When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
injuneer are you telling me that my unvented msd opti might be off? i replaced the timing set and just slid the new opti on....as you know it only goes in one way....how can it be up to 20*'s off? please enlighten me because now im curios. these lt1 are some crazy motors...also does the cam pin drive the opti rotor on the newer opti's? because my opti had no opening in the back of it
Ok so more bad news... of course. I was driving home from work after working 2 and a half hours overtime going through a mountain cut through on the interstate and hit a big a$$ rock that fell into the road while it was dark and raining and bent my brand new chrome Z06 wheel and popped my hankook tire I don't know whether to scream,cry or laugh I guess I will do all within a few seconds, always has to be something. So gonna have to deal with that problem first before anything, but Injuneer did you get to take a look at the data log file, I sent you a PM with the info in there? I can email my TTS DataMaster log file to anyone that might be able to help. I am gonna go crazy if something doesn't start going my way! Thanks to all who is trying to help BTW
I downloaded the DataMaster log. Looks like the LTFT's (BLM's) are still being pulled down. In a cell that you spent the most time in (#6) they are down to 113/114 and probably going to go even lower with time.
Knock retard is caused by increasing knock count, and that may not be a response to the knock sensor, but the PCM's response to an operating condition that it feels may cause knock. Spark timing seems pretty aggressive.
I'll look some more, but I don't see anything way out of line. I wouldn't be concerned by the duty cycle. DM highlight the DC in red starting at 80%. That's very conservative, and as I mentioned, DM seems to come up with excessively high DC's.
More great news instead of having 1 front bent rim and popped tire I have 1 bent rim and 2 flat tires errrrrrr gotta love nature. Those things were only a month old which really sucks. Thanks Injuneer for taking a look at my log, I am showing no DTC's during the entire log either? So what I can gather from your last post is that my fuel looks pretty good at WOT? The belt is fairly new put it on when I put on my under drive pulley which was maybe 6 months ago but the tensioner is making a sweeking noise so that could be losing some tension on the belt causing it to slip, but you never know. After all the crap thats going on I am about to park the thing for a while hahahaha, no I could never do that just gotta get everything straightened out. Went to a junk yard and got some older rims off a camaro that are 15's lol they look really cute on there with my big 18 inch chrome Z06 wheels on the back. But always looking for more help guys keep the ideas coming. So I guess I need to go pick up a tensioner in a lil bit and try that on, might just go ahead and get some water pump gaskets and pull the cap off the opti but that sounds like a lot of stress on top off whats already going on!!!
[QUOTE=Injuneer;6388100]The PCM uses the mass air data from the MAF sensor at WOT. Why would it ignore it and default to speed-density? It also uses the long term fuel corrections (if they are adding fuel) from cell 15 at WOT, and those corrections are developed based on O2 sensor readings at part throttle, so a faulty O2 sensor can affect WOT performance. The primary difference at WOT is that the PCM can no longer use the short term corrections because the O2 sensor data is not useable.
If his Opti (97/vented) was indexed incorrectly, it would be off by 120 cam degrees = 240 crank degrees. Engine wouldn't even run. Its not like the unvented/slpined Opti that can be off by 20 cam degrees.QUOTE]
Lol, thanks for clearing some of this up. I think you might have helped me when I was experiencing some similar problems, thought I was translating good info...I guess not. Thanks for the help you provide on here!
OK got some good news finally. Went and bought a new belt tensioner, fuel filter and put those both on. Also found a crap vacum hose that was spilt underneth so I couldn't see it at first glance, and was checking the spark plugs again only this time I noticed when I grabbed one of the very back wires ( #7 ) and moved it I realized the spark plug moved with it. So I tightened that plug back down and took it for a test drive and it was 10 times better. I am not saying that it is fixed totally just yet because it's hard to have a loud Corsa exhaust flying through the subdivision at WOT at 4 am lol although I came pretty close to it. So far so good, I felt just a slight miss around 4800 when I was going through 1st but it was very slight. So I guess on my way to work tonight I will get all over it on the interstate and see what happens. I really think the whole big miss was due to the loose spark plug and losing compression at high RPMs, so yes your spark plugs and wires HAVE A LOT to due with the performance of your car, so I would highly recommend a change of wires and plugs if you haven't done it recently ( do not go cheap here, stick with the AC Delco plugs, do not use bosch). All symtoms pointed me towards the fuel pressure so that was the main thing I thought it would be. Although I did change the fuel filter and belt tensioner I strongly believe the plug was the cause of the problem. I will report back tommorrow night and let you guys know how it runs. I hope this thread can help someone else out. Thanks to everyone who helped me along the way. Wish me LUCK!!!
