North American Turbocoupe Organization



new a/f gauge slow...bad ground on new gauges?
Matt S Offline
Posting Freak
#1
Alright. Got the la2 in (thanks Hawk).

It seems to sound a little better now, but still has a miss felt and seen in the engine vibration.

My A/F gauge is very slow, taking about 2 or 3 seconds to make a cycle. It was never reading full rich, even when cold. Most it got was 1 yellow bar above green, and part of the cycle is to blank out lean completely. It never changed as it warmed up with 2 fan cycles, and rpm has no effect. I didn't drive it though. This thing should be switching many times a second, right? The O2 is 2 1/2 years (maybe 1,500 miles) old. Do I drop another fitty bones for one?
I have a 10sec quicktime movie of the operation but I can't post it so let me know and I'll mail it to you.
Also, my gauges seem to be a bit low, water especially. When thermostat opened it said about 170*, I have a 195* in there. Fan came on at 200*, and climbed to about 205* before it went off, then slowly dropped to about 195*.
I did use 1/2 thread of liquid sealer on the sensors, knowing teflon is bad. Was that a bad move? All 3 gauges are grounded to the same terminal, screwed to the center metal of the dash.


[This message has been edited by Matt S (edited 09-22-2003).]
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Pete D2 Offline
Member
#2
My observation has been that thermostats start to open well below their rated temp. I think the rated temp is for when they are full open.

I'll send you some info on the 02. Mine was slow like your once and then it went away. I never did determine a cause. Min eusually switch a couple or more times a second
Turbo
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natmac3 Offline
Administrator
#3
I've heard that unless you ground the A/F guage to the battery, it'll register incorrectly. I don't know if it's different for other gauges, but Darren Dawes at Dawes Devices recommended grounding his ONLY to the battery, so I did.
1987tc
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rairbird Offline
Senior Member
#4
I don't have mine grounded to the battery and it cycles very quickly. It has been my experience that when it slows down the O2 sensor needs to be changed. Check all of your connections first though to make sure they are making good contact.

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87 T/C, 5sp., Ported/Polished head, 1.89, 1.59 S.S Valves. Motorsport Lifters, A-234 cam, ported lower, gutted upper intakes, Rod's S/S headers, 3" DP, T3/T04E 46, Gillis BCV, K&N Air Filter, 42LB injectors, kirban Adj. FPR, Walbro 255 FP, Diablo chip, Head and Main studs, APR rod bolts.
The next mod is to install the GN intercooler.
88 T/C stock, 5sp.
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Jeff K Offline
Administrator
#5
Quote:Originally posted by natmac3:
I've heard that unless you ground the A/F guage to the battery, it'll register incorrectly. I don't know if it's different for other gauges, but Darren Dawes at Dawes Devices recommended grounding his ONLY to the battery, so I did.



Not necessary. Any good ground will work fine, assuming the batt to frame and engine to frame grounds are in good shape.

Matt: At idle, with motor warm, 02 should cycle rich/lean maybe 2 times a second. At, say, 2000 RPM 50 mph cruise, it should cycle somewhat faster, like 3 times a second. It wont read full rich with a cold motor unless coolant temps are under about 50 deg F.

It does sound like you have a lazy 02 sensor. Have you recently had any problems with running excessively rich? Rich A/F can contaminate the sensor and cause slow response. The cure is some good old high speed, high RPM driving to burn it clean. Blown a HG lately? antifreeze contamination on an 02 can cause slow response, incorrect output, etc.


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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 02 Taurus Vulcan(wifes car)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Matt S Offline
Posting Freak
#6
Quote:Originally posted by Jeff K:

Not necessary. Any good ground will work fine, assuming the batt to frame and engine to frame grounds are in good shape.


The couple ground straps I ran across were in fine shape. I will check the resistance of my current location back to battery.

Quote:
Matt: At idle, with motor warm, 02 should cycle rich/lean maybe 2 times a second. At, say, 2000 RPM 50 mph cruise, it should cycle somewhat faster, like 3 times a second. It wont read full rich with a cold motor unless coolant temps are under about 50 deg F.


