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2G Dies With Maf Plugged In

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smoked28

10+ Year Contributor
107
4
Jul 14, 2012
Keystone Heights, Florida
Hi, guys!

After a few years of being out of the DSM scene, I finally picked up a 2G TSI AWD yesterday as a project. The guy I got it from had 3 DSM's. He said the MAF on the one he was selling was bad, so he unplugged it and hooked his DSM Link up to the car. It started right up and idled okay (very rich because it wasn't tuned to this car). However, as soon as he would plug in the MAF the car would die right away. The car has an HX35 turbo and 1200 cc injectors, so I know I'll need a way to tune it. The car has a black box ECU, so I was going to go about tuning with ECUFlash. He gave me literally 6 MAF's that he said were all bad. He told me I would need to get a new 2g MAF, hook up the black box ECU and get it tuned for it to start and run correctly. Does anyone have an opinion on this before I buy a new MAF? It just seems hard to believe that all 6 of these MAF's are bad. Could there be something else that is likely prohibiting it from starting? It just turns over, never really tries to start. Any help is much appreciated.

A pic of the engine bay for reference.
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Odds are that most of those MAF's are perfectly fine. He probably assumes they are bad because when you plug it in the car starts looking at airflow and your wideband and see's something bad and kills the car. Then unplugged the MAF and it started running. That doesn't necessarily mean the MAF is bad, could mean there's a issue with something else.. Perfect example I had the same issue where the car would die with my MAF plugged in, lots of parts and money later I found out the ecmlink MAF cable was sending a bad signal to the ecu causing it to die when plugged in.
 
I may be wrong but I believe you still will have to check the "invert signal" box in ecmlink you just wont have to change the plug sequence. You will be able to get it to start up and run but you will need to either have it tuned (that's what I did to learn off a good tune rather than blow up my car learning) or learn to tune yourself. Compression is definitely good. Could possibly have been rebuilt at some point, never know I ended up finding a receipt in my car from a tire shop and in the notes it said the motor was rebuilt in April. But the seller said it never was rebuilt. Dis you end up getting v3 full?

On the threads I've read on here, there seemed to be some controversy over whether or not to swap plugs, injectors, invert signal, etc. Mine is kind of an odd issue because I have a 95 ECU with a 97 engine and harness and then a 1G CAS. So, I reached out to Tom from ECMTuning and he told me that I will need to swap the plugs and to select the invert option.

Wow, that's really lucky for you! I doubt I'll have the same luck though. Apparently it was driven by his wife, who left him and he doesn't want to look at it for obvious reasons. I did some research on the car and found videos of a woman with it (goes by ladi2g), so the story adds up. Possibly it just wasn't driven that hard for all 130k. As far as tuning, I did get V3 Full and I know nothing about it, nor do I know of any shops around me who deal in DSMs anymore. However, I am hoping that with the help of ECMTuning support forums as well as this site, I'll be able to figure it out.
 
Odds are that most of those MAF's are perfectly fine. He probably assumes they are bad because when you plug it in the car starts looking at airflow and your wideband and see's something bad and kills the car. Then unplugged the MAF and it started running. That doesn't necessarily mean the MAF is bad, could mean there's a issue with something else.. Perfect example I had the same issue where the car would die with my MAF plugged in, lots of parts and money later I found out the ecmlink MAF cable was sending a bad signal to the ecu causing it to die when plugged in.

Well, that's definitely good to know! I asked him that very question because I too thought it sounded unlikely that all of them were bad. He told me he tested them on other cars and they were all bad. Why he felt the need to included a pile of unusable MAfs in the trunk, I do not know. I did just receive my new MAF, however, and started the car with it installed. Although it didn't run great (likely because I was using the non-turbo ECU with different injector settings and such), it did idle a lot better than the other MAFs.
 
Well either way I would invert the signal, try to fire it up if it doesn't work (mine backfired) just swap the plug wires there's only 2 ways it can work. It should be only based off what ecu is in the car. Should be a fun setup once its all up and going though! Is the BOV vented to the atmosphere? Cars not going to like that with the 2g MAF. You can run a gm MAF or SD if you want to keep it like that.
 
Well either way I would invert the signal, try to fire it up if it doesn't work (mine backfired) just swap the plug wires there's only 2 ways it can work. It should be only based off what ecu is in the car. Should be a fun setup once its all up and going though! Is the BOV vented to the atmosphere? Cars not going to like that with the 2g MAF. You can run a gm MAF or SD if you want to keep it like that.

Yeah that's something I noticed that is on my list of things to look into. On my other DSM, I had a recirculated Greddy Type S that worked well with the 2G MAF.
 
