Overboost event - how to know if something has gone wrong? - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 04-11-2007, 11:38 PM   #1
Junior Member
Thread Starter
 
Join Date: Sep 2006
Posts: 225
Total Cats: -4
Default Overboost event - how to know if something has gone wrong?

I've been diagnosing why I am only getting 3-4 PSI at present, and I determined it to be the wastegate actuator... done by removing the actuator line from the system and seeing what happened...

Well - it's definitely the actuator - I tested it lateish last night after dinner, and I was taken completely by surprise at how quick it spooled up - it was near immediate - I was watching the AFM/boost gauge closely but as it shot up so quick (can't recall the peak) she hit the lean mark for a fraction of a second, and as I lifted off immediately the boost both popped off a silicone hose joiner (I presume in addition to/alternative to opening the BOV), which obviously made it run like a pig - I discovered what had happened after I limped the couple of hundred metres into my home garage. I reconnected all the hoses and started it again - it idled and still idles perfectly. I also pulled plugs 1 & 3 to have a look - obvious signs of carbon buildup (like fine black soot) on them (running rich on normal boost) but no signs of scorching or anything I'd expect to show something wrong.

I also drove the car again this morning under normal conditions, and it all seems fine - idle, running, boost, temp, oil temp and pressure.....

Should I be concerned, and what should I look for specifcally that would indicate signs that I broke something significant/ly? I'm (understandably) a little skitzed out by it - just finished the install and the LAST thing I want is to break it.

And yes - I knew/know about being careful with this disgnosis method - it just took me completely by surprise.
Uncle Arthur is offline   Reply With Quote
Old 04-11-2007, 11:50 PM   #2
Elite Member
iTrader: (14)
 
Join Date: Mar 2006
Location: Edmonton, AB
Posts: 4,921
Total Cats: 0
Default

How much boost did you make? Is you guage connected to a Narrowband sensor?

What are you running for fuel and ignition?

If you didn't hear any really obvious ping and and everything seems good I think you're golden.
jayc72 is offline   Reply With Quote
Old 04-11-2007, 11:53 PM   #3
Senior Member
iTrader: (1)
 
Join Date: Aug 2006
Location: Illinois
Posts: 1,011
Total Cats: 7
Default

If it works don't fix it? If everything seems to be running ok then I wouldn't worry too much. Maybe you could peek in the compressor inlet to inspect the fins.
lazzer408 is offline   Reply With Quote
Old 04-11-2007, 11:57 PM   #4
Junior Member
Thread Starter
 
Join Date: Sep 2006
Posts: 225
Total Cats: -4
Default

Quote:
Originally Posted by jayc72 View Post
How much boost did you make? Is you guage connected to a Narrowband sensor?
Couldn't tell you now - it was so quick and the lean light took my attention and yes (Autometer Stoichmeter)

Quote:
Originally Posted by jayc72 View Post

What are you running for fuel and ignition?
Stock pump, 1.8 injectors, and EMB with tune set up for 8psi plus O2 clamp

Quote:
Originally Posted by jayc72 View Post

If you didn't hear any really obvious ping and and everything seems good I think you're golden.
It was so quick - literally got there and I lifted off immediately and pushed the clutch - the pipe joiner (almost straight after the turbo and well before the IC) popping off went bang (I think because the pipe/joiner actually banged against bodywork), and she spat and farted running rich on the short limp home (which of course makes sense now I know the AFM was taken out of the equation).

But yes - everything seems OK - no obvious issues on a decent length run this morning.
Uncle Arthur is offline   Reply With Quote
Old 04-11-2007, 11:58 PM   #5
Junior Member
Thread Starter
 
Join Date: Sep 2006
Posts: 225
Total Cats: -4
Default

Quote:
Originally Posted by lazzer408 View Post
If it works don't fix it? If everything seems to be running ok then I wouldn't worry too much. Maybe you could peek in the compressor inlet to inspect the fins.
Looking for signs of bending/deformation?
Uncle Arthur is offline   Reply With Quote
Old 04-12-2007, 12:00 AM   #6
Senior Member
 
Join Date: Dec 2005
Posts: 865
Total Cats: 0
Default

time for me and you to install external wastegates!
i had enough of playing games with internals..
turbopezz is offline   Reply With Quote
Old 04-12-2007, 09:49 AM   #7
:(
iTrader: (7)
 
Join Date: Jul 2006
Location: nowhere
Posts: 8,281
Total Cats: 2
Default

Arthor chill out dude . you probably didnt even top 8psi get a real WG and make sure the it is installed so that the actuator is pulled shut. Also i doubt you did anything to the turbo itself, if motor damage is your concern then run a compression check and maybe a leak down but i doubt anything is amiss. GL. FWIW i did the same on my motor to see if i had WG issues and seen 23 psi and no failure this was before my dyno runs and with stock fuel system and RRFPR. Sometimes you just get lucky.
magnamx-5 is offline   Reply With Quote
Old 04-12-2007, 10:17 AM   #8
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

With just an open boost line to the actuator, you are slowly opening the wasegate...even at 1psi, so the turbine spool is negatively affected.

This is why I always advocate MBCs. Even at the same boost level it's going to force the actuator to stay closed as long as possible....giving you better spool.
Braineack is offline   Reply With Quote
Old 04-12-2007, 07:23 PM   #9
Junior Member
Thread Starter
 
Join Date: Sep 2006
Posts: 225
Total Cats: -4
Default

Thanks guys - my sense of chill is restored

I checked the turbo fins, the plugs, and looked down the sparkplug shafts inside the chambers last night - all looks good - the plugs are clean again - no huge build up of soot (NGK Iridiums), so I guess I got lucky too - just that everything I have read about boost+lean=bad+breakage.

Then again - the BP motor is a tuff bit'o'gear.

And explaining to the g/f that I've just spent a huge amount of our money on a turbo kit only to have to spend more cause I broke it would have been bad - very bad.
Uncle Arthur is offline   Reply With Quote
Old 04-12-2007, 08:09 PM   #10
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,900
Total Cats: 1,792
Default

what they don't know don't hurt
Braineack is offline   Reply With Quote
Old 04-12-2007, 08:21 PM   #11
Senior Member
 
Join Date: Mar 2006
Location: Ireland
Posts: 534
Total Cats: 0
Default

Quote:
Originally Posted by turbopezz View Post
time for me and you to install external wastegates!
i had enough of playing games with internals..
Can you recommend an external wastegate and have you any pics of one installed ?
Fergus is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Buzzing from driver side of engine bay? (MS3 install) nick470 MEGAsquirt 7 06-16-2017 02:53 PM
WTB MP62 (Hotside) (NB2) Rick02R WTB 3 01-03-2016 08:18 PM
Bizarre connection issue? nick470 MEGAsquirt 1 09-30-2015 11:32 PM
Missing/knock at idle, can someone point me in the right direction? Mikel MEGAsquirt 4 09-28-2015 05:46 PM
why is my car running like pewp? (tune/datalog) itsMikey MSPNP 3 09-28-2015 07:40 AM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:57 PM.