Problems running with MAS plugged in

[Big Willy]

Ok guys/girls, hopefully someone here can help me out with this. Myself nor anyone else has been able to figure this one out yet. I've got a 92 GSX and have swapped in a 90 Tsi motor due to the 92 throwing a rod. During the swap I changed out the 90 TB & all attached sensors, fuel rail, cam sensor, coil & the ignitor with the ones from the 92 due to their differences. Also while I was at it I installed a 2G MAS. The MAS was wired with the instructions straight from the VFAQ and this isn't my first time wiring one. After some trouble starting the car runs but now I have more problems. With the Mas plugged in the car pops, backfires, barely idles and as soon as you touch the throttle it trys to die. As soon as the MAS is unplugged; idle returns to almost normal, it will take fuel and rev fairly well but it's still not perfect and obviously... the MAS is unplugged. The car has 37psi of fuel pressure, 130psi of compression, and brand new BPR7ES's. I've changed the MAS, TPS, & IAC to no avail. Also I've tryed running the car off the 92 ECU with normal pinning and with the 6 & 14 pins swapped, and just for shits and giggles also tryed the 90 ECU with normal and swapped pinning; still nothing. Now I'm stumped. Anyone have any idea's?
*EDIT* forgot, base timing is set at 5 degrees BTDC.

*OT* BTW, on this forum if your account is idle for a while and you forget your password then have the password changed does your status return to newbie? Because now I can only post in the newbie section.

 

[Big Willy]

No one?

 

[Lordpaxin]

Bumping your own thread will get you harassed



its obvious your problem is centered around the MAS

When you unplug it your ecu goes into closed Loop mode.
and does not rely on the maf signal.

Id double check your wireing, from multiple sources. Try a Different 2g Mas.

ive read a lot where people have your same problem, Though its not a mas swapped car, and its just a bad mas.

ill send you mine in a few weeks when i swap it out with a gm

just try a known good mas, im sure youll get it figured out remember to get your "big willy style all in it"

 

[Lordpaxin]

youve only made 10 posts in 2 years? wtf

 

[Big Willy]

Id double check your wireing, from multiple sources. Try a Different 2g Mas.

I've changed the MAS, TPS, & IAC to no avail.

I swapped for another known good 2G MAS and even went as far as taking the 2G plug off the car, splicing the 1G back in and using the good 1G MAS that came off the car. Still didn't help any. So I rewired the 2G back in. And since the wiring for the MAS also passes through the TPS and IAC before it gets to the ECU I changed them as well.

youve only made 10 posts in 2 years? wtf

Yeah, I joined back when I bought my 91 Tsi and only had time to make a couple posts before I had to move and was without internet then sold the car. But now since the 91 I've been through a 90 Tsi FWD, a 94 Tsi FWD then another 94 Tsi FWD and have now gotten to my 92 GSX with the 90's engine thats giving me these headaches now. Yeah, I'm a DSM fan . But now I'm in a new city (Orlando, moved here yesterday), I'm online again, and looking to be a post whore. j/k. Thats why I asked at the bottom of my first post about the going back to a newbie thing. I registered 2 years ago, made a couple posts, then was idle till now and now I can only post in the Newbie forum. wtf

 

[dedlewamp]

You know that using a 2G MAF in a 1G will make the car run very lean. You are going to need some bigger injectors, or a AFC at the least to get it to work properly.

 

[Lordpaxin]

You know that using a 2G MAF in a 1G will make the car run very lean. You are going to need some bigger injectors, or a AFC at the least to get it to work properly.

If this is the case then it would be fixed when he put in his old 1g maf.

did you check for leaks.

 

[Big Willy]

You know that using a 2G MAF in a 1G will make the car run very lean. You are going to need some bigger injectors, or a AFC at the least to get it to work properly.

Nope didn't know that. Hmm, learn something new everyday I guess. . But that won't cause the problems I'm having will it? This is the first of my cars I've had a 2G MAS on but I have friends on stock injectors with no controllers with 2G MAS's with no problems. The car does have an AFPR but still on stock injectors. I have a SAFC II sitting in my closet and plan on putting a set of 550s or 660s in it after a while but I want to try and get it tuned right as close to stock as possible for now untill my clutch is broke in and I know the car will do ok in city traffic (yeah, I'm a country boy).

Lordpaxin - I haven't done a pressure check yet. The car is still up in Palatka (2 hours away). I'm going back up there to work on it a little 2moro and I'll check it then.

 

[fp-green-95tsi]

Any luck? As stated above you will need some type of fuel control to run the 2g mas on your car or some 550's to get you close. Install the safcII and get a logger to monitor and adjust your fuel trims and youll be good to go with the 2g mass and stock injectors.

 

[Big Willy]

Ok, I've been playing with the car for a couple days now. After I learned from Dedlewamp that the 2G makes the car run lean I decided just to splice the 1G MAS back in and try to get the car running off of it. After playing with the car a little it does run somewhat better (barely, but noticable). I tryed a boost leak test and found a pretty big leak coming from my EGR block off plate so I fixed that. After that, I found one coming from the intake manifold gasket and sounds like another coming from the TB shaft seal. So I just decided to pull the intake off of it, pull the TB off the intake and just clean everything thorouly and replace all gaskets just so I have peace of mind on that. My TB gaskets will be in 2moro so I'll see how all this worked. Even if it doesn't completely fix the problem, it sure can't do anything but help.

Also, whats the best way to clean the inside of the intake manifold? Mine definatly has 16 years worth of crap in it. . I tryed degreaser and carb cleaner which helped a little but it's really hard to get all the way into the back of the intake. Any suggestions?

 

[Mike Marnik]

sea foam in a spray can for just the intake mani or go with the bottle and suck it in while its running.

 

[Big Willy]

sea foam in a spray can for just the intake mani or go with the bottle and suck it in while its running.

Thanks


Another question. Will a 2G knock sensor work with the 1G? I've searched and keep getting mixed results. Some say no to only use 1G with 1G because it throws CEL codes if using a 2G sensor on a 1G, But I don't care if all it does is throw a CEL as long as it functions the same. Others on here say they run the 2G sensor with no problems. *shrug* So what's the final decision?

 

[Big Willy]

Ok, this is really pissing me off. Still haven't got it fixed yet. I've been through everything I can possibly think of. So far I've:

Changed:
MAS (2 2G's and a 1G)
CAS (92 metal cover and a 90)
Coil
Ignitor
TPS
IAC
Plugs
Wires
ECU (92 w/normal and switched pinning & 90 w/normal and switched pinning)
All were known good parts and even double checked all the parts I could with an Ohm meter according to specs in my Chiltons

Checked:
Timing (all marks line up perfectly)
Boost Leaks (fixed all but a small one at the #1 injector o-ring and a small one at the TB shaft seal, and I'm waiting on the parts for them now)
Fuel Pressure
Compression (kinda low but within spec)

Car still won't idle right, pops & backfires. With a timing light, the mark on the crank pulley jumps all over the place. So I know it's some sort of timing problem but I've just completely run out of ideas. I don't know what else to check and/or change.