5 minutes after start
09-04-08, 09:44 AM
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5 minutes after start
What happens on an S5 NA around 5 minutes after you start it?
The reason I ask is mine dies and is flooded after (can't get it to refire) around that time.
Basically, it starts, runs the 3K cycle for ~6-8 secs, drops down to about 1500, and then slowly begins to drop down towards regular idle as it starts to warm up.
During this time, it runs great and smooth especially since I just rebuilt the engine (note that this problem first started when it was only running on the back rotor before the rebuild).
Then, as it starts to warm up (~ 5 mins), it just dies like you turned off the key.
I have good compression, I can't find any vac leaks (although I caused one during troubleshooting and it didn't seem to make any difference to the problem other than the car ran rough), I tested to make sure the computer wasn't shutting down spark and it isn't, I swapped the ECU with a known working one, swapped TPS, tried unplugging the coolant temp sensor after I started it to force the computer to run the engine in a limp home mode, tried swapping to a known working MAF, changed my air temp sensor as the prongs got broken off the original, re-stabbed the CAS multiple times to make sure my timing is close, redid all my ground connections, etc.
Nothing seems to change the problem.
But, it will remain running longer than the 5 minutes if I keep the RPM's up somewhere over 1500 and increases easily when I step on the gas so it seems to be getting plenty of fuel.
Does anybody have any more ideas? What all happens around that time that might be my culprit?
Any help or suggestions are appreciated.
Grant
The reason I ask is mine dies and is flooded after (can't get it to refire) around that time.
Basically, it starts, runs the 3K cycle for ~6-8 secs, drops down to about 1500, and then slowly begins to drop down towards regular idle as it starts to warm up.
During this time, it runs great and smooth especially since I just rebuilt the engine (note that this problem first started when it was only running on the back rotor before the rebuild).
Then, as it starts to warm up (~ 5 mins), it just dies like you turned off the key.
I have good compression, I can't find any vac leaks (although I caused one during troubleshooting and it didn't seem to make any difference to the problem other than the car ran rough), I tested to make sure the computer wasn't shutting down spark and it isn't, I swapped the ECU with a known working one, swapped TPS, tried unplugging the coolant temp sensor after I started it to force the computer to run the engine in a limp home mode, tried swapping to a known working MAF, changed my air temp sensor as the prongs got broken off the original, re-stabbed the CAS multiple times to make sure my timing is close, redid all my ground connections, etc.
Nothing seems to change the problem.
But, it will remain running longer than the 5 minutes if I keep the RPM's up somewhere over 1500 and increases easily when I step on the gas so it seems to be getting plenty of fuel.
Does anybody have any more ideas? What all happens around that time that might be my culprit?
Any help or suggestions are appreciated.
Grant
09-04-08, 12:36 PM
#2
Former Moderator. RIP Icemark.
sounds like a vac leak, as that is about when the cold start assist stops working entirely.
How did you check for vac leaks that you don't seem to think there is one???
How did you check for vac leaks that you don't seem to think there is one???
09-08-08, 11:16 PM
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I've been all over the engine with a mechanics stethescope but I couldn't hear any leaks anywhere.
When I caused a leak during troubleshooting (left one hose off), you could easily hear it and the car ran like **** until I fixed it.
Even as it is, the car runs absolutely perfect until it warms up - no hiccups, no misses, nothing. Runs better than my friend's NA that hasn't been rebuilt and has about 70K miles on it.
Then, it's like you shut it off when it dies, it's flooded after that, and it won't restart until it cools down again (even if you clean the flood out).
Grant
When I caused a leak during troubleshooting (left one hose off), you could easily hear it and the car ran like **** until I fixed it.
Even as it is, the car runs absolutely perfect until it warms up - no hiccups, no misses, nothing. Runs better than my friend's NA that hasn't been rebuilt and has about 70K miles on it.
Then, it's like you shut it off when it dies, it's flooded after that, and it won't restart until it cools down again (even if you clean the flood out).
Grant
09-09-08, 05:33 AM
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A cold engine runs rich when you start it. Say 11-12afr. When the water temp reaches about 125* it ceases to run as rich. It'll raise that 11-12afr to 13afr, which is less fuel.
Anybody with a wideband has/can see that happen. The figures above are an example. Not hard figures.
The above might have something to do with the *five minute* period. It takes about that much time to reach 120*F.
Just in case: the afr does not gradually change from the 11-12afr to 13 plus afr, as the temps rise. It happens in one large clump.
Anybody with a wideband has/can see that happen. The figures above are an example. Not hard figures.
The above might have something to do with the *five minute* period. It takes about that much time to reach 120*F.
Just in case: the afr does not gradually change from the 11-12afr to 13 plus afr, as the temps rise. It happens in one large clump.
Last edited by HAILERS; 09-09-08 at 05:43 AM.
09-09-08, 09:32 AM
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That sounds exactly like what's happening - it's like someone flipped a switch.
