3rd Generation Specific (1993-2002) 1993-2002 Discussion including performance modifications and Technical Support Sections.
Sponsored by:

strange vibration of the engine on startup

Thread Tools
 
Search this Thread
 
Old 08-24-07, 12:03 AM
  #1  
Rotary addict since 86

Thread Starter
iTrader: (7)
 
WanKeL FD RX-7's Avatar
 
Join Date: Mar 2002
Location: Montreal, QC, Canada
Posts: 2,519
Likes: 0
Received 2 Likes on 2 Posts
strange vibration of the engine on startup

Hey guys i searched about it and didnt find what i was looking for. My new engine acts weird a little bit. When i start the car, it shakes a lot for 3-4 seconds and after its normal... just on startup.. engine runs smooth , pretty strong engine so far, but i dont know where to check for this little problem.

could it be my Fuel pressure reg (aeromotive)... because its not keeping its pressure when the car is OFF. Fuel pressure is good when the engine runs...


Max
Old 08-24-07, 01:56 AM
  #2  
Patience

iTrader: (1)
 
spandy's Avatar
 
Join Date: Jun 2006
Location: Oregon
Posts: 1,483
Likes: 0
Received 0 Likes on 0 Posts
Do you feel anything while driving, shifting, etc? Or is it just on startup?
Old 08-24-07, 02:17 AM
  #3  
rotor rotor pow.

iTrader: (1)
 
sevensix's Avatar
 
Join Date: Mar 2005
Location: Southern CA
Posts: 3,170
Received 1 Like on 1 Post
sounds like maybe a bit of flooding? maybe a small coolant leak. i had the same thing with my dead coolant seals.
Old 08-24-07, 02:19 AM
  #4  
Finally I have LSD

 
twistedriver's Avatar
 
Join Date: Jul 2003
Location: Los Angeles
Posts: 528
Likes: 0
Received 0 Likes on 0 Posts
+1 on the slight coolent leak. Maybe check your coolent level and have some one smell the exhast for a sweet smell. (hope is not a coolent seal). Oh by the way try clicking the key on and off a few times before starting the car (with 3-5 second in between). This should get the pressure up if pressure is bleeding off.
Old 08-24-07, 07:43 AM
  #5  
Rotary addict since 86

Thread Starter
iTrader: (7)
 
WanKeL FD RX-7's Avatar
 
Join Date: Mar 2002
Location: Montreal, QC, Canada
Posts: 2,519
Likes: 0
Received 2 Likes on 2 Posts
i'll check the coolant for sure. it just makes it when i start the car, otherwise, it runs pretty good, no vibrations.. btw engine is new ... i doubt it could be coolant seals.

Max
Old 08-24-07, 07:56 AM
  #6  
All out Track Freak!

iTrader: (263)
 
Fritz Flynn's Avatar
 
Join Date: Jul 2001
Location: Charlottesville VA 22901
Posts: 10,672
Received 412 Likes on 250 Posts
Originally Posted by WanKeL FD RX-7
i'll check the coolant for sure. it just makes it when i start the car, otherwise, it runs pretty good, no vibrations.. btw engine is new ... i doubt it could be coolant seals.

Max
If the engine is a new reman then it good easily be coolant seals. I've had a new reman with a pinched O ring and some others on the forum have experienced the same thing.

Good luck
Old 08-24-07, 04:16 PM
  #7  
Rotary addict since 86

Thread Starter
iTrader: (7)
 
WanKeL FD RX-7's Avatar
 
Join Date: Mar 2002
Location: Montreal, QC, Canada
Posts: 2,519
Likes: 0
Received 2 Likes on 2 Posts
the engine was built by adam from rx7 specialties, he built it in front of me. I hope its not a coolant seal.

Max
Old 08-24-07, 05:09 PM
  #8  
Rotary addict since 86

Thread Starter
iTrader: (7)
 
WanKeL FD RX-7's Avatar
 
Join Date: Mar 2002
Location: Montreal, QC, Canada
Posts: 2,519
Likes: 0
Received 2 Likes on 2 Posts
ok it doesnt smell coolant at all in the exhaust.... coolant is full in the filler neck. I tried clicking the key on off 3-4 times and there was a little vibration, much better than before... it shaked a little bit, but its nothing to compare when i dont let the on off key thing.

my old engine was doing the same thing... it was shaking, we saw that my aeromotive fpr wasnt keeping the fuel pressure when the car is shut down.

