Possible unknown mods causing problems???
Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
Likes: 0
From: FL
Possible unknown mods causing problems??? Hi everyone, I have a 99 c5 AT, shorty headers, bbk intake, OBX exhaust (superlight barely has mufflers), and a mail order tune from ECS. Did everything but the tune myself.
Every since I got the car its had idle issues, stock plugs, wires, exhaust leaks (rusted out Flowmaster mufflers), normal symptoms of a neglected 14 year old car. So, I got headers and exhaust, got the stainless gaskets, fixed the exhaust leaks. Got msd wires and NGK plugs, cleaned the MAF, TB and put on a air intake. Fixed atleast 3 air leaks... still idle problems. The tune helped a lot by raising it and enabling it to idle over 550rpms, it was wanting to drop below 500 before. It still has good days and bad.
I actually have another thread about some of my issues, and even threads on other forums and people seem stumped.
Im starting to think I possibly have unknown untuned mods that are giving me problems. Like a sleeper cam that doesn't have a noticeable lope.
With my current mods I'd be lucky to have 320 330whp (correct me if I'm wrong).
I shot this video this morning on my way to work and the acceleration suggests I have a good amount more... Just looking for an opinion.
Its an auto, I'm tackin 2k at 40mph, spin the tires and shoot to 70 in like a second... Also left traction control on by mistake so it cut the throttle and slowed me down.
I know C5 are extremely light in the back and spin happy but just need to check.
It would explain a lot, I've watched other C5 acceleration videos and especially the automatics don't pull like that.
Just wondering if everyone thinks that's right for my mods so I can move in the right direction. Thanks in advance.
Every since I got the car its had idle issues, stock plugs, wires, exhaust leaks (rusted out Flowmaster mufflers), normal symptoms of a neglected 14 year old car. So, I got headers and exhaust, got the stainless gaskets, fixed the exhaust leaks. Got msd wires and NGK plugs, cleaned the MAF, TB and put on a air intake. Fixed atleast 3 air leaks... still idle problems. The tune helped a lot by raising it and enabling it to idle over 550rpms, it was wanting to drop below 500 before. It still has good days and bad.
I actually have another thread about some of my issues, and even threads on other forums and people seem stumped.
Im starting to think I possibly have unknown untuned mods that are giving me problems. Like a sleeper cam that doesn't have a noticeable lope.
With my current mods I'd be lucky to have 320 330whp (correct me if I'm wrong).
I shot this video this morning on my way to work and the acceleration suggests I have a good amount more... Just looking for an opinion.
Its an auto, I'm tackin 2k at 40mph, spin the tires and shoot to 70 in like a second... Also left traction control on by mistake so it cut the throttle and slowed me down.
I know C5 are extremely light in the back and spin happy but just need to check.
It would explain a lot, I've watched other C5 acceleration videos and especially the automatics don't pull like that.
Just wondering if everyone thinks that's right for my mods so I can move in the right direction. Thanks in advance.
TECH Enthusiast
Joined: Nov 2012
Posts: 555
Likes: 0
From: NearHouston, TX
the tune on my LS1 has been driving me crazy for a long time. It feels like a race tune, basically tweaked on the track. It is how I bought it, I have a small cam, all the bolt ons, exhaust, and the idle is too low and car can die at any time sitting at a redlight or just backing out of drive way. I have factory stall and I'm getting that replaced right now (car is at LMR in Houston for a circle D 3600 stall and new dyno tune). I'm thinking that previous owner may have had bigger intake / TB on it, and removed those when he sold this car (he had other LS cars).
I'm hoping that the new stall, and new tune will make my car more fun to drive, I don't even care if I lose a few horses, just want car to stay awake at low rpm. I will follow up after the work is done and let you know. I do plan on upgrading to FAST intake and TB / and ported heads this summer.
I'm hoping that the new stall, and new tune will make my car more fun to drive, I don't even care if I lose a few horses, just want car to stay awake at low rpm. I will follow up after the work is done and let you know. I do plan on upgrading to FAST intake and TB / and ported heads this summer.
The cam is easy enough to check. Get a dial indicator place it on a intake valve rotate the engine by hand and see how much valve lift you have. Then do the same with an exhaust valve. This won't tell you the duration but you can check the stock valve lift against what you have. That would answer one question.
Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
Likes: 0
From: FL
the tune on my LS1 has been driving me crazy for a long time. It feels like a race tune, basically tweaked on the track. It is how I bought it, I have a small cam, all the bolt ons, exhaust, and the idle is too low and car can die at any time sitting at a redlight or just backing out of drive way. I have factory stall and I'm getting that replaced right now (car is at LMR in Houston for a circle D 3600 stall and new dyno tune). I'm thinking that previous owner may have had bigger intake / TB on it, and removed those when he sold this car (he had other LS cars).
I'm hoping that the new stall, and new tune will make my car more fun to drive, I don't even care if I lose a few horses, just want car to stay awake at low rpm. I will follow up after the work is done and let you know. I do plan on upgrading to FAST intake and TB / and ported heads this summer.
I'm hoping that the new stall, and new tune will make my car more fun to drive, I don't even care if I lose a few horses, just want car to stay awake at low rpm. I will follow up after the work is done and let you know. I do plan on upgrading to FAST intake and TB / and ported heads this summer.
Afew people have told me that, including a really well known local mechanic that works on high-high end stuff. But if anything the tune helped my idle, it was much worse before, shaking, making interior pieces rattle ect, just begging to drop below 500. Now its really smooth most days in comparison but still not right. Like the tune is a band aid that wants to fall off.
Thread Starter
Teching In
Joined: Apr 2013
Posts: 47
Likes: 0
From: FL
Some one on another forum told me that C5 have to have a 25% malfunction to throw a cel.. is this true??
So theoretically I could have a bad coil pack that's ABOUT to throw a cel?
My Boss's work van starting showing the VERY similar symptoms on the way to work one day but the light came on immediately when the problem started. Turned out to be the manifold leaking coolant on a coil pack and shorting it out.
I know that particular thing can't happen to LS1's but the bad coil pack showed the same symptoms. Is there a way to find one that's malfunctioning enough to ruin my idle and smoothness but not throw a cel yet????
Original packs 60k miles
So theoretically I could have a bad coil pack that's ABOUT to throw a cel?
My Boss's work van starting showing the VERY similar symptoms on the way to work one day but the light came on immediately when the problem started. Turned out to be the manifold leaking coolant on a coil pack and shorting it out.
I know that particular thing can't happen to LS1's but the bad coil pack showed the same symptoms. Is there a way to find one that's malfunctioning enough to ruin my idle and smoothness but not throw a cel yet????
Original packs 60k miles
