see if you can datalog this condition as it happens. look at your afr, spark timing and knock sensor. if the computer sees something it doesnt like it will go into power reduction mode. it appears your tune is a bit rich at the top end and you maybe causing misfires from the plugs failing. it doesnt take much for spark plugs to get damaged from excessively rich conditions, lean conditions and spark knock/detonation.
AFR are in the 11.x:1 during the WOT acceleration. Afterwards they are at 10.0:1 when it flatlines at 3-4k RPM.
Spark timing has been between is strange. in one instance it was in the twenties and drop to the tens and flatline there (i.e. was at 24 and dropped to 16 and stayed there). But then another time it did the opposite (i.e. was at 16 and jumped to 22 and stayed there).
As for knock retard, always at 0.
When I am logging info everything seems to act in conjunction. everything is high or rising as it accelerates at WOT and then everything drops and flatlines after the engine cuts off. RPM, Load, MAP, Ignition, Injectors Pulse, etc. I'll see if I can post an example.
Mine did the same thing, it was the fuel regulator under hard boost.
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I might have to look into the FPR, since my idle PSI has been noticibly getting lower.
As for updates: I was inspecting the harness and replaced a few connectors. I was suprised to find that some of thre wires had become discolored as if the wire was pulling too many amps and was overheating. Recall that I had previously mentioned that this discoloration was present on the blue connector of the harness that plugs into the PCM.
This discoloration was especially noticeable in the wiring before the connector that plugs into the injector and MAP harness. After splicing, sodering, and heat shriking the new connectors/wires, the throttle response is nicer, but the original problem still persist, although now it will rev up to 6400 RPM before it cuts off. And as before, it will only occur when WOT from a stop or under apprx. 35 MPH (when the transmission is still able to down shift into first).
So next is either a complete harness or the PCM.
As an update:
I've replaced the ICM and parts of the harness. No change other than now it revs to 6400 RPM and then cuts off.
Thoughts might be of a damaged ECM, full harness, or the transmission sensor or foward clutch problem.
Probably will swap in old tranny and see what happens or get another ECM first.
Jesus. If you need another ecm I might have an auto/abs/cruise one laying in my cache of jbody parts. Shoot me a pm if you decide to do that.
its running too rich. if too much fuel is being injected into the engine the spark plugs/coil cant ignite the fuel as there is not enough air to burn the fuel. when this happens the engine will not rev anymore and have no power. your afr gauge only reads as rich as 10:1 but your actual afr can be lower. afr of 8:1 or lower cannot sustain ignition. so at that specific rpm your losing power, i can assume your afr is at 8:1.
have it re-tuned
if his afrs are 8:1, then there is something more going one. I know the GM flash runs rich, but that is almost rediculous. especially considering he is running a smaller pulley too.
JOE L wrote:its running too rich. if too much fuel is being injected into the engine the spark plugs/coil cant ignite the fuel as there is not enough air to burn the fuel. when this happens the engine will not rev anymore and have no power. your afr gauge only reads as rich as 10:1 but your actual afr can be lower. afr of 8:1 or lower cannot sustain ignition. so at that specific rpm your losing power, i can assume your afr is at 8:1.
have it re-tuned
Good god please shut up before you spout more misinformation...
If AF mix can't ignite at 8:1 why do most ICE's running on gasoline have to be started at near 2:1 or 3:1 AFR? Plus think about what you said.. what conducts electricity better... air or water? Fuel is the same way, fuel is a better conductor than air. Now it COULD be that the fuel is causing the spark to travel up the plug instead of going across the gap. but this is not the issue, liquid fuel should never make it into the combustion chamber at these kind of RPM's and boost levels.
Lets look at this problem here people... He is running into a wall almost every time at the same RPM... This has nothing to do with ignition or parts or anything else for that matter. IF it did it would have been occurring at different RPM's
To the OP... Fix your damn car first, then worry about this issue if it;s still around. The TFP issue HAS to be addressed. This very well could be the cause of your issue...Honestly, something as important as a TFP switch or circuit would be the FIRST thing I would fix regardless of what the drive ability symptoms are.
IF you do not have HPT I doubt you will be able to fix this issue. This sounds ALOT like a torque management issue... Try unplugging your IAT on a colder day and running the car. It will enable limp in mode and will shift hard after a few minutes but should disable torque management. If it pulls just fine I would bet it is a torque management issue. In which case you will need to re tune with HPT.
Buildin' n' Boostin for 08' - Alex Richards
Sorry for the double post, but also if it was a misfire condition (ignition or fuel misfire) it would read lean... not rich. So thats another clue that should have been looked at before the OP dumped money into replacing parts.