Max
Old 08-24-07, 09:49 PM
  #9  
Patience

iTrader: (1)
 
spandy's Avatar
 
Join Date: Jun 2006
Location: Oregon
Posts: 1,483
Likes: 0
Received 0 Likes on 0 Posts
Well if the previous motor was doing it, then it's obviously not the motor (lucky you!!).
Old 08-24-07, 11:04 PM
  #10  
Finally I have LSD

 
twistedriver's Avatar
 
Join Date: Jul 2003
Location: Los Angeles
Posts: 528
Likes: 0
Received 0 Likes on 0 Posts
might want to put a fuel gauge in to make sure your fuel pressure is good. Don't want to kill a new motor due to a bad fuel filter or fuel system.
Old 08-24-07, 11:58 PM
  #11  
Rotary addict since 86

Thread Starter
iTrader: (7)
 
WanKeL FD RX-7's Avatar
 
Join Date: Mar 2002
Location: Montreal, QC, Canada
Posts: 2,519
Likes: 0
Received 2 Likes on 2 Posts
i have a digital fuel gauge, pressure is good. really seems to be the defective aeromotive unit.

Max
Old 08-24-07, 11:58 PM
  #12  
Rotary for life!

 
rexhvn's Avatar
 
Join Date: Oct 2005
Location: Somewhere...
Posts: 1,155
Received 1 Like on 1 Post
Motor mounts?
Old 08-25-07, 12:12 AM
  #13  
Rotary addict since 86

Thread Starter
iTrader: (7)
 
WanKeL FD RX-7's Avatar
 
Join Date: Mar 2002
Location: Montreal, QC, Canada
Posts: 2,519
Likes: 0
Received 2 Likes on 2 Posts
maybe that could be.... i changed one two months ago, they were looking fine..

Max
Old 08-25-07, 12:54 AM
  #14  
Rotary for life!

 
rexhvn's Avatar
 
Join Date: Oct 2005
Location: Somewhere...
Posts: 1,155
Received 1 Like on 1 Post
Maybe the other motor mount is bad? but if it only happens at start up, I doubt it would be...
Old 08-25-07, 03:52 AM
  #15  
Call me gramps!

 
WaLieN's Avatar
 
Join Date: Jul 2003
Location: Temecula, CA
Posts: 2,334
Received 0 Likes on 0 Posts
It could be that your IAC is gummed up after being shut down for an extended time, and takes a little bit for it to actuate.

http://www.clubrx.org/default.asp?id...ntent=63&mnu=5 (scroll down)

It could be a lot of things, though. And with such a small window of time where the problem occurs, it makes diagnosing the issue even more difficult. Good luck!
Old 08-25-07, 09:06 AM
  #16  
Urban Combat Vet

iTrader: (16)
 
Sgtblue's Avatar
 
Join Date: Oct 2003
Location: Mid-west
Posts: 12,021
Received 866 Likes on 615 Posts
I'd still test the coolant for hydrocarbons and/or pressure test it.
Old 08-25-07, 10:40 AM
  #17  
Rotary addict since 86

Thread Starter
iTrader: (7)
 
WanKeL FD RX-7's Avatar
 
Join Date: Mar 2002
Location: Montreal, QC, Canada
Posts: 2,519
Likes: 0
Received 2 Likes on 2 Posts
I'll check everything, thanks guys
Old 09-13-07, 12:44 PM
  #18  
Magnet Boy

 
rxcited2's Avatar
 
Join Date: Jan 2007
Location: NorCal
Posts: 251
Likes: 0
Received 1 Like on 1 Post
Originally Posted by WanKeL FD RX-7
i have a digital fuel gauge, pressure is good. really seems to be the defective aeromotive unit.

Max
What is considered GOOD? The manual says 71 - 107 psi. When I measured mine with a jury rigged (possibly not so accurate) gauge, I get 50 - 60 psi. I don't appear to be having fuel starvation, but this pressure seems low. Mine keeps pressure with the key off, no problem.
Old 09-13-07, 01:30 PM
  #19  
Registered User

 
DigDug's Avatar
 
Join Date: Jan 2003
Location: Sterling, VA
Posts: 1,038
Likes: 0
Received 0 Likes on 0 Posts
Did you have your injectors checked/cleaned during the rebuild? Maybe one's sticking open. How quick does it lose fuel pressure after shutdown?

Check plugs shortly after shutdown to see if they're wet in one chamber. You should be able to smell if it's coolant or fuel.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
07-01-23 04:40 PM
sherff
Adaptronic Engine Mgmt - AUS
9
02-24-19 12:09 PM
Rotospectre
New Member RX-7 Technical
3
03-28-18 03:33 PM
stickmantijuana
Microtech
30
04-23-16 06:37 PM



Quick Reply: strange vibration of the engine on startup



All times are GMT -5. The time now is 10:12 PM.