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Old 11-09-2012, 02:29 AM   #31
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I think I remember it somewhere in the 20* area but I am going to hunt down my ethos tomorrow and see if I can't get some good videos of what the scanner shows.

What parameters should I concentrate on?
I can only fit a few on the screen at once
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Old 11-10-2012, 07:13 AM   #32
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Just look at RPM, spark advance, and IAC steps. Spark advance will fluctuate a few degrees. I am not sure exactly where it should be, but I would think mid to upper 20's with a hot cam.

I had similar idling issues. I would have a high 1500 RPM idle in park to get 1000 RPM in gear.. if I set 1000 rpm in park it would stall in gear. I bumped the timing at idle to 32 degrees and reset the throttle blades to idle in park at 1000 RPMs. It made a huge improvement and fixed the stalling issue.
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Old 11-10-2012, 07:24 PM   #33
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Still can't get ahold of the scanner. ugh
I did however attempt to drive it today and tinkered a little bit.
It is running good enough to drive now. ( I had the ICM and coil spaced off the head and it started arcing the coil wire to things other than the distributor)
So I placed it back on the head and made a new coil wire. All is good there no random arcing now.
Now the problem is a little different with the idle screw and tps and iac adjusted at what I think is optimal. Holds idle. Until you play with the throttle and basically try and make it die with quick revs and slow revs. I have a video that might help better if need be.

If you rev it quick it comes back down to idle correctly idling down but if you hold the rpms steady for awhile then let off quick it dies or tries to and I catch it with the throttle so to speak. (only to avoid starting it again)

So Getting fed up with it I decided why not unplug the passenger o2 see if it does better.
Well I drove it and it never died on be but I did see it catch itself a few times assuming the Iac did that.

But o2 plugged in or not when I rev the engine to anywhere below 2,000 rpm the engine appears to be loading up. Example. I give it throttle and it quickly goes up to 1500 or so then it starts to sound funny and the rpms slowly lower. Doesn't sound like a miss but that there is extra strain on the motor. the only thing I can think of is it's loading up with fuel.

Should I have unplugged both o2 sensors?
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Old 11-11-2012, 12:01 AM   #34
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So after driving it for a bit it seems the idle issue has been completely resolved by disconnecting the driver side o2 sensor?
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Old 11-11-2012, 01:38 AM   #35
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That would indicate either a faulty O2, faulty O2 wiring, or fueling problems in the driver's side bank of cylinders. What was the O2 reading with these problems and which O2 did you remove from the left side, the front or the back?


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Old 11-11-2012, 03:29 AM   #36
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Not sure what the was reading recently but last I checked they both switch fine although maybe a bit slowly. But still switching and it would go into closed loop but the idle is up and down and it stalls randomly. ( starting to sound like o2s?)
Could it be anything else? I mean by disconnecting the driver upstream o2 only does that keep it in open loop or do I need to disconnect both of them to get that effect?
Either way whatever I did it now idles smooth and I don't think Iv'e ever heard it idle so quietly.

But if by just removing the one o2 does keep it in open loop wouldn't it also suggest that maybe the map tps iat or the maf could be bad?
Although all of these sensors read normally in the past (why I'm stumped and o2's are the last thing I know of to mess with)

I don't even have wiring for the downstream o2's and they are simulated in the tune.
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Old 11-11-2012, 04:31 AM   #37
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Quote:
Originally Posted by Keesling View Post
Could it be anything else? I mean by disconnecting the driver upstream o2 only does that keep it in open loop or do I need to disconnect both of them to get that effect?
Disconnecting the upstream (front) O2 will send it into open loop. It could be other things, which is why a scan tool is so valuable in this situation. Spark advance is one thing to pay attention to as mentioned. Like I said, I'm not really a tuner (yet), but if there's a big jump in spark advance when the PCM is using one cell for spark advance to another cell (tuning error), as in when MAP values and RPMs change, it could be constantly chasing itself causing erratic idle.

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But if by just removing the one o2 does keep it in open loop wouldn't it also suggest that maybe the map tps iat or the maf could be bad?
No. Closed loop uses the O2's for fuel calculations, but still uses MAP, IAT, and RPMs for spark. The PCM aims only to achieve 450mV at the O2 to maintain stoichiometric as best it can. This is where you were having trouble.

Once the O2 is disconnected and the PCM enters open loop, it then uses the appropriate fuel and spark tables to calculate pulse widths an spark advance based on inputs from IAT, MAF, MAP, TPS, ECT. Using only these sensors you are running good.
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Old 11-11-2012, 08:02 AM   #38
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I had a couple fouled O2 sensors in the past cause a stalling issue. Also the car ran pig rich. I bench tested the O2 sensors with a propane torch to confirm they were bad.

