Notices
General Technical
Sponsored by:
Sponsored by: CARiD

MY94 WRX coughing, spluttering, flat spot....

Thread Tools
 
Search this Thread
 
Old May 29, 2009 | 08:01 AM
  #1  
Tomonsw's Avatar
Tomonsw
Thread Starter
Scooby Regular
 
Joined: May 2009
Posts: 38
Likes: 0
Default MY94 WRX coughing, spluttering, flat spot....

Hi all,

Had a problem a few weeks back where the car was hesitating under load. Well that is fixed now due to a bad coil pack. The car has been running great for the past 2 weeks........ THEN.......... It has developed a flat spot, coughing spluttering issue. Sometimes it does it first thing in the morning when I take off, other mornings it will be fine. Some days it will run fine, other days it will cough and fart all over the place. It is mainly on light accelaration, but has done it under load also. Its like, you put your foot down and it splutters and sounds like it is going to stall and jerks back n forth.....????
The fuel filter is new, just had an oil change, new coil pack on one cylinder, the plugs are in good condition and gapped right, I have cleaned the Idle air control valve, the PCV valve, the AFM is clean and Im running out of ideas and getting a little frustrated as this is my first scooby and have only had it for a month and a bit and all Ive done is work on it!!!

Any help or suggestions much appreciated. Thanks all.
Reply
Old May 29, 2009 | 09:12 AM
  #2  
JT386's Avatar
JT386
Scooby Regular
 
Joined: Oct 2008
Posts: 51
Likes: 0
Default

are you running it on a high RON fuel? probably isnt the cause but 95 RON in some cases causes the engines to run really rough if they have previously been run on 99, especially imports as they are mapped to 100 RON as standard
Reply
Old May 29, 2009 | 09:20 AM
  #3  
dan83590's Avatar
dan83590
Scooby Regular
 
Joined: Aug 2006
Posts: 3,214
Likes: 0
Default

Does it have any mod's?

It could be another coil pack. It's always a good idea to change all 4 at the same time. Try brand new plugs gapped correctly I think 0.7 is the gap PRF7B or 6B rings a bell.

Earlier Imports are not mapped for 100ron fuel...
Reply
Old May 29, 2009 | 09:39 AM
  #4  
Tomonsw's Avatar
Tomonsw
Thread Starter
Scooby Regular
 
Joined: May 2009
Posts: 38
Likes: 0
Default MY94 WRX coughing, spluttering, flat spot....

Yeh Im using 98 RON. Im thinkin I mite have to do the other coil packs and replace the plugs. Im going to test for any fault codes tomorrow and see what I get.......

Thanks guys
Reply
Old May 29, 2009 | 09:40 AM
  #5  
my94wrx's Avatar
my94wrx
Scooby Regular
iTrader: (4)
 
Joined: Feb 2009
Posts: 2,885
Likes: 1
Default

Originally Posted by dan83590
Does it have any mod's?

It could be another coil pack. It's always a good idea to change all 4 at the same time. Try brand new plugs gapped correctly I think 0.7 is the gap PRF7B or 6B rings a bell.

Earlier Imports are not mapped for 100ron fuel...
as above probably coil packs if one was already shot then the chances are that the rest are on there way out.
Reply
Old May 29, 2009 | 09:44 AM
  #6  
myblackwrx's Avatar
myblackwrx
Scooby Regular
iTrader: (1)
 
Joined: Mar 2006
Posts: 8,787
Likes: 1
From: Dorset
Default

Cheap fix for the coil packs if they are cracked is to remove the rubber and wrap the end in insulating tape.
Reply
Old May 29, 2009 | 10:53 AM
  #7  
KLR16V's Avatar
KLR16V
Scooby Regular
iTrader: (2)
 
Joined: Oct 2002
Posts: 1,052
Likes: 0
From: Chester
Default

Would bet it is the coil packs

Mark
Reply
Old May 29, 2009 | 04:33 PM
  #8  
dan83590's Avatar
dan83590
Scooby Regular
 
Joined: Aug 2006
Posts: 3,214
Likes: 0
Default

https://www.scoobynet.com/general-te...tics-test.html

Lets tie these threads together.

Originally Posted by Tomonsw
Your right, they were a bugger to find...!!!! But I found them. I just did the test and got codes....

23 : MAF sensor

45 : MAP sensor.

I did a couple of tests on the MAF by disconnecting while the car was running and it stalled, therefore I assumed it was working ok. Would disconnecting it have given the fault code?

The MAP sensor, I have a fuel cut defender plumbed into the vacuum line. Would that make the MAP sensor give an error code and play up??

Confused!!

Last edited by dan83590; May 29, 2009 at 04:39 PM.
Reply
Old May 30, 2009 | 09:43 AM
  #9  
Tomonsw's Avatar
Tomonsw
Thread Starter
Scooby Regular
 
Joined: May 2009
Posts: 38
Likes: 0
Default MY94 WRX Coughing, Spluttering hesitation.

So I did a fault test using the black connectors under dash and got fault code 23: MAF sensor.

Today I removed the MAF sensor and noticed that all 4 bolts that hold the maf to the air box were loose..... Anyway, cleaned the MAF, let dry and reinstalled and tightened the bolts up properly and........

Running beautifully now. No more hesitation or coughing.

Do you think the loose bolts may have contributed to poor running also?
Reply
Old May 30, 2009 | 12:41 PM
  #10  
dan83590's Avatar
dan83590
Scooby Regular
 
Joined: Aug 2006
Posts: 3,214
Likes: 0
Default

Probably not. More than likely the fact that you have cleaned it. I did the same with mine and the same result. Well done mate. It's nice when your work pays off int it..
Reply
Old May 30, 2009 | 01:20 PM
  #11  
joz8968's Avatar
joz8968
Scooby Regular
15 Year Member
iTrader: (13)
 
Joined: Aug 2006
Posts: 23,764
Likes: 9
From: Leicester
Default

Originally Posted by Tomonsw
...Do you think the loose bolts may have contributed to poor running also?
I doubt it - as the air upstream of the sensor hasn't been metered yet.


As above, probably just needed the clean to restore it.

Last edited by joz8968; May 30, 2009 at 01:25 PM.
Reply
Old May 30, 2009 | 01:36 PM
  #12  
Tomonsw's Avatar
Tomonsw
Thread Starter
Scooby Regular
 
Joined: May 2009
Posts: 38
Likes: 0
Default MY94 WRX coughing, spluttering, hesitation

Cool. Thanks guys. I'd cleaned everything else and left the maf till last and so far so good. Thanks again everyone
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
shorty87
Full Cars Breaking For Spares
19
Dec 22, 2015 11:59 AM
PetrolHeadKid
Driving Dynamics
10
Oct 5, 2015 05:19 PM
M4RKG
General Technical
3
Sep 30, 2015 07:51 PM
Sub-Subaru
General Technical
1
Sep 28, 2015 12:47 PM
alex_00s
Drivetrain
2
Sep 26, 2015 06:07 PM




All times are GMT +1. The time now is 06:44 PM.