am new to the tuning world so Good luck to me.

 

[oldman]

I forget what the service limits are but I know 0 is a bit too low.

I'm not sure but that might be slightly under the service limit.

I still haven't heard about my tuning question. Are the rough settings from DSM link enough to run with while I break in my clutch? I am new to the tuning world so Good luck to me.

Get your LTFT low and mid close to 0 and disconnect your wastegate actuator arm, good luck.

 

[teamo2t]

Disconnect wastegate actuator arm... Didn't think of that. Good plan!