The car is a 95 Impala SS with an LT1 out of a 1994 z28. The car starts up great and idles fine but when I try to go from idle/stop it is hesitating. I push the gas and I go nowhere. When it finally decides to move it is missing really bad. Once the car is moving it is fine. Funny thing is I was putting it out for sale right when it started to do this. Must be putting up a fight. The car is throwing no codes at all. Fuel pressure is good at 43psi

Motor has around 40,000
replaced wires/plugs right before I put it away for winter

Mods to motor are hotcam kit

Thanks
Brandon

 

My car has an Lt1 scanmaster. I went out this moring and here are the results right after start up. The car was in gear but not moving.
On the left is exactly what the scanner says, on the right is what data it gave
Those that know the lt1 scanmaster well may be able to help with the problem.
when theere are more than one number it was fluctuating between the two.

naf 12-14
sp 28-31
LP 2.5-2.7
rp 3.3 cold and 2.5 when it warmed up a bit
dtc -
nph 0 That is mph
LBL 143
RBL 120
CEL 16
Lin 128
rin 128
O2L 700-726
O2R 480-503
ATS 59 aftyer warmed up a bit went to 70
CLT 92 DEG
TPS .60
TPP 0
R 875-925 R stands for rpm
IAC 155 went to 135 after warmed up a bit
bat 13.8
egr 0 (I have it blocked off and programmed out)
nap 17.5 +/- a tad
bar 29.2
ACP .00
CCP 00
200-500 I don't have a clue what these stand for, but they come right after the ccp

Hopefully someone can help with these readings. The scanner was in the car when I bought it and I have no paperwork on it so I am clueless about somethings.

I also found that my iac count it way high at 155 cold/ 135warm.
Sounds like that is my hesitation prob, AGREE?


Thanks
Brandon

 

Could be. I used some cleaner a while ago and pretty much soaked my intake/throttle body. Helped a slightly rough idle and the car "seamed" a bit more snappier... of course sometimes when we do things like that, it's all in our heads!

 

Update:
I went and backed out the stop screw on the throttle body for the butterlies. I got the IAC down to 41 counts idling in gear. I drove it and it didn't fall on its face once. While driving at around 2000 rpms it was somewhere near 60. I would guess that is a good indication that the IAC is bad. Can I just leave it the way it is now or should I replace the IAC? Kinda feel as though I am just putting a band aid on it instead of really fixing it.

I also got lazy and used n.nose pliers to back the screw out instead of taking off the cable bracket to get to the t10 torx! Just didn't feel like f@$&Y with it tonight.

later