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Discussion Starter #1
I bought a 91 Stealth RT TT back in August and I love the car. It only has 49000 miles on it. Anyway, since the weather has started getting colder it has developed a problem. When the outside temp is below about 50 deg. the car has a kind of stumbling idle and hesitates bad when accelerating. The faster I try to accelerate the worse the problem seems to be. It's most noticeable in 1st and 2nd gear, but also in 3rd. After the car warms up the problem mostly goes away, but still doesn't feel exactly right. Anybody else had this problem or maybe know what's causing it? BTW, the car is stock.....for now!
 

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Fo Shizzle
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dude I have the EXACT same problem

dunno whats really causing it, however after it warms up a bit, its ok.

1st gear is nasty, you get on it and as soon as you hit boost, the car jumps and bucks like you poped the clutch on it, 2nd and 3rd ride out smoother but you can still feel the hesitation
 

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Fo Shizzle
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my main fear is that one of these days my drive line is gonna pop, or it will do some nasty damage to either the tranny or rear diff.

so far its both of us with 91 stealth TT cars

I gotta wonder if anyone else gets this problem
 

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UP THE IRONS!!!
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The electronic control causes the car to run lean until the engine reaches normal operating temperature. Running lean increases cylinder head temperature and reduces power. Once you start registering engine temperature on the temp guage though...it should run normally...if not, then there is a malfunction. Check all vacuum hoses first. It is a wise practice to allow the engine to reach normal operating temp before attempting high rpm shifts ESPECIALLY on turbos. When that oil is cold...it's like honey....and provides as much friction as it does lubrication...which requires MORE power than usual to overcome...but the mixture is providing just the opposite. Cold oil also does not flow as readilly further decreasing performance. Allow the car to reach normal operating temp and if the problem disappears...that's pretty much normal.
 

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Fo Shizzle
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no probs starting up

just that first 15 min o warmup.. crap idle, bad hesitation.. etc

after it warms up.. all is well
 

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Turbo-Less
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Check in with another '91 rt/tt that has the exact same problem (problem??).

Today it was 48 degrees, it happened for the FIRST time since last spring.

Wrathchild's explanation sounds about right.

But don't you just LOVE IT when it's 50degrees out once the car warms up!?!?!? Oh man those turbos love this cold air!!
 

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stumbling through my 92 rt/tt owners manual, it says "allow car proper warm up time before "intense" driving". Ive had that problem on all cars, whether my 86 firebird, 92 cougar or 88 mustang, my stealth as well. Just let her warm up before you go racing that ricer
 

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Discussion Starter #12
Thanks for the answers guys and though I'm willing to bet many of you know more about cars than I do, I have trouble believing that this is "normal" for these cars. I've owned Corvettes, Z28's, Mustang GT's, and a turbocharged Conquest and never encountered this. No problems starting and this isn't just a slight hesitation, it's VERY severe! And it happens even when I'm accelerating very slowly, not "intense driving". Also, I have a friend with a 98 VR4. I asked if he ever has this problem and he said no. His first guess was a bad O2 sensor. Any thoughts on this? Just for the record, If this is "normal", some engineer somewhere should be flogged with a spark plug wire.
 

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Speed is our life-blood
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I got this in an email from another member. I haven't tried to fix my problem yet, but have at it..

Hesitation problem gone!

It was a combination of 2 problems
1. Timing was at least 10 degree below O, it is supposed to be 5 +-2 so it was
at least 15 degrees off.
2. Massive vacuum leak cause by y-pipe rubber seal being folded over itself.

Fixed both of these problems today and the car is screaming. I am going to order
a Manual boost controller tomorrow and let it really rip. I alreayd have
aftermarket boost gauge.

What were the symptoms:
The car has a misfire/hesitation at low RPMS especially first thing in the
morning. after it warmed up it wouldn't hesitate but it just didn't run that
strong. I had just finished a complete engine rebuild so I was breaking the
engine in. Driving very easy I barley noticed the problem. Once I started
running hard the hesitation became a real problem.

How did I mess up this bad?
The y-pipe was an easy mistake the gasket look perfect from the top. With a
flashlight I noticed I couldn’t see the seal lip on the lower side. Pulled the
y-pipe off and it was folded over itself.
When I tore the engine apart I decided to prevent this problem by marking the
timing so I could put the Crank Angle Sensor back in the same spot. I figures I
would only be a few degree off that way. What I discover was that the ADVANCED
timing was set at 5 degree. When I grounded the timing terminal to set it to
basic timing (Thanks to Jeff Lucius’ WebPages) I noted the timing was way off. I
believe that the dealer set the timing w/o grounding the timing terminal. This
was a year before the timing belt slipped and I started my 1 /12 year 4-bolt
main conversion project. I have having these same issues back then but it wasn’t
as bad. A few extra degrees of timing was all it really took to make the
hesitation problem very noticeable.

One other ting I noticed the Crackling in my exhaust is almost completely gone.
The timing was causing that too.
 

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Discussion Starter #14
Thanks for the info Eric, I'll check those out
 

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Fo Shizzle
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man.. intense driving? boost starts to kick in around 2.5-3k

you mean I have to shift out before boost when driving till it warms up??? blah .. then again.. she sure does pull around 3k.. hoo wee!!

theres gotta be some other cause besides just cold weather, lest I spend 10 min every day warming this piece o crap up
 

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maybe it's time for the spark plugs to retired in the trash can...... :D :D :D
 

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I have the same trouble but more advanced, I run 15 psi on stock vr-4. Has Denso fuel pump, gutted pre cats with no main cat and blitz dsbc. If the motor is not warmed up when I get on it I have big trouble. There is a hard shock to the car that can only be described as too much air. The shock was hard enough that it knocked out 2 indiglo gauges. I have a new denso fuel pump and cleaned the injectors with the 2 part treatment. This happens way before the rev limiter and fuel cut. When I floor it at high boost on a cold engine. Any thoughts? :eek:
 
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