So I took the car for a lil spin on the way to work and home from work and it seems to be 90% better so far, still has a very slight mess going from around 4800 to 5800 but no where near what it was. I am gonna do some checking on the rest of the plugs and see what I come up with, hopefully it is just another plug loose in there somewhere. It is so hard to mess with the plugs on these cars with headers on them errrrrrr. Oh well, guess I'll see what I can come up with after I check on them.
so i am having issue as well i know its a long shot tht this was a while ago. atound 5 to 6000 it breaks up new harness opti plugs wires etc even new icm, i get the feeling the high resolution issue could either be coil its an msd coil or somethin i was going to put a Oscilloscope tester on to see but i just dont know, can anyone help me?
What are you referring to as “the high resolution issue”? Do you have a PCM code for the Opti high resolution pulse signal? What year is your car? How extensive are the modifications, if any? Has is been tuned for the mods? What brand is the Opti?
What are you referring to as “the high resolution issue”? Do you have a PCM code for the Opti high resolution pulse signal? What year is your car? How extensive are the modifications, if any? Has is been tuned for the mods? What brand is the Opti?
yeah its a code 36, its still all stock except for a few upgrades like msd wires,box, and coil, there has been no tune yet except a base tune for turning off traction control and some other stuff that have been deleted. but the high res code i changed the harness the icm, i am thinking injectors because it only starts to break up and pop like crazy at 5 to 6k then shift to third, the last time i had it on the high way and sent it the rev limiter on the msd box was set to 5500rpm then it broke up. then i pulled over at a toll gate changed the rev limiter to 6500 and checked the codes and it still has a code 36 and at some point it did have a code 42 but it never came back, but just recently like a day ago i change the harness to the opti with a new one and it still puts out the same code. so i might be thinking its either the pcm thats all left or could be fuel related like injectors...i have changed most of everything and its throwing me off. i am trying to make this motor last before the winter and i change it out to a stronger built motor which i dont have money for right now. so i just need to figure this out somehow by narrowing it down...
DTC 36 is set when the PCM detects low resolution pulses from the optical cam position sensor in the Opti, but does not detect high resolution pulses. It has NOTHING to do with the ICM, injectors, etc. You have to solve the source of that problem.
You didn't answer two questions:
1 - WHAT YEAR IS YOUR CAR? There are subtle differences between each year of the LT1 engine. Since you have a two-digit code, which is OBD-1, you have either a 93, 94, or 95. Since you mention traction control, I could guess it is a 95, because traction control was not available until 95. But we shouldn't have to guess what year your car is.
2 - WHAT BRAND IS THE OPTI? Did the misfire/breakup problem exist BEFORE is was replaced? Most Opti's available today are cheap Chinese junk.
DTC 36 is set when the PCM detects low resolution pulses from the optical cam position sensor in the Opti, but does not detect high resolution pulses. It has NOTHING to do with the ICM, injectors, etc. You have to solve the source of that problem.
You didn't answer two questions:
1 - WHAT YEAR IS YOUR CAR? There are subtle differences between each year of the LT1 engine. Since you have a two-digit code, which is OBD-1, you have either a 93, 94, or 95. Since you mention traction control, I could guess it is a 95, because traction control was not available until 95. But we shouldn't have to guess what year your car is.
2 - WHAT BRAND IS THE OPTI? Did the misfire/breakup problem exist BEFORE is was replaced? Most Opti's available today are cheap Chinese junk.
yes its a 95...the opti is like a duralast autozone part but i plan on buying either a acdelco or a petris opti, but it does have somethin todo with the injectors bc i havent checked them in the longest time so not to mention it was sitting for like two years when the guy blew the tranny in it after he gave it to me.
Some unclear writing here. Appeared you were attributing DTC 36 (the high resolution issue) to the ICM and injectors. Yes, the ICM, injectors, etc. could be the cause of the problem, but so could DTC 36.
In theory, the engine can run without the high resolution pulse. But there will be a small loss of ignition and sequential injector timing accuracy. Might not even notice the timing error, but in practice a missing high res pulse seems to affect the smoothness of the engine.
If the car sat with stale gasoline for 2 years the entire fuel system is suspect.
Rather than randomly replacing parts, might want to consider running a data log of the PCM, using GaryDoug's (free) Scan9495 software.
06-11-2010, 04:47 PM
