LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Problem that I can not figure out!

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Old Nov 23, 2008 | 07:32 AM
  #21  
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anyone?
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Old Nov 23, 2008 | 08:08 AM
  #22  
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If you can find some old 02s I would try that 1st. Or if you got a buddy with an f-bod then swap them out. Theyre too expensive just to throw parts at it for diagnostics sake.
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Old Dec 1, 2008 | 04:34 PM
  #23  
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This is from my car after letting it idle for about 15 mins. I tried to get one while driving but it was only me in the car and there was too much traffic. I'm trying use this to diagnose my problem but I'm no expert about all the sensor readings, so can anyone help me out?

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Old Dec 1, 2008 | 07:12 PM
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Seems a bit too hot to me. fans should've came on around 195 -205 if on stock tune to cool it down. And I noticed your tranny temp at -40. What's up with that. Even if you didn't drive it it should still be above 0 degs. other than that everything looks good but i'm far from a tuner who understands that mumbo jumbo.
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Old Dec 1, 2008 | 07:24 PM
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Yea, the fans usually kick on right at 220 or so then it cools back down. And the tranny temp, I don't know whats up with that.

I would like to know why it says learn disabled and aslo why the knock counts are so high even with the lt4 knock sensor module. I don't hear any type of noise coming from the engine. Is it supposed to be like that?
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Old Dec 1, 2008 | 07:32 PM
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sounds like an o2 since it runs fine until it goes into closed loop
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Old Dec 1, 2008 | 07:45 PM
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^^^He very well could be right. Don't give up on her.
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Old Dec 1, 2008 | 07:53 PM
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Theres no way I'm giving up now. I'm in the middle of an engine build and I would like to get this problem taken care of so I can get back to spending money on parts for that.

Is there anyway to confirm its the o2's before going and spending at least $100 on new ones to replace these new ones?
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Old Dec 2, 2008 | 02:43 AM
  #29  
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hows your thermostat? i had a turd gen that threw a fit like that and we found out she though it was -40 degrees outside, new thermo and it was fine. id check that and your timing and 02's, i go with inexpensive first, good luck buddy!!!



take it to a mechanic and have em do a diagnostic on it, theyll plug it in and it SHOULD tell you whats up, mine was free.. but i have ***** so.... (dont go to autozone)
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Old Dec 2, 2008 | 02:45 AM
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Originally Posted by 95phoenix

I would like to know why it says learn disabled and aslo why the knock counts are so high even with the lt4 knock sensor module. I don't hear any type of noise coming from the engine. Is it supposed to be like that?


just out of curiosity why are you running an lt4 knock module?
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Old Dec 2, 2008 | 05:38 AM
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Originally Posted by brynnda
hows your thermostat? i had a turd gen that threw a fit like that and we found out she though it was -40 degrees outside, new thermo and it was fine. id check that and your timing and 02's, i go with inexpensive first, good luck buddy!!!



take it to a mechanic and have em do a diagnostic on it, theyll plug it in and it SHOULD tell you whats up, mine was free.. but i have ***** so.... (dont go to autozone)
Ok cool. Thats actually something I havent heard yet. I'll have to give that a try afrter work.
But I do have a question about that. If it was just the thermostat was bad, why would the car think it was -40?
And I'm running the lt4 knock sensor module because I have true duals that are pretty loud and when I first did it I was having problems. Someone suggested that it could be getting a false knock and retarding my timing and that the lt4 knock sensor module would fix it, and it did.
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Old Dec 2, 2008 | 10:48 AM
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Originally Posted by 95phoenix
Ok cool. Thats actually something I havent heard yet. I'll have to give that a try afrter work.
But I do have a question about that. If it was just the thermostat was bad, why would the car think it was -40?
And I'm running the lt4 knock sensor module because I have true duals that are pretty loud and when I first did it I was having problems. Someone suggested that it could be getting a false knock and retarding my timing and that the lt4 knock sensor module would fix it, and it did.
If the car is reading -40 then it has to be the coolant temp sensor in the WP or head. If the car reads it's cold then it will pull timing and idle higher to try and warm the motor up. Change out the temp sensors first and go from there.
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Old Dec 2, 2008 | 03:10 PM
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You have a vacuum leak i think.

My car was doing the exact same thing as you explained, puttered under a light load so bad i can hear and FEEL the motor shuddering around under the hood. But when I hammered the gas she would scream like normal... how ever 20 minutes or so later at cruising speed my SES light would trigger. If i reset the PCM it would just do this all over.

So i prematurely ordered a OBD2 code reader (although im sure ill need it in the future) and im waiting on that now. Today after i work i was bored and just waned to double check everything under the hood just in case. While looking at the bundle of three hoses that come up from the DS, (The feed &return gas line and EVAP) Well the Evap has a portion of hose about 3-4 inches that bridges the hose to another hose and had corroded completely and sure enough that was my problem. I believe there is another "bridge" hose about the same length leading to the ?gas tank? directly under the driver seat on the underside...

