General [M]ayhem

Go Back   General [M]ayhem > General [M]ayhem > Automotive [M]ayhem
Register Members List Mark Forums Read [M]erchandise Calendar

Reply
 
Thread Tools
Tex Arcana
I am a mean disrespectful person hiding anonymously and need an attitude adjustment.
 
Tex Arcana's Avatar
 
Quote:
Originally Posted by labixiaoxin View Post
I want to say thank you a lot for the job you have made in writing this piece of writing. I am hoping the same most reliable work from you down the road too.

BWAHAHAHAHAH!!! More spammage from the master spammer, trying to get the post counts up and use the sig lines for spam links!!

Damn, $an, you're desperate.
__________________
People should not be afraid of their governments. Governments should be afraid of their people.--V


Men heap together the mistakes of their lives, and create a monster they call destiny.
--John Hobbs


~~~ ~~~ Tea[m] Pyratex ~~~ ~~~
Old 07-08-2012, 09:46 PM Tex Arcana is offline  
Reply With Quote
#16  

Advertisement [Remove Advertisement]

[H]ard|On
tell me i is retarded and i will just potato
 
[H]ard|On's Avatar
 
Quote:
Originally Posted by Jehannum View Post
That doesn't sound like a coil pack to me. It sounds more like a metering issue.

Happening after warmup leads me to think you've got issues with your coolant temperature sensor (or, whatever the BMW ECU uses to determine when to step the idle down and roll out the startup enrichment).

Quote:
Originally Posted by Colonel Sanders View Post
Or maybe an O2 sensor problem (after the computer switches to closed loop.)



The damn thing won't stay broke long enough to tell what it is It will get a misfire code after being fully warmed up and start missing, then if you turn it off and on again it will run fine I'm going back to the shop for some more testing because we did this on the weekend all half-assed but basically:

-swapping coils doesn't change anything, #2 cylinder misfire code comes back after clearing codes

-compression test showed 30 psi less in that cylinder at first; adding oil didn't help so it isn't ring related. Then it was normal after the car was warmed up...


So it may be a sticking valve or something, i have no idea, or why it goes away when you shut the motor down and restart. Going to do a leakdown this time. Hopefully i can fix this with seafoam and not have to pull the head off.
__________________
Make Genmay Great Again
Old 07-10-2012, 05:09 PM [H]ard|On is offline  
Reply With Quote
#17  

Jehannum
 
Jehannum's Avatar
 
If it were a sticking valve, wouldn't you hear the clacking from the cam and the tappet/lifter? When the valve was sticking on my Datsun, it made horrible noises every time the cam hit the rocker (until the valve stuck down to the point that the piston hit it, when it would pop back up and throw the lash pad off into the valve cover, causing even more awesome noises).

Could still be valve related. Without the noises, I'd suspect valve seats, which is a head removal sort of job, and on a 24v motor, a lot of money, even if they can be cut back.
__________________
Your powers are useless! I'm wearing my tin foil underwear!

1992 300ZX: Not stock, 433 RWHP
1971 240Z: Toyota front brakes, 123 RWHP
1967 Pontiac GTO: not stock.
Old 07-10-2012, 07:27 PM Jehannum is offline  
Reply With Quote
#18  

[H]ard|On
tell me i is retarded and i will just potato
 
[H]ard|On's Avatar
 
Quote:
Originally Posted by Jehannum View Post
If it were a sticking valve, wouldn't you hear the clacking from the cam and the tappet/lifter? When the valve was sticking on my Datsun, it made horrible noises every time the cam hit the rocker (until the valve stuck down to the point that the piston hit it, when it would pop back up and throw the lash pad off into the valve cover, causing even more awesome noises).

Could still be valve related. Without the noises, I'd suspect valve seats, which is a head removal sort of job, and on a 24v motor, a lot of money, even if they can be cut back.

There's no clatter or anything. Bent valve maybe? Do you think valve seats would give such inconsistent results?

Haven't touched it since last post btw. What would you do while the head is off? Im thinking those springs are probably toast after 140k worth of raised redline; maybe the #2 piston gave one of the valves a kiss....
__________________
Make Genmay Great Again
Old 07-11-2012, 09:10 PM [H]ard|On is offline  
Reply With Quote
#19  

Colonel Sanders
 
Colonel Sanders's Avatar
 
I think you are over complicating (so far anyway.) IMO you should still do some more basic trouble shooting like moving plug wires around to see if the misfire moves to another cylinder, swap the plugs even though the current ones looked fine, etc etc

edit: Another thing would be to swap around a fuel injector from a diff. cylinder.
Old 07-11-2012, 09:16 PM Colonel Sanders is offline  
Reply With Quote
