Hard start
12-12-2012, 07:10 PM
#1
Got Nothin'
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Hard start
My car is giving me fits trying to start when cold. (As in hasn't run for a while)...it's 80 here in FL today.
I thought I was not getting fuel pressure. But that does not appear to be the case. As you can see in this video http://youtu.be/CxOjJxZRSpE the fuel pressure comes right up and stays even though the car is not starting. Eventually it will fire, run rough, die once or twice and then stay running.
The car is an 86 n/a and the engine was rebuilt last year, for a while things were great, but now it is a pain to get started.
Appreciate advice.
I thought I was not getting fuel pressure. But that does not appear to be the case. As you can see in this video http://youtu.be/CxOjJxZRSpE the fuel pressure comes right up and stays even though the car is not starting. Eventually it will fire, run rough, die once or twice and then stay running.
The car is an 86 n/a and the engine was rebuilt last year, for a while things were great, but now it is a pain to get started.
Appreciate advice.
12-12-2012, 07:40 PM
#3
Got Nothin'
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have not checked this particular temp sensor it was new with the rebuild. I have another. Can swap.
Tach bounces. Runs like a scalded cat once started and stabilized...good acceleration, smooth idle etc.
But we can definitely check the temp sensor.
Tach bounces. Runs like a scalded cat once started and stabilized...good acceleration, smooth idle etc.
But we can definitely check the temp sensor.
12-13-2012, 09:35 AM
#4
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Pete,
Nice inventory of vehicles.
The video is painful to listen to for the first 20 seconds.
quote- "The car is an 86 n/a and the engine was rebuilt last year, for a while things were great, but now it is a pain to get started."
Fara & sponsor 944 online have the same idea about the engine temp sensor:
http://www.944online.com/cgi-bin/for...num=1294677445
I tend to go back to basics when "for a while things were great" .
Positive battery connection, especially the small 3 wires. Clean and tighten. If the end is corroded, cut and replace with a military cable end (NAPA)
When you got the engine rebuilt, did you send the injectors to get cleaned, balanced and resealed? A leaky injector can cause "flooding" and hard starts.
Did you replace the FPR & FPD? Old parts cause problems with a rebuilt engine.
Clean and gap the reference sensors. Check the connector for cracks. bad pins, cracked sheilding or just replace if old.
Check for vacuum leaks. RL member mytrplseven made a simple tool:
http://forums.pelicanparts.com/6192985-post1.html
Does the AFM "door" move freely"? Clean all electrical connections on top of engine.
GL
J_AZ
Nice inventory of vehicles.
The video is painful to listen to for the first 20 seconds.
quote- "The car is an 86 n/a and the engine was rebuilt last year, for a while things were great, but now it is a pain to get started."
Fara & sponsor 944 online have the same idea about the engine temp sensor:
http://www.944online.com/cgi-bin/for...num=1294677445
I tend to go back to basics when "for a while things were great" .
Positive battery connection, especially the small 3 wires. Clean and tighten. If the end is corroded, cut and replace with a military cable end (NAPA)
When you got the engine rebuilt, did you send the injectors to get cleaned, balanced and resealed? A leaky injector can cause "flooding" and hard starts.
Did you replace the FPR & FPD? Old parts cause problems with a rebuilt engine.
Clean and gap the reference sensors. Check the connector for cracks. bad pins, cracked sheilding or just replace if old.
Check for vacuum leaks. RL member mytrplseven made a simple tool:
http://forums.pelicanparts.com/6192985-post1.html
Does the AFM "door" move freely"? Clean all electrical connections on top of engine.
GL
J_AZ
12-13-2012, 11:56 AM
#5
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Thanks for the reply - responses in bold below...
Pete,
Nice inventory of vehicles. --Thanks!
The video is painful to listen to for the first 20 seconds. - I suck at editing video....
quote- "The car is an 86 n/a and the engine was rebuilt last year, for a while things were great, but now it is a pain to get started."
