Welded in Cage and now M3 runs rough!!

[slitz]

Looking for some tips / hints before I start trouble shooting and buying parts.


I just built the car and have low miles on it (~50 miles) so it could be anything really at this point.


Symptoms:

-I started the car and it started to smoke, I thought it was white but its actually a bit darker and smells like unburnt fuel (phwewww :stickoutt). The car has bad idle naturally becuase of a vacuum leak, but now stutters and hesitates when giving it any throttle. There are moments where it runs fine (I can nail it and it comes back to life).






Possible Cuases:

-Car ran great before I parked it. I had my roll bar welded in and now it runs like balls. They disconnected the battery but I am wondering if it could have arked through the frame somehow and shorted the DME??? It was MIG welding if the frequency makes any difference.

-Its possible that the DME reset and is having trouble recalculating the car. I never had this issue before but who knows...

-MAF or Coils coincidentally went bad. All of the parts were man handled into the car recently so it is possible that something was knocked around.






Any ideas??!? My thought process right now is to buy a used DME, new coil packs, plugs, and check the cat. I hate buying stuff to trouble shoot but I need it to drive July 16th and dont want to mess around right now.

:shifty

[strad]

I'd plug into it with a proper diagnostic computer before starting to buy parts.

I know there's something you have to do regarding the computer before welding -- like grounding the chassis or disconnecting the battery or something like that. I can't remember specifically.

[coconutmnky]

If the chassis wasn't grounded then all the electronics might be screwed up, it's not just disconnect the battery.

Did you cut any wires? Check for codes. Make sure nothing is disconnected.

This is assuming electrical issues, haven't listed any mechanical or air/fuel delivery issues.

[flyfishvt]

Check the simple stuff first (how many times have I said that this week?) Plugs, vacuum leaks, Unplug the MAF while its idling rough and see if the idle improves. If it improves then clean the MAF and try again. If cleaning it doesn't fix it then replace the MAF. since it OBDII you should check the pre cat O2 sensors and make sure the plugs aren't swapped to the wrong sensors.

Check the oil separator to see if it needs to be cleaned.

And YES hook it up to a diagnostic scanner. Take advantage of the fact its OBDII. You didn't mention any Check Engine Light but a scanner might be able to pick up a misfire.

[SethuM]

lol look at his sig, its OBD1 guys

[ckpitt55]

did they disconnect the alternator and computer before welding?

[slitz]

Check the simple stuff first (how many times have I said that this week?) Plugs, vacuum leaks, Unplug the MAF while its idling rough and see if the idle improves. If it improves then clean the MAF and try again. If cleaning it doesn't fix it then replace the MAF. since it OBDII you should check the pre cat O2 sensors and make sure the plugs aren't swapped to the wrong sensors.

Check the oil separator to see if it needs to be cleaned.

And YES hook it up to a diagnostic scanner. Take advantage of the fact its OBDII. You didn't mention any Check Engine Light but a scanner might be able to pick up a misfire.



thanks man, I forgot to mention but I pulled the plugs and reset the DME but nothing fixed it. I also unplugged the MAF but it didnt change the symptoms at all.

Its an OBD1 S52 so I dont run the precat 02's and I do have a CEL but it is 1281 which i have had since day one. It is intermittent and doesnt seem to have any affect on the performance.




did they disconnect the alternator and computer before welding?


not sure but most likely not... I am asking the guys now

[mclovin02]

Can you switch your Dme with a friends Dme?

[slitz]

just ordered a red label DME for 80 shipped

30 day warranty came with it... I hate spending money but I can always sell it or keep it as a spare

[E36B1MM3R]

That sucks....id definantly check dme first since only $80...let us know if that fixes it...if not could be something simple like wire or hose disconnected.

[Moron95M3]

1281 is DME memory/voltage right? Usually you only should get it when you just disconnected/hooked up the battery. Maybe the DME has been an issue and maybe it got just enough current somehow from the welder and that did it.


Or...this is dumb...but fix your vacuum issues! Then go from there. That stuff is cheap, and you will want that done anyways. Do it right, and fix that too.


Hope the DME clears it up though.


PS your car looks hot, going to read through your build thread :P

*edit, love the build thread*

[slitz]

1281 is DME memory/voltage right? Usually you only should get it when you just disconnected/hooked up the battery. Maybe the DME has been an issue and maybe it got just enough current somehow from the welder and that did it.


Or...this is dumb...but fix your vacuum issues! Then go from there. That stuff is cheap, and you will want that done anyways. Do it right, and fix that too.


Hope the DME clears it up though.


PS your car looks hot, going to read through your build thread :P

*edit, love the build thread*

Yea 1281 is memory but I have had it intermittently since the swap. Ordered a DME so I'm hoping thats it!

