Car misfires and sputters really really bad when under boost
02-22-2006, 02:14 PM
#1
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Car misfires and sputters really really bad when under boost I was driving to pick up dinner last night and the car starting idling really bad and kept stalling. I got it home and and checked codes and the computer says O2 sensor 1 bank 1 & 2 lean. I changed both O2's with some spares I have laying around and got the same problem. I got up this morning to work on it and the car woldn't start. Come to find out since I put a Walbro pump in, the car runs empty at 1/8 of a tank. Put some gas in it an went to get it filled up and still having the same problem. The car runs a little choppy at idle now and when I drive it normal it runs fine, but when I step into it; causing boost from turbo; the car misfires and sputters really, really bad. My A/F gauge says the car is running really rich, but the codes the computer keeps spitting out says it's running lean. The car is still a little hard to start every time. Could the fuel pump, an injector, or the MAF sensor have crapped out? Or maybe god for sake it be something with the turbo? Are there anyways to check any of these? And wouldn't the computer spit out a code saying on of these is failing? Please help it 's my daily driver and I need to get back up and running. Good thing I'm off of work the rest of the week! Hope someone can help? Thanks!!
02-22-2006, 04:16 PM
#2
Start with the basics: Check all 8 plugs; check your fuel pressure at the rails. For the sake of your motor, don't drive it like this. You may make a simple problem worse. Start it as little as possible til you find out what's up. Follow up with a compression test then a leakdown test, to see if your motor is damaged.
Jim
Jim
02-22-2006, 04:57 PM
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Plugs look good. They're a light shade of gray from running lean I guess. I can put my spare set of TR66's in and see if it makes a difference. The wires look good, but I have no way to check and make sure. No FP gauge. Where is a good place to install a FP gauge under the hood? Anywhere on the fuel rail to put it? I've got fittings, I just don't have a FP gauge. Guess I'll get someone to take me to get one. Going to go with a manual one. Just need to know where I can put it. I'll borrow a compression tester and leakdown tester and see what's up on the inside. Thanks!!
Last edited by blackbeautyWS6; 02-22-2006 at 05:29 PM.
02-22-2006, 06:54 PM
#5
looks like your still on stock rails, so take the scharder(sp?) valve out of the end of the drivers side rail, screw a -4 line on to it, and then run it to a fuel pressure guage. Then you can tell your pressue at the rails.
02-22-2006, 09:49 PM
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Does the car sputter or mis before it hits boost? I had a somewhat similar experience when my car was running really rich in boost areas ( like 9:1 afr). What afr is the wideband reporting?
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02-22-2006, 09:52 PM
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mine was misfiring really bad at light throttle and 7+ boost . . . had 2-3 bad wires. Replaced them and problem went away, easy enough to check that first.
- Dug
- Dug
02-22-2006, 10:33 PM
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It is happening right before boost now that bring it up. Under light throttle or normal driving it's good. It feels a slight hesitant on take of but once you get the rpm's up it o.k. until I step into it and then it sounds like a war in the back of the car. All the cracking and popping and backfiring. It sounds bad, and not bad in a good way either.
Chevy: Did your wires go bad w/ stock wires or aftermarket? My 8.5 MSD's are only about a yr. old. I might go buy a cheap set and see what happens and if it doesn't help then I'll just take them back and say I didn't need em?
Other than that my FP setup hardware and gauge will be here in the morning so I'll be able to tell if it's a fuel delivery problem or not. Does anyone know the procedures to ops ck the injectors? If one's bad it'll give me a reason to tell the wife I need more parts for the car!! So far I've checked all plugs, all vacuum lines, and all turbo piping and hoses and everything's good so far. Tomorrow morning it'll be wires, FP gauge, comp & leak-down ck, and maybe injector cks. It's gotta be on of those things. There aint much else left!! If anyone else has got there own opinion let me know please. Thanks guys for the help so far!!! 
It's way past beer 30.
Later
Chevy: Did your wires go bad w/ stock wires or aftermarket? My 8.5 MSD's are only about a yr. old. I might go buy a cheap set and see what happens and if it doesn't help then I'll just take them back and say I didn't need em?
Other than that my FP setup hardware and gauge will be here in the morning so I'll be able to tell if it's a fuel delivery problem or not. Does anyone know the procedures to ops ck the injectors? If one's bad it'll give me a reason to tell the wife I need more parts for the car!!
So far I've checked all plugs, all vacuum lines, and all turbo piping and hoses and everything's good so far. Tomorrow morning it'll be wires, FP gauge, comp & leak-down ck, and maybe injector cks. It's gotta be on of those things. There aint much else left!! If anyone else has got there own opinion let me know please. Thanks guys for the help so far!!! It's way past beer 30.
Later
02-22-2006, 10:46 PM
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Originally Posted by Slowhawk
Also check the MA meter to make sure there is no oil on the sensor wires.
02-22-2006, 10:48 PM
#13
when you changed the o2 sensors you pluged everything back in and disconnected the batt. to reset the pcm right?, fuel or spark, just remember that, take off the filter to the turbo and make sure it spins freeley, start the engine and you can touch each injector top area w/your finger and listen and feel if there working, you will hear a light ticking each time it opens, could also be a maf or map sensor, if the map is reading wrong could be causing the timing tables to be waaay off, hard to do an internet diagnosis though..
02-22-2006, 10:50 PM
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No oil that I know of under the car, but I did notice a little oil film in the intake pipe going towards the TB. What's safe to clean the MAF sensor with?
Last edited by Turbo T/A; 02-23-2006 at 12:11 AM.
02-22-2006, 10:53 PM
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I just diconnected the comp. about 30 min. ago to reset everything. Turbo still spins really well. Where's the map sensor? I've never had to deal with that before. Thanks for heads up on the injectors I'll give that a shot.
02-23-2006, 12:09 AM
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SES light came on. Checked codes and got a O2 Sensor 1 bank 1 & 2 Lean. I've been kinda leaning towards a bad pump all along. With the FP gauge install tomorrow that will be able to tell me what I'm looking for outta the pump.
02-23-2006, 08:37 AM
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Originally Posted by ABeasst
if you ran out of fuel the fuel pump may have overheated and burned up since its cooled by the fuel