Well either way I would invert the signal, try to fire it up if it doesn't work (mine backfired) just swap the plug wires there's only 2 ways it can work. It should be only based off what ecu is in the car. Should be a fun setup once its all up and going though! Is the BOV vented to the atmosphere? Cars not going to like that with the 2g MAF. You can run a gm MAF or SD if you want to keep it like that.

You have to remember he bought it non running.

He leaves the maf unplugged and it idles.

He needs to perform a boost leak test.

A major boost or vacuum leak will cause the mass air flow sensor to show inaccurate readings to the ECU, the map sensor takes over when the maf is unplugged and can tell the ECU exactly how much air is entering the combustion chamber at idle.

So again, the map sensor is part of the speed density setup, a calibrated map that senses boost and vacuum is far more accurate than a pre turbo mass air sensor that also has a pre turbo air temperature sensor.
 
You have to remember he bought it non running.

He leaves the maf unplugged and it idles.

He needs to perform a boost leak test.

A major boost or vacuum leak will cause the mass air flow sensor to show inaccurate readings to the ECU, the map sensor takes over when the maf is unplugged and can tell the ECU exactly how much air is entering the combustion chamber at idle.

So again, the map sensor is part of the speed density setup, a calibrated map that senses boost and vacuum is far more accurate than a pre turbo mass air sensor that also has a pre turbo air temperature sensor.

Last week I fixed all the boost/vacuum leaks I could find. When I finished, it was only dropping about 5-10 PSI/min. Not sure how exact it needs to be, but it's definitely a lot better than it was before. It wasn't even holding compression. When I'd put air in, it'd be out within a few seconds. Found a large hole in one of my intercooler couplers and tightened up a lot of hoses. I have been considering SD as I've heard it's much more accurate. Want to get it tuned and running well first before I worry about anything new though. My ECMLink just came in the mail this morning, so I'll be hooking it up tomorrow.
 
Quick update:

I got link installed. Wouldn't start, so I swapped the plugs and it fired right up. Idling pretty high and sounds like it's missing a little. I took it down the road and it felt like I wasn't building boost, although I can't verify that. The previous owner had told me there was a wideband installed (and there is a gauge), however, it turns out the sensor needs to be welded to a bung. So I wanted to ask if it is a good idea to try to start tuning with link, or if I should wait until I can get the wideband installed?
 
Yeah you need a wideband first. Dont try to build boost til it is setup right. Do you plan on doing something with the bov? Get a boost gauge aswell

Damn, I wanted to get rolling with this. Idk when I'll be able to get the sensor installed because I'll have to tow it to a muffler shop:cry:

I have a boost gauge and I think that gauge works (hopefully). I was just too busy worrying about shifting when I took it out on the drive last night to look at the boost gauge. The clutch feels very soft to me and 3rd and 4th were grinding a little:|

As far as the BOV, I may be wrong but I don't think it needs to be recirculated. Looking at it now, I don't see a port for recirc. I'll attach a pic.
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Yeah there's no way to recalculate it but with a stock 2g maf if needs to be. So you can run gm maf or SD, or get a bov that can be rec. Is there no ports for a wideband? What exhaust does it have on it? Even if its in the rear that's better than nothing. You should be able to use a stock 02 port if there's one somewhere on the car. Can cross your fingers that the clutch just isn't fully disengaged when shifting that will cause a grind. I would try bleeding the clutch to see if you can get a better pedal. The trans is what I was first thinking when I said expect something to pop up.
 
Yeah there's no way to recalculate it but with a stock 2g maf if needs to be. So you can run gm maf or SD, or get a bov that can be rec. Is there no ports for a wideband? What exhaust does it have on it? Even if its in the rear that's better than nothing. You should be able to use a stock 02 port if there's one somewhere on the car. Can cross your fingers that the clutch just isn't fully disengaged when shifting that will cause a grind. I would try bleeding the clutch to see if you can get a better pedal. The trans is what I was first thinking when I said expect something to pop up.

Well damn...I just got this MAF installed. I've been thinking more and more about SD. What's the equipment cost of that roughly? Maybe I'll just get a new BOV.

The exhaust is 3" straight pipe cut about under the driver seat. I see the front 02 in the downpipe, but I think that's the only 02 sensor. Someone told me not to put the wideband on the front 02 on a DSM.


Yeah I'm hoping it's not the tranny. Since the pedal feels soft, that gives me a little hope. I tried to bleed it last night, but didn't have the right size vacuum hose, so I think I'll give it another go after I pick up some smaller hose today. Previous owner says it never had a grind but who knows.
 
Out here changing the plugs now. Hoping that miss goes away. These things are fouled to hell. Thinking about experimenting with seafoam, never tried it before.
 
