Leave the timing where it is and get a new mechanic.
89MX5
Timing
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derek.elliott
Timing
Hi all,
Yesterday I had my MX5 in for a service and I casually asked "Could
you please check my timing". The timing was running between 15
and 16 degrees but my mechanic said he could not set the base
timing. On grounding out the diagnostic terminals to set the timing
the engine speed increased. Is this normal? The mechanic said the
engine speed should decrease. Can this be remedied?
I hope the above makes sense... As you can probably tell I am no
mechanic, it was actually the mechanic who asked me to ask the
MX5 list for advice.
Regards,
Derek.
Yesterday I had my MX5 in for a service and I casually asked "Could
you please check my timing". The timing was running between 15
and 16 degrees but my mechanic said he could not set the base
timing. On grounding out the diagnostic terminals to set the timing
the engine speed increased. Is this normal? The mechanic said the
engine speed should decrease. Can this be remedied?
I hope the above makes sense... As you can probably tell I am no
mechanic, it was actually the mechanic who asked me to ask the
MX5 list for advice.
Regards,
Derek.
-
Fletcher Blades
Timing
When you connect the TEN to GND in the diagnostic connector, you are
bypassing the ECU's idle management circuit, and the car will idle at
its "base idle" speed.
Often base idle is too low, and this will lead to MX-5's nearly
stalling when coming to a stop, before the ECU takes over control of
idle speed.
I imagine yours has a temporarily fast idle when coming to a stop,
for half a second or so, before the ECU takes over.
Either way, with the jumper connected, you can adjust the throttle
bypass screw (on the throttle body, usually under a rubber plug, but
not always) to set the correct idle speed.
Timing should be adjusted with the base idle at 850-900 RPM.
16 degrees is actually a good setting for both mid-range and top-end
power, but may require 96 octane if pinging is heard.
Fletch.
bypassing the ECU's idle management circuit, and the car will idle at
its "base idle" speed.
Often base idle is too low, and this will lead to MX-5's nearly
stalling when coming to a stop, before the ECU takes over control of
idle speed.
I imagine yours has a temporarily fast idle when coming to a stop,
for half a second or so, before the ECU takes over.
Either way, with the jumper connected, you can adjust the throttle
bypass screw (on the throttle body, usually under a rubber plug, but
not always) to set the correct idle speed.
Timing should be adjusted with the base idle at 850-900 RPM.
16 degrees is actually a good setting for both mid-range and top-end
power, but may require 96 octane if pinging is heard.
Fletch.
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Bill Rehm
Timing
Regarding this timing matter.
When I had a mechanic change my cam belt I asked him about setting the
timing. If I recall correctly, he stated that this was something
automatically done by the car's computer.
Am I missing something??? Someone please educate me. What if anything must
I do about this (or any other) timing issue??
When I had a mechanic change my cam belt I asked him about setting the
timing. If I recall correctly, he stated that this was something
automatically done by the car's computer.
Am I missing something??? Someone please educate me. What if anything must
I do about this (or any other) timing issue??
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Fletcher Blades
Timing
Its true that the ECU does indeed adjust your timing to suit your RPM
and engine load conditions... but it does it all from a reference
that can be adjusted.
Factory setting is to adjust the reference so that the spark fires 10
degrees before top dead centre (BTDC)... but its a common hop-up to
set it for 14 or 18 degrees.
This is spark timing and is unrelated to the timing belt, which
controls cam-timing.
Assuming your mechanic put the timing belt on correctly, you dont have
to do anything about it... but checking your spark timing is always
part of a tune-up.
If you want to read how to set or check your timing, go to the
"garage" area of www.miata.net and look in the engine section.
Fletch.
and engine load conditions... but it does it all from a reference
that can be adjusted.
Factory setting is to adjust the reference so that the spark fires 10
degrees before top dead centre (BTDC)... but its a common hop-up to
set it for 14 or 18 degrees.
This is spark timing and is unrelated to the timing belt, which
controls cam-timing.
Assuming your mechanic put the timing belt on correctly, you dont have
to do anything about it... but checking your spark timing is always
part of a tune-up.
If you want to read how to set or check your timing, go to the
"garage" area of www.miata.net and look in the engine section.
Fletch.
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Bill Rehm
Timing
Thanks Fletch...with your help and others I am becoming
mechanically informed about these puddle jumpers!
I checked the miata site out and now recall some list messages referring to
this subject. Is there any "I've learned from experience" knowledge you or
others can share on advancing the BTDC to 14 vs 16 or maybe 18?
mechanically informed about these puddle jumpers!
I checked the miata site out and now recall some list messages referring to
this subject. Is there any "I've learned from experience" knowledge you or
others can share on advancing the BTDC to 14 vs 16 or maybe 18?
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Fletcher Blades
Timing
The thing to avoid is detonation or "pinking"... an over advanced
engine will make noises like a marble being shaken in a tin can when
you try to accelerate hard... This is not good, it can damage your
engine.