The 10:1 is normal... ignore it for now, the issue is the vehicle laying down... not the rich condition. Solve the first and you'll fix the second.
Buildin' n' Boostin for 08' - Alex Richards
Good god please shut up before you spout more misinformation...
If AF mix can't ignite at 8:1 why do most ICE's running on gasoline have to be started at near 2:1 or 3:1 AFR? Plus think about what you said.. what conducts electricity better... air or water? Fuel is the same way, fuel is a better conductor than air. Now it COULD be that the fuel is causing the spark to travel up the plug instead of going across the gap. but this is not the issue, liquid fuel should never make it into the combustion chamber at these kind of RPM's and boost levels.
Lets look at this problem here people... He is running into a wall almost every time at the same RPM... This has nothing to do with ignition or parts or anything else for that matter. IF it did it would have been occurring at different RPM's
LOL! 2:1 -3:1 afr at cold start? ok.... fisrt of all cold start is competely different than an up to temp engine. a cold started engine needs more fuel because the fuel particles are larger and stick to the cold cylinder walls which makes it difficult to ignite. ive never seen a gas engine run at that rich of a mixture. im not talking about conductivity or liquid fuel. im talking about combustion. without the air, fuel is useless so running lower than 8:1 will not fully ignite fuel.
ive had this problem on my cobalt build. i had the engine tuned for 20lbs of boost but wasnt able to come up with the money to build the engine so i only ran the engine at 10 psi. at a specific rpm the engine stopped increasing rpm and the vehicle stopped accelerating no matter how much throttle i gave it. i dont know how you can say 10:1 afr is normal considering you dont even know what afr his engine is running at because the wideband stops reading below 10:1afr.
so i would say to you please stop misinforming people.
JOE L wrote:
LOL! 2:1 -3:1 afr at cold start? ok.... fisrt of all cold start is competely different than an up to temp engine. a cold started engine needs more fuel because the fuel particles are larger and stick to the cold cylinder walls which makes it difficult to ignite. ive never seen a gas engine run at that rich of a mixture. im not talking about conductivity or liquid fuel. im talking about combustion. without the air, fuel is useless so running lower than 8:1 will not fully ignite fuel.
ive had this problem on my cobalt build. i had the engine tuned for 20lbs of boost but wasnt able to come up with the money to build the engine so i only ran the engine at 10 psi. at a specific rpm the engine stopped increasing rpm and the vehicle stopped accelerating no matter how much throttle i gave it. i dont know how you can say 10:1 afr is normal considering you dont even know what afr his engine is running at because the wideband stops reading below 10:1afr.
so i would say to you please stop misinforming people.
Think about what you are saying... You stated cold start engines need a rich mixture because the fuel will not correctly atomize requiring gratuitous amounts of fuel to get started... And yet you say you have never seen a gasoline engine run that rich? I'll tell you what... go ahead and believe what you want to believe, I will let my Bachelors in Automotive Technology and vast research on combustion properties, VVT, Direct Injection, Turbocharging and Power train management speak for me. OF course I know you've had a cobalt so that pretty much trumps the 4 years of research and experience in the field that the degree got me...Just because you have never seen it does not mean it doesn't happen. Your right, best power is not found that rich, but it will burn and it will continue to run.
You were the one "assuming" it was lower than 10:1 in the first place... I never said anything about it... All I said is that on a stock tune there is no way that is the root cause. It is laying down for some other reason.
Buildin' n' Boostin for 08' - Alex Richards
Oh geez here we go........
Truthfully it isn't even worth arguing about because at this point there is no substantial data to come to any relative conclusion to what is happening. Without some kind of data log or listing of the full pictures worth of parameters while the symptom is occurring everyone is just speculating. He could be running 9.9:1 for all we know. This is the reason I haven't responded yet either because there really isn't any data to go off of. AFR is only a small part of the equation and as someone stated: the first rule is to fix what's currently broken before diving into symptoms that may be a direct result of what's broken. Tossing parts at a car is effective at accomplishing one thing and one thing only...................... draining your wallet.
Get some real data and stop wasting your time tossing parts at the problem without knowing what the problem even is.
ASE Master Certified Automotive Technician
Well the ICM and all the ignition parts where in relation to the random misfire issue, which has been cleared up.
The harness hunch is due to the fact that the weekend I pulled the harness out and checked it, then put it back on, it worked great until the weekend I lowered it and then it started acting up again.
As for the ECM/GM Flash hunch, that is becuase i never had problems with Low 1 and Low 2 stalling out until the flash.
