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post #1 of 22 (permalink) Old 03-11-2018, 05:45 PM Thread Starter
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Slight idle surge while reverse and backing up.

I can't say it's normal or abnormal but I notice minor but frequent almost not enough to complain about idle surges during idle like when I reverse to idle out backwards to my main road it idle surges not a bog down but a tiny rpm jump .
58k miles the car runs looks like literally just thought I'd take notice to that and see what's what
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post #2 of 22 (permalink) Old 03-12-2018, 10:14 AM Thread Starter
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Originally Posted by mcm51 View Post
My first thought was IAC or TPS, either ever been changed ?
That's what I thought it's so vague and barely issue compared to how perfect the car runs but still..
And I assumed hell with 58k miles and the way it's been stored and rarely driven how could it be anything ...but things happen .

I noticed when I put it back in storage today I got out to let it run for a minute and it does a regular idle but idle jumps from 700 rpm range or so to 1000 then back every 10 seconds.
It's not a idle drag but rpm surge but purrs so smoothly during the jump
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post #3 of 22 (permalink) Old 03-13-2018, 03:08 PM Thread Starter
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my guess would be that the IAC would be more affected from sitting than the TPS........the way u described that idle jumping from 700 to 1000 back and forth while sitting there sounds like your describing exactly what my SVO (25K) was doing about a year ago, I changed the IAC and no more idle moving around just like u mentioned and it's still on o.e.m TPS.......and it sounds like u store this Bird the same way I store my SVO, i start her up and run her about 5-10 miles every few months, this method has worked for many, many years, she runs like a champ........
Well previous owner that's been the history with it meticulous kept and barely driven.
I plan to drive it maybe 1500 miles a summer season i hope to estimate ..have to see how eager i am this summer which isnt much to drive considering only 60k miles since 1997.
I'm gonna try the iac is there a test they can be done prior to throwing money out for iac.
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post #4 of 22 (permalink) Old 03-13-2018, 05:55 PM
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If not the IAC, check all - and I mean ALL - your vacuum lines.

My 2000 Malibu did that when the PCV line started to fail.

RwP

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post #5 of 22 (permalink) Old 03-16-2018, 05:47 AM Thread Starter
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Well I haven't got to fixin anything yet but determined something today that it runs perfect when it isn't and when it is doing this. Took from storage unit this morn.. early "cold out " took to work noticed while In... Parking lot after 30 min idle running and fully to operating temp is when it starts. Does not surge up and down until then it also get a worse now goes from 700rpm to 1500 and surges a lot when I turn off or on the heater . None of this is while driving

I'll check lines and iacz
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post #6 of 22 (permalink) Old 03-16-2018, 07:02 AM
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Originally Posted by 1991 5.0 View Post
Well I haven't got to fixin anything yet but determined something today that it runs perfect when it isn't and when it is doing this. Took from storage unit this morn.. early "cold out " took to work noticed while In... Parking lot after 30 min idle running and fully to operating temp is when it starts. Does not surge up and down until then it also get a worse now goes from 700rpm to 1500 and surges a lot when I turn off or on the heater . None of this is while driving

I'll check lines and iacz
That sounds more like a vacuum line to me; it starts surging when the ECU goes closed loop and starts actually paying attention to the O2s.

(The deal is that there's air coming in that it doesn't expect because it's not being measured by the MAF, and it's hunting the right point.)

RwP

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post #7 of 22 (permalink) Old 03-16-2018, 08:08 AM Thread Starter
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Quote:
Originally Posted by 1991 5.0 View Post
Well I haven't got to fixin anything yet but determined something today that it runs perfect when it isn't and when it is doing this. Took from storage unit this morn.. early "cold out " took to work noticed while In... Parking lot after 30 min idle running and fully to operating temp is when it starts. Does not surge up and down until then it also get a worse now goes from 700rpm to 1500 and surges a lot when I turn off or on the heater . None of this is while driving

I'll check lines and iacz
That sounds more like a vacuum line to me; it starts surging when the ECU goes closed loop and starts actually paying attention to the O2s.

(The deal is that there's air coming in that it doesn't expect because it's not being measured by the MAF, and it's hunting the right point.)

RwP
What's the easiest do it your self at home vacuum test for each hose without any special tools on hand ?
I'll buy whatever needed
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post #8 of 22 (permalink) Old 03-16-2018, 11:52 AM
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Cigar test, propane, starting fluid, carb cleaner.

All those methods can be used to look for leaks.

Vacuum leaks are really common on a 20+ year old car.

