Datamaster logs - Something not right with my LT1 - Any ideas?
02-24-2010, 07:05 PM
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Datamaster logs - Something not right with my LT1 - Any ideas? Hello, I recently did an engine upgrade (see sig) and of course it didn't just run perfectly, had to fix a bunch of things done wrong.
Right now I'm out of ideas. What is still happening is the engine feels hesitant. Idle fluctuates a bit too much, at low rpm it hesitates/bogs down, makes for a crappy ride. Starts up fast enough cold, but sometimes cranks too much when starting it warm.
I did pretty much everything LE recommended but I don't completely trust the people who actually did the work.
When given 50%+ throttle it seems like it pulls ok, maybe a bit hesitant, much more power than before the build but still there's definitely something wrong here. It's very uncomfortable to drive "normally".
I attached some logs I took tonight. They progress from cold start, cold running to full temperature running. Run6 I think is the most useful since it is the perfect example of my problems: bogging down a lot while running at 1500-1700 RPM constantly.
If you have any ideas please let me know.
Right now I'm out of ideas. What is still happening is the engine feels hesitant. Idle fluctuates a bit too much, at low rpm it hesitates/bogs down, makes for a crappy ride. Starts up fast enough cold, but sometimes cranks too much when starting it warm.
I did pretty much everything LE recommended but I don't completely trust the people who actually did the work.
When given 50%+ throttle it seems like it pulls ok, maybe a bit hesitant, much more power than before the build but still there's definitely something wrong here. It's very uncomfortable to drive "normally".
I attached some logs I took tonight. They progress from cold start, cold running to full temperature running. Run6 I think is the most useful since it is the perfect example of my problems: bogging down a lot while running at 1500-1700 RPM constantly.
If you have any ideas please let me know.
02-24-2010, 07:16 PM
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What I can easily notice from the logs, but have no idea how to interpret, is:
1 - STermCounts have a tendency to go down to 110 from time to time
2 - Spark advance jumps up from 40 to 44 and goes down to 35 then goes back to 39-40 in split seconds - 10 degree fluctuation
3 - LTermCounts are higher than normal and when idleing passenger side is 150ish while drivers is 130ish.
Apparently 1 and 2 are related as they seem to happen at about the same time. I can guess whenever the advance wonders the bogging/shaking happens.
1 - STermCounts have a tendency to go down to 110 from time to time
2 - Spark advance jumps up from 40 to 44 and goes down to 35 then goes back to 39-40 in split seconds - 10 degree fluctuation
3 - LTermCounts are higher than normal and when idleing passenger side is 150ish while drivers is 130ish.
Apparently 1 and 2 are related as they seem to happen at about the same time. I can guess whenever the advance wonders the bogging/shaking happens.
Last edited by flexusz28; 02-25-2010 at 06:59 AM.
02-25-2010, 07:02 AM
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I'll try reprogramming the PCM as a number of fixes + fuel upgrade have happened since last written.
I have noticed the PCM retains some memory even after battery disconnect. For example after fixing problems with idle air it wouldn't idle right whatever I did except a completely new PCM write. Worked perfectly after.
Up! Any other ideas?
I have noticed the PCM retains some memory even after battery disconnect. For example after fixing problems with idle air it wouldn't idle right whatever I did except a completely new PCM write. Worked perfectly after.
Up! Any other ideas?
02-27-2010, 03:56 PM
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We took out the plugs, took pressure readings and adjusted the valves.
- 1 plug was completely black, 2 were half black
- 1 cyl wasn't making much pressure, 2 were slow to do so
- valves were of two kinds: some didn't close and others didn't let the lifters fill up.
Ran like this for 300 miles or something. No point explaining why this happened. Sufficient to say it's hard to get decent help around here.
Fixes:
- re-checked gap and shuffled plugs back in
- released all valves until zero lash (2 complete turns) and ran the engine (5 minutes) until all lifters started push oil up the pushrods on the rockers;
- with all lifters solid we went zero-lash + small preload, started engine, no clicking/noise.
Results:
- smoother and more stable idle, better revving
- faster starting up
- exhaust still smells like fuel, brings tears to eyes and chokes
- bogging/shaking still there, but significantly less violent - still not good enough to let pass.
I'll take some more running datalogs tomorrow and see how things show.
Attached is a log recorded at idle after we finished today.
