Hard start when warm
Thread Starter
Instructor
Joined: Aug 2009
Posts: 146
Likes: 0
From: Broadway Virginia
FlaMale: Thanks for the link, I printed it out and will use it as a reference.
jfb: Thanks for the fuel press check procedure. If the pressure leaks down faster when hot, I presume thats not good? Or as long as it doesn't drop down to say zero to 10 psi, but is a greater drop rate to be expected when hot? Can you elaborate a bit?
I am somewhat familiar with inductance, at least I have heard of it. My father in law, is a retired electronic technician who worked for Sperry and then NASA for many years. I will ask him regarding measuring inductance and Q. He has always been a great help and resource. He actually rebuilt my Bose Amps for me when they went South.
I just need a free weekend to get all this done. I want to do my homework on the matter before I open the hood.
Also, I have not checked spark when hot yet.
MANY Thanks to all. I will let you all know what I find when time permits.
WS
jfb: Thanks for the fuel press check procedure. If the pressure leaks down faster when hot, I presume thats not good? Or as long as it doesn't drop down to say zero to 10 psi, but is a greater drop rate to be expected when hot? Can you elaborate a bit?
I am somewhat familiar with inductance, at least I have heard of it. My father in law, is a retired electronic technician who worked for Sperry and then NASA for many years. I will ask him regarding measuring inductance and Q. He has always been a great help and resource. He actually rebuilt my Bose Amps for me when they went South.
I just need a free weekend to get all this done. I want to do my homework on the matter before I open the hood.
Also, I have not checked spark when hot yet.
MANY Thanks to all. I will let you all know what I find when time permits.
WS
Drifting
Joined: May 2008
Posts: 1,694
Likes: 490
From: Denver, NC
1988 Coupe. When cold the car starts immediately when the key is turned. Problem, (what I 've noticed), is when car is warm/hot the engine takes longer to start, up to five seconds of cranking.
I do not believe that this is a starter hot soak issue as it cranks fine and at the same speed hot or cold.
I suspect either an ignition or fuel injector problem. But do not know.
Anybody have this and get it resolved? Any ideas?
Thanks in advance.
WSS
I do not believe that this is a starter hot soak issue as it cranks fine and at the same speed hot or cold.
I suspect either an ignition or fuel injector problem. But do not know.
Anybody have this and get it resolved? Any ideas?
Thanks in advance.
WSS
Injector resistance out of spec when hot is a possibility, but for it not to start, nearly the whole set would be bad - possible yes - do the test. Look at the videos in the sticky section from Jon.
Ignition components can cause this - been there have the t-shirt.
I've also seen bad coolant temp sensors cause this. I've seen sensors fail on the cold side and it starts great when the car is cold but when it's hot, it's dumping fuel.
I would start with basic data scan values and see if everything is normal.
A systematic approach to diagnostics is where you should start.
Thread Starter
Instructor
Joined: Aug 2009
Posts: 146
Likes: 0
From: Broadway Virginia
Hmmm, my exhaust pipes are black and sooty. What does that tell me?? Injectors or Temp sensor??
Crossfire: It never did idle smooth even on the day it was driven off the lot, BUT, I have noticed, (Its all perception and relative) that it does not have the 'seat of the pants kick' it used to when new, especially when an aggressive downshift is performed.
Crossfire: It never did idle smooth even on the day it was driven off the lot, BUT, I have noticed, (Its all perception and relative) that it does not have the 'seat of the pants kick' it used to when new, especially when an aggressive downshift is performed.
Thread Starter
Instructor
Joined: Aug 2009
Posts: 146
Likes: 0
From: Broadway Virginia
This is what I found so far:
Cold injector resistance readings (Ohms) All were within 15.9 to 16.1 Most were 16.0.
Fuel pressure: Cold- Initially 0, then 44lbs w/ Ign on. after 3 minutes=40, 6 min.=38,
9 min.=36, 15 min.=34, 20 min.=32, 25 min.=30, 36 min.=25.
Then, after a brief 3 minute run of the engine: 44lbs at first, then after 3 min.= 38lbs.,
6 min.= 35, 9 min.= 33, 25 min.= 26, 40 min.= 22lbs.
The fuel pressure when the engine was running at idle was steady between 37-38 lbs.
It had a slightly faster leak down rate after a brief 3minute warm up. I intend to check again after the engine is hot and up to operating temp. I will post those readings when I have them.
Until then.....comments anyone??
Cold injector resistance readings (Ohms) All were within 15.9 to 16.1 Most were 16.0.
Fuel pressure: Cold- Initially 0, then 44lbs w/ Ign on. after 3 minutes=40, 6 min.=38,
9 min.=36, 15 min.=34, 20 min.=32, 25 min.=30, 36 min.=25.
Then, after a brief 3 minute run of the engine: 44lbs at first, then after 3 min.= 38lbs.,
6 min.= 35, 9 min.= 33, 25 min.= 26, 40 min.= 22lbs.
The fuel pressure when the engine was running at idle was steady between 37-38 lbs.
It had a slightly faster leak down rate after a brief 3minute warm up. I intend to check again after the engine is hot and up to operating temp. I will post those readings when I have them.
Until then.....comments anyone??
Thread Starter
Instructor
Joined: Aug 2009
Posts: 146
Likes: 0
From: Broadway Virginia
These are the same tests but at operating temp.
Injector resistance = 17.8 Ohms
Fuel pressure
start = 44psi
5 min. = 40
10 min = 38
12 min = 33
13 min = 31
14 min =30
15 min = 28
1 hour 20 min = 16 psi
Looks like I have one or more leaky injectors???
When HOT the pressure drops faster after 10 minutes when compared to the cold test, which shows a drop sooner.
Injector resistance = 17.8 Ohms
Fuel pressure
start = 44psi
5 min. = 40
10 min = 38
12 min = 33
13 min = 31
14 min =30
15 min = 28
1 hour 20 min = 16 psi
Looks like I have one or more leaky injectors???
When HOT the pressure drops faster after 10 minutes when compared to the cold test, which shows a drop sooner.
