Need misfire/idle help
Thread Starter
TECH Regular
Joined: Nov 2001
Posts: 410
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From: Madison Heights, MI
Need misfire/idle help My car set the p0300 code and this morning I was looking at the car and it's not misfiring on any cylinders but it still is running real rough, it was idling at 1200 rpm and still was about to stall. I checked my o2's and the b1s1 was fluctuating between 900 and 020 at idle in park. I have a 224-114 cam which has been running for many months with no problems. What can I look at to fix this problem. I don't hear any ticking knocking, knock sensor says 0. IAC is 190-210.
When i tap the throttle the car drops in rpm's from 1000 to 400 then works it's way back to 1000 in about 45 seconds. If I jab the throttle hard it will rise in rpm but is real rough then drops down to 1500 for a few seconds then down to 1000. My idle is set at 800.
When i tap the throttle the car drops in rpm's from 1000 to 400 then works it's way back to 1000 in about 45 seconds. If I jab the throttle hard it will rise in rpm but is real rough then drops down to 1500 for a few seconds then down to 1000. My idle is set at 800.
On The Tree
Joined: Jan 2002
Posts: 120
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From: Aloha, Oregon
Re: Need misfire/idle help well, if you are sure the ignition system is kosher (no misfires, all are firing) then i'd have to say this sounds a lot like Limp Mode (Reduced Power Mode on my C5). i have encountered this before; it can happen for a variety of reasons. I dont have the code book in front of me: what is P0300? My car ran like this when the MAF went heywire. do all your basics first: check all sensor connections, check for big vac leak, etc. How is fuel pressure? Something will stick out like a sore thumb real soon, i would imagine.
Thread Starter
TECH Regular
Joined: Nov 2001
Posts: 410
Likes: 0
From: Madison Heights, MI
Re: Need misfire/idle help I checked the connections and everything seemed fine but I did find a bung plug that was halfway out from where I had tuning done and they hooked up a wideband. But that didn't fix it. I just took it to the dealer and I'm going to let thoes monkeys mess with it.
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TECH Regular
Joined: Jun 2002
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From: Georgia
Re: Need misfire/idle help I feel u pain man I just went through this lat week but luckily for me it turned out to be a loose plug on a fuel injector. I did find this after doing everything else including checking compression. Which piston did they say?
Pull the valve cover and check the springs or pull the rocker arms and look at the push rods too. I'd start there.
Pull the valve cover and check the springs or pull the rocker arms and look at the push rods too. I'd start there.
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Re: Need misfire/idle help if you have no compression then it muct be a spring???
BUT if you have a broken vavle spring then atap will show misfire hell on that cyl or the ones around it. When my 918 broke i got like 100 misfires under current history in the cyl that had the break!
car will idle like crap.. and run like crap of coarse cause its only running on 7cyl.
BUT if you have a broken vavle spring then atap will show misfire hell on that cyl or the ones around it. When my 918 broke i got like 100 misfires under current history in the cyl that had the break!
car will idle like crap.. and run like crap of coarse cause its only running on 7cyl.
