Broken Turbo Bolt

[bewstin]

Hey guys, first post on this forum. I know I'm new to the forums, but I've been in the DSM game for about 5 years, and I hope to help out when I can. Anyways to the good stuff! I've put about 1400 miles on my car since I rebuilt the motor, driving like a grandma of course. Runs good except for two things. First thing, when the car has sat overnight and the engine is 100% cold, for the first 20-30 seconds after starting it, it will idle fine at 1500 rpms, but it sounds rough like a misfire. If I give it a couple 2-2500 revs it will smooth out for the most part. No excessive smoke from the exhaust either. Once the car has been running for about 1 min its fine, drives fine and isn't sluggish, feels normal.
Second thing; car idles at 14.7 AFR, cruises around the same. But as SOON as my boost gauge reads any boost, no matter how much I'm on the throttle, the gauge spikes 10.0 and stays. I haven't been beating on the car because my tune isn't for another two weeks when my ECMlink comes in, but i did go WOT at 10psi twice to investigate. When I did, the wideband read 10.0 the entire time all the way to 5500, and I could feel it was a little hesitant from being too rich, and could smell it too. So all in all, whether I'm at 1psi at 20% throttle, or 10psi at WOT, the car spikes rich rich rich. I am missing one turbo to manifold bolt, so i have 3 instead of 4. Could this cause such a problem?? Turbo seems to boost fine, nice and quick. Ill be replacing the bolt next weekend, but just sort of curious until then, just wondering. Thanks! (sorry for the novel but i figure its best if you all can get the whole scoop!)

 

[bcracecar]

Hey guys, first post on this forum. I know I'm new to the forums, but I've been in the DSM game for about 5 years, and I hope to help out when I can. Anyways to the good stuff! I've put about 1400 miles on my car since I rebuilt the motor, driving like a grandma of course. Runs good except for two things. First thing, when the car has sat overnight and the engine is 100% cold, for the first 20-30 seconds after starting it, it will idle fine at 1500 rpms, but it sounds rough like a misfire. If I give it a couple 2-2500 revs it will smooth out for the most part. No excessive smoke from the exhaust either. Once the car has been running for about 1 min its fine, drives fine and isn't sluggish, feels normal.
Second thing; car idles at 14.7 AFR, cruises around the same. But as SOON as my boost gauge reads any boost, no matter how much I'm on the throttle, the gauge spikes 10.0 and stays. I haven't been beating on the car because my tune isn't for another two weeks when my ECMlink comes in, but i did go WOT at 10psi twice to investigate. When I did, the wideband read 10.0 the entire time all the way to 5500, and I could feel it was a little hesitant from being too rich, and could smell it too. So all in all, whether I'm at 1psi at 20% throttle, or 10psi at WOT, the car spikes rich rich rich. I am missing one turbo to manifold bolt, so i have 3 instead of 4. Could this cause such a problem?? Turbo seems to boost fine, nice and quick. Ill be replacing the bolt next weekend, but just sort of curious until then, just wondering. Thanks! (sorry for the novel but i figure its best if you all can get the whole scoop!)

Go ahead and replace the bolt, but if it seems to be sealed okay I don't think its the problem. You just said it yourself that it needs a tune. Bingo. Tune the car then see how she does.

 

[Mecheng1993]

A boost leak would cause the 10.0 afr. For example, I boost leak tested my car to 15psi (throttle body is leaking) and anything after that my car runs stupid rich. You likely have a rather big boost leak. It's still easy for the stock 14b to feel like the spool is normal even with a leak.

 

[bcracecar]

A boost leak would cause the 10.0 afr. For example, I boost leak tested my car to 15psi (throttle body is leaking) and anything after that my car runs stupid rich. You likely have a rather big boost leak. It's still easy for the stock 14b to feel like the spool is normal even with a leak.

he is running a 20g

 

[bewstin]

Yea i did a boost leak test and didn't find anything. The only place it leaks from is the valve cover breather. I know you will pressurize the crankcase a little bit in a BLT, but from what i could tell there's no other leaks. And yes I'm on a 20g turbo. But i left the stock fuel setup in until i planned on getting tuned, which is why im super surprised it runs so rich. Also last night i went for a drive and noticed something. I was in 3rd gear at about 2k rpm, put the pedal to the floor and watched my gauges. Boost gauge got up to around 6 psi and stayed there, then once it got up to around 5k rpm it shot up to 11psi and held there. Seems like the broken bolt could be the culprit, and the turbo isn't spooling as well as it should. I would think the turbo should spool up to 11psi, not stop halfway until the RPMS get really high. Ill take a video today and link to youtube.

 

[bewstin]

Alrighty so, it turns out my manifold was leaking really bad because of that bolt being missing. I ordered an FP manifold tonight, but earlier today i just put a smaller size bolt through the hole where i was missing a bolt, and put a nut on the bottom and snugged it up. The stock size bolt is a M10, so i just put an M8 through there. The hole is stripped out BAD so i didnt want to mess with it. After i tightened up that bolt and nut, the other 3 bolts were loose, so i know for sure my turbo was not tight against the manifold, should hold till i get my new manifold on and helicoil the threads in the turbo. Thanks for all the help!