You'd think that if it's not giving the engine enough fuel though that it wouldn't be flooded afterwords though and it is.
I did try starting the car, and then immediately unplugging the coolant sensor (I thought it might be the issue) to force the ECU to run it as "the limp home temperature" but that didn't seem to make any difference. It still shut down in about the same amount of time.
Grant
You'd think that if it's not giving the engine enough fuel though that it wouldn't be flooded afterwords though and it is.
I did try starting the car, and then immediately unplugging the coolant sensor (I thought it might be the issue) to force the ECU to run it as "the limp home temperature" but that didn't seem to make any difference. It still shut down in about the same amount of time.
Grant
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09-09-08, 03:39 PM
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In that case it sounds like the waterthermowax has warmed up, and its cam has fallen off the rollpin and therefore the throttle valve is going fully closed.
It kinda sounds like the engine needs to be fully warmed up, and the idle set per the FSM to approx 750rpm. Timing set with a timing light also at the same time.
It kinda sounds like the engine needs to be fully warmed up, and the idle set per the FSM to approx 750rpm. Timing set with a timing light also at the same time.
09-18-08, 10:50 AM
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OK, so now my problem has changed.
I trailered it down to a mechanic that was working for Mazda in Japan when Rotaries first came out (he worked on them for them) and he and his son worked on it.
They did some troubleshooting and sometime during that, the 5 minute shutdown issue went away on it's own but they didn't find the cause of it.
Now when you start it cold, the engine doesn't go into the fast idle warm-up, it starts revving up and down, and continues to do so until it warms up.
When cruising around 50-60 kms/hr (~30-40MPH) in 3 or 4th gear and holding your foot still on the accelerator, the car surges on and off as if you're taking your foot on and off of it but you aren't (on lasts about 3-4 seconds and off 1-2). Seems to cruise along fine though when in 5th gear doing highway speeds (around 60MPH).
If you shut the car off when it's at normal operating temperature it's extremely hard to start. The mechanic told me that he was able to restart it if he held the throttle open a little bit but I haven't had any luck with that.
The only way I've been successful at restarting is to pull the EGI fuse, turn it over for 10-20 secs, plug the fuse back in, and turn it over without touching the throttle. I'm guessing this is partly because it's flooding since it's newly rebuilt and isn't broken in yet (I'll be adding a fuel cut-off switch for this) but I think there's more to it.
The mechanic put it on the scope and found the following:
1) plugs and wires are fine and producing lots of spark
2) compression is prefect on both rotors for a newly rebuilt rotary
3) fuel injectors are working fine (showed me the chart with the pulse outputs) but when starting are cutting out with only half throttle or more (instead of full throttle) and I believe he said that during the revving up and down after a cold start, they're cutting in and out (being told to for some reason by the ECU).
4) TPS tests fine and is also within the proper narrow and wide ranges
5) coolant temp sensor seems to be fine
6) my fuel pressure line was weeping near the back wheel so he replaced that but doesn't think it had any effect on the issue as he said there's always lots of fuel.
He went ahead and did an emissions test on it as I had told him I needed to do one but I had also told him I wanted to break it in more first before trying it.
It failed with extremely high hydro-carbons (734 when limit is 64 for 2297 RPM and 1088 when limit is 200 for idle test) and CO percentages (5.64 when limit is 0.35 for 2297 RPM and 3.26 when limit is 1.00 at idle).
The HC would be caused by lots of unburnt fuel being put through but that's from not being broken in yet.
I'm hoping break-in will fix these numbers but wow - I've got a long way to go in the next month.
Anybody have any suggestions on what to look at next for the problem starting and the revving?
Grant
I trailered it down to a mechanic that was working for Mazda in Japan when Rotaries first came out (he worked on them for them) and he and his son worked on it.
They did some troubleshooting and sometime during that, the 5 minute shutdown issue went away on it's own but they didn't find the cause of it.
Now when you start it cold, the engine doesn't go into the fast idle warm-up, it starts revving up and down, and continues to do so until it warms up.
When cruising around 50-60 kms/hr (~30-40MPH) in 3 or 4th gear and holding your foot still on the accelerator, the car surges on and off as if you're taking your foot on and off of it but you aren't (on lasts about 3-4 seconds and off 1-2). Seems to cruise along fine though when in 5th gear doing highway speeds (around 60MPH).
If you shut the car off when it's at normal operating temperature it's extremely hard to start. The mechanic told me that he was able to restart it if he held the throttle open a little bit but I haven't had any luck with that.
The only way I've been successful at restarting is to pull the EGI fuse, turn it over for 10-20 secs, plug the fuse back in, and turn it over without touching the throttle. I'm guessing this is partly because it's flooding since it's newly rebuilt and isn't broken in yet (I'll be adding a fuel cut-off switch for this) but I think there's more to it.
