Another P1688 (look anyways)
 

So here's the deal, I just got this car, 03 MCS, and while I was test driving it the check engine light came on and lost all power. The dealership I got it from said they would fix it. So I take the car, happens a couple more times and the dealer is like"oh I know exactly what it is, it's the map sensor". So he replaced it, and it seems to be fixed, for about a day. Bad happens again, call him and he says it's the BPV, that he is gonna order it. I told him from my research it is probably the crank pulley, but he doesn't listen to me. My question is, what are the chances that it is the BPV? I got my scan tool out and was able to view some data, both from the freezer frame when the code was thrown and I recorded some data and made it do it again. It shows I was making around 16psi of boost at around 4300rpm, then at about 5500rpm, bam, 2psi, check engine light and no power. From everything I have read it sounds like the crank pulley. But he sure thinks it's the BPV. Also, if it is the crank pulley, has anyone used the Detroit Tuned Craven 2% pulley? I have all the info written down from my scan tool if anyone is interested in viewing it.
Thanks
Dustin

Sounds more like belt slipping to me. I'd think a failed crank pulley would make some noise and slip constantly...

Also, do you have a reduced s/c pulley? 16psi @ 4300rpm sounds like a lot for a stock pulley.

As far as I know it is all stock. It does make a ratling noise, sounds like it is coming from belt area, that changes with rpm. Also, I looked at it last night, and it looks like the crank pulley is willingwa little at idle.

My scan tool was showing 114kPa from the map sensor, I guess that might also be accounting for ambient pressure too? Does that sound right? I don't have a boost guage, just going off what the scan tool shows me.

The P1688 comes back to BPV or Crank Pulley most of the time. If you zip tie the BPV shut and drive the car hard and nothing happens, it the BPV but if the car goes into limp mode again, it's the crank pulley. You should be able to repeat the limp mode on demand by this point now. As the summer heat kicks in we are seeing more Crank pulley failures. And i would assume you know that we use all the parts you asked about all the time with no problems.


Option A: http://www.detroittuned.com/ati-super-damper/

Option B: http://www.detroittuned.com/detroit-...-crank-pulley/


Option C: http://www.detroittuned.com/detroit-tuned-bypass-valve/


Let us know how we can help.


Chad
Detroit Tuned.

Awesome! Thanks for the info Chad. Does it cause any added stress on the engine using the Craven pulley?

This for sure sounds like a crank pulley as it is by far the most common cause of the 1688 code.
I would only recommend the ATI damper as it is a true damper and even dampens better than the stock one so we often find the cars running smoother with them.
https://www.waymotorworks.com/super-...ulley-r53.html

I don't recommend lightweight pulleys like the Craven as that is hard on the bearings and oil pumps along with other issues they will cause.

As for it being a bypass valve. I wouldn't bet on that. Been working on MINIs for 16yrs now and the number of actually failed bypass valves I have replaced out of the thousands of MINIs I've worked on is 4. YES ONLY 4. I've sold many of them but I think often people wrongly buy them because of the internet.

Also double check that there is no other reason for the belt to slip as that could be a cause.

So what should I be getting as a map reading? My scan tool only does kPa and "hg.

Well the dealership replaced the BPV because that's what they thought it was. Actually seems to have fixed the issue, but we noticed my tires were well beyond being safe, so I'm picking the car up later today from the tire shop and will be able to really test it to see if the issue is fixed. This car feels like a whole new animal.