Timing causing dieseling??
Ok so heres an update.. Its almost 1030 and imma try again 2mrw.
Last thing we did today-
We hooked up the map sensor and zeroed out the map table.
Gradually added more and more timing until we got to 52 deg at idle. Tried it several times and lo n behold the car shuts off! We still think its too much timing at idle so brought it back down to 40 at idle and 2mrw we will mess with the carb and hopefully we get this figured out.
Any input or any more ideas?? Thanks again for all the help.
Last thing we did today-
We hooked up the map sensor and zeroed out the map table.
Gradually added more and more timing until we got to 52 deg at idle. Tried it several times and lo n behold the car shuts off! We still think its too much timing at idle so brought it back down to 40 at idle and 2mrw we will mess with the carb and hopefully we get this figured out.
Any input or any more ideas?? Thanks again for all the help.
I have watched the timing on many cars over the years from the 60s through modern and I have found that when the vacuum advance or computer is hooked up, many of them idle between 38 to 44 degrees and go above 50 at a light cruise.
The VE is so low at idle and light cruise when the throttle bodies are nearly closed that they need the additional timing to get a complete burn.
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 64
Likes: 0
From: Northern Ca
I didn't think the timing alone was going to fix it. Octane is usually what does.
Do you have a wideband? What are your AFR at idle and slightly off idle? I had and old car that had a solenoid in the carb idle circuits to turn them off and prevent dieseling. If your car is sucking too much gas through at idle combined with high compression and low octane gas, that is what causes dieseling.
Did you readjust the idle speed and mixture when you dropped the timing? Primary and secondary? What do the plugs look like?
Do you have a wideband? What are your AFR at idle and slightly off idle? I had and old car that had a solenoid in the carb idle circuits to turn them off and prevent dieseling. If your car is sucking too much gas through at idle combined with high compression and low octane gas, that is what causes dieseling.
Did you readjust the idle speed and mixture when you dropped the timing? Primary and secondary? What do the plugs look like?
When I first tried to correct this, the spark plugs were black.. I adjusted the carb, changed spark plugs, and EVERY time I have adjusted the timing, I adjust the Primary and secondarys. What is considered high compression for this motor? From what I calculated on summits compression calculator I have 10.2:1. I didnt think that was high. Is it? I use 91 oct
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 64
Likes: 0
From: Northern Ca
Just got off phone with MSD.. Them foos said too much timing? They did say it was just a recommendation. Gave em a quick run down of the setup and they did say they thought it was too much. Should I even consider what they said?
A stock LS2 is about 10.9 CR. Not really high but more than an LS1. Like I said GM says 93 octane for these motors. Is 91 your mid grade gas or the best pump stuff available to you?
If your plugs are black you are probably too rich. Is the motor recently rebuilt or well used? could the combustion chambers be carboned up? cause that could be contributing to the problem.
I can almost guarantee you that running enough octane will stop the dieseling. But you shouldn't have to run race gas either.
I think your timing is way too high, but like I said I don't think that is causing the engine to run on after the ignition is turned off.
Every now and then we get someone posting that their car diesels. They always try all sorts of stuff to make it stop but then don't seem to post what fixed it. Just get your tune right, some 93 octane gas then run it at high speed to blow out the cylinders and see what gives.
If your plugs are black you are probably too rich. Is the motor recently rebuilt or well used? could the combustion chambers be carboned up? cause that could be contributing to the problem.
I can almost guarantee you that running enough octane will stop the dieseling. But you shouldn't have to run race gas either.
I think your timing is way too high, but like I said I don't think that is causing the engine to run on after the ignition is turned off.
Every now and then we get someone posting that their car diesels. They always try all sorts of stuff to make it stop but then don't seem to post what fixed it. Just get your tune right, some 93 octane gas then run it at high speed to blow out the cylinders and see what gives.
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 64
Likes: 0
From: Northern Ca
A stock LS2 is about 10.9 CR. Not really high but more than an LS1. Like I said GM says 93 octane for these motors. Is 91 your mid grade gas or the best pump stuff available to you?
If your plugs are black you are probably too rich. Is the motor recently rebuilt or well used? could the combustion chambers be carboned up? cause that could be contributing to the problem.
I can almost guarantee you that running enough octane will stop the dieseling. But you shouldn't have to run race gas either.
I think your timing is way too high, but like I said I don't think that is causing the engine to run on after the ignition is turned off.
Every now and then we get someone posting that their car diesels. They always try all sorts of stuff to make it stop but then don't seem to post what fixed it. Just get your tune right, some 93 octane gas then run it at high speed to blow out the cylinders and see what gives.
If your plugs are black you are probably too rich. Is the motor recently rebuilt or well used? could the combustion chambers be carboned up? cause that could be contributing to the problem.
I can almost guarantee you that running enough octane will stop the dieseling. But you shouldn't have to run race gas either.
I think your timing is way too high, but like I said I don't think that is causing the engine to run on after the ignition is turned off.
Every now and then we get someone posting that their car diesels. They always try all sorts of stuff to make it stop but then don't seem to post what fixed it. Just get your tune right, some 93 octane gas then run it at high speed to blow out the cylinders and see what gives.
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 64
Likes: 0
From: Northern Ca
I can get my hands on 100 oct tonight.... Only problem is its 52.99 for 5 gallons?!?!!! jeez. can casually drive my car at that price. I will try 100 tonight if I cant get the dieseling fixed.
At that compression ratio, you should have no need to be stuck on racing fuel. This has to be a tuning issue.
I would buy a wideband a/f ratio meter like the NGK AFX. Start experimenting with idle ratios and timing. I won't take many gallons of racing fuel to pay for the wideband.