As for the TFP Switch, that code randomly exist and it existed only after the GM flash and both with the old tranny, which never had problems, and the new one, which I am having the cutting off problem with. As of now that code no longer exist.
By the way, the reason for the new tranny was because the dealer who flashed it said my Low 1 and Low 2 problem was due to an old and abused trany (lie).
And just to clarify the problem, when accelerating in first gear and it reaches 6400 RPM the engine suddenly drops to a flatline 4000 RPM and the transmission goes into neutral. AFR are 10.7 t0 11.7 as it accelerates, but when it flatlines, that's when it goes to 10.0:1
Checked the new spark plugs yesterday and they are clean, no fouling or anything, as were the old ones.
As stated, the problem is not fuel or ignition per say, but either a bad sensor signal/circuit, ECM damage, or torque management issues.
The third sounds more likely now because if I watch my throttle I can maintain acceleration without causing it to cut off.
Also when watching the transmission datastream I've noticed that this problem occurs around the time when the Input Speed Sensor (ISS, in the tranny) and Output Speed Sensor (OSS, Vehicle Speed Sensor) have a difference of 2000 RPM or more, possibly indicating transmission slip.
I can record data logs on the Snap On scanner, but I can't get them on the computer, cause we lost the PC cord. And I would need to figure out a way for you guys to view the recordings without needing the Snap On scanner program installed on your PC. Working on resolving this so I can get some more help.
At this point I think my tranny rebuild might of gone funky and that may be the problem.
Jesus Jacobo wrote:The third sounds more likely now because if I watch my throttle I can maintain acceleration without causing it to cut off.
Also when watching the transmission datastream I've noticed that this problem occurs around the time when the Input Speed Sensor (ISS, in the tranny) and Output Speed Sensor (OSS, Vehicle Speed Sensor) have a difference of 2000 RPM or more, possibly indicating transmission slip.
I can record data logs on the Snap On scanner, but I can't get them on the computer, cause we lost the PC cord. And I would need to figure out a way for you guys to view the recordings without needing the Snap On scanner program installed on your PC. Working on resolving this so I can get some more help.
At this point I think my tranny rebuild might of gone funky and that may be the problem.
Sounds like torque management to me! Good diagnosis on watching the ISS/OSS
Take a screenshot (or two, or three) of the datalog on a regular computer, upload to photobucket, post to JBO.
Buildin' n' Boostin for 08' - Alex Richards
Sounds like "limp mode" to me. Low rev limit and car not wanting to go is what is does.
- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs
Oedwards wrote:Sounds like "limp mode" to me. Low rev limit and car not wanting to go is what is does.
Nope, Line Pressure would be maxed if it was limp mode.
Buildin' n' Boostin for 08' - Alex Richards
Alex, noticing you are from Joilet, ever been to Autobahn?
jason norwood wrote:Alex, noticing you are from Joilet, ever been to Autobahn?
Sure have, have made many deliveries there to world class international race teams when I worked at Napa (Think walking into a 30'x90' shop lined with drive on four post in ground lifts lining the long sides of the shops and cars underneath the lifts and on the lifts... 100 or so shifter karts in the back corner, ZR1's enzos, full race 911's, LMP and GT2 cars... everything... many many toys.)
MY buddy Chris also races a Datsun 510 in SCCA as part of a club he is in. So I have crewed for him several times when he is at the autobahn.
Buildin' n' Boostin for 08' - Alex Richards
Thats funny, I got a tour through work. They shut down the coarse and I got to race quite a few cars there. Met Ron Dabish, the owner and got to play for a day. lol Really out in the middle of no where ill tell ya. lol Got to drive some badass cars that day and meet the " teams" that have garages there, have plenty of pictures of that garage with all the porsches! Forget his name.... lol
jason norwood wrote:Thats funny, I got a tour through work. They shut down the coarse and I got to race quite a few cars there. Met Ron Dabish, the owner and got to play for a day. lol Really out in the middle of no where ill tell ya. lol Got to drive some badass cars that day and meet the " teams" that have garages there, have plenty of pictures of that garage with all the porsches! Forget his name.... lol
Ah its only about 15 mins from downtown joliet... not too bad... Plus the speedway is literally two country blocks East of the Autobahn... So it ain't THAT bad...lol
Pretty cool though! Dabish is a decent guy.. met him in passing and talked a bit... not much else.
The big ones I remember are Team Stradale, and Fall Line, they are the first two right at the entrance and they are big time members... Fall Line has a ton of BMW Z's Stradale is the one with just about one (or four) of everything. They are also the ones who do alot of driving programs as well.
Buildin' n' Boostin for 08' - Alex Richards