- 1 plug was completely black, 2 were half black
- 1 cyl wasn't making much pressure, 2 were slow to do so
- valves were of two kinds: some didn't close and others didn't let the lifters fill up.
Ran like this for 300 miles or something. No point explaining why this happened. Sufficient to say it's hard to get decent help around here.
Fixes:
- re-checked gap and shuffled plugs back in
- released all valves until zero lash (2 complete turns) and ran the engine (5 minutes) until all lifters started push oil up the pushrods on the rockers;
- with all lifters solid we went zero-lash + small preload, started engine, no clicking/noise.
Results:
- smoother and more stable idle, better revving
- faster starting up
- exhaust still smells like fuel, brings tears to eyes and chokes
- bogging/shaking still there, but significantly less violent - still not good enough to let pass.
I'll take some more running datalogs tomorrow and see how things show.
Attached is a log recorded at idle after we finished today.
03-04-2010, 10:54 PM
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same thing Hey I am having a lot of the same problems you are. I wanted to see if you could tell me more about the Sterm counts and Lterm counts. I dnt know what these are but I do know on my Tech2 scanner it says the long term is 108 at idle and the other 3 are all around 122-126. The 4th one doesnt catch up to these numbers until I am in the throttle moving. Plus my low res circuit code keeps tripping and shutting the car off hard. Also when I'm driving and just costing I can feel the car buck just a little. Any ideas there? Lastly my KS Actuvity keeps reading counts north of 80 up to 113 or more. What is this. I assume it Knock Sensor activity but I can't hear any egine knowck and I ahve no loss of performance. I drove the car and the low res code popped killed the car so I cleared the code with the tech 2 and it drove fine. I even slammed the pedal to the floor at about 15 mph the car hooked and took off like it was nothing and yet that were no prblems no backfire no bucking nothing it ran hard and strong. Do you have any ideas for me? I am really new to the diagnostics side of the car. Thank You
03-04-2010, 11:49 PM
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We have a new idea.
The plugs that weren't black were very white and clean. Too much so actually. We attribute permanently open valves to the blackening so the cylinders that did burn we suspect aren't burning right anyway.
I've looked it up on the net and it says that white clean plugs means too hot/lean. At idle the oxygen sensors show lean as you noticed, and on the passenger side very lean.
I'm already using 2 steps colder plugs (Autolite 104 gapped at 0.032").
I'm thinking maybe the engine isn't burning right and this is what is causing the surging and the rough running. What if there's not enough fuel... I have upgraded injectors (Trickflow #30) and custom tune for all my mods, but it's mailorder still.
After reading around a bit I've added to the list of things to check:
- fuel pump / regulator / check pressure (the filter is new) - besides the leanness shown at idle (140-160 LTermCounts) and even while accelerating by the oxygen sensors (135 LTermCounts) and foul exhaust smell, I could swear the car runs less badly with more fuel in the tank than with almost empty tank
- EGR Valve - used to give code all the time, we soaked it in anti-seize and gave it a few whacks to make it come back (it's kinda new), but still...
No cats for a while now, even before the build. The way it smells and stings now though is waaay more aggressive. From what I've read high NOx comes from high temps in engine which come from leanness, so I find the gasses support the "not enough gas" theory
If i were to consider changing the fuel pump, what should I go for? Can I just bolt on an in-line pump after the original one without removing that one? What options do I have?
383Camaro95:
Code 16- Low resolution pulse (distributor) - looks like an opti failure code here!
LTermCounts is the integrated result of the O2 sensors which shows how rich/lean the car runs. 128 is perfect, more than that is lean, less is rich. STerm are integrated values also but on smaller periods of time, as far as I know the LTerm are the ones to watch for.
Unfortunately these values are easily affected by air leaks in the exhaust or intake.
Knock sensor counts are nothing to be afraid of, they show up even if there is no knock, you only need to worry if they increment really fast, every once in a while is ok (even engine startup itself is read as knock).
The plugs that weren't black were very white and clean. Too much so actually. We attribute permanently open valves to the blackening so the cylinders that did burn we suspect aren't burning right anyway.
I've looked it up on the net and it says that white clean plugs means too hot/lean. At idle the oxygen sensors show lean as you noticed, and on the passenger side very lean.
I'm already using 2 steps colder plugs (Autolite 104 gapped at 0.032").
I'm thinking maybe the engine isn't burning right and this is what is causing the surging and the rough running. What if there's not enough fuel... I have upgraded injectors (Trickflow #30) and custom tune for all my mods, but it's mailorder still.