You can put it in the front. Just try not to install it in the 02 housing. You want it on the downpipe or a little after the downpipe. SD may be a better choice ive seen people selling the full setup for around $125. The problem with your setup right now is your calculating air that's going to be lost when the bov opens. So if the air is metered after the BOV rather than before then your good. Sorry for the crappy bunched together and spelling errors I have a $20 work phone. It sucks haha.
 
You can put it in the front. Just try not to install it in the 02 housing. You want it on the downpipe or a little after the downpipe. SD may be a better choice ive seen people selling the full setup for around $125. The problem with your setup right now is your calculating air that's going to be lost when the bov opens. So if the air is metered after the BOV rather than before then your good. Sorry for the crappy bunched together and spelling errors I have a $20 work phone. It sucks haha.

Yeah it looks to be in the downpipe. So I can just replace that with the WB sensor, pin it to my ECU (pin 75 I believe it is) and be good to go? Then I wouldn't need to weld a new bung. Yeah maybe I'll look into getting a SD setup. I'll watch the classifieds and see if any pop up.

What plugs are you using?

I use NGK BPR7ES. Got them in a little while ago. About to go fire it up and see if I notice a difference.
 
So I bled the clutch again. Pumped and released it like 15 times just to be sure and it still is grinding going into 3rd and 4th:notgood: I am really hoping that since it's a couple of gears that are doing it, it isn't syncros. Can't really find much info on gear grinds in DSMs though:hmm:
 
Start the car and try to put it into the gear that grinds without the clutch pushed in. Dont force it to hard. If it "falls" in just a bit and makes a grind noise then the synchros are failing. Or so I have read that is a way to test
 
Start the car and try to put it into the gear that grinds without the clutch pushed in. Dont force it to hard. If it "falls" in just a bit and makes a grind noise then the synchros are failing. Or so I have read that is a way to test

Well, I just tried that and 3rd does what you said. It falls in and grinds. All other gears are preventing me from pushing them in. So this means for sure I need to rebuild the tranny? Or just drop it, crack it and replace the syncro?
 
U have to setup the wideband for the front O2 sensor to work in link. U can use narrowband simulation from link. And yes the wire u would solder into is white I forget the pin. I ran my aem wideband on the front O2 for over 5 years with no issues and running e85. U should be fine.

As far as speed densiity goes u can find these sensors at a local junkyard for cheap and u can build your own harness.
 
Boostdawd any problems logging your aem? I want to get rid of this afx and I already have aem boost I wanted to match gauges

That test is suppose to be a syncro only test. I cant tell you how healthy the rest of the transmission is so I'm not sure it only replacing the syncro would fix all your issues.
 
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That test is suppose to be a syncro only test. I cant tell you how healthy the rest of the transmission is so I'm not sure it only replacing the syncro would fix all your issues.

I'm trying to decide whether I want to drop the trans and go about rebuilding it myself with a kit from Jack's or somewhere or if I want to just wait to find a stock awd trans on the classifieds. Or maybe just part the damn car out and cut my losses:ohdamn:
 
White shed speed has a $500 rebuild on there website look in the supported vendors. If you do part it let me know. Haha

You will learn pretty quick that people who say you can run these cars for cheap dont have the best idea of what it takes. Its cheaper then other cars that's true. But taking someone else's project and getting it on the road again normally isn't super cheap. I have 5k into mine just fixing everything that was wrong with it. That's why I dont understand why people laugh at someone selling a perfectly running DSM for 6k, then turn around and buy a hacked up DSM for 2500, and spend 5-6k to get it just back to somewhat reliable.
 
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You will learn pretty quick that people who say you can run these cars for cheap dont have the best idea of what it takes. Its cheaper then other cars that's true. But taking someone else's project and getting it on the road again normally isn't super cheap. I have 5k into mine just fixing everything that was wrong with it. That's why I dont understand why people laugh at someone selling a perfectly running DSM for 6k, then turn around and buy a hacked up DSM for 2500, and spend 5-6k to get it just back to somewhat reliable.

Well my only real experience with DSMs before this one was a GST I had years back. Bought it from a guy who couldn't have it where he lived (noise) and needed to get rid of it. He wanted $3000 and I ended up giving him $1350 for the car and $150 for two boxes of upgrade parts (SAFC-II, stage 4 clutch, 50 trim, etc.). I didn't really know what I was getting myself into, but I took it to a DSM mechanic at JAX beach who went through it for me. Told me it had a rebuilt trans, very strong engine (said it couldn't be over 40k), etc. I made out like a bandit with that car. Ended up putting a little bit into it and doubling my money. Not so much with this one though LOL:confused:
 
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