Fara & sponsor 944 online have the same idea about the engine temp sensor:
http://www.944online.com/cgi-bin/for...num=1294677445 Yes...the engine temp sensor is the only thing that is common to hard-starting AND rough running when cold. But it is relatively (with the rebuild) new.
I tend to go back to basics when "for a while things were great" .
Positive battery connection, especially the small 3 wires. Clean and tighten. If the end is corroded, cut and replace with a military cable end (NAPA) - I can certainly clean the connections and take a look.
When you got the engine rebuilt, did you send the injectors to get cleaned, balanced and resealed? A leaky injector can cause "flooding" and hard starts. -- Actually replaced the injectors with new ones.
Did you replace the FPR & FPD? Old parts cause problems with a rebuilt engine.
I have swapped the FPR, the damper was relatively new.
Clean and gap the reference sensors. Check the connector for cracks. bad pins, cracked sheilding or just replace if old.
-- I need to pull the sensors and take a look at them.
Check for vacuum leaks. RL member mytrplseven made a simple tool:
http://forums.pelicanparts.com/6192985-post1.html
-- Will continue to look, but I think the vac system is tight.
Does the AFM "door" move freely"? Clean all electrical connections on top of engine. - The AFM door does move freely.
GL
J_AZ
Nice inventory of vehicles. --Thanks!
The video is painful to listen to for the first 20 seconds. - I suck at editing video....
quote- "The car is an 86 n/a and the engine was rebuilt last year, for a while things were great, but now it is a pain to get started."
Fara & sponsor 944 online have the same idea about the engine temp sensor:
http://www.944online.com/cgi-bin/for...num=1294677445 Yes...the engine temp sensor is the only thing that is common to hard-starting AND rough running when cold. But it is relatively (with the rebuild) new.
I tend to go back to basics when "for a while things were great" .
Positive battery connection, especially the small 3 wires. Clean and tighten. If the end is corroded, cut and replace with a military cable end (NAPA) - I can certainly clean the connections and take a look.
When you got the engine rebuilt, did you send the injectors to get cleaned, balanced and resealed? A leaky injector can cause "flooding" and hard starts. -- Actually replaced the injectors with new ones.
Did you replace the FPR & FPD? Old parts cause problems with a rebuilt engine.
I have swapped the FPR, the damper was relatively new.
Clean and gap the reference sensors. Check the connector for cracks. bad pins, cracked sheilding or just replace if old.
-- I need to pull the sensors and take a look at them.
Check for vacuum leaks. RL member mytrplseven made a simple tool:
http://forums.pelicanparts.com/6192985-post1.html
-- Will continue to look, but I think the vac system is tight.
Does the AFM "door" move freely"? Clean all electrical connections on top of engine. - The AFM door does move freely.
GL
J_AZ
12-13-2012, 12:07 PM
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Pete, are you pressing the throttle at all when it doesn't want to start?
Next time it does this, try giving it ~80% throttle - it sounds to me like there is too much fuel.
Definitely check the coolant temp sensor (the one for the DME), and the associated wiring. If there is a short in the wiring, it will cause the DME to add a bunch of extra fuel.
The main battery -> engine ground is very important too. I even run a second supplemental ground to the block from the battery.
Finally, how old are you spark-plugs, and what gap?
Next time it does this, try giving it ~80% throttle - it sounds to me like there is too much fuel.
Definitely check the coolant temp sensor (the one for the DME), and the associated wiring. If there is a short in the wiring, it will cause the DME to add a bunch of extra fuel.
The main battery -> engine ground is very important too. I even run a second supplemental ground to the block from the battery.
Finally, how old are you spark-plugs, and what gap?
12-13-2012, 12:46 PM
#7
Got Nothin'
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Rogue - Thanks...replies in bold.
-new with the rebuild.
Pete, are you pressing the throttle at all when it doesn't want to start? -- No, always foot off throttle when starting.
