Think I fried my ECU after exhaust welding.... runs bad!

[gnx7]

I forgot to unplug my battery and ECU before doing a small tack weld for mock up of the exhaust system I'm making on my car. Well after tacking some pieces together for test fit I realized my mistake.

Took the exhaust system off and welded it fully on the ground and then reinstalled.

Started the car and now it runs like crap. Sounds like only 4 cylinders firing now. Takes a long time to get started and backfired too which is not normal.

Could I have maybe fried my coilpack?

Is my chip fried as well?

Going to change out my ECU today and see if this fixes it. I'm pretty sure this sucker is wasted.

Not happy,

GNX7

3" downpipe done.... 3.5" single mandrel bent exhaust nearly complete. This is going to flow a ton!

 

[gnx7]

swapped ECU and still runs poorly.

Pulled #5 and #6 plug wires and no spark at all from them. Maybe the coilpack went out thru coincidence or the amperage fom my mini MIG did a number on it.

Changing out coilpack now.

Hope to report back with good news in about 1 hour.

GNX7

 

[gofstbuick]

You know there are flow chart procedures to test things on your GNX before going out and just parts changing. I do have a set of factory manuals and access to a library full of Mitchell, Motors and Chilton professional manuals. If you need assistance, just email.

 

[elevensecgn]

FWIW, I recommend to unplug the ECM, ign module, and alt, along with disconnecting BOTH terminals of the battery anytime welding is done on a car. This may sound overkill, ald Lot's of times you can get by with not doing it. Probably most of the time, as muffler shops do it all the time.

BUT--- ocassionally there will be a stray electric gremlin that will fry something. Many years ago I was welding a trailer hitch on the back of an old truck. No electronics at all on it. Somehow a stray jolt went thru the frame and hit the battery (under hood on opposite end of truck) a blew the complete top off of it. That taught me a lesson that will stayed with me forever.

I know that if the ground of the welder is close to where you are welding this isnt suppose to happen, but Murphy's law sometimes kicks in and $hit happens.

My guess at this point is your ign module got toasted.

Good luck
Dwight Hayden

 

[gnx7]

Well I Ohmed the coil pack and #3/#6 were dead. Figures why I wasn't getting any spark from them either.

So I swapped a working coil pack in and gave it a whirrrr...

Still nothing. But it did backfire so loud that my ears rang from inside the car (open downpipe).

Well I figured the plugs may be wet from soo much fuel and no spark.... so I pulled them all.

Well the #3 plug had the electrode fried off! Only about 1/8" left of it!

Swapped in a new CR43TS plug in #3 and brake cleaner on the rest of them and VOILA!

It is alive again !

I was getting a little worried there for a while.

Thanks for everyone's input. I feel lucky because my ECU didn't fry.... and it was a cheap mistake that will never be made again.

GNX7

 

[AsphaltAnihil8r]

Originally posted by gnx7
Well I Ohmed the coil pack and #3/#6 were dead. Figures why I wasn't getting any spark from them either.

So I swapped a working coil pack in and gave it a whirrrr...

Still nothing. But it did backfire so loud that my ears rang from inside the car (open downpipe).

Well I figured the plugs may be wet from soo much fuel and no spark.... so I pulled them all.

Well the #3 plug had the electrode fried off! Only about 1/8" left of it!

Swapped in a new CR43TS plug in #3 and brake cleaner on the rest of them and VOILA!

It is alive again !

I was getting a little worried there for a while.

Thanks for everyone's input. I feel lucky because my ECU didn't fry.... and it was a cheap mistake that will never be made again.

GNX7

Darn, and I thought you were going to hae to sell the single shot since the car is broke
Did you do the bends in the pipe ,if so do you hae planes of selling these on the side for $$$
Thanks

 

[TurboJim]

Umm...dare I admit, I never disconnect the battery when I weld? Not a problem in almost 20 years

 

[elevensecgn]

Niether did I till the top blew off that truck battery many years ago

Like I said, it's not normally a problem, but once in a great while, bad stuff happens.

Then too you may have been born under the right moon

I'm not lucky enough to try it again




Dwight Hayden

 

[gnx7]

Dennis-

In reference to the Single shot... I wish there was an off the shelf one.

I spend over 12 hours making the downpipe (from a TH TTA 3" elbow), my 3" cat (that feels really light ), and then over the trans crossmember where I ran out of steam. It is still not done. Homebuilt mandrel bent exhaust takes a damn long time to do!

I'm having a shop fab the 3.5" remainder since the "cat" is now on the car.

GNX7

 

[gnx7]

just to add..... I fried my alternator as well.

So that is 1 coil pack, 1 spark plug, 1 alternator.

Unplug ECU and battery when welding. Hell... unplug the damn alternator as well.

GNX7 mad.... but really laughing at my own stupidity