trying to solve slight engine bucking...ideas?
02-24-2015, 08:33 PM
#77
Team Owner
Sorry, I fixed my last bit of info,
you do have the correct plugs.
you do have the correct plugs.
Last edited by Mrmerlin; 02-24-2015 at 11:19 PM.
02-25-2015, 01:44 AM
#78
Instructor
I have an '82 and had a similar problem. Around 3000 rpm would buck and jerk back and forth. Drove me nuts. Did all the usual repairs/replacements and finally switched the Ignition Control Unit and it has never bothered me since.
I think you indicate you replaced it but was it with a known good unit? The symptoms sound so similar. A very frustrating problem to fix.
I think you indicate you replaced it but was it with a known good unit? The symptoms sound so similar. A very frustrating problem to fix.
02-27-2015, 02:56 PM
#82
Three Wheelin'
Thread Starter
Replaced the little injector hoses last night, as I had a leak.
The car starts cold instantly now, and normally when hot. I must of had a slight loss of FP due to the leaks.
the car pass smog this morning with flying colors. So that tells me its running well in that regard at least.
this morning, driving to smog, cold, the car was bucking as normal in 1st and 2nd, and in 3rd its less so. so this is still there....slighting improved when warm.
The car starts cold instantly now, and normally when hot. I must of had a slight loss of FP due to the leaks.
the car pass smog this morning with flying colors. So that tells me its running well in that regard at least.
this morning, driving to smog, cold, the car was bucking as normal in 1st and 2nd, and in 3rd its less so. so this is still there....slighting improved when warm.
02-27-2015, 03:28 PM
#83
Three Wheelin'
Join Date: May 2007
Location: Newcastle upon Tyne. England
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Is the car doing this every time you drive it ,at least mine is selective, and not too much of a bear. Mine only appears with foot off the gas or just a light feathering of the gas pedal, and can be in 2nd, 3rd , or 4th gear. When it starts if I knock it out of gear, and then after a few seconds engage gear , it is pretty much normal again, until it does it again, no rhyme or reason ?
Ken
80 928 S
5 Speed
UK
Ken
80 928 S
5 Speed
UK
02-27-2015, 07:45 PM
#84
Team Owner
Buzz kill I know,
but the airfilter is in upside down.
NOTE the hump points to the sky
but the airfilter is in upside down.
NOTE the hump points to the sky
02-27-2015, 09:12 PM
#85
Three Wheelin'
Thread Starter
when I got this car I didnt know what way it went. once its one way for awhile I didnt want to flip and suck in the dirt already there. the arrows on the side dont indicate if it means "up" or airflow "down".
Mark
02-27-2015, 09:28 PM
#86
Team Owner
its funny you mention the arrows,
there was big discussion on these things a few years back,
someone posted pictures with them going both ways on two different filters.
Anyway you should see a performance gain with the filter flipped over and the idle may also change due to the airflow.
FWIW as far as the operation of the filter goes,
its made so the the edges closest to the inlet tubes have small ramps,
so the biggest particles of dirt will be trapped at the portion of the filter furthest from the intake.
Take a dirty filter and dump it onto some white paper,
tap it a few times ,
you will find that the edges contain the biggest particles and the center has the smallest.
NOTE for others that may read this in a year or two,
the hump always points to the sky.
Link to thread
https://rennlist.com/forums/928-foru...rfilter+upside
there was big discussion on these things a few years back,
someone posted pictures with them going both ways on two different filters.
Anyway you should see a performance gain with the filter flipped over and the idle may also change due to the airflow.
FWIW as far as the operation of the filter goes,
its made so the the edges closest to the inlet tubes have small ramps,
so the biggest particles of dirt will be trapped at the portion of the filter furthest from the intake.
Take a dirty filter and dump it onto some white paper,
tap it a few times ,
you will find that the edges contain the biggest particles and the center has the smallest.
NOTE for others that may read this in a year or two,
the hump always points to the sky.
Link to thread
https://rennlist.com/forums/928-foru...rfilter+upside
02-28-2015, 12:42 PM
#87
Rennlist Member
Mine was in upside down too. I just hope I didn't flip it...I don't THINK I did. I have a replacement which I'll put in correctly, and which oddly does not have any arrows at all on it.
02-28-2015, 05:12 PM
#88
Under the Lift
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Glad you passed smog! Did you change the cat converters or was the fuel hose fix all that you did to pass smog? Oh, wait, that's you S4 that has the aftermarket cats, right?
02-28-2015, 06:55 PM
#89
Three Wheelin'
Thread Starter
Bob, it was the s4 that failed with aftermarket cats. This car, has original cats. This was the first time i did this car for its biannual.
I was trying to solve the issue that this thread is about...before i smogged it. Tags expired today.
I was trying to solve the issue that this thread is about...before i smogged it. Tags expired today.
03-06-2015, 11:34 PM
#90
Three Wheelin'
Thread Starter
problem still persists. not any better after the recent work done.
Drives me nuts every time I drive it. Sooooo Frustrating.
stupid stuff like this make we want to sell this car
The car starts great cold but still is hard too sometimes when hot.
yesterday it took several moments to start when hot and it when it did it was running rough- smelled bad- like it was missing (ignition).
after letting it run for a few minutes it clears up.
Anyone have a good known ECU I can test with?
Mark
Drives me nuts every time I drive it. Sooooo Frustrating.
stupid stuff like this make we want to sell this car
The car starts great cold but still is hard too sometimes when hot.
yesterday it took several moments to start when hot and it when it did it was running rough- smelled bad- like it was missing (ignition).
after letting it run for a few minutes it clears up.
Anyone have a good known ECU I can test with?
Mark