Recently threw the infamous p1688 code on my 02 r53. High load situation about 15.5-16psi and bam a fast burning plastic/rubber smell followed by limp mode and 2 codes.

Did a quick search found a tsb fpr bypass valve, knew I was do for one so I went ahead and plunged also went ahead and jumped on a new crank pulley which I haven't installed yet.

My question is, with the tension off the belt, trying to wiggle the crank pulley there is some wiggle to it but nothing drastic. I only smelled that burning smell once when it first happened and never again, the car idles fine and drives fine in light load and vacuum. Trying to build boost it hits about 4-6psi then starts falling off around 4-4500k rpm.


If it were a bad pulley would I not constantly smell the burning rubber or see a wobbly pulley while its running? Would it not build boost at all then or just minimal? Why would it fall off?

Stumped that I dont have the same symptoms really of a bad pulley?

Any help guys?

 

Crank pulley deterioration is gradual. If you have a new 1, why wait? Was lucky I was able to baby it home w/o overheating when mine failed. It did not pop that code, just had the burnt rubber smell that 1 time & pulley seemed to spin fine w/ belt. Alternator, A/C, PS didn't work. Had I been farther from home, it would've been towed. Upon removal, it split in 2. I opted for ATI.

 

Ive had no overheating issues or any belt related problems other then low boost pressure. Just waiting on the crank pulley to arrive by mail. The car is surprisingly driveable to apparently have a bad balancer is all I am noting, and I wanted to see other ppls symptoms

 

I just had the same problem. I thought it was my BPV as well, but after replacing it with a DT BPV, I still had no boost.

My serpentine belt tensioner was making a hellacious noise, so I'm thinking that was probably it. It's just not providing enough tension on the belt, so it's slipping.

Here's the thread I made during my diagnosis:

https://www.northamericanmotoring.co...e-or-belt.html

 

I appreciate the further info but I have no out of ordinary sounds or events with anything in the belt assembly. I have smoked tested and boost leak tested the car with no leaks found. I am waiting on the crank pulley to arrive so I can eliminate that, but at this moment I have no basket to put my eggs in.

I have put the new bpv on amd cannot get the 1688 code to recreate

 

New bpv, new crank pulley, boost leak tested and smoke tested no leaks found yet still getting a p1688. Car builds about 6psi max and then starts to fall back off, sluggish to rev out, has no acceleration, wont even make it to redline car struggles to climb the range.

Anybody experienced anything similar?

 

I had the same problems today while speeding off to work, got up to about 85mph then nothing, had to limp to the side of the freeway shut it down, and started back up with the same symptoms. I had no tools other then my PLX OBDII and Iphone with Dashcommand. Pulled the codes and got P1688, P0107, P1106. Couldnt figure out exactly what to look for so checked here on NAM and saw people with either MAP or TMAP problems. Popped the hood, looked down beneath the rubber seal infront of the inlet manifold, and saw the TMAP hanging loose from the housing. Popped it back in, started it up, cleared the codes and seemed to run fine. I cycled the ignition 5x to clear the engine lights and it hasnt come back. Thanks for the great repository of infomration here.