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2G Car can’t hit an idle, crackles and dies.

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Kai Hefner

Freelancer
480
272
Jun 21, 2018
Calgary, AB_Canada
Just put on a new intake manifold and needed to put on a 1g TB. The car starts great but when it comes down to idle, it goes really really low and crackles, most of the time it kills the car.

What am I missing?
 
Do you have a wideband? What are afrs.
Double check wire connections.
Start car spray brake cleaner around intake manifold and throttle body.
If rpm changes there is a vaccum leak.
 
If you think you have a leak, why would anyone venture to guess what your issue is? Fix the boost leak! Do a BLT and fix any other leaks!

Then post a log after you have NO boost leaks, and people can try to help you out.

Best of luck
 
Alright this is getting annoying. I fixed the boost leak at the throttle body (just put in a gasket in the wrong orientation and it was a bit wonky).
The idle is still so weird, seems like its running on two cylinders down low but sounds totally fine when I blip the throttle. Follow this link and watch the video please to help me figure out my issue.
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I want to say, it totally sounds like knock when I listened to the playback but it's not, it's a weird crackling out of the exhaust and it sounds like a 2-stroke when idleing. Also note that I only blipped the throttle twice, I didn't hold it at all (pretty sure tps is not adjusted correctly).

Someone please let me know what I'm doing wrong so I can stop ripping my hair out.
 
Nice video, where is the log though????

Post a log at idle and we can actually try to help instead of playing the guessing game.

In the video is the camera's auto-focus causing the dimming and brightening of your instrument cluster? or is your battery voltage dropping off? A log would answer this question... See my point yet?
 
I found the problem!!!
I’m not sure how this is supposed to help me solve my problem?

The dimming of the lights is because the car is coming down so low on idle that it’s almost turning off.

I can see what I can do about throwing v3 into my car but I have 0 tuning experience.
 
You have to start somewhere... if nothing else you can use it as a diagnostic tool with the added benefit of tuning.
ecmlink is critical to maintaining and tuning a modified DSM. if you cant go V3 there are other options I think, and if its all not in the budget, try to find something that can at least log and stream data from obd2. you will be able to read clues of why your car isn't running right.

ECMlink should be everybody's first mod (in my smelly opinion). You will not regret buying it.
Best of luck!!
 
Well I misplaced the cable so I’ll see if I can buy one locally or worst case order it.

Let’s just pretend I didn’t have v3 on the shelf or had $600 to blow on an ecu just to log data for you to help me out.

Anyone know what this behaviour could be? I’ll hop on the v3 if I can find a cable somewhere but until then any ideas?
 
Go through the list of things and quite frankly there is a lot. But seeing how you swapped to a 1g throttle body, do you have a 1g TPS or 2g? If 1g then you are missing the IPS reading unless you wired it to get it from the 1g switch. If its 2g then just adjust it unless you have already done so. The ISC/IAC could not be working right and I would check it. If the ISC isnt working it could have the passage closed off too much bringing a low idle, the FIAV could be stuck closed as well which if its stuck closed it wont hurt anything and with Link I have heard you can set it so the ISC does the work of both ISC and FIAV on cold starts.

When you start getting into the idle it can be any number of things. I would check ISC, TPS and go from there. I just wonder if the crackle is that the ECU thinks the throttle plate is open sending in more fuel (if it even works that way) which results in the crackle. Thats usually what pops and crackles are from, too much fuel which only a certain amount can be burned and the rest is burned in the exhaust creating pops and crackles. At least that is what I read. It makes sense to me since you need oxygen to burn fuel. That is why I bring up the IPS.
 
I believe I switched over the 2g TPS, although I'll go home and try the other one I have. Might actually make sense if I still have the 1g one attached because the missing IPS reading might cause the idle to be very stupid and die? Is this how that works?

On the other hand, I'm pretty sure I switched over the ISC. I have an orange-top ISC on my TB, that's the 2g one right? I just made sure I put on the one that was working when I tore the car apart.
 
A missing IPS will make it so the ECU doesn't know that the throttle plate is closed so the idle would be weird.

The orange top ISC is the stock ISC from my understanding and the 91-94non-turbo and 91-99 turbo are all the same. It could be very well that it went bad. All the aftermarket ones read 39ohms though instead of the 28-33 from the stock ones.
Check pins 1&2 2&3 and 4&5 5&6 if any of those are missing then it's bad. Also check to see if it is working with the key turned to the on position. Remove the negative battery cable for 10 sec, reconnect it and then test the ISC motor. Of course you have to have it out of the throttle body to see how it moves. There is a video showing how to test with an ohm meter and with the key.

