Car lost 50% of power after sitting still.

[Mr. Antonov]

Hey guys, I have a '91 BMW 318i, I drove it to school fine but after class I got out and the car had lost about 50% of it's power, a lot of it near the higher RPMs.. I'm pretty stumped as to what it is, I checked the coils for spark and they are all firing fine, I believe the sparkplugs are good also.. I don't think it's my engine because I can drive it and the engine check light isn't on..

I asked the Auto Tech teacher at school and he said it might be Vaccume hoses..

Has anyone else had problems like this? Just need some advice.. Thanks in advance.

[Sammich]

shoulda got a honda lol.

just a question. have u done any maintenance to it since u got it a little while back? tune up, oil change, etc?

btw i believe if it was vaccuum hoses it'd have a idle problem also

[G.C]

Its probably in limp mode

[Mr. Antonov]

It idles fine

I had some mechanic look at it but I don't think he did a good job

I did get an oil change when I bought the car..

EDIT: So I looked up Limp mode and it seems to fit what my problem is.. So I guess all I can do at this point is take it to a shop?

[Sammich]

I IMAGINE SO. I'VE HEARD OF LIMP MODE, BUT I DONT KNOW WHAT IT IS EXACTLY..I THINK W/ THE MAX, I THINK IT WAS RELATED TO MY MAF. I WAS THINKING FUEL FILTER MYSELF

[G.C]

Limp mode is basically "safe mode". It will run, but have no power and its locked in 3rd gear i think.(If you have automatic)

A lot of things can trigger limp mode so you won't destroy your engine, but most of the time you will get EML light or CEL.

[Mr. Antonov]

Limp mode is basically "safe mode". It will run, but have no power and its locked in 3rd gear i think.(If you have automatic)

A lot of things can trigger limp mode so you won't destroy your engine, but most of the time you will get EML light or CEL.

Well I have a manual and it shifts fine into all the gears.. I'm pretty sure my CEL isn't on but I'll double check it once I get out of school today..

If it isn't on though, could it still be in "safe mode"? It really does sound like that's the problem.. It's probably a sensor or somethings fucked up with my ECU.

[j0nbunklah0m]

could be timing ?

[Mr. Antonov]

It could be that, but like I said it changed while the car was sitting still, so I think it's just a bug in the ECU or something..

Hopefully I can use the Auto Techs car scanner thing and see if it's throwing any codes.

[Mr. Antonov]

So I took it to a shop and they said the Catalytic Converter was blown, so we took the exhaust off and hollowed out the CC.

Everything is good now except I won't pass emissions anymore and it's substantially louder. And I lost some low end torque because I lost back pressure by having it the CC open.

[G.C]

So the problem was a plugged cat?? Good to hear it wasn't anything major.

[Kaiser]

So I took it to a shop and they said the Catalytic Converter was blown, so we took the exhaust off and hollowed out the CC.

Everything is good now except I won't pass emissions anymore and it's substantially louder. And I lost some low end torque because I lost back pressure by having it the CC open.

It's debatable that you lost backpressure when you hollowed out the CC. The vortexes in that empty space with all those jagged edges inside and the rapid shape and size change back and forth probably causes more backpressure than the original cat did. Either weld a pipe through it to make a catafooler or just weld up a test pipe.

[Mr. Antonov]

It's debatable that you lost backpressure when you hollowed out the CC. The vortexes in that empty space with all those jagged edges inside and the rapid shape and size change back and forth probably causes more backpressure than the original cat did. Either weld a pipe through it to make a catafooler or just weld up a test pipe.

Haha If I had a job I'd totally do something about it but right now I'm broke and just thankful they fixed it for free.

[Kaiser]

Ah, can't bitch much about free then, was just commenting on the lost torque. When you get a chance, the pipe welded into the muffler will make a difference.

[G.C]

Haha If I had a job I'd totally do something about it but right now I'm broke and just thankful they fixed it for free.

Or he can just get a magnaflow for cheap on ebay. Either way i bet the difference in TQ is minimal.