annoying issue still

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pulsar kid

New Member
Mornig guys,

I'm still after some advice,
My tick over issue, i have had the car for over a month and still cant get this tick over issue sorted,
In the mornings from cold, sits around 1800rpm, leave to warm for up to a min,
i'll drive down the road and once pulled up to the junction she will either rise to 1900/2000rpm or drop to 1500 then straight back to 1900 and do this 3/4times at the junction like baaa burr baaa burr sought of thing lol,
Once driven she will idle at 1050/1100, but then at the next couple of junctions sit at 1500, its driving me mad.
it stinks of richness,
Things i've done,
New standard platinum plugs
new genuine leads
new dizzy
new rotary
new fuel filter
new coolant temp sensor,

cleaned the maff, then swapped it over in-case faulty
cleaned the idle control valve which had already been done, spring is spot on too,
boost leak test all fine,
Tps set right,
Throttle body's shut propley.
pcv valve working fine,
No DV.

Car is running just a Apexi filter, goose decatted system, Forge fmic and pump,

think the fuel lines were swapped out from pump to filter with larger new rubber ones i believe,
Trouble is the guy i got it off didn't have a clue at all so cant take his word :sad:
Any other things to check im going mad here!!:evil:
 
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Gtirjoeynew

Member
If its hunting and running as you say i bet it will be the valve that sits under the inlet manifold think its called the iac valve pig to change, but ive had it cause exactly the same issue on my car
 
G

Gtirjoeynew

Member
Yeah if u just start it from cold and let it idle does it struggle to be to come off cold start and thats where the hunting begins?
it wont be ignition related so forget that route
 
B

BMCC

Member
What about 02 sensor if it is running rich? Is the exhaust sound?

The one thing I have found connecting into the ecu via datascan is that when my car was idling about 1250 or above the ignition timing was at 20deg btdc. Now when the idle fell to about 1000, the ecu cut the ignition to 10deg btdc. It is just that it took the ecu time to do this. Some times quicker than others. So yes check your base timing . The other thing I found using datascan was that you could clear the self learn which should drop the idle straight off. If not your drawing in air from somewhere. I found some of the pcv pipes had perished on mine.
 
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Gtirjoeynew

Member
BMCC said:
What about 02 sensor if it is running rich? Is the exhaust sound?

The one thing I have found connecting into the ecu via datascan is that when my car was idling about 1250 or above the ignition timing was at 20deg btdc. Now when the idle fell to about 1000, the ecu cut the ignition to 10deg btdc. It is just that it took the ecu time to do this. Some times quicker than others. So yes check your base timing . The other thing I found using datascan was that you could clear the self learn which should drop the idle straight off. If not your drawing in air from somewhere. I found some of the pcv pipes had perished on mine.
Click to expand...
So are you saying your base timing was out then? And altering it made the ecu drop the ign timing drop with revs consistently ???
i would of thought it would be your laptop not updating quick enough to keep up? Rather than the ecu ? Or have i mis read what you are saying
 
keastygtir

keastygtir

Well-Known Member
there is a procedure for testing the o2 sensor which makes the light on the dash flash when in closed loop. However I dont remember what it is
 
B

BMCC

Member
Gtirjoeynew said:
So are you saying your base timing was out then? And altering it made the ecu drop the ign timing drop with revs consistently ???
i would of thought it would be your laptop not updating quick enough to keep up? Rather than the ecu ? Or have i mis read what you are saying
Click to expand...
While watching the ignition point on datascan it was really obvious that while Idling high the timing was at 20 deg btdc ( rpm about 1250). It looked to me as if the ecu cut the ignition to 10deg BTDC to get the idle as close to it target value of 850-950rpm which makes sense. I couldn't see a pattern in terms of time taken when the ecu decided to cut the ignition. I could give it a rev up to 2k and it would idle at 1250 (the ignition would have advanced during the rev). It would idle high and then at some point the ecu would cut the ignition to 10deg BTDC and the idle would fall back to about 950-1000. Sometimes the ecu would cut the ignition straight away and it would idle about 1k other times it took what seemed like an eternity to do it. It was just a bit random.

I checked the base timing with a light and it was close to 20deg BTDC going by the marks on the fly wheel. So I would check the base timing on yours to make sure it is not running overly advanced (i.e >20Deg BTDC) which will cause the idle to be very high (>1250 IMO).

I am not sure if these cars could do with running a little less base timing given that they were set up in Japan. The air in Japan is warm a lot go the year while ours in comparison is colder and denser so we get more air in the cylinders etc. Don't know for certain if it would make much of a difference to idle just a thought.
 
PobodY

PobodY

Moderators
Staff member
As I understand it; the ECU can't actually read the timing, it reads how far advanced or retarted the ignition is in comparison to what it has been told the base timing is. - If the base timing isn't 20º BTDC, but datascan is reporting that it is everything will be offset accordingly.