Also, i have the ticking in the same location, how ever i have a new exhaust gasket and that will be fixed tomorrow hopefully

good luck!

-justin
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Old Dec 2, 2008 | 04:11 PM
  #34  
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Originally Posted by DAVE00
If the car is reading -40 then it has to be the coolant temp sensor in the WP or head. If the car reads it's cold then it will pull timing and idle higher to try and warm the motor up. Change out the temp sensors first and go from there.
Thats the trans temp. The water temp is at 223. The gauge is working in the car, and the computer so that pretty much rules that out. I still dont know why it would say the trans temp is -40 though. Weird...
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Old Dec 2, 2008 | 04:12 PM
  #35  
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Originally Posted by ORedRoc4
You have a vacuum leak i think.

My car was doing the exact same thing as you explained, puttered under a light load so bad i can hear and FEEL the motor shuddering around under the hood. But when I hammered the gas she would scream like normal... how ever 20 minutes or so later at cruising speed my SES light would trigger. If i reset the PCM it would just do this all over.

So i prematurely ordered a OBD2 code reader (although im sure ill need it in the future) and im waiting on that now. Today after i work i was bored and just waned to double check everything under the hood just in case. While looking at the bundle of three hoses that come up from the DS, (The feed &return gas line and EVAP) Well the Evap has a portion of hose about 3-4 inches that bridges the hose to another hose and had corroded completely and sure enough that was my problem. I believe there is another "bridge" hose about the same length leading to the ?gas tank? directly under the driver seat on the underside...

Also, i have the ticking in the same location, how ever i have a new exhaust gasket and that will be fixed tomorrow hopefully

good luck!

-justin
I'll take a look at that. It sounds very possible.
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Old Dec 3, 2008 | 06:10 PM
  #36  
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Well I searched and came up with no vaccum leak. So now I'm back where I started.

Is it possible that I might just be in need of a tune? Someone I know suggested that because I deleted all the emissions stuff, and added full exhaust and haven't tuned it. But I have had no SES light, so I don't know. I'm just getting kind of desperate at this point.
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Old Dec 4, 2008 | 12:05 AM
  #37  
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Have you checked the fuel pressure? I went through the same thing recently and found the fuel pump was going bad. Good luck!!!!!
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Old Dec 4, 2008 | 02:48 AM
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Originally Posted by john93m6z
Have you checked the fuel pressure? I went through the same thing recently and found the fuel pump was going bad. Good luck!!!!!
Exactly what I was going to say. How many miles have you put on it since you deleted all emission stuff? I threw code after 150 miles or so. Get a tune, but get a fuel pressure guage and hook it up and try to get it to a place where you can go WOT and see the guage.. It should read about 43 psi.

After I did heads/cam it ran fine, but I later realized it was leaning out up top. Fuel pump was crappin out, then it got REALLY noticeable. Shook alot at low rpm's then it would start to smoothen up as rpm's grew. The guage is like $35 or so. If you have a dyno in your area, hook it up to the dyno and get it tuned. Good luck!
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Old Dec 4, 2008 | 05:47 AM
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Originally Posted by lt1z28camaro
Exactly what I was going to say. How many miles have you put on it since you deleted all emission stuff? I threw code after 150 miles or so. Get a tune, but get a fuel pressure guage and hook it up and try to get it to a place where you can go WOT and see the guage.. It should read about 43 psi.

After I did heads/cam it ran fine, but I later realized it was leaning out up top. Fuel pump was crappin out, then it got REALLY noticeable. Shook alot at low rpm's then it would start to smoothen up as rpm's grew. The guage is like $35 or so. If you have a dyno in your area, hook it up to the dyno and get it tuned. Good luck!
Ok cool. I'll do that today. But I do have a question about that though. If it was the fuel pump why does it seem like its running super rich at idle? And only in closed loop. I'm not questioning your diagnoses because you've been through the same thing, I'm just curious. Anyway I'll let you guys know what I find out later tonight.

Oh, and I have had the emissions stuff off for almost a year. Never got ANY codes...
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Old Dec 4, 2008 | 11:43 AM
  #40  
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Hi, My car smells rich at idle all the time. I have no other signs of it being rich though. I replaced the plugs that were in the car (when I got it) after putting about 5k on them. I have about 13k on these plugs and neither show signs of burning rich.
My car would start most of the time and run perfect. sometimes it would stumble for a bit while it was warming up. After a few weeks it got to after it would warm up it would start back firing and cutting out untill I got to about 3k rpm (that's what had me confused) and run ok? I would ride the clutch to 4k and shift into second.
I tested and or replaced all of the ignition system and finally checked the fuel pressure Hope this helps! John

Oh one last thing you mentioned something about 2k rpm. In my car something happens at about 1800-2000rpm, It's like someone flips a switch or something and it really gets into the power, I don't know if this is common or not.
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