#20  

[H]ard|On
tell me i is retarded and i will just potato
 
[H]ard|On's Avatar
 
There are no plug wires to speak of, it's coil over plug. The plugs looked okay, I should switch them too i guess but I'm more concerned about the fluctuating compression. Not a factory feature of this motor - lol.... not something that would be caused by an injector either right...

Seems like the exhaust valve doesn't fully seat some of the time which is when the misfires begin. Then it seats ok...

I dont have a leakdown gauge but I can bring the car in again in the next couple of days. We'll have a confirmed diagnosis.
__________________
Make Genmay Great Again
Old 07-11-2012, 10:56 PM [H]ard|On is offline  
Reply With Quote
#21  

Jehannum
 
Jehannum's Avatar
 
Quote:
Originally Posted by [H]ard|On View Post
There's no clatter or anything. Bent valve maybe? Do you think valve seats would give such inconsistent results?

Haven't touched it since last post btw. What would you do while the head is off? Im thinking those springs are probably toast after 140k worth of raised redline; maybe the #2 piston gave one of the valves a kiss....

I'm not sure how big your cam is, but a bent valve is certainly possible, if the lift and duration are big enough, and the redline high enough.

If you have to pull the head, I'd chase all the threads with good bottoming taps, swap to some good ARP head studs, MLS metal head gasket, replace all the intake and exhaust hardware, rebuild whatever variable cam timing/lift your car came with, and then drop it off at the machine shop to fix whatever's broken.

At the machine shop, if a valve is sticky, I'd replace all the valves, the seats, the guides, and the springs. That implies doing a valve job to mate the new surfaces. I'd do that because if one is sticky, then the odds are that the wear is bad enough that more issues are pretty close down the road. It's pretty easy to measure wear on the valvetrain, and any competent machine shop will do it.

If it's just a bent valve, and the rest are all within spec for wear, I'd just swap the guide and valve in that hole, and cut the seat, and then replace the springs on all the rest of 'em.

edit: and if you don't absolutely have to (like > .02" of distortion), I wouldn't fly-cut the face. Clamping forces from the head bolts deform the head, so every time you pull the head off, it ends up slightly banana shaped, and if you cut the head, the wear patterns on the cams change.
__________________
Your powers are useless! I'm wearing my tin foil underwear!

1992 300ZX: Not stock, 433 RWHP
1971 240Z: Toyota front brakes, 123 RWHP
1967 Pontiac GTO: not stock.

Last edited by Jehannum; 07-12-2012 at 08:42 AM..
Old 07-12-2012, 08:31 AM Jehannum is offline  
Reply With Quote
#22  

ScHpAnKy
The only place you can get milk in a bag.
 
this is on your e36? check your FPR, even the advance part works great and fixed my misfire from before. Coilpacks on e36's rarely go bad and if it's getting a pulse and not moving with the cylinder I'd suspect DME/sensor issues (when was the last time your crank/cam sensors were replaced?)

or, as mentioned - FPR
__________________
Yup, still from Boston
SexiOne's pool boy
Old 07-12-2012, 07:20 PM ScHpAnKy is offline  
Reply With Quote
#23  

ScHpAnKy
The only place you can get milk in a bag.
 
Quote:
Originally Posted by [H]ard|On View Post
Looks like i need a coil pack

Had CEL on for 2 days and finally today the car started misfiring. It's hard to tell of course because the i6 is so smooth Coils are OE and lasted 142k so far, not too bad I guess.


Starts fine, then a bit after fully warming up it begins to stumble, pops through exhaust like crazy and smells like raw gas. I checked the plugs they're all fine it seems. Going to a friend's shop manana - they got some spare/used coil packs he said I can have, plus i still dont have a code reader.

Should I replace them all when I get enough moneys together? Or just carry a spare like VW owners?

actually, re-reading the OP - definitely not your coils. Had the exact same issue and switched to a red-label 413 ecu and a new CPS and everything was fine. Might as well do the coolant temp sensor (not sender) too just to be safe. What year is your car, pre-OBD2?

except for loudness and fire (I'm running straight pipes after my first cat) does it sound similar to this?
+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
__________________
Yup, still from Boston
SexiOne's pool boy
Old 07-12-2012, 07:25 PM ScHpAnKy is offline  
Reply With Quote
#24  

[H]ard|On
tell me i is retarded and i will just potato
 
[H]ard|On's Avatar
 
Quote:
Originally Posted by Jehannum View Post
I'm not sure how big your cam is, but a bent valve is certainly possible, if the lift and duration are big enough, and the redline high enough.