Jeff, it does not cycle that quick for sure, I can count 2 seconds or more, and when it goes on the lean cycle, it's all the way off the gauge, and stays lean for 1/2 sec...then goes to 1 bar green for about 1/2 sec or so.
But it's not anywhere near even 1 cycle/sec. Definately longer. I can mail you the .mov I took tonite if you're interested.

Quote:
It does sound like you have a lazy 02 sensor. Have you recently had any problems with running excessively rich? Rich A/F can contaminate the sensor and cause slow response. The cure is some good old high speed, high RPM driving to burn it clean. Blown a HG lately? antifreeze contamination on an 02 can cause slow response, incorrect output, etc.

I'm not loosing antifreeze, I have no reason to believe I have a blown hg or cracked head.
I've had a couple stored codes for the rich condition...but this was when I was fooling with timing etc.
Have I had any problems...?
Uh..yeah. [Image: smile.gif]
So I wonder if all those other problems took out the o2. It was last driven Friday, and I'm usually not in the lower RPM much; 4th gear, 3k to 3500 in traffic around the freeway - unless someone gets out of my way (yeah right).

When I get home this afternoon I'll put my fluke right on the sensor and see how it acts; but it sounds like I'm buying one either way to rule out that problem.

Anything else I should check?
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tylerport Offline
Senior Member
#7
My A/F Guage does the same thing. Very slow to cycle. I just figured that was the way it worked. Maybe I've got a problem. I hit 5500rpms almost everytime I drive it though. During normal cycling of the gauge it only lights one green, sometimes two and only lights the third at WOT. I've never had the fourth and fifth green lights come on.

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Jim Portteus
NATO Member
86 Turbo Coupe, LA3 w/ Intercooler and Larger VAM, Gillis Valve, 2 1/2" Downpipe to 2" Duals w/ 18" Glasspacks, 245/50R16's, 140MPH Speedo, A-pillar pod w/ Boost and A/F Ratio Gauges and Steeda Tri-Ax Shifter.
Jim Portteus
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Matt S Offline
Posting Freak
#8
Hold on to your butts!

I got in the new o2 and it - say it with me - still runs like crap. Worse than yesterday, which was the best idle I've seen. Today is some of the worst, it sounds like it's backfireing without the crack, just a pft, which to me means unburned gas.
This time I took it out for a spin. The a/f meter is more active now, but I noticed it going to full rich every time it gets over about 3400 rpm. Even without moving; no load!! 3400rpm, BAM, all lights. It's a cyberdyne meter. Once or twice it was up to one yellow on a decel even without any throttle. It goes one bar yellow only flickering back green with any more than a light touch on the throttle (maybe 1/8).

Checking the TPS, trying to hit base idle is very hard now as it dies as soon as it misses with that pft sound out the pipe. I got it about 800rpm without much adjustment and the TPS was .965v. Still runs as described.

I ran out of light and didn't get a chance to mess with the gauges ground that's behind the center panel and the radio, or tap the o2 sensor with my fluke. The plugs that came out 3 weeks ago for new ones weren't sooty at all. When I had my pipes off last month they were sooty, but nothing extreme. My o2 sensor was grey on the metal tip, with medium carbon/soot round the thread rim.
But does this sound like a VAM to you??
I guess that's my next step, it's the only thing that hasn't been replaced. If anyone has a known good VAM I can borrow I would glady pay shipping both ways and something for your trouble.
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jabobia Offline
Member
#9
so you think youre running rich?...have you checked the FP regulator for gas in the vac. line?

-james

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87 TurboCoupe - 5spd
87 Thunderbird TurboCoupe - 2.3T, T5, 3.55L - K&N, 18psi - [email protected](2.37 60')
88 Thunderbird Sport - 5.0SO, AOD, 2.73L - [email protected](2.39 60')
www.cardomain.com/id/jabobia
jabobia.com
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Matt S Offline
Posting Freak
#10
jabobia, there's a new napa regulator on there. Pressure was 39 or so no vac, and boosts to 49 at 10lbs. However I've notice sometimes that the intercooler has a fuel smell when I take it off.
Since this is a new deal aside from my gauge question, I opened a new post.
Thanks.

[This message has been edited by Matt S (edited 09-24-2003).]
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