After reading around a bit I've added to the list of things to check:
- fuel pump / regulator / check pressure (the filter is new) - besides the leanness shown at idle (140-160 LTermCounts) and even while accelerating by the oxygen sensors (135 LTermCounts) and foul exhaust smell, I could swear the car runs less badly with more fuel in the tank than with almost empty tank
- EGR Valve - used to give code all the time, we soaked it in anti-seize and gave it a few whacks to make it come back (it's kinda new), but still...
No cats for a while now, even before the build. The way it smells and stings now though is waaay more aggressive. From what I've read high NOx comes from high temps in engine which come from leanness, so I find the gasses support the "not enough gas" theory
If i were to consider changing the fuel pump, what should I go for? Can I just bolt on an in-line pump after the original one without removing that one? What options do I have?
383Camaro95:
Code 16- Low resolution pulse (distributor) - looks like an opti failure code here!
LTermCounts is the integrated result of the O2 sensors which shows how rich/lean the car runs. 128 is perfect, more than that is lean, less is rich. STerm are integrated values also but on smaller periods of time, as far as I know the LTerm are the ones to watch for.
Unfortunately these values are easily affected by air leaks in the exhaust or intake.
Knock sensor counts are nothing to be afraid of, they show up even if there is no knock, you only need to worry if they increment really fast, every once in a while is ok (even engine startup itself is read as knock).
Last edited by flexusz28; 03-05-2010 at 02:22 AM.
03-05-2010, 06:12 AM
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Another thing to think about is a voltage booster kit that increases the power to your fuel pump and entire electrical system at throttle openings above 80%.
There is also a kit that increases the wire gage size to your fuel pump. Because of the N2O on the car, I have all of the above except the Walbro in tank pump. My fuel pump is basically new and I didn't want to pull that one out. One last thing is to make certain you have a new fuel filter of course.
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03-06-2010, 02:44 PM
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Ty for the info 
We did some more testing today.
1.First we checked the spark plugs - they were white with faded black areas.
2.We checked for false air with some spray - nothing found.
3.Tried changing the injector flow rate setting in the tune to 36 (ran like crap), 28 and 26 (ran ok/same, LTermCounts came down in both idle and 17 and 18 fuel cells).
4.Left it set at 27 lb/hr and went out for a ride. It ran smoother (exhaust sounds like it flows better), still surges, less violent.
5.Checked plugs again - white and the black areas went away. LTermcounts are 130 left 140 right at idle, fuel cells 17 and 18 are 126 left 129 right.
I still have to check the fuel pressure as we didn't have this tool available. If fuel pressure shows problems I'll go for a new pump, else I am thinking maybe I need even colder plugs (I have Autolite 104, maybe I should go 103/102?).
LATER EDIT: New datalog on the 27lb/hr tune
We did some more testing today.
1.First we checked the spark plugs - they were white with faded black areas.
2.We checked for false air with some spray - nothing found.
3.Tried changing the injector flow rate setting in the tune to 36 (ran like crap), 28 and 26 (ran ok/same, LTermCounts came down in both idle and 17 and 18 fuel cells).
4.Left it set at 27 lb/hr and went out for a ride. It ran smoother (exhaust sounds like it flows better), still surges, less violent.
5.Checked plugs again - white and the black areas went away. LTermcounts are 130 left 140 right at idle, fuel cells 17 and 18 are 126 left 129 right.
I still have to check the fuel pressure as we didn't have this tool available. If fuel pressure shows problems I'll go for a new pump, else I am thinking maybe I need even colder plugs (I have Autolite 104, maybe I should go 103/102?).
LATER EDIT: New datalog on the 27lb/hr tune
Last edited by flexusz28; 03-06-2010 at 04:24 PM.
03-08-2010, 12:06 PM
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Look what I found on some Volvo forum, quoted from the manuals:
Fault Symptoms: faulty fuel pump will cause low line pressure.
The following symptoms may arrise.
- engine difficult to start or does not start
- engine misfires during driving, under heavy load
- poor acceleration
- poor engine performance
This is spot on with my symptoms.
On top of this we have noticed the following:
- lowering the injector rating made the car run better
- in time, the car is slowly running and pulling worse
- after pushing it harder for a few minutes it runs like crap
- after reverting to the 30lb/hr tune the O2 sensors are showing even leaner condition, 150/160 at idle and 135-140 running...