Red '96 Cougar XR-7 240k mi. '02 4R70W, PST DS : '03 PI engine, 04 maf, 24lb injectors, 2.5" exhaust, '02 4r70w + Jmod, DirtyD0g TC + cooler + 3/8" lines, 255 walbro fp. Alpine system.
Black '96 Cougar XR-7 (Lazarus) 210k mi PI Intake, '02 4R70W, Jmod, PST DS, GrogTune, Konis, Mark LCA+Poly, racecougar Custom Engine Chain, and JL and racecougar Bracing.
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post #9 of 22 (permalink) Old 03-16-2018, 05:25 PM Thread Starter
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Originally Posted by Grog6 View Post
Cigar test, propane, starting fluid, carb cleaner.

All those methods can be used to look for leaks.

Vacuum leaks are really common on a 20+ year old car.
What'ever it is getting worse... or as I originally thought only at idle but now affects driving I can be driving at a 35mph 45mph off the pedal and coast and the surge kicks up the throttle some during the surge I can be braking coming to a stop light and the surge pulls me into a stop .
I opened up hood.. unplugged the iac and it idled down smooth smooth and didnt stall plugged in iac surged and idled higher then smoothed out which I believe was the maf kicking back in on readings that sound right ? Coming from my lack of terminology lol ?looked at vacuum lines but not to a good extent I didn't wanna make a mess with carb cleaner
What do you do with the cigar test? Put cigar In brake booster vacuum? See if smoke comes out any lines ? Or am I way off again
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post #10 of 22 (permalink) Old 03-16-2018, 07:07 PM
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Just walk each line and replace it.

It's all 20 years old. Wait - if it's a 1991, it's 27 years old.

RwP

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post #11 of 22 (permalink) Old 03-17-2018, 09:42 AM
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If you decide to clean the IAC valve, you can use carb or MAF cleaner spray. Just do it off the car,

MikeB
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post #12 of 22 (permalink) Old 03-17-2018, 05:54 PM
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Are the egr passages in the 91 VB setup as bad as the 95 4.6?

EGR mismatch of "requested vs present EGR" can cause problems with idle, after close d loop.

On my 96, I would unbolt the egr valve from the manifold, and look into the VB, and see how much crap is there.

If there's a bunch, it all needs to be cleaned out.

Don't wash the crud into the engine, remove it to clean it.

EGR tubes are unobtanium, last I checked, so be careful.

Red '96 Cougar XR-7 240k mi. '02 4R70W, PST DS : '03 PI engine, 04 maf, 24lb injectors, 2.5" exhaust, '02 4r70w + Jmod, DirtyD0g TC + cooler + 3/8" lines, 255 walbro fp. Alpine system.
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post #13 of 22 (permalink) Old 03-18-2018, 12:21 PM Thread Starter
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Quote:
Originally Posted by MikeB View Post
If you decide to clean the IAC valve, you can use carb or MAF cleaner spray. Just do it off the car,
Quote:
Originally Posted by Grog6 View Post
Are the egr passages in the 91 VB setup as bad as the 95 4.6?

EGR mismatch of "requested vs present EGR" can cause problems with idle, after close d loop.

On my 96, I would unbolt the egr valve from the manifold, and look into the VB, and see how much crap is there.

If there's a bunch, it all needs to be cleaned out.

Don't wash the crud into the engine, remove it to clean it.

EGR tubes are unobtanium, last I checked, so be careful.
Just cleaned iac looked decent to begin with took off egr tube and egr normal carbon coating maybe 1/64th thick nothing accumulated or plugged at all.. still cleaning all that with carb cleaner .
Curious as to any specific inlet to cigar test for vaccum leaks I ask that way in not unknowingly letting the smoke flow back out in any specific wrong pattern.
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post #14 of 22 (permalink) Old 03-18-2018, 01:29 PM
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Well, if the cigar smoke comes out ANYWHERE, there's a vacuum leak there.

Only exception is the throttle body; it may seep some out due to not being a hermetic seal.

RwP

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post #15 of 22 (permalink) Old 03-18-2018, 02:11 PM Thread Starter
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Quote:
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Well, if the cigar smoke comes out ANYWHERE, there's a vacuum leak there.

Only exception is the throttle body; it may seep some out due to not being a hermetic seal.

RwP
Can't believe i can't figure out where this tube end goes to after a simple take apart .. any ideas?
Maybe It's right in front my eyes
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post #16 of 22 (permalink) Old 03-18-2018, 02:15 PM Thread Starter
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Quote:
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Quote:
Originally Posted by RalphP View Post
Well, if the cigar smoke comes out ANYWHERE, there's a vacuum leak there.

Only exception is the throttle body; it may seep some out due to not being a hermetic seal.