If you have to pull the head, I'd chase all the threads with good bottoming taps, swap to some good ARP head studs, MLS metal head gasket, replace all the intake and exhaust hardware, rebuild whatever variable cam timing/lift your car came with, and then drop it off at the machine shop to fix whatever's broken.

At the machine shop, if a valve is sticky, I'd replace all the valves, the seats, the guides, and the springs. That implies doing a valve job to mate the new surfaces. I'd do that because if one is sticky, then the odds are that the wear is bad enough that more issues are pretty close down the road. It's pretty easy to measure wear on the valvetrain, and any competent machine shop will do it.

If it's just a bent valve, and the rest are all within spec for wear, I'd just swap the guide and valve in that hole, and cut the seat, and then replace the springs on all the rest of 'em.

edit: and if you don't absolutely have to (like > .02" of distortion), I wouldn't fly-cut the face. Clamping forces from the head bolts deform the head, so every time you pull the head off, it ends up slightly banana shaped, and if you cut the head, the wear patterns on the cams change.

Thanks man I want to avoid cutting the head, that way I won't need the thick gasket either (which i assume is weaker) The cam isn't too aggressive, and symptoms I've got are kinda rare after searching all the kraut forams but not unheard of. Usually it's the valve seat like you said, shit stuck to the valve or a bent stem/failing spring.

Ill ask about all the things you mentioned and see what my guy wants to do. He has two e36 M3 race cars, a twin turbo ls2 e36, and recently sold his turbo E30 so I'm sure he can figure this out.
__________________
Make Genmay Great Again

Last edited by [H]ard|On; 07-13-2012 at 01:06 AM..
Old 07-13-2012, 01:00 AM [H]ard|On is offline  
Reply With Quote
#25  

[H]ard|On
tell me i is retarded and i will just potato
 
[H]ard|On's Avatar
 
Quote:
Originally Posted by ScHpAnKy View Post
actually, re-reading the OP - definitely not your coils. Had the exact same issue and switched to a red-label 413 ecu and a new CPS and everything was fine. Might as well do the coolant temp sensor (not sender) too just to be safe. What year is your car, pre-OBD2?

except for loudness and fire (I'm running straight pipes after my first cat) does it sound similar to this?
+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.

Holly fucking shit

No it's more like this but louder because of my mad tyte Remus exhaust

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
__________________
Make Genmay Great Again
Old 07-13-2012, 01:02 AM [H]ard|On is offline  
Reply With Quote
#26  

[H]ard|On
tell me i is retarded and i will just potato
 
[H]ard|On's Avatar
 
+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.


This seems helpful. I haven't tried to simply hook up a vac guage, apparently that is step #1 - this dude is ASE certified
__________________
Make Genmay Great Again
Old 07-13-2012, 01:07 AM [H]ard|On is offline  
Reply With Quote
#27  

grjr
 
grjr's Avatar
 
be sure that your compression tester is sealing well against the head, if the tester is leaking that could explain your different compression numbers on the same cylinder.
__________________
irc.slashnet.org #cartalk
Old 07-13-2012, 09:04 AM grjr is offline  
Reply With Quote
#28  

[H]ard|On
tell me i is retarded and i will just potato
 
[H]ard|On's Avatar
 
Quote:
Originally Posted by grjr View Post
be sure that your compression tester is sealing well against the head, if the tester is leaking that could explain your different compression numbers on the same cylinder.

Aye. Also im a newb and forgot to hold the gas pedal down the first time... d'oh



So i messed with it today. Took about 35 mins of driving to get it to misfire. The vacuum guage holds rock steady at 17 inches. So not valves...

Did seafoam and the problem became fairly obvious, i think the seafoam made it worse. Now I have hiss and steam from the oil fill on the valve cover. Looks like a BHG to me after all. We will see if that's all it is after the head is off I guess.
__________________
Make Genmay Great Again

Last edited by [H]ard|On; 07-13-2012 at 08:35 PM..
Old 07-13-2012, 08:30 PM [H]ard|On is offline  
Reply With Quote
#29  

Jehannum
 
Jehannum's Avatar
 
Manifold vacuum won't be affected by an exhaust valve leak.

Good luck on the BHG hypothesis. Check the coolant for contamination.
__________________
Your powers are useless! I'm wearing my tin foil underwear!

1992 300ZX: Not stock, 433 RWHP
1971 240Z: Toyota front brakes, 123 RWHP
1967 Pontiac GTO: not stock.
Old 07-13-2012, 10:04 PM Jehannum is offline  
Reply With Quote
#30  

Reply


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

Forum Jump



All times are GMT -7. The time now is 03:26 PM.



Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.