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So I have a c4 with an ls6 I recently swapped. I haven't driven it out of my neighborhood until today. That's because I didn't have an exhaust and was just running open.
Today I went to get the pipes installed and after about 6 miles of very loud, but gentle running....it got very rough.
I was hoping that it was just not enough back pressure was messing up the o2s. But it turns out I had a crack behind the throttle body
1. Which is chicken, which is egg? The crack or the rough running?
2. Was this most likely cracked when I got it 6 months ago, and I just didn't notice until it heated up?
3. Anything else to check?
4. Can I just solvent weld this, or is the intake toast?
Any thing is possible. Clean the area with solvent. Stop drill the cracks where they stop. Use a dremmel or air drill and rough the area and V notch 1/2 way thru the crack on top. Use some 2 part epoxy (JB Weld works excellent) and fill in the damaged area. Do the same repair on the inside.
Cover any other cracks with epoxy. Let it cure and do the inside.
I would look carefully for other cracks. Looks like back fire damage.
Spray the manifold with solvent and let it evaporate. Any cracks will stay WET longer because the crack retains the solvent longer.
Thanks....do you think it backfired from no pipes causing the computer to run it lean?
I'm new to the LS engine so trying to figure what caused the crack or if it was the cause
Last edited by The Plastic Lizard; Oct 2, 2014 at 09:53 PM.
I doubt it,,, You would have KNOWN if it back fired. Unless a LS engine is really screwed up, they dont usually backfire. The plugs and wire are a fool proof connection.
Repair the manifold and put it back together and once its running, read and post the DTCs. You did incorporate the OBD2 port correct??
I doubt it,,, You would have KNOWN if it back fired. Unless a LS engine is really screwed up, they dont usually backfire. The plugs and wire are a fool proof connection.
Repair the manifold and put it back together and once its running, read and post the DTCs. You did incorporate the OBD2 port correct??
Bill
Yes I did. Hope to be able to do that this weekend.
From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Check to be sure there's not something underneath the manifold making contact, causing it to crack when the bolts were tightened.
Check the front engine cover and water pump area to see if the manifold is resting on it.
I agree with post 2 and 7. Check the fit on top of the air bleed pipe. I know my fast 92 wouldn't clear. Test fit it without the gaskets/seals. It should rest easily on the heads with no rocking.
it was running fine then all of a sudden felt like it just wanted to limp. If I turned it off (on the side of the road mind you) and started it back up after a few minutes of looking around for obvious causes, it was ok again. I originally thought the fuel pump wasnt delivering enough fuel, or that a coil pack wire had come loose. it was running very rough and sounded like it was not running on all 8. But then when I restarted....everything was fine and smooth....just got bad at speed.
....do you think it backfired from no pipes causing the computer to run it lean? What else could cause the backfire? I am going to try and plug the leak enough to get home, and to prove that is all that is wrong. I will put another intake on it, but I dont want it to happen again....assuming I did it at all...could have been there before and I didnt notice it.
it was running fine then all of a sudden felt like it just wanted to limp. If I turned it off (on the side of the road mind you) and started it back up after a few minutes of looking around for obvious causes, it was ok again. I originally thought the fuel pump wasnt delivering enough fuel, or that a coil pack wire had come loose. it was running very rough and sounded like it was not running on all 8. But then when I restarted....everything was fine and smooth....just got bad at speed.
....do you think it backfired from no pipes causing the computer to run it lean? What else could cause the backfire? I am going to try and plug the leak enough to get home, and to prove that is all that is wrong. I will put another intake on it, but I dont want it to happen again....assuming I did it at all...could have been there before and I didnt notice it.
Did it backfire or not
There several things that could cause a backfire, was this a new engine build or just a swap
Right now,, reading DTCs is the best bet to get things sorted out. What scanner do you have? Recommend a CAN BUSS compliant scanner that is able to read and display LIVE SENSOR DATA. You car isnt CAN BUSS but,, thats the latest and greatest and can be used on other newer cars.
From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Originally Posted by The Plastic Lizard
.............
and it was a swap from a rear-ended 2002 corvette.
That being the case, I would definitely say a strong case can be made for the damage occurring as a result of rough/careless handling during either the removal, installation, or both.
That being the case, I would definitely say a strong case can be made for the damage occurring as a result of rough/careless handling during either the removal, installation, or both.
I had a C4... That being said,, C5 PCM and all the other modules,, DO NOT WORK WELL with low voltage.
Before you get too far into replacing parts,,,, MAKE PROOF POSITIVE that you have 100% adequate voltage to ANYTHING that you converted.
Your IGNITION SWITCH provides feeds to the PCM. IF,, the car starts to run poorly, (at that time) measure the voltages that are being supplied to the PCM.
Also measure the alternator and battery outputs. If your not charging at 14 VDC,, or near that, something is wrong. The C5 operates at 13.5 - 14.5 in normal conditions. Normal is 14.2
MAKE SURE the PCM has adequate voltages on ALL of its fuses.. Especially the KEY on fuses..
From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Originally Posted by Bill Curlee
I had a C4... That being said,, C5 PCM and all the other modules,, DO NOT WORK WELL with low voltage.
Before you get too far into replacing parts,,,, MAKE PROOF POSITIVE that you have 100% adequate voltage to ANYTHING that you converted.
Your IGNITION SWITCH provides feeds to the PCM. IF,, the car starts to run poorly, (at that time) measure the voltages that are being supplied to the PCM.
Also measure the alternator and battery outputs. If your not charging at 14 VDC,, or near that, something is wrong. The C5 operates at 13.5 - 14.5 in normal conditions. Normal is 14.2
MAKE SURE the PCM has adequate voltages on ALL of its fuses.. Especially the KEY on fuses..
If it were me, I would also run a extra, separate, fused cable (probably 100 amp fuse), directly from the alternator to the battery, and NOT rely on the junction on the starter solenoid alone being used to feed/charge the battery. A 4 ga would be plenty big.
Cracked ls6 intake!
If it were me, I would also run a extra, separate, fused cable (probably 100 amp fuse), directly from the alternator to the battery, and NOT rely on the junction on the starter solenoid alone being used to feed/charge the battery. A 4 ga would be plenty big.