RwP
Can't believe i can't figure out where this tube end goes to after a simple take apart .. any ideas?
Maybe It's right in front my eyes
Fixed: cleaned the iac and egr which werent filthy to begin witb and used maf cleaner for the maf.
"0" vacuum leaks found with cigar test ... Idled smooth and no more rpm surges thus far.

Last edited by 1991 5.0; 03-18-2018 at 03:43 PM.
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post #17 of 22 (permalink) Old 03-18-2018, 03:47 PM Thread Starter
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My first thought was IAC or TPS, either ever been changed ?
Does the Tps have any method to testing good functioning partamaters with a volt meter of some sort ? Or do people just replace them if every other symptoms ruled out.
I just wondered cause next if the car begins to act up again which it hasnt yet that's my next culprit I'm thinking
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post #18 of 22 (permalink) Old 03-19-2018, 10:31 AM
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Can't believe i can't figure out where this tube end goes to after a simple take apart .. any ideas?
Maybe It's right in front my eyes
Is that hose a 90 deg elbow, or are you just holding it that way? If so, I'm sure you discovered it's for the PCV valve.

I have a question: does anyone know where to get that 90 deg PCV hose?

I would rather have a factory vacuum type fitting, than just use 3/8" fuel line that will never come off again without cutting it, and possibly ruining the plastic pipe.

I tried the "HELP" packages in 4 different parts stores. I also tried fordparts.com, which doesn't recognize my 1997 vin #, nor does it even list a "Thunderbird" in the model listings. Have we been cut from the parts listings from some kind of "20 year" thing?

Thanks,
Al

97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
04 CVPI- Brenda's car - 76k miles
Previous Fords:
95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles
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post #19 of 22 (permalink) Old 03-19-2018, 08:47 PM Thread Starter
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Can't believe i can't figure out where this tube end goes to after a simple take apart .. any ideas?
Maybe It's right in front my eyes
Is that hose a 90 deg elbow, or are you just holding it that way? If so, I'm sure you discovered it's for the PCV valve.

I have a question: does anyone know where to get that 90 deg PCV hose?

I would rather have a factory vacuum type fitting, than just use 3/8" fuel line that will never come off again without cutting it, and possibly ruining the plastic pipe.

I tried the "HELP" packages in 4 different parts stores. I also tried fordparts.com, which doesn't recognize my 1997 vin #, nor does it even list a "Thunderbird" in the model listings. Have we been cut from the parts listings from some kind of "20 year" thing?

Thanks,
Al
If was a 90 hose it sneaks under that black bracket that looks useless to me but bolts to the intake I believe and one bolt to the alternator bracket I believe. That 90 I posted went to a little vacuum port under that bracket plate . It snuck past me during reassembling but I don't think it was the pcv I missed.that .PCV tube is a long black tube that goes across the engine almost from cyl head to cyl head practically.
This 90 Degree hose began at the TB below the iac amongst the 50 other vacuum lines and ports.
I can see where anyone who has no attention skills could screw up any repair let alone a full PI Swap lol
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post #20 of 22 (permalink) Old 03-20-2018, 08:29 AM
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I verified on my car, and that small 90 deg hose is for the PCV valve, but it runs over top of the black bracket and too the pass side valve cover. I don't think anything can go underneath that bracket - it's purpose is to mount one alternator bolt, lol!

There is a second black pipe that runs to the breather on the driver's valve cover.

That 90 deg hose is the one I need. Mine has a split in it. Yours has some telltale signs of starting to split too, but it's fine for now. Mine isn't!

Al

97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
04 CVPI- Brenda's car - 76k miles
Previous Fords:
95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles
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post #21 of 22 (permalink) Old 03-20-2018, 11:20 AM Thread Starter
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I verified on my car, and that small 90 deg hose is for the PCV valve, but it runs over top of the black bracket and too the pass side valve cover. I don't think anything can go underneath that bracket - it's purpose is to mount one alternator bolt, lol!

There is a second black pipe that runs to the breather on the driver's valve cover.

That 90 deg hose is the one I need. Mine has a split in it. Yours has some telltale signs of starting to split too, but it's fine for now. Mine isn't!

Al
I'll remove the bracket for fun and show you where the 90 attaches at least on my car . On my car that hard tubing is under the black bracket which apparently is for the pcv I never looked to see where it went cause I didn't yield any vacuum leaks .So during reassembly I didn't see anywhere for 90 to attach after i bolted the bracket back only until I assumed wherever the 90 attaches must be very very close and so removing that plate exposed the unattatched pcv tube where I missed 'the reconnection.
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post #22 of 22 (permalink) Old 03-20-2018, 01:51 PM
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Maybe somehow it ended up above the bracket on mine when they installed the intake manifold before I got it.

Al

97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
04 CVPI- Brenda's car - 76k miles
Previous Fords:
95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles
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