The mechanic put it on the scope and found the following:
1) plugs and wires are fine and producing lots of spark
2) compression is prefect on both rotors for a newly rebuilt rotary
3) fuel injectors are working fine (showed me the chart with the pulse outputs) but when starting are cutting out with only half throttle or more (instead of full throttle) and I believe he said that during the revving up and down after a cold start, they're cutting in and out (being told to for some reason by the ECU).
4) TPS tests fine and is also within the proper narrow and wide ranges
5) coolant temp sensor seems to be fine
6) my fuel pressure line was weeping near the back wheel so he replaced that but doesn't think it had any effect on the issue as he said there's always lots of fuel.
He went ahead and did an emissions test on it as I had told him I needed to do one but I had also told him I wanted to break it in more first before trying it.
It failed with extremely high hydro-carbons (734 when limit is 64 for 2297 RPM and 1088 when limit is 200 for idle test) and CO percentages (5.64 when limit is 0.35 for 2297 RPM and 3.26 when limit is 1.00 at idle).
The HC would be caused by lots of unburnt fuel being put through but that's from not being broken in yet.
I'm hoping break-in will fix these numbers but wow - I've got a long way to go in the next month.
Anybody have any suggestions on what to look at next for the problem starting and the revving?
Grant
09-18-08, 11:48 AM
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****If you shut the car off when it's at normal operating temperature it's extremely hard to start. The mechanic told me that he was able to restart it if he held the throttle open a little bit but I haven't had any luck with that.********************************************* ************
On a series five, if you HOLD the pedal to the floor while cranking the engine, that act defloods the engine and it starts. You say the fuel injectors are cutting out with partial throttle during starting...........which indicates a TPS problem of some sort. A properly set TPS will show a value of approx one volt dc at idle and the engine fully HOT. I don't own a series five, so I can't EXACTLHY say when or how far the pedal has to be held down during STARTING, for the fuel injectors to cut out.
If under a cold start, the engine is reving up/down, and the injectors are cutting out during this.........I'd say the TPS is set wrong. Mild guess, since during normal driving, if you let off the pedal, the primary fuel injectors cut out til the rpms are under approx 1300rpm, where they come back on.
On a series five, if you HOLD the pedal to the floor while cranking the engine, that act defloods the engine and it starts. You say the fuel injectors are cutting out with partial throttle during starting...........which indicates a TPS problem of some sort. A properly set TPS will show a value of approx one volt dc at idle and the engine fully HOT. I don't own a series five, so I can't EXACTLHY say when or how far the pedal has to be held down during STARTING, for the fuel injectors to cut out.
If under a cold start, the engine is reving up/down, and the injectors are cutting out during this.........I'd say the TPS is set wrong. Mild guess, since during normal driving, if you let off the pedal, the primary fuel injectors cut out til the rpms are under approx 1300rpm, where they come back on.
Last edited by HAILERS; 09-18-08 at 11:55 AM.
09-18-08, 11:53 AM
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Smoke moar
****If you shut the car off when it's at normal operating temperature it's extremely hard to start. The mechanic told me that he was able to restart it if he held the throttle open a little bit but I haven't had any luck with that.********************************************* ************
On a series five, if you HOLD the pedal to the floor while cranking the engine, that act defloods the engine and it starts.
On a series five, if you HOLD the pedal to the floor while cranking the engine, that act defloods the engine and it starts.
You can also pull the master vacuum line that goes to the TB my dad did that for years before I learned the pedal to da floor cuts fuel.
Removing the EGI cuts spark & fuel, so it'll just dump the gas down the exhaust, if you hold the pedal to the floor it'll still spark, when it catches you can just let go and sometimes she'll stay on.
09-18-08, 12:54 PM
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09-18-08, 09:55 PM
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Thanks to everybody who's had suggestions.
I haven't checked the TPS since I got it back but I did set it according the service manual before it went.
I don't have it in front of me right now, but I think the narrow range is supposed to be just under 1K at idle and when I checked it (I had never changed or checked it since I got the car) it was about 1.5K. All other resistance measurements were within spec.
I swapped to another TPS as part of my troubleshooting (before taking it to the mechanic) and changed the adjustment while I had it on.
I didn't see that the different TPS made any changes to my quitting issue so I swapped back to my own (I had the other borrowed) and verified that both the narrow range and wide range were both now within spec.
I'll recheck them again but what else should I look at to verify proper setting?
Grant
I haven't checked the TPS since I got it back but I did set it according the service manual before it went.
I don't have it in front of me right now, but I think the narrow range is supposed to be just under 1K at idle and when I checked it (I had never changed or checked it since I got the car) it was about 1.5K. All other resistance measurements were within spec.
I swapped to another TPS as part of my troubleshooting (before taking it to the mechanic) and changed the adjustment while I had it on.
I didn't see that the different TPS made any changes to my quitting issue so I swapped back to my own (I had the other borrowed) and verified that both the narrow range and wide range were both now within spec.
I'll recheck them again but what else should I look at to verify proper setting?
Grant
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