I just brought those up because you swapped the throttle body to a 1g and some things that could be happening with the airflow. Idle issues are an absolute pain.
 
I tested the ISC, all of the pins you specified measured around 29 ohms.

It’s a 2g tps on there alright. The other one has a pick and pull marking on it so it’s definitely from the 1g throttle body (that’s where I got it).

Just going to attach some pictures and maybe someone can help me out. All of these issues spiralled because I put in a new intake manifold and 1g TB.

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Nothing interesting going on at the TB. Took the pic when the TPS was off but don’t you worry it exists. My MDP sensor is not connected, but I’ve seen people who connect it then line it to the TB. Would not connecting it cause any issues?

Maybe this pic will be important, it’s vacuum shit for the manifold, maybe I hosed it wrong?
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Leftmost one is the one with the check valve. Second to the left goes to the T that goes to AFPR, etc. Second to the right goes to my BOV. Rightmost goes to my valve cover.

Any issues with this?
 
Sounds like the ISC is good though the wisemen on here suggest getting the black plastic ones since the stock ones have a high chance of messing something up in the computer. Something to look into at least.

One thing that stands out to me is the vacuum line closest to where the throttle body bolts too doesn't look to be on there all too well. If I remember correctly when I pulled a vacuum line off, like let's say the brake vacuum line the car would run like comeplete garbage. It I put my finger on the hole it would run better. It sounded like it would want to stall. I would try to get that line on there better with a better clamp if at all possible.

I am assuming that it was running fine before the change though? If so I wonder if the fiav is stuck closed, have you gotten it up to operating temps? With the only things changed being the intake manifold and throttle body that is where I would start. Intake mani could be the vacuum lines and in terms of the throttle body something could just be stuck and needs cleaned. Or it could very well be something someone else would be better to help with.
 
Huh maybe I'll pedal it a bit to get it up to operating temp. I have gotten it close to temp but not hit it.

I tightened that hose this morning. Honestly it was pretty loose now that I look back at it. Couldn't test this morning though because 8am and I have neighbors. I'll come back with some results this evening.

I'm a bit confused about adjusting the TPS. People are saying you prong pins 3 & 4 with a ammeter when the key is in the "ON" position. I haven't been able to get a voltage reading from these pins. I was thinking "how you would get a voltage reading from having the TPS wire unplugged and just reading it from the sensor" but then I read people backprobe the TPS when it's plugged in? I don't really want to back-probe it, there isn't a lot of room back there and with my luck I'll break off a paperclip in there. How specifically do I measure the TPS voltage?
 
Weird update. Maybe I routed a vacuum hose wrong? I payed more attention to my boost gauge this time around. The idle for some reason is 0lbs at idle. When I rev it goes to -15 and the harder I rev the closer it gets to -18. What did I route wrong?

Edit: I just realized this doesn’t make a lot of sense mechanically. Is my boost gauge lieing to me? How does it even rev if it’s not in vacuum.
 
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Pin 3 is your IPS that tells the computer the throttle plate is closed and 4 is your ground. You use ohms and not voltage to set it. I have a 2g TPS here, but I never knew when to stop turning it for adjustment, I guess when it starts showing something other than open loop but I never really quite understood it. I had gotten it for my S90 throttle body but that thing and the JM Fab intake manifold leaked so I put the n/a stuff back on.

With the boost gauge, I have absolutely no idea since I havent begun messing with boost, still N/A and getting everything set before I start messing with boost.
 
Bump, anyone have any idea? Boost gauge reads 0 psi at idle. When I rev it, it gets more negative vacuum.
It sounds fine when revving, just the idle is ridiculous.

Could my timing have jumped a tooth or two? Starting to consider that possibility now.
 
You should not have a T in your vacuum hose to your AFPR. Your brake booster line looks like its barely on. Fix that.

Your boost gauge line is also messed up clearly. Redo the lines.

Also, what throttle cable are you using? That looks incorrect. The mounting. The length. It looks wrong.
 
You should not have a T in your vacuum hose to your AFPR.
I had it set up this way before and it worked perfectly fine. Why would a new intake manifold change that? Regardless I will do this.
Also, what throttle cable are you using? That looks incorrect. The mounting. The length. It looks wrong.
I'm just doing a direct line from the firewall, is that not okay? I figured I could save a few bucks and make the bay look a lot cleaner if I figured out a mounting solution for that part of the throttle cable (It's basically the line that used to go to the black box). It works perfectly in terms of using the pedal, would it effect my idle though?
 
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