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  #1  
Old 03-16-2010, 08:38 PM
coguzzi coguzzi is offline
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stumbling SVX ans select monitor data

background on my problem, had a hard start issue on a 92 SVX traced to 2 leaky injectors serviced by witch hunter. ran great for 10 miles, and poorly ever since. I did find a bad (wrong) plug and eventually killed a coil pack, still runs poorly after warmup. kind of a stumble under 2K and when i really get on it. it sounds like an exhaust leak, but exhaust is tight

sent injectors back to witchhunter and test perfect up to 12K rpm (excellent service BTW). reinstall, still stumbles after warmup.

borrowed a friends select monitor today--man that thing is sweet, im gonna have to invest in one. So i have all this data now, but cant seem to find a source of what parameters should be. anyone know where to look? if so ill try to compile it together in one easy to use data sheet and post it up.

BUT, the 2 red flags i got, F13-O2 sensor 1 (RH) numbers were bouncing alot where as the F14 O2 sensor 2 (LH) held steady and RH was generally higher

DATA:

F13 O2 sensor 1 (rh) .32-.80V
F14 O2 sensor 2 (rh) .04V
F15 O2 max (rh) .76V
F16 O2 min (rh) .04V
F17 O2 max (lh) .04V
F18 O2 min (lh) .02V

so it seems i have a rich problem on O2 #1, right hand bank.

ideas? O2 sensor is the easy but slightly expensive bet, but i guess there are a couple other things it could be. still havent ruled out jumpin a tooth on the belt either since i did hydro lock it when i was trying to flush the fuel system.
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  #2  
Old 03-16-2010, 09:00 PM
NiftySVX NiftySVX is offline
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Re: stumbling SVX ans select monitor data

The real trick with the select monitor is knowing what it is telling you. This is more of the advanced stuff that isn't really common knowledge. Having said that, I am confused as to why you are condemning the oxygen sensor.

The purpose of the sensor 1 position (pre cat) oxygen sensors is to provide the ECU with data so that it can fine tune the injector pulsewidth to ensure optimal fuel delivery. I.e if it is lean then increase injector duty and if it is rich then reduce. This is commonly called "fuel trim"

The oxygen sensor is likely showing you information you need to use. It may be telling you which side is off. If you actually hydrolocked the motor it would likely have bent rods and then you'd be really in trouble. But that's alot of liquid to get in there to cause that to happen. If your 02 shows rich on one side then you could assume there is an ignition misfire or a leaking injector, If there is a lean condition you could assume that there is a fuel delivery problem in that bank.

I don't recall if the old select monitor provides you with fuel trim data, if it does that is what you want to see. If the computer is telling bank 1 to increase to 20%, say, then you'd know the computer was trying to add fuel to it. Or if you had a leaking injector, it would say -20% or so, and it would be trying to lean it out.

RH bank is oscillating around .5 v, this is normal. I would assume that your RH bank is runnin pretty good.
LH bank at .4? Sounds pretty lean to me. Are your injectors firing on the LH side? is one clogged? do they have pressure?

Of course there are other possibilites that could cause these symptoms (including a bad O2)but based on the fact that you have plug/injector issues that's where I start.
If possible I would look at the scope pattern of the sensor.
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Last edited by NiftySVX; 03-16-2010 at 09:26 PM.
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Old 03-16-2010, 09:06 PM
NiftySVX NiftySVX is offline
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Re: stumbling SVX ans select monitor data

also can I assume F14 should be 02 sensor "LH"?
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Old 03-17-2010, 04:59 AM
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Re: stumbling SVX ans select monitor data

prob a cam timing issue

Tom
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Old 03-17-2010, 09:06 AM
coguzzi coguzzi is offline
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Re: stumbling SVX ans select monitor data

DOH, yes F14 is LH, my bad.

I think i have ruled out injectors. granted problem started after service from witchhunter for 2 leaky injectors (who i found to have excellent service). I did in fact send them back (along with some spares) for a retest. all tested perfect up to 12K rpm. He even recleaned them just to be sure. I could start swapping in spares. Noid light shows they are all firing.

the hydrolock i refer to was just with the starter (non running). i should have pulled the plugs before turning over, kind of a brain fart on my part.

also note it runs fine until warm up
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Old 03-17-2010, 04:47 PM
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Re: stumbling SVX ans select monitor data

Quote:
Originally Posted by TomsSVX View Post
prob a cam timing issue

Tom
..................
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Old 03-17-2010, 05:06 PM
NiftySVX NiftySVX is offline
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Re: stumbling SVX ans select monitor data

Cam timing is easy to check. I thought that you meant you had already checked it but I see now I misread. just pop the outer belt covers loose and see if it jumped a tooth.
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Old 03-18-2010, 08:55 AM
coguzzi coguzzi is offline
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Re: stumbling SVX ans select monitor data

ill pull the covers off here in the next few days, time isnt on my side right now.

I did switch the O2 side to side, still stumbles, but the select monitor data seems correct now, both O2's oscillate voltage (above idle anyway, at idle a steady .04) and the min and max values match.
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Old 03-20-2010, 01:59 PM
coguzzi coguzzi is offline
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Re: stumbling SVX ans select monitor data

cam timing is perfect. all marks line up as they should. i was hoping for this easy fix actually. now what--haha
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Old 03-20-2010, 02:04 PM
NiftySVX NiftySVX is offline
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Re: stumbling SVX ans select monitor data

Compression test is where I would go. Just as a first step. You may have a headgasket issue or something. It's hard to say.
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  #11  
Old 03-20-2010, 03:41 PM
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Re: stumbling SVX ans select monitor data

Pull the cam pullies and check their keyways for wear or damaged keys
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Old 03-20-2010, 04:55 PM
coguzzi coguzzi is offline
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Re: stumbling SVX ans select monitor data

I actually did a compression check about a month ago when i started having this problem, all were even and very high (the actual numbers elude me right now).

im down to maybe MAF, vacumm leaks or O2 sensors i think.
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