Run a can of Seafoam in the tank, that may help.
Help diagnose...
Thread Starter
Instructor
Joined: Dec 2007
Posts: 202
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From: Carrollton TX
Help diagnose...
'02 Z with 65K just started running rough with bucking/surging at speed and idle is low and would probably die if I didn't give it gas. This problem has been intermittent for the last couple of days and the only code it has thrown has been P0522 H which is a low voltage warning on the oil pressure sensor. The oil pressure dips way down when the idle drops under 800-900 but at anything over 1000rpm's seems to read correctly. The Service Vehicle Soon light has popped up a few times also. I've read that the Oil Pressure Sensors suck on these cars and often need replacement but have yet to hear of anyone with drivability problems associated with a bad or failing sensor.
Drifting
Joined: Feb 2007
Posts: 1,793
Likes: 7
From: Santa Maria Ca.
At 67k it could be that the fuel filter needs replacing-that would explain the rough running.
If the rpm's fall too much at idle(due to the plugged fuel filter),you'll get the low oil pressure code
Something to check.
If the rpm's fall too much at idle(due to the plugged fuel filter),you'll get the low oil pressure code
Something to check.
Melting Slicks
Joined: Jun 2008
Posts: 2,500
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From: Lower, Slower Delaware, formerly from Mobtown, MD (Baltimore)
Le Mans Master
Joined: Nov 2005
Posts: 6,993
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'02 Z with 65K just started running rough with bucking/surging at speed and idle is low and would probably die if I didn't give it gas. This problem has been intermittent for the last couple of days and the only code it has thrown has been P0522 H which is a low voltage warning on the oil pressure sensor. The oil pressure dips way down when the idle drops under 800-900 but at anything over 1000rpm's seems to read correctly. The Service Vehicle Soon light has popped up a few times also. I've read that the Oil Pressure Sensors suck on these cars and often need replacement but have yet to hear of anyone with drivability problems associated with a bad or failing sensor.
Thread Starter
Instructor
Joined: Dec 2007
Posts: 202
Likes: 0
From: Carrollton TX
Fuel pressure is rock steady 53# while not running but the needle is shaking like crazy when idling. It's bouncing all over the scale between 52-58# and when the car started idling rough it got down to 42-44# for a split second.
Le Mans Master
Joined: Feb 2003
Posts: 6,682
Likes: 144
From: Memphis Tennessee
I would check two more things.
Look at the throttle body for loose or leaking vacuum lines. I had the PCV line develop a leak and had the same symptoms.
Secondly I would remove and clean my MAF sensor. Easy to do with the appropriate cleaner and may be the culprit as well.
Good Luck and keep us posted to your results.
Look at the throttle body for loose or leaking vacuum lines. I had the PCV line develop a leak and had the same symptoms.
Secondly I would remove and clean my MAF sensor. Easy to do with the appropriate cleaner and may be the culprit as well.
Good Luck and keep us posted to your results.
Thread Starter
Instructor
Joined: Dec 2007
Posts: 202
Likes: 0
From: Carrollton TX
I took a good look around all the vacuum hoses first thing...I'll go look around some more though. Right now I plan on starting with the fuel filter and going from there. Where in the pcv system was your leak?
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Le Mans Master
Joined: Feb 2003
Posts: 6,682
Likes: 144
From: Memphis Tennessee
I had installed a CH catch-can and had a line (or two) that did not seal without clamps. Car ran like crap, threw codes and maint light. Put clamps on, stopped the leaks,......all was good again.
good luck
Thread Starter
Instructor
Joined: Dec 2007
Posts: 202
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From: Carrollton TX
Thanks-all vacuum and wiring looks good. Ran out of time to track down a fuel filter today-Autozone doesn't stock one and O'reillys closes too early. I'm pretty sure that the fuel pressure should stay steady and not dip down as much as I saw on the gauge so this should be either the filter or the pump...hopefully the former.
Intermediate
Joined: May 2010
Posts: 41
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From: Long Island New York
does this issue change in relation to engine temperature, i.e., fine on a cold start but progressively worse after 180*'s. Is the "bucking/surging" only at idle? Does it run smooth above 2k and the issue is only present at idle?
Thread Starter
Instructor
Joined: Dec 2007
Posts: 202
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From: Carrollton TX
Temp and rpm do not matter. I banged on the fuel filter a few times with a screwdriver handle while I was looking the car over this evening so who knows if that knocked some sense into it or not? It did seem to be running a little better on a trip up the street at the end of the night to get some fresh premium and a bottle of Techron. Anybody got a brand of fuel filter and source in DFW they recommend? I usually use Wix...
Thread Starter
Instructor
Joined: Dec 2007
Posts: 202
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From: Carrollton TX
I noticed that the oil pressure reading is fluctuating at all rpms when the car starts to run poorly/misfire. Pressure looks to be running on the low side (under 35 psi and unstable) when car starts running poorly and then when the problem clears up the oil pressure goes back up to normal levels i.e. over 40 psi and holds steady. Car ran decent last night and very poor today. Almost ready to 
Thread Starter
Instructor
Joined: Dec 2007
Posts: 202
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From: Carrollton TX
Found my coolant sensor to be crumbling apart so replaced that and still having same probs even with the coolant gauge. It either works and the car runs fine or pegs out at 260 deg. when the car starts running poorly. Also the fuel pressure and oil pressure going wacky at the same time. All wiring looks good including around the pcm. Battery only reading 12.0 volts with engine off. Age of battery is unknown (undated Delco Proffesional), has anyone heard of drivability probs like this before with a failing battery?
Drifting
Joined: Apr 2007
Posts: 1,496
Likes: 1
From: LEBANON PA.
Hey cool bubba;
Your on the right track.Code p-0116 is a coolant sensor that always reads hot & causes cold driveability problems such as stalling , hesistation as well as r/idling. I,am wondering since you changed that if your t/stat is stuck open or closed?
robsc501
Your on the right track.Code p-0116 is a coolant sensor that always reads hot & causes cold driveability problems such as stalling , hesistation as well as r/idling. I,am wondering since you changed that if your t/stat is stuck open or closed?
robsc501
Last edited by robsc501; May 18, 2010 at 10:02 PM.
Thread Starter
Instructor
Joined: Dec 2007
Posts: 202
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From: Carrollton TX
I'm not 100% sure but it seems that a new battery has solved the problem. Replaced it this evening after work and the car is running like a champ again. We'll see if this lasts but the car was going haywire-I had more warning lights than Apollo 13. Even threw up the "Pull key and wait 10 seconds". Replaced the coolant temp sensor because I found it to be cooked (crumbling) by the header and the gauge was still pegging at 260 deg.. Put on a fuel pressure gauge and it was fluctuating like crazy, oil pressure on the DIC was erratic at best even setting codes for the oil pressure sensor and the car generally would run like crap. However the voltmeter never acted strange and the car fired right up everytime...? 
keeping my fingers crossed-thanks to all for the help
keeping my fingers crossed-thanks to all for the help