I also want to fix the vac leak but can't find it. Damn notoriously horrible e36 idle... Cleaned ICV, checked all lines, etc.


Thanks for the compliments though!

-Rich

[dcskate102]

Congrats you fried your electrical system!

[slitz]

Congrats you fried your electrical system!

Hush! The only thing that could be affected is the DME, correct?


Do you think it could have altered or destroyed my tune too?

[Moron95M3]

put your original chip in? see if it's just that? I've read that they can die :/ although yours is new :shifty

[dcskate102]

Hush! The only thing that could be affected is the DME, correct?

Do you think it could have altered or destroyed my tune too?

Theoretically worst case scenario everything electrical is ruined. While that's not likely it'll be hard to tell via interwebs. That's your job.

[slitz]

Theoretically worst case scenario everything electrical is ruined. While that's not likely it'll be hard to tell via interwebs. That's your job.



I didnt think a MIG frequency was capable of that!?

If so, I am going to rape the harness and race wire the entire car.

[efiniGTX]

I just had an exhaust made and nothing happened. I know it's not the same as welding a cage to the chassis, but the exhaust is connected to the engine and grounded to the battery.

[slitz]

ok so I finally got home on time today and had some time to check the car.



I swapped DME's to a working 413 red and ----nothing changed---


Checked plugs - they had a good bit of carbon them but no oil or coolant. Cleaned the plugs aaaannnd ---nothing changed---

Replaced coil packs with a working bremi set ---nothing changed---

Pulled filter and it was dry, no residue.

MAF looked good visibly but no way to really test it and dont want to buy another 540 to check.


Throttle body had oil/gas residue on the intake side of the butterfly (oil separator?)

Checked all vac lines including the FPR, gas lines, and all electrical connections.






Would the oil separator go bad almost immediately? The car ran fine, shut off for a few days and now sucks. It does smoke but wouldnt think of this as a quick thing.


Ideas?!?! I hate throwing parts at the car trying to trouble shoot.

just ordered FPR, fuel filter, 88* thermostat




I also know I have a leaking VCG so I am going to go ahead and replace that. The only piece that I think may have any affect is the FPR.



Does anyone know offhand the ID of the FPR vac line? I am going to replace all vac lines while I have the manifold off.... AGAIN!

[flyfishvt]

Actually you can test the MAF. Just unplug it and see if the car runs better. If it does then clean the MAF and try again. If it doesn't improve then try cleaning it again. If cleaning it a second time doesn't improve things when its plugged back in then the MAF is most likely bad.

You mentioned the oil separator. You have an OBDI car so I don't believe you have an oil separator.

You should also check the hose that connects from the ICV to the underside of the intake manifold. its very easy for that hose to get loose from the manifold. If it does then it will cause a huge vacuum leak and the engine will run like crap.

The last of the things you can do that don't cost anything is a compression test. You could have something as simple as a piece of carbon built up on one of the valves.

[slitz]

I am doing a compression test tonight so I may find something new.

I actually did the MAF unplug test first but no result. I also am running an OBD1 S52 but still doubt the separator could go bad so quickly.



looks like I may not be able to hit the track this weekend :(

[flyfishvt]

OBDI S52? Its one or the other not both as far as I know. If its OBDI then its an S50 with no oil separator. If its an S52 then its OBDII and it has an oil separator and that little beast can definately cause issues if its dirty. If you do some research you'll find it can cause blue smoke and poor performance.

[slitz]

I actually should have mentioned this in the original post.


The car is a 95 M3 (OBD1) with an S52. I already did the gas pedal cel check but nothing is showing up, other than my never ending 1281.

[LockDots]

OBDI S52? Its one or the other not both as far as I know. If its OBDI then its an S50 with no oil separator. If its an S52 then its OBDII and it has an oil separator and that little beast can definately cause issues if its dirty. If you do some research you'll find it can cause blue smoke and poor performance.

You can downgrade from OBDII to OBDI

[slitz]

You can downgrade from OBDII to OBDI



Haha theoretically its an upgrade!

[Toby B]

err... just to pee in everyone's cereal, MIG's a DC weld process...

I guess if it was my car, I'd check carefully at every cage attachment point
first. On both sides of the panel- especially if there are knee attachment points
to the firewall.

Yeah, it's THEORETICALLY possible to fry electronics with a welder if you're dumb about it
and let ground currents return to the ground clamp via the body. But it's pretty
hard to do that if you're paying attention, grounding to the cage, etc etc etc... as in,
you know what you're doing....

t

[LockDots]

Haha theoretically its an upgrade!

of course:stickoutt

[slitz]

looks like it was a vac leak... just hunting it down now but I am never home anymore!



Caught a 1215 code the other night too so I am going to reclean the MAF to see if that was it.