The computer still uses MAP, TPS, and MAF readings in open loop. If you disconnected the O2 sensor and the car is running better I'd say you are on the right track.
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Old 11-11-2012, 05:38 PM   #39
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Okay so if when the pcm enters closed loop it's using the input to calculate fuel,
and since it has trouble idling and stalling that the o2 is maybe not reading the exact amount of air in the exhaust stream, If it is lazy would that then confuse the pcm if it added fuel too late and the engine is already rich thus killing it by flooding it? or the opposite and running it out of fuel? or is it affecting something else?

Now when I unplug it and it stays in open loop, It still uses the map iat ect Like speed density but also the maf? Does it just use whatever is left plugged in?


I know the maf is good and the iac is new the tps reads voltage throughout the throttle range and the coolant temp is correct both on the scantool and the gauge the iat also reads normally (usually hotter than I'd like but still accurate)
So this leaves me with the o2's and thats it?

So why wouldn't it start sometimes when cold I would have to rev it? the o2's shouldn't even be working yet?
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Old 11-11-2012, 08:43 PM   #40
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Okay! Got my scanner woohoo right?

On my way to get the scanner it ran flawlessly No stalling and it actually was fast. Before I left I decided to see if it would start cold without the o2 in and idle good. And well it did it started up right away and idled normally

Little did I know when I got the scanner hooked up I looked over the codes and there were tps ones and a maf one and the o2 one well those I had unhooked at one point. So I clear all of them and start driving. Checked again, maf code still there. hmmm. Also the reading was stuck at 2.43 or something I got all excited thinking it was the maf all along.

Btw I raced a challenger omw home onto the on ramp and I gave him the jump off the line I feather it through first and hit it in second sliding left and right (very cold out) and finally pass him at the top of second and third.

Well I got home and popped the hood (low and behold in my drunken slumber last night must have disconnected it to see what happened and never plugged in back in. but it ran good without it plugged in

So I plugged it back in and recorded the scanner with my camera(sorry not as good as datalogging but close)

So here it is at idle all sensors hooked up
Also the o2's when I hold it at 2000 I think
http://youtu.be/jO3_HhTrxqA
Long term trim 1 at -7 is a little weird right?

Tps is as low as it will go with the throttle opened up that much and it should be higher so the iac won't be at 60ish

This one shows when I rev anywhere below 1500 rpm the rpm start dropping and then if I let off it will die if don't give it some throttle

http://youtu.be/0BNd3hJYQmY
I hope someone will watch these videos and see something I don't


Ill maybe take some more "data logs" lol when I go to my buddies house tonight
Or sooner if someone requests certain info under load or whatever it might be,

Thanks!

Whoops I guess it decided to post. Will post the videos as soon as youtube has uploaded them
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Last edited by Keesling; 11-11-2012 at 08:59 PM.
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Old 11-11-2012, 11:03 PM   #41
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I think the tps is bad. I tried to adjust it and the lower I adjust it the lower the throttle % is at full throttle.
I can remove the tps and twist it with a screwdriver and get full voltage 4.8 or something but when installed it won't go high enough unless it is set at .90 at closed throttle then I can get full throttle but the base voltage is way too high.

I think this may be my issue. When the tps is removed and not twisted at all it can only go down to .71 which is still too high and when set there it only shows about 25% throttle. With any setting it shows 0% throttle even at .90

Does everyone elses tps have a lower voltage when removed I hear people adjusting it to .54 and lower.

What do you think?

Also when I set the tps to .90 to get full throttle voltage it won't idle unless given gas. Assuming this is something to do with one of those tps fuel trim tables?
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Old 11-12-2012, 03:27 AM   #42
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Upon further diagnosis of the tps I found the black and blue wires to be mixed up on my tps harness. It runs much better with the correct tps reading.(not sure how it worked as well as it did that way) but much smoother throughout the rpm range.

But I cannot get the iac to stay in one spot. I adjust it just barely (.02 volts on the tps and the iac want to close or open all the way and it acts different everytime I start it.
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Old 02-09-2013, 03:30 PM   #43
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I hate this car lol
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Old 10-12-2013, 11:31 PM   #44
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my 96 slp has similar mods,,ported heads , lt4 hotcam etc and when i take off regular the idle builds up to 2000+ rpms and slows down as i slow down,,,,and actually in neutral i can hear it start to slowly climb up until i bump the throttle,,smdh
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