If your car "pinks" or "plinks" like this, you have to retard your
timing, or run higher octane fuel.
Each car has been made with slightly different tolerances from the
factory, and can cope with a slightly different combination of advance
or octane... If your car is at the extreme end of the tolerance
range, it may not be able to take as much timing as others...
But generally, most MX-5s can run 14 degrees on 91 octane, but a few
will require 96.
Most MX-5's will need 96 octane to run 18 degrees, but one or two rare
ones wont need it (I'd advise running 96 on any car at 18 degrees,
even if you think its not detonating).
Generally, 14 degrees will give you some extra low-mid RPM "oomph" and
will keep on pulling hard right to the top of the RPM range.
18 degrees will give even more increase at the low-mid-range but the
effect will die off and it will not pull to redline quite as well...
So, 14 if you like to hoon it up a bit, and 18 if you sit in traffic
jams a lot.
Each driver's preferences and each car's responses can vary in this,
and its best to just play with it and see what you like...
Fletch.
engine will make noises like a marble being shaken in a tin can when
you try to accelerate hard... This is not good, it can damage your
engine.
If your car "pinks" or "plinks" like this, you have to retard your
timing, or run higher octane fuel.
Each car has been made with slightly different tolerances from the
factory, and can cope with a slightly different combination of advance
or octane... If your car is at the extreme end of the tolerance
range, it may not be able to take as much timing as others...
But generally, most MX-5s can run 14 degrees on 91 octane, but a few
will require 96.
Most MX-5's will need 96 octane to run 18 degrees, but one or two rare
ones wont need it (I'd advise running 96 on any car at 18 degrees,
even if you think its not detonating).
Generally, 14 degrees will give you some extra low-mid RPM "oomph" and
will keep on pulling hard right to the top of the RPM range.
18 degrees will give even more increase at the low-mid-range but the
effect will die off and it will not pull to redline quite as well...
So, 14 if you like to hoon it up a bit, and 18 if you sit in traffic
jams a lot.
Each driver's preferences and each car's responses can vary in this,
and its best to just play with it and see what you like...
Fletch.
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Louisa Currie
Timing
Fletcher your a life saver! The problem you describe of low idling has been
happening to my car since I had it serviced. When the engine is cold if I
come to a stop (traffic lights etc), she stalls. Once the engine is warm
there's no problem.
I'm taking it back tomorrow for the THIRD attempt at getting the timing
right. I'll take along your email which made sense to me (non mechanic) so
hopefully they'll get it right this time!!!
Cheers
Louisa
happening to my car since I had it serviced. When the engine is cold if I
come to a stop (traffic lights etc), she stalls. Once the engine is warm
there's no problem.
I'm taking it back tomorrow for the THIRD attempt at getting the timing
right. I'll take along your email which made sense to me (non mechanic) so
hopefully they'll get it right this time!!!
Cheers
Louisa
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derek.elliott
Timing
Thanks Fletcher for the advice on adjusting the idle speed. The fast
idle speed could also be attributed to the car being cool after the
service... so when it was started (to check the timing) it would idle a
little quicker.
Derek.
On 1 Feb 2002 at 18:42, Fletcher Blades wrote:
[...]
idle speed could also be attributed to the car being cool after the
service... so when it was started (to check the timing) it would idle a
little quicker.
Derek.
On 1 Feb 2002 at 18:42, Fletcher Blades wrote:
you areWhen you connect the TEN to GND in the diagnostic connector,
atbypassing the ECU's idle management circuit, and the car will idle
ofits "base idle" speed.
Often base idle is too low, and this will lead to MX-5's nearly
stalling when coming to a stop, before the ECU takes over control
endidle speed.
I imagine yours has a temporarily fast idle when coming to a stop,
for half a second or so, before the ECU takes over.
Either way, with the jumper connected, you can adjust the throttle
bypass screw (on the throttle body, usually under a rubber plug, but
not always) to set the correct idle speed.
Timing should be adjusted with the base idle at 850-900 RPM.
16 degrees is actually a good setting for both mid-range and top-
[...]
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Fletcher Blades
Timing
Well, you could always sign up to www.miataforum.com or the US Miata
mailing list...
This is where I've got most of my info from over the years...
But, I do actually check the validity of the info I pass along... I'm
not just a parrot with a good memory
I'm no expert, but I do have six years experience of working on my own
MX-5... (I've always been a hands-on type of guy, and I hate giving my
money to others if I think I can do what's involved...)
We are lucky, the MX-5/Miata has one of the most knowledgable on-line
communities around... and most problems have been encountered before!
Fletch.
mailing list...
This is where I've got most of my info from over the years...
But, I do actually check the validity of the info I pass along... I'm
not just a parrot with a good memory
I'm no expert, but I do have six years experience of working on my own
MX-5... (I've always been a hands-on type of guy, and I hate giving my
money to others if I think I can do what's involved...)
We are lucky, the MX-5/Miata has one of the most knowledgable on-line
communities around... and most problems have been encountered before!
Fletch.
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