Next time it does this, try giving it ~80% throttle - it sounds to me like there is too much fuel. -- The fuel pressure at start-up appears to be in spec. (see you tube video) unless I am reading the gauge wrong. Would too much fuel show
Definitely check the coolant temp sensor (the one for the DME), and the associated wiring. If there is a short in the wiring, it will cause the DME to add a bunch of extra fuel. -- This seems to be a recurring theme.
The main battery -> engine ground is very important too. I even run a second supplemental ground to the block from the battery. -- I have upgraded battery cables installed (Light-shark)
Finally, how old are you spark-plugs, and what gap?
Next time it does this, try giving it ~80% throttle - it sounds to me like there is too much fuel. -- The fuel pressure at start-up appears to be in spec. (see you tube video) unless I am reading the gauge wrong. Would too much fuel show
Definitely check the coolant temp sensor (the one for the DME), and the associated wiring. If there is a short in the wiring, it will cause the DME to add a bunch of extra fuel. -- This seems to be a recurring theme.
The main battery -> engine ground is very important too. I even run a second supplemental ground to the block from the battery. -- I have upgraded battery cables installed (Light-shark)
Finally, how old are you spark-plugs, and what gap?
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12-13-2012, 12:55 PM
#8
Proprietoristicly Refined
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OK,
This is what I see as a problem:
Clean and gap the reference sensors. Check the connector for cracks. bad pins, cracked sheilding or just replace if old.
-- I need to pull the sensors and take a look at them.
Check the flywheel pins when you pull the sensors.
COVER THE TDC HOLE WITH DUCT TAPE--do not let a bolt fall in the clutch
There are half price reference sensor interchanges available-usually a early '85 BMW will work.
J_AZ
This is what I see as a problem:
Clean and gap the reference sensors. Check the connector for cracks. bad pins, cracked sheilding or just replace if old.
-- I need to pull the sensors and take a look at them.
Check the flywheel pins when you pull the sensors.
COVER THE TDC HOLE WITH DUCT TAPE--do not let a bolt fall in the clutch
There are half price reference sensor interchanges available-usually a early '85 BMW will work.
J_AZ
12-13-2012, 12:55 PM
#9
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The fuel pressure looks good, but that doesn't mean the injectors are running too long of a pulse duration... which would be caused by the coolant temp / wiring and or the AFM sticking / bad.
By giving it some throttle when trying to start, you are adding air... if it is too rich, then adding air should help it start.
Good to hear that you have the upgraded cables! I still would double-check that the one going to the block/bellhousing is tight.
By giving it some throttle when trying to start, you are adding air... if it is too rich, then adding air should help it start.
Good to hear that you have the upgraded cables! I still would double-check that the one going to the block/bellhousing is tight.
12-13-2012, 01:15 PM
#10
Got Nothin'
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When I get home from work, I will try to start with throttle depressed. Easy and cheap to do.
I will look at the coolant temp sensor. It is brand new with the rebuild, but that doesn't mean good.
Then I will check the speed/ref sensors.
Sounds like a fun night.
I will look at the coolant temp sensor. It is brand new with the rebuild, but that doesn't mean good.
Then I will check the speed/ref sensors.
Sounds like a fun night.
12-13-2012, 01:52 PM
#12
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12-13-2012, 05:17 PM
#14
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The repeatability of it all is maddening. it is consistently hard to start, and it takes about the same number of attempts, with the same process. no fire, no fire, no fire. cough, cough, run and die, run and die..run -- poorly and eventually smooth out.
Just like the video. Wouldn't ref sensors be good, or not?
Just like the video. Wouldn't ref sensors be good, or not?
12-13-2012, 05:37 PM
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The repeat-ability is a good thing - it makes diagnosis easier...
Reference sensors give a weaker signal at low engine speeds, but that doesn't sound like your issue. Your issue sounds like fueling.
Reference sensors give a weaker signal at low engine speeds, but that doesn't sound like your issue. Your issue sounds like fueling.