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Topic: Hesitating? (Read 3579 times) previous topic - next topic

Hesitating?

Reply #30 –
My car still isn't fixed so i'm taking it backto the mechanic.
now its starting to lunge forward when im at a full stop.
any ideas?


Hesitating?

Reply #31 –
Is it only acting up when it's real cold out?
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***** Project "EVOLUTION" 1987 Cougar LS  & 1985 Cougar Convertible *****
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5.0 HO 306 roller block, machined GT-40P heads, Wiseco dished forged pistons, Eagle forged floating I-beam connecting rods, Lunati pushrods, ARP bolts, Scorpion aluminum 1.6 rockers, Comp Cams Magnum 266HR, Explorer intake, 65mm TB, MAF Conversion, 19# injectors, Ford Racing stainless P-headers, 2-1/2" cat-less exhaust w/ Flowtech Afterburner lers , SC AOD with 2800 BDR torque converter, 3.73 T-Lok rear, CHE rear control arms, full 2-1/2" frame w/1" jacking rails & seat supports, Rear disk brakes, Turbine wheels, All original interior w/ floor shift upgrade .......
Pretty much every panel on my 87 is new, rebuilt, or re constructed. :D
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Hesitating?

Reply #32 –
nope even after i've been driving it for a while and its warmed up.


Hesitating?

Reply #33 –
I bet it's the IAC.....
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

Hesitating?

Reply #34 –
Yeah I'll second that. I'd say vacuum leak too but for it to wind up high enough to overcome the brakes like that it would have to be pretty major, wonder if that's even possible from any of the lines.
1987 20th Anniversary Cougar, 302 "5.0" GT-40 heads (F3ZE '93 Cobra) and TMoss Ported H.O. intake, H.O. camshaft
2.5" Duals, no cats, Flowmaster 40s, Richmond 3.73s w/ Trac-Lok, maxed out Baumann shift kit, 3000 RPM Dirty Dog non-lock TC
Aside from the Mustang crinkle headers, still looks like it's only 150 HP...
1988 Black XR7 Trick Flow top end, Tremec 3550
1988 Black XR7 Procharger P600B intercooled, Edelbrock Performer non-RPM heads, GT40 intake AOD, 13 PSI @5000 RPM. 93 octane

Hesitating?

Reply #35 –
Quote
to overcome the brakes like that it would have to be pretty major, wonder if that's even possible from any of the lines.


If it's one of the larger vacuum lines, yes.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Hesitating?

Reply #36 –
Yeah I had thought perhaps the 1/2" one going to the MAP sensor. Interesting.
1987 20th Anniversary Cougar, 302 "5.0" GT-40 heads (F3ZE '93 Cobra) and TMoss Ported H.O. intake, H.O. camshaft
2.5" Duals, no cats, Flowmaster 40s, Richmond 3.73s w/ Trac-Lok, maxed out Baumann shift kit, 3000 RPM Dirty Dog non-lock TC
Aside from the Mustang crinkle headers, still looks like it's only 150 HP...
1988 Black XR7 Trick Flow top end, Tremec 3550
1988 Black XR7 Procharger P600B intercooled, Edelbrock Performer non-RPM heads, GT40 intake AOD, 13 PSI @5000 RPM. 93 octane

Hesitating?

Reply #37 –
if the idle is too low, it will do that.  I know it might seem that the idle "sounds good" but being too low in P or N is a whole lot different than being too low in drive.  A lurching or lunging forward symptom results from this.

In drive, the idle naturally drops a little so if your N idle speed is already too low, it stands to reason when you let off the gas and hit the brake the engine will try to recover.

Also, a binding smog pump might be pulling down engine power when the brake is depressed , which inturn forces the computer to rev up a little to recover from a boarder line stall.

You never did pull the  codes so we will never know.  Like anyone else who has problems like this , the codes are the place to start even with no check engine light.

Hesitating?

Reply #39 –
ok well when i have it in mix (defroster) and im at a complete stop that is what is causing me to lunge forward . and the hesitating he thinks that the tranny is very weak so i might have to get that thing replaced .


Hesitating?

Reply #40 –
Does your A/C work? I'm thinking the lunging forward at a stop might be the idle bumping up for the A/C compressor when it's on defrost. It wouldn't be much of a bump, but you can feel it sometimes.
Matt
1984 Thunderbird - 89 302 HO, GT40 heads w/ Trick Flow springs, E303 cam, Edelbrock Performer 289 intake and 600 cfm 4bbl, Mustang headers, Jegs o/r H pipe, Dynomax lers, Mustang AOD and shifter, Mustang 8.8 w/ 3.73s, 3G alternator, Mustang front and rear sway bars, KYB 87-88 Turbo Coupe shocks and struts, and 11" front brakes.

1988 Mustang GT - GT40 heads, Explorer intake, 70mm throttle body, 70mm MAF, Crane 1.7 rrs, E303 cam, Kirban Kwik shifter w/ Pro 5.0 deluxe handle, aluminum clutch quadrant and firewall adjuster, o/r h pipe, Dynomax lers, 3G alternator, aluminum radiator, and 3.27 gears.
 
1986 Cougar 5.0, 1989 Mark VII LSC 5 speed, 1980 Mercury Zephyr 4 door (sold)

Hesitating?

Reply #41 –
I drove a rental Escort once that was slow to downshift. When you were almost stopped it would finally shift to 1st gear. When it did, all of a sudden you were not on the brakes hard enough.

Hesitating?

Reply #42 –
I had a 2.3 Stang with a bad TPS sensor that caused hesitation... It never set a code, but decreased voltage to the EEC on part throttle... Took a buttstuffogue volt meter, monitoring the voltage from zero to part throttle to find that one...

If your problem is only at part throttle, it's probably sensor related issue(was it ever scanned???) It's very possible to have a TPS or IAC problem with a code and never turn on the CEL(check engine lamp)... If it happens only at heavy throttle, I'd be more inclined to think it was a fuel system issue... If it's interminent and the tach makes sudden wild changes in it's readings(while you are driving only), problem is iginition related... Anything that causes engine to change speed will be indicated while it's running out of gear...

Hesitating?

Reply #43 –
Quote
It never set a code, but decreased voltage to the EEC on part throttle... Took a buttstuffogue volt meter, monitoring the voltage from zero to part throttle to find that one...


The PROPER way to check a TPS.....throughout the entire range of movement.  It's not uncommon for them to develop "dead spots" as Tom describes.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Hesitating?

Reply #44 –
Again run codes before you put out $$$$$ for a trans and the problem isn't solved. My car doesn't light up the Check Engine Light but it always throws codes for the Thermactor System (removed) and the fuel pump monitor (I didn't run the wire when I did the MAF conversion).

Just wondering but have you adjusted the TV cable on the trans? Here is how to do it: http://www.tccoa.com/articles/tranny/tv-ajust/index.shtml
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.