I would buy a wideband a/f ratio meter like the NGK AFX. Start experimenting with idle ratios and timing. I won't take many gallons of racing fuel to pay for the wideband.
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 64
Likes: 0
From: Northern Ca
So heres an update....
MORE TIMING AT IDLE HAS SOLVED THIS PROBLEM..
I have it at 45@ 0
52@ 1000 .
All @ 91 oct
Car starts n shuts off perfectly now. Sounds like a lot of timing, but I will keep it here unless some one has some proof of some real bad **** happening from this kinda set up. THANKS AGAIN TO ALL WHO HELPED---- Speedtigger n Popnwood special thanks yo!
MORE TIMING AT IDLE HAS SOLVED THIS PROBLEM..
I have it at 45@ 0
52@ 1000 .
All @ 91 oct
Car starts n shuts off perfectly now. Sounds like a lot of timing, but I will keep it here unless some one has some proof of some real bad **** happening from this kinda set up. THANKS AGAIN TO ALL WHO HELPED---- Speedtigger n Popnwood special thanks yo!
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Verdad Gallardo So heres an update....
MORE TIMING AT IDLE HAS SOLVED THIS PROBLEM..
I have it at 45@ 0
52@ 1000 .
All @ 91 oct
Car starts n shuts off perfectly now. Sounds like a lot of timing, but I will keep it here unless some one has some proof of some real bad **** happening from this kinda set up. THANKS AGAIN TO ALL WHO HELPED---- Speedtigger n Popnwood special thanks yo!
MORE TIMING AT IDLE HAS SOLVED THIS PROBLEM..
I have it at 45@ 0
52@ 1000 .
All @ 91 oct
Car starts n shuts off perfectly now. Sounds like a lot of timing, but I will keep it here unless some one has some proof of some real bad **** happening from this kinda set up. THANKS AGAIN TO ALL WHO HELPED---- Speedtigger n Popnwood special thanks yo!
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 64
Likes: 0
From: Northern Ca
I feel the same way... Way too much timing right? But my car starts perfectly, n shuts off perfectly. When I say perfect i mean it. Before it would struggle to start, but now it starts right every time. Shutting off is right on too. I still am unsure bout it too, n early this week i will mess with it some more. What are some warning signs I should look out for? The timing drops down after 1000, to 37 all the way thru. I figure if the car starts n shuts off waaaaaaay better than it did before, problem solved? Maybe i still have more work to do...
Can't argue with results. Just keep an ear out for detonation.
I would honestly try and rig up some type of timing mark to double check what the box is telling you. IDK, is it possible for the crank sensor to be off by 30 degrees or something?
What is your idle speed and what timing is it showing at idle?
I would honestly try and rig up some type of timing mark to double check what the box is telling you. IDK, is it possible for the crank sensor to be off by 30 degrees or something?
What is your idle speed and what timing is it showing at idle?
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 64
Likes: 0
From: Northern Ca
Can't argue with results. Just keep an ear out for detonation.
I would honestly try and rig up some type of timing mark to double check what the box is telling you. IDK, is it possible for the crank sensor to be off by 30 degrees or something?
What is your idle speed and what timing is it showing at idle?
I would honestly try and rig up some type of timing mark to double check what the box is telling you. IDK, is it possible for the crank sensor to be off by 30 degrees or something?
What is your idle speed and what timing is it showing at idle?
My idle is at 750.. Showing about 44 @ that.. I could try n mark the dampner to see if its really right. As far the sensor being of 30, i have no clue bout that. Like i said tho i will b messing with it some more this week. And just an fyi i didnt just jump to 50 degrees and conlcude it works. I gradually tried less timing (got worse) then gradually tried more timing (got better). I also read some post where a member had a mustang with an LS and he said the only correction he could find was more timing. Around 50+ for his setup. My car stays at about 180 degrees, idles healthy, nothing seems outta place other than the numbers
Thread Starter
Staging Lane
Joined: Oct 2011
Posts: 64
Likes: 0
From: Northern Ca
UPDATE UPDATE UPDATE
So after taking what yall said about way too much timing, i finally got around to trying a different setup.
First i set a curve that made sense. (Atleast from what ive researched)
15*@0
30*@1800
36@2600 all in after.
So once i set that i started messing with the map advance. I didnt touch the curve, just kept tweaking the map graph. Until i got a steady reading from all the gauages. I kept raising the map graph between 10* and 25* ... Got to 24psia, gauges steadied out, (total timing @ idle was 45*) car was hot already, tried to shut off n it shut right off. When i started it, it started right up! Let it run for a while drove around a bit, then shut it off and NO DIESELING.
I feel now i really have this issue resolved?? What do u guys think? Looking back i now realize i have a big *** cam.. i may have needed more vacuum out the gates? Anyways thought i would fill yall in, let me know if this seems right to yall.
So after taking what yall said about way too much timing, i finally got around to trying a different setup.
First i set a curve that made sense. (Atleast from what ive researched)
15*@0
30*@1800
36@2600 all in after.
So once i set that i started messing with the map advance. I didnt touch the curve, just kept tweaking the map graph. Until i got a steady reading from all the gauages. I kept raising the map graph between 10* and 25* ... Got to 24psia, gauges steadied out, (total timing @ idle was 45*) car was hot already, tried to shut off n it shut right off. When i started it, it started right up! Let it run for a while drove around a bit, then shut it off and NO DIESELING.
I feel now i really have this issue resolved?? What do u guys think? Looking back i now realize i have a big *** cam.. i may have needed more vacuum out the gates? Anyways thought i would fill yall in, let me know if this seems right to yall.