2008 135i down on power--please help me figure out why

[lakylester]

Originally Posted by Davyhay

If it's the turbos, they would be covered under my powertrain warranty. The only thing about that is that I can't get it fixed until 90 days has elapsed since I bought the car. However, I am thinking that if it was the turbos, the car would not even run low 14's.

This is not true in most cases. In my instance, as well as others witnessed, the power lost grew at a slow rate exponentially. I was done probably 40hp then I should be.. I was ran a 12.6 with defective turbos.

The only way to tell is listening for it. If you don't hear a slight metal tapping at start up, your turbos are probably fine. I could not tell as it was so silent I thought it was a tiny leak or perhaps rubbing on a heat shield.

[Davyhay]

Before I leave for work this morning, I will raise the hood and listen for foreign sounds at startup. I have not noticed anything thus far.

[Davyhay]

Okay, is the sound rhythmic or sporadic?there is a rhythmic tapping at startup that sounds like valves and goes away after about 30 seconds.

[BeamerandBimmer]

You say that the car is down on power, but only provide a 1/4 mile ET as evidence. You say the car feels strong. I would guess that cleaning the intakes would help regardless, but we don't really know if or how much the car is down on power. What were the other specs from your trip to the track? 60Ft.? Trap speed? Also keep in mind that all the things you mentioned plus other factors at the track can influence your results. It could also be transmission related. Do you have access to a dyno?

My first trip to the track(JB4 map5, race gas, and stock run flats) I ran a best of 13.2 with 2.1 60Ft.(launching in 1st Automatic transmission). My second trip(JB4 map5, race gas and new Conti DWs) I ran a 12.09 with 1.77 60Ft. Launching in 2nd. After that I upgraded my FMIC and went with BMS downpipes and on the subsequent test drive trashed my transmission. Turns out the transmission had a lot of wear and tear on it. I bought the car with 43,000 miles on it. My rebuild of the AT with parts from Level10 is almost done and I hope to get back to the track the weekend after next. I suspect that I'll be in the high 11s, but who knows it could be much lower than that If my transmission was slipping on the previous runs. The best way to gauge the strength of the motor is to put it on a dyno.

[Davyhay]

Originally Posted by BeamerandBimmer

You say that the car is down on power, but only provide a 1/4 mile ET as evidence. You say the car feels strong. I would guess that cleaning the intakes would help regardless, but we don't really know if or how much the car is down on power. What were the other specs from your trip to the track? 60Ft.? Trap speed? Also keep in mind that all the things you mentioned plus other factors at the track can influence your results. It could also be transmission related. Do you have access to a dyno?

My first trip to the track(JB4 map5, race gas, and stock run flats) I ran a best of 13.2 with 2.1 60Ft.(launching in 1st Automatic transmission). My second trip(JB4 map5, race gas and new Conti DWs) I ran a 12.09 with 1.77 60Ft. Launching in 2nd. After that I upgraded my FMIC and went with BMS downpipes and on the subsequent test drive trashed my transmission. Turns out the transmission had a lot of wear and tear on it. I bought the car with 43,000 miles on it. My rebuild of the AT with parts from Level10 is almost done and I hope to get back to the track the weekend after next. I suspect that I'll be in the high 11s, but who knows it could be much lower than that If my transmission was slipping on the previous runs. The best way to gauge the strength of the motor is to put it on a dyno.

I'm sorry, I thought I included my trap speed. It was 98 with a 60' of 2.2. The car would have kicked butt as a bracket racer--all 5 runs were within 1/10th.

Yes, it feels strong--compared to the 200hp 4 cylinder I was driving, before. And dragracing is not something I am new to. I could regularly cut a 13.2 in my e46 M3 6MT bone stock.

I only provided my 1/4 mile time as evidence because that is all I have at the moment. But even with the heat-soak and gunked up valved, I figure I should have still broken into the 13's. I will be swapping plugs this afternoon, so I may hit the track again and make a couple runs with a cool car to get a better idea of where I stand.

Even if this makes all the difference in the world, this thread is still very beneficial because I want to learn all the weak areas of our cars.

[BeamerandBimmer]

Try launching in second gear. You should be able to get your 60Ft. times below 2 seconds and your trap speeds suggest that your car is losing something on the top end(heat soak/limited timing/detonation). My guess is that your entire intake system needs a good cleaning. When I upgraded my FMIC there was oil everywhere. It wasn't dripping but it certainly lubricated the internal passages. My first upgrade to my 135 was an oil catch can from BMS.

Good luck. I bet your motor/turbo is in decent shape for it's miles. Years ago I had a GMC Syclone(turbo v6,all wheel drive), I beat the snot out of that thing for 177,000 miles and the only things that broke on that was the tranny(4 times) and propshaft(3 times).

