New H/C/H build doesn't feel right
09-21-2008, 10:06 PM
#1
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New H/C/H build doesn't feel right I just got done with a build...to sum it up it's a 96 355cid LT1 with stock bottom end, Speed Pro pistons, Lingenfelter (LPE) heads, LPE 58mm TB, LPE intake, LPE 74211 cam, Corvette MAF, LPE CAI, Pacesetter LTs/ORY/Borla. I also had a Centerforce Dual Friction clutch installed.
When I drove the car home from the builder's shop it idled well and taking off was no problem. As soon as I tried to get on it a little, there was nothing but alot of noise. Felt like I had a 4 banger under the hood. Got 'er home and the first thing I found was a totally burned through #8 spark plug wire and the PS 02 sensor was unplugged. OK...so I replaced the wires with MSD 8.5mm Supers and plugged the sensor in and it runs better but it kinda feels like the same old motor (had 154K on it). The builder used the cheesy 02 extensions provided with the headers...spliced 'em in. I bought some 02 extensions yesterday but to my surprise found that there was nowhere to plug 'em in on the chassis side...****! How do I get the OEM plug setup back in there?????? I don't even know if he has it still.
I know the ceramic coating on the headers messes up the 02 sensors but would that make a huge difference? I'm planning on installing some OEM sensors in about a week...will I notice a substantial difference? I'm pretty disappointed with the results of this build right now...
Thanks.
When I drove the car home from the builder's shop it idled well and taking off was no problem. As soon as I tried to get on it a little, there was nothing but alot of noise. Felt like I had a 4 banger under the hood. Got 'er home and the first thing I found was a totally burned through #8 spark plug wire and the PS 02 sensor was unplugged. OK...so I replaced the wires with MSD 8.5mm Supers and plugged the sensor in and it runs better but it kinda feels like the same old motor (had 154K on it). The builder used the cheesy 02 extensions provided with the headers...spliced 'em in. I bought some 02 extensions yesterday but to my surprise found that there was nowhere to plug 'em in on the chassis side...****! How do I get the OEM plug setup back in there?????? I don't even know if he has it still.
I know the ceramic coating on the headers messes up the 02 sensors but would that make a huge difference? I'm planning on installing some OEM sensors in about a week...will I notice a substantial difference? I'm pretty disappointed with the results of this build right now...
Thanks.
09-22-2008, 11:29 AM
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I'm hoping it's a combination of the o2 sensors, the new clutch, the stock knock module and an exhaust leak (header to collector). Sucky part is that there are no LT1 tuners anywhere within 150 miles of me.
09-24-2008, 09:51 PM
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I don`t know what this is doing to your combo, but 58mm throttle bodies are really for bigger ci motors rather than a 355. Also, ceramic coating on the outside of a header will not affect the O2 sensor. You definately need to get new pigtails for the 02`s and PROPERLY install them.
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09-25-2008, 10:41 AM
#8
I don`t know what this is doing to your combo, but 58mm throttle bodies are really for bigger ci motors rather than a 355. Also, ceramic coating on the outside of a header will not affect the O2 sensor. You definately need to get new pigtails for the 02`s and PROPERLY install them.
Not true at all about the 58 TB. I will be running a stock short block with a LE2 H/C. Lloyd Elliot told me to use a 58mm for best gains. Im hoping the car will turn over 400rwhp though.
Get those o2s fixed and double check all your plugs and wires again. The 58 wont hurt.
09-25-2008, 11:54 AM
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Thanks for the replies. Ion at madtuner.com recommends the following:
"If you have recently installed new, ceramic-coated headers and you did not remove the o2 sensors during the first week or so of running, you must replace them. New coating ruins oxygen sensors."
I didn't remove my O2 sensors because I planned on replacing them anyway but I'm not showing a CEL so does that mean they're fine?
I'm not sure on how to get the O2 sensor extensions hooked up now...the original connector on the chassis side has been cut off and the crappy Pacesetter wires have been spliced in and connected to the sensor harness itself. Will it help at all if I get the original chassis-side connectors and splice those back in and then use the proper extensions or will that just be the same result (as in "the damage is done")?
"If you have recently installed new, ceramic-coated headers and you did not remove the o2 sensors during the first week or so of running, you must replace them. New coating ruins oxygen sensors."
I didn't remove my O2 sensors because I planned on replacing them anyway but I'm not showing a CEL so does that mean they're fine?
I'm not sure on how to get the O2 sensor extensions hooked up now...the original connector on the chassis side has been cut off and the crappy Pacesetter wires have been spliced in and connected to the sensor harness itself. Will it help at all if I get the original chassis-side connectors and splice those back in and then use the proper extensions or will that just be the same result (as in "the damage is done")?
09-25-2008, 08:26 PM
#13
There could be alot of potential issues here,,, I would be suspicious of the builders competence right away if you already had a burnt plug wire and O2 unplugged.
Under full throttle I don't believe the 02 sensors matter. What are the noises you are hearing? Like backfiring?
Valves may need to be properly adjusted. Knock sensor hooked up? Car could be a DOG if the computer is pulling a ton of timing etc...
Under full throttle I don't believe the 02 sensors matter. What are the noises you are hearing? Like backfiring?
Valves may need to be properly adjusted. Knock sensor hooked up? Car could be a DOG if the computer is pulling a ton of timing etc...
09-25-2008, 08:52 PM
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I've got confidence in the build quality of the motor...I think the builder grew tired of this project after dragging it out for so long and rushed the installation. He'd never done an LT1 in an Fbody before an I think he was frustrated/overwhelmed by the whole install which has led to some less than ideal adjustments. I'm gonna have the valves adjusted by a guy who installed an LT1 in his 280Z...he's pretty comfy with the process and also tunes his own car (OBD1). We're hooking up this weekend so he can give his opinion.
Knock sensor hooked up? It's inside the PCM, isn't it? If so, I got the PCM from Ion at Madtuner so it better be in there! The tune included knock sensor desensitizing as well.
The plug wire was definitely a product of the builder rushing it...same with the O2 plug...and I talked with him about those issues and asked him what else might not be quite right.
Wouldn't I hear the valves if they weren't adjusted properly? The engine sounds pretty damned good to me. Maybe my LT1 buddy will hear something odd but I can't.
Like I said, it idles well hot or cold...initial acceleration is good but it stops pulling at 2500-3000rpm. It doesn't die, the pull just isn't as strong as down low...by a large margin. It also just started hanging revs when warm after letting of the throttle...hangs at around 2K for a few seconds then comes down.
This sucks.
Knock sensor hooked up? It's inside the PCM, isn't it? If so, I got the PCM from Ion at Madtuner so it better be in there! The tune included knock sensor desensitizing as well.
The plug wire was definitely a product of the builder rushing it...same with the O2 plug...and I talked with him about those issues and asked him what else might not be quite right.
Wouldn't I hear the valves if they weren't adjusted properly? The engine sounds pretty damned good to me. Maybe my LT1 buddy will hear something odd but I can't.
Like I said, it idles well hot or cold...initial acceleration is good but it stops pulling at 2500-3000rpm. It doesn't die, the pull just isn't as strong as down low...by a large margin. It also just started hanging revs when warm after letting of the throttle...hangs at around 2K for a few seconds then comes down.
This sucks.