Fault Symptoms: faulty fuel pump will cause low line pressure.
The following symptoms may arrise.
- engine difficult to start or does not start
- engine misfires during driving, under heavy load
- poor acceleration
- poor engine performance
This is spot on with my symptoms.
On top of this we have noticed the following:
- lowering the injector rating made the car run better
- in time, the car is slowly running and pulling worse
- after pushing it harder for a few minutes it runs like crap
- after reverting to the 30lb/hr tune the O2 sensors are showing even leaner condition, 150/160 at idle and 135-140 running...
Last edited by flexusz28; 03-08-2010 at 04:46 PM.
03-09-2010, 06:12 PM
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Getting a Racetronix Fuel Pump Assembly. Should be plenty for my setup. Can upgrade it later with the harness for even more juice.
Will let you know if this fixed it.
Will let you know if this fixed it.
03-10-2010, 08:14 AM
#12
spark plugs You should never clean fuel fouled plugs (Black), for what ever reason after fouling even if they have a couple of miles on them it seems to just ruin the plugs. I had several cars where they had installed larger injectors and tried to drive the car, of course the plugs got fouled. I told the customers to install new plugs but since they only had a couple of miles on them, they decided to just clean them, Tuned the car and it still hesitated, had a miss, I told them to install new plugs....problem went away...
03-10-2010, 12:01 PM
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I know of this rule and I would go ahead and change them (I have a set of spares) if the symptoms weren't this severe.
I can't imagine they could fail so bad that they would cause problems this severe. I will change them though as soon as I consider I've solved the big problems. If I do it now I am afraid I'll kill the new ones too...
As I said, the way the engine runs is seriously affected by how I set the injector flow rate, meaning it runs crap with the correct value and only runs a bit better with lower rating! How would the spark plugs affect this? Also the problem is progressing, it's running more and more crappy
I do sound sort-of fixed on the fuel pump idea, but I can't see anything else I could do right now. The only thing I'm afraid of is that something else in the fuel delivery system is faulty (except the filter which is new). I can't check pressures as no-one seems to have the equipment. Hopefully the pump alone fixes it.
I can't imagine they could fail so bad that they would cause problems this severe. I will change them though as soon as I consider I've solved the big problems. If I do it now I am afraid I'll kill the new ones too...
As I said, the way the engine runs is seriously affected by how I set the injector flow rate, meaning it runs crap with the correct value and only runs a bit better with lower rating! How would the spark plugs affect this? Also the problem is progressing, it's running more and more crappy
I do sound sort-of fixed on the fuel pump idea, but I can't see anything else I could do right now. The only thing I'm afraid of is that something else in the fuel delivery system is faulty (except the filter which is new). I can't check pressures as no-one seems to have the equipment. Hopefully the pump alone fixes it.
Last edited by flexusz28; 03-10-2010 at 12:07 PM.
03-10-2010, 12:38 PM
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The plugs would make the engine run bad of course it they are fouled, The pump may be the problem in that if the pressure is fluctuating then the PCM might be trying to adjust to the IFR, maybe this is why when you change the flow rate it seems to run a little better. So no one/shop has a guage that they can connect to the fuel rail?
03-10-2010, 12:54 PM
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The plugs were never really soaked/black. 3 of them were partially smoked but not all the way to the tip, the rest were clean.
Right now they're pretty clean white all around (after adjusting the valves on all cyls)...
I've asked around for a pressure gauge and no-one seems to have anything like this... I'd have to buy one myself and figured I'd rather buy the pump then equipment to diagnose the stock one
Right now they're pretty clean white all around (after adjusting the valves on all cyls)...
I've asked around for a pressure gauge and no-one seems to have anything like this... I'd have to buy one myself and figured I'd rather buy the pump then equipment to diagnose the stock one
03-10-2010, 02:08 PM
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We cleaned it as instructed by LE at the time of the rebuild.
It seems to work fine... You can look at "27lb tune run" file a few posts back, it's the latest recording. AGFS doesn't fluctuate much at approximately constant 1500 rpm in 4th gear (16.2 +- .4), varies every few recordings but not randomly...
No error codes pop up.
It seems to work fine... You can look at "27lb tune run" file a few posts back, it's the latest recording. AGFS doesn't fluctuate much at approximately constant 1500 rpm in 4th gear (16.2 +- .4), varies every few recordings but not randomly...
No error codes pop up.