[Experimental]

Originally Posted by Davyhay

Okay, is the sound rhythmic or sporadic?there is a rhythmic tapping at startup that sounds like valves and goes away after about 30 seconds.

My guess...that tapping you hear at startup is the valves...as I've heard they are rather noisey on direct injection engines. By 30 seconds in, the oil has circulated to the top of the engine and quiets everything down. The build up on the valves probably makes it louder as well.

Might help to post a video with audio of what you are hearing...sometimes that helps diagnose what the sound is. (I need to do the same, as I have some noises I would like confirmed...)

[Davyhay]

Originally Posted by BeamerandBimmer

Try launching in second gear. You should be able to get your 60Ft. times below 2 seconds and your trap speeds suggest that your car is losing something on the top end(heat soak/limited timing/detonation). My guess is that your entire intake system needs a good cleaning. When I upgraded my FMIC there was oil everywhere. It wasn't dripping but it certainly lubricated the internal passages. My first upgrade to my 135 was an oil catch can from BMS.

Good luck. I bet your motor/turbo is in decent shape for it's miles. Years ago I had a GMC Syclone(turbo v6,all wheel drive), I beat the snot out of that thing for 177,000 miles and the only things that broke on that was the tranny(4 times) and propshaft(3 times).

Never thought about launching in second. Does that let you build up a higher RPM? It seems counter-intuitive that it would yield a lower 60'.

[Davyhay]

Swapped plugs this morning and I am happy to report that the old plugs with 50K on them looked really good. No sign of carbon buildup or lean running.

[Davyhay]

So much for having the $500 for walnut blasting. Water pump took a dump on me today. Even with the "deal" BMW gave me on replacing it, I'm still out $1200.

[BeamerandBimmer]

Originally Posted by Davyhay

Never thought about launching in second. Does that let you build up a higher RPM? It seems counter-intuitive that it would yield a lower 60'.

It's all about getting traction. There is to much TQ to be able to launch in first with minimal wheel spin.

Sorry to hear about the water pump. I'm currently at $4k in parts alone for my transmission rebuild. I could have removed a couple of mods and gone for a warranty replacement but I wanted to not have to do it again.

[BeamerandBimmer]

Anyone in your area that could help you with a DIY? Post in the regional section and ask. One of the motorcycle forums I go to is big on hosting "tech days" maybe we could do something like that here.

[Davyhay]

Originally Posted by BeamerandBimmer

It's all about getting traction. There is to much TQ to be able to launch in first with minimal wheel spin.

Sorry to hear about the water pump. I'm currently at $4k in parts alone for my transmission rebuild. I could have removed a couple of mods and gone for a warranty replacement but I wanted to not have to do it again.

Okay, so now I know something is wrong. The car does not spin in first--at all.

[Davyhay]

Originally Posted by BeamerandBimmer

Anyone in your area that could help you with a DIY? Post in the regional section and ask. One of the motorcycle forums I go to is big on hosting "tech days" maybe we could do something like that here.

I am a very capable DIYer and I will certainly look into the regional forum. However, I needed to have the car fixed then and could not wait to order the water pump and thermostat--$550 from Turner--and get it installed. I got the car to BMW at 3pm and they had it back to me at 6pm.

[Davyhay]

After another night at the track with a couple adjustments and I did the following:
Best 60' 2.1
Best 1/4 mile 13.95
Best MPH 102.3

Oddly enough, by quickest ET was with a 98mph trap.

[hbiscuit]

Pull and clean your vanos solenoids

[Davyhay]

Originally Posted by alpnwhite96

Pull and clean your vanos solenoids

I researched this and it seems pretty straight forward. The car does not exhibit any of the symptoms, but this seems like good easy preventive maintenance.

Since the car ran a 13.9 1/4, I am now satisfied that it is only an issue with carbon buildup. I will stop whining now and report back on power after this is completed.

[hbiscuit]

Originally Posted by Davyhay

I researched this and it seems pretty straight forward. The car does not exhibit any of the symptoms, but this seems like good easy preventive maintenance.

Since the car ran a 13.9 1/4, I am now satisfied that it is only an issue with carbon buildup. I will stop whining now and report back on power after this is completed.

I am glad there are other high mileage owners out there now.

Original owner, 87k miles... Still in love, but some work will be involved to get her back into tiptop shape.

My solenoids may need to be replaced... wish I had a scan tool right now!

[Davyhay]

Is there a good DIY on cleaning?

[hbiscuit]

Originally Posted by Davyhay

Is there a good DIY on cleaning?

There are plenty (in a rush right now or I'd link them directly).

just google "VANOS Solenoid cleaning" or "N54 vanos solenoid cleaning" and you'll get plenty of results

Pulling them out takes literally 5minutes - although if you have big hands, it might be a PITA.