i had bad stalling issues with a past CV... the TFI was goin bad and also replaced the air density thing... cant remember its name... did the swap and it ran fine... than a few months later it acted up again because i am guessin the TFI was goin bad since it was used dizzy installed... i just pulled spout plug since i was drivin different car and that CV was too much from electrical gremlins since it was a previously salvaged title situation where body mounts were tweeked and car had issues
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Addicted to 86-87 Panthers -
just for future reference; what are the symptoms of a bad TFI that you were experiencing?
My problem is quite specific. In park it'll idle @1000rpm and when I turn on the AC, and therefore the fan since it's relayed to go on, it all still runs fine. In drive at a stop light all warmed up, it idles at 500rpm. The moment the fan kicks on, the engine stumbles and dies. At the moment, I've got the fan disconnected, and so at stop lights idling @500rpm it runs just fine. Although I can't be at a stop light for too long!
I'd imagine a TFI issue would lead to rough engine firing all the time?Comment
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Now just for shits & giggles... let's say tonight I put a voltmeter on the TPS and I find that I have to crack the throttle open by over 1/16 of an inch to get the tps voltage to be .9V, or some such scenario. That would be new TPS time then?
How closed should the throttle plate be when voltage is .9V; if it ends up cracked just a little bit open, is that OK?
Just speculative. I haven't looked at anything yet.Comment
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It did also stall out yesterday morning when I started it up and threw it immediately into reverse. Started right up again on try two and worked. I figure it's the same issue; rpms dipped to much when put into gear.Comment
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Adjust the TPS. You have a slight adjustment with the TPS. Ideally you want the TPS voltage to be .9 volts exactly, or a little bit less. The range is actually about .7 to 1 volt. But you want the voltage under 1, otherwise the IAC won't control the idle. Since it thinks you're holding the throttle open a little bit. From what I was shown by my engine performance teacher that the throttle response would be best at .9v. So that's what I did, and it is pretty responsive.Originally posted by BerniniCaCO3 View PostComment
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Ohhh, thanks for those details. While I could have set it to .9V anyway, that explains it better.
You know, I may have toyed with the screw, and if it's set to 1.1V and the IAC is not opening, so I'm only getting air through the little hole, that would explain everything.
And while setting it to .7V would work, makes sense that the less slack there is before you start opening the throttle plate for real, the snappier the response; just short of cutting off the IAC again of course. Then, .99V might be better still... but too close to the margin of error in the readings!Comment
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you dont want the throttle plate(butterfly) too far closed or gas pedal will feel stuck when you push it like its jammed.. it is because the butterfly is jamming in the throttlebody being closed... you want it just a hair open to avoid that issue... after the butterfly is adjusted... i would loosen TPS screws and adjust to right voltage... here is another thing... have you ever replaced gaskets on the upper intake/plenum? many times the gasket for EGR spacer goes bad and allows coolant in system which can cause antifreeze buildup, residue and moisture being sucked into the engine... i always bypass them hoses so i dont worry about that leaking into the engine as a mystery coolant leak... and ask John 86Vicky about the car i had at SF07... it barely wanted to run and stalled alot till the dizzy was swapped along with the air density thing ...Last edited by 87_crown_vic; 09-19-2011, 12:27 PM. Addicted to 86-87 PanthersComment
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Last time I had a car that stalled that much the engine was just flat wore out.1989 Grand Marquis LS
flat black, 650 double pumper, random cam, hei, stealth intake, Police front springs, Wagon rear, Police rear bar, wagon front ,exploder wheels, 205/60-15 fronts 275/60-15 rears, 1 5/8" headers, 2.5" offroad x pipe, Eclipse front bucket seats, Custom floor shifter, 4.10 gears, aluminum driveshaft and daily driven. 16.77@83mphComment
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The HO IAC will fit. The trick is plugging it in before bolting it to the intake. Its impossible to connect it otherwise. I ran one on my car for a couple years before finding a nice shiny lopo one randomly while looking for something unrelated.86 Lincoln Town Car (Galactica).
5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley
91 Lincoln Mark VII LSC grandpa spec white and cranberry
1984 Lincoln Continental TurboDiesel - rolls coal
Originally posted by phayzer5
I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers
Everything looks like voodoo if you don't understand how it worksComment
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Unscrew the base from the valve and rotate it 180 degrees, then you can plug it in.Originally posted by gadget73 View PostComment
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Someone told me that I could not rotate it 180 and have it still work (I'd thought about that)?
Anyway, too late, bought the lopo one from napa for $55 and have installed it
I think someone told me earlier that the IACs were the same anyway.
OK! A report!
I checked the TPS. It was set @.77V. In factory spec range, and most importantly, far from that 1V threshold that would have disabled the IAC. I did advance the screw a little bit and got it to exactly .9V with no problem.
I also replaced the IAC.
Unhooked the battery, let all computer memory drain, rehooked it.
Started 'er up, tried the a/c (which also starts the fan), drove it home to warm it up...
It DOES idle higher. It now does 700rpm hot. It probably has not learned proper idle yet, if the 8 heat cycles mentioned before is correct.
If I'm at hot idle and turn the a/c on, it WILL dip and stumble and then recover. Since it started at 700rpm, its stumble is now not fatal; whereas before it would never be able to recover.
If I turn the a/c on while on the highway cruising at 1000rpm, it dips to 900rpm and immediately recovers. If I weren't looking for it, if I were an uninterested non-car-guy public motorist, I might not notice. Having turned the a/c and fan on while cruising, when I came back to an idle, the car never stumbled, as the load had been there all along. Introducing it suddenly while stopped at a red light and the fan kicks on, no longer stalls it out, but you feel the engine lug for a second and can watch the rpms dip worrisomely.
So, maybe that's just life.
Or maybe it will correct itself as it learns idle procedures?
Or, wondering if my 20 year old fuel pump might not be putting out 40psi... is that worth double-checking?
But, it's only run for 15 minutes and one heat cycle. Let me see how it does by the end of the week. Merely hesitating badly and not actually dying is quite a big improvement, dare I say it's fixed?
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