I think the timing on the Japanese ECU is more about running with 100RON fuel rather than air temperature; the average temperature is only a little warmer than the UK (~5ºC in winter and ~25ºC in summer), but there's a huge variation between the east and west coast... or so I was told.

keastygtir said:
there is a procedure for testing the o2 sensor which makes the light on the dash flash when in closed loop. However I dont remember what it is
Click to expand...
Put it into diagnostic mode once, then do it again... and you're in mode II which gives a narrow-band lambda response.

You're aiming for one flash every second (i.e changing from rich to lean) to indicate stoichiometry.
 
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Gtirjoeynew

Member
BMCC said:
While watching the ignition point on datascan it was really obvious that while Idling high the timing was at 20 deg btdc ( rpm about 1250). It looked to me as if the ecu cut the ignition to 10deg BTDC to get the idle as close to it target value of 850-950rpm which makes sense. I couldn't see a pattern in terms of time taken when the ecu decided to cut the ignition. I could give it a rev up to 2k and it would idle at 1250 (the ignition would have advanced during the rev). It would idle high and then at some point the ecu would cut the ignition to 10deg BTDC and the idle would fall back to about 950-1000. Sometimes the ecu would cut the ignition straight away and it would idle about 1k other times it took what seemed like an eternity to do it. It was just a bit random.

I checked the base timing with a light and it was close to 20deg BTDC going by the marks on the fly wheel. So I would check the base timing on yours to make sure it is not running overly advanced (i.e >20Deg BTDC) which will cause the idle to be very high (>1250 IMO).

I am not sure if these cars could do with running a little less base timing given that they were set up in Japan. The air in Japan is warm a lot go the year while ours in comparison is colder and denser so we get more air in the cylinders etc. Don't know for certain if it would make much of a difference to idle just a thought.
Click to expand...
I dont see what your saying then? You didnt really find anything nor did you cure it?
 
B

BMCC

Member
Didn't find anything? Yes i found that the car idled faster when the ignition was advanced by the ecu and slowed when it retarded it (as you would expect). Why it takes the ecu so long to cut the ignition to 10deg BTDC I have no idea as this lowers the idle to about 950-1000rpm which is nearly where it should be and what the ECU should be trying to get to. Why it does this sometimes within seconds of blipping the throttle and in others it can take 5 or more mins I don't know and would like to find out. However it always gets close to 950-1000rpm when the ECU retards the ignition. Maybe I need to a new dizzy?
Some of the sensors the ecu is using for ignition will be in this (crank position sensor?) Hence make sure your base timing is 20 deg BTDC +/- 2 degrees. Maybe your base timing is too far advanced from 20 degree BTDC. If so it may explain why your idle is so high. If you can get a copy of datascan and a connector for the ecu then you can go into it and see your ignition timing etc. You can also clear the self learn from the ecu. According to the manual this should cause the idle to drop, if not you've got an air leak somewhere which will be causing your high idle.

Clearing the self learn helped and my idle is better but sometimes it idles at near 1000rpm, sometimes nearer 1250 sometimes higher. However it is now more likely to be closer to 1000rpm after clearing the self learn and renewing some of the PCV pipes which were leaking. My question to the forum is why does the ecu not cut the ignition to 10deg BTDC immediately everytime the car idles? From what I am seeing using datascan it doesn't do this straight away 100% of the time and so my idle will not always be 950-1000rpm.

@ PobodY so if I get datascan to hold the ignition timing at base idle it will just hold it at 20deg BTDC regardless of where the dizzy is actually at (in terms of being advanced or retarded) So I could retard the ignition by moving the distributor but Datascan will always show 20 deg BTDC when I ask it to go into base timing mode?
 
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PobodY

PobodY

Moderators
Staff member
I could be wrong, but this is how I understood it:

If you've set the base timing at 16ºBTDC (for example), but told datascan that's 20º it will always be 4º out since it just references how advanced or retarded it is from the base timing. So I thought the option to hold the base timing was just so that you can effectively synchronise it with the actual timing.

It's probably not an issue unless you've changed something, but I'm sure people have had this problem in the past because the ECU was out of sync.
 
B

BMCC

Member
PobodY said:
I could be wrong, but this is how I understood it:

If you've set the base timing at 16ºBTDC (for example), but told datascan that's 20º it will always be 4º out since it just references how advanced or retarded it is from the base timing. So I thought the option to hold the base timing was just so that you can effectively synchronise it with the actual timing.

It's probably not an issue unless you've changed something, but I'm sure people have had this problem in the past because the ECU was out of sync.
Click to expand...
I think I'll need to read the manual for datascan again as I was using the active tests- base timing and setting it to zero then checking with a timing light against the marks on the pulley. I thought this would have held the timing constant so that the ecu is not adjusting it. Should I just pull the tps plug and rev to 2500rpm a few times and then check using a timing light and not use datascan?
 
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