Issues with surging, stumbling, and p0300 after Procharger install
03-26-2010, 01:09 AM
#1
Issues with surging, stumbling, and p0300 after Procharger install OK guys, I got my Procharger build finished up and got my computer back from Frost yesterday. Got everything hooked back up, and tried starting the car. Took several turns for it to fire, but it finally did. Idle was very erratic, from 500rpm up to 1000rpm. No big deal, I figure...pcm needs time to relearn with the 60lb injectors. Let the engine warm all the way up to operating temp, and the idle smooths out fairly well, but is still a touch rough...I can see the engine shaking a little more than usual. If I barely touch the accelerator, the engine stumbles and bogs badly, but will eventually bring the idle up to meet the accelerator position. If I give it 1/4 throttle or so, it revs fine.
I figure it may take a few starts for the PCM to do its thing, so I go back out later last night and start it up again. This time, I have a SES light. Check the code, and its p0300...random misfire. I clear the code, and go back through everything looking for vacuum leaks, etc. Tightened all the clamps throughout the system, made sure everything was plugged in, etc. Fire it back up again today, get the code again. Same idle issues as before.
I changed the plugs and wires (used wires from a friend...the Delco red ones that only had about 1000 miles) during the install, so I'm going to go back and check those first. Probably going to swap my old wires back on since they were fine, and there could be an issue with the used wires I'm using. I replaced the PCV system with 3/8 hose and a catch can / check valve setup, so I'll double check those connections as well...
Any other suggestions here guys? I'm sure its probably something stupid I'm missing...just want some opinions on where to look. AIR has been deleted, no EGR, no rear O2s. Rest of mods in sig.
TIA
I figure it may take a few starts for the PCM to do its thing, so I go back out later last night and start it up again. This time, I have a SES light. Check the code, and its p0300...random misfire. I clear the code, and go back through everything looking for vacuum leaks, etc. Tightened all the clamps throughout the system, made sure everything was plugged in, etc. Fire it back up again today, get the code again. Same idle issues as before.
I changed the plugs and wires (used wires from a friend...the Delco red ones that only had about 1000 miles) during the install, so I'm going to go back and check those first. Probably going to swap my old wires back on since they were fine, and there could be an issue with the used wires I'm using. I replaced the PCV system with 3/8 hose and a catch can / check valve setup, so I'll double check those connections as well...
Any other suggestions here guys? I'm sure its probably something stupid I'm missing...just want some opinions on where to look. AIR has been deleted, no EGR, no rear O2s. Rest of mods in sig.
TIA
03-26-2010, 10:40 AM
#4
Steve at Frost assures me something else is going on, so I'm not sure...
The engine is otherwise stock. I would have thought a base tune would at least let me fire it up and idle. Steve even said I'd be safe to make 2-4psi boost, but not to go wide open throttle.
Any other ideas?
The engine is otherwise stock. I would have thought a base tune would at least let me fire it up and idle. Steve even said I'd be safe to make 2-4psi boost, but not to go wide open throttle.
Any other ideas?
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03-26-2010, 01:03 PM
#8
See, that's the thing...it really idles pretty well...especially after it warms up. It will idle fine for 20-30 seconds, then dip a little for a couple seconds, then come back up and idle fine. And it's really erratic...it could idle fine for a couple minutes, or a few seconds...no pattern to it.
The real problem is throttle off idle. Extremely light acceleration off idle produces a bog or stumble...part throttle acceleration revs fine. If anything, there's a slight delay in response...
The real problem is throttle off idle. Extremely light acceleration off idle produces a bog or stumble...part throttle acceleration revs fine. If anything, there's a slight delay in response...
03-26-2010, 01:15 PM
#10
Eaglewood subdivision...behind Wal Mart. I'll be home by around 5. Thinking the new PCV/catch can routing may be the culprit, or possibly the hoses from the plenum ->MAF->TB. Those things looked a little shady from the start...like they're a bit too long.
03-26-2010, 01:42 PM
#13
On my first start up with the procharger I was in the same boat as you, shitty idle and it was missing and poping when you cracked the throttle. I ended up pulling the intake and replacing the 8 "O" ring gaskets. That fixed all my problems. So I would look at the PCV hoses you where questioning and replace the intake manifold gaskets --- if you have removed and reinstalled the intake with out changing the gaskets.
03-26-2010, 01:48 PM
#14
What is funny about that is I did the same thing when I changed the knock senors on my truck. I found out that I tapped the egr valve on the manifold just enough to cause a vaccum leak. The carb spray did nothing to help me find it since it was such a really small leak. Also the same code P0300. Let me know about needing any help or a second pair of eyes.
03-26-2010, 02:33 PM
#15
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P0300 is a random engine misfire, not a specific cylinder. might check the Throttle position sensor and the Idle Air Control valve. IAC can make all kinds of problems when it goes haywire
03-26-2010, 02:47 PM
#16
I used the IAC that the previous owner included already mounted in the plenum, and I was wondering if maybe it didn't get messed up during shipping/install. I still have my old one, so I could swap them out...any way to check the IAC to see if it's within spec?
03-26-2010, 03:01 PM
#18
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leave the IAC off but plugged in, cover the hole with your finger, have somebody start the car and watch the IAC. Modulate the air going through the hole with your finger and see if the IAC moves.
i would say swap it with your old one first though.
i would say swap it with your old one first though.
03-26-2010, 10:06 PM
#19
OK, this thing is freaking killing me. The idle is pretty good, but it still stumbles just off idle if I barely give it any gas. Replace the plug wires with the old ones...still does it. Trimmed and checked all the hoses from the plenum to MAF to TB...still does it. The hoses for the catch can system are all plugged in tight, and I can't see where I could have a vacuum leak anywhere. I haven't thrown the code again yet, but I'm sure its a matter of time...
Should the bypass valve be venting air at idle? Because it's not. The valve is actuating (I pulled the vacuum hose off while it was idling and it moved), but there is no venting of air at idle. Not sure if it is supposed to be doing it or not...it's the stock plastic valve.
I checked the ground wire on the drivers cylinder head while I was under the car, and its hooked up tight as well. I'm running out of ideas here...
Should the bypass valve be venting air at idle? Because it's not. The valve is actuating (I pulled the vacuum hose off while it was idling and it moved), but there is no venting of air at idle. Not sure if it is supposed to be doing it or not...it's the stock plastic valve.
I checked the ground wire on the drivers cylinder head while I was under the car, and its hooked up tight as well. I'm running out of ideas here...
