1994 Chevy Impala misses

Tiny
BAHERMIT
  • MEMBER
  • 1994 CHEVROLET IMPALA
  • V8
  • 2WD
  • AUTOMATIC
  • 71,000 MILES
94 impala ss- When it is cold, starts fine, accelerates fine but once it warms up to operating temp, any acceleration causes severe missing, to the point it might stall. No scanner codes present, new distributor, new coil, new plugs, new wires, injectors check ok, fuel pressure is 41 psi w/vacuum disconnected. Any suggestions? Thanks

Specs on Engine cold/before starting




RPM 0
Left-INT 122 Rt-INT 129
Open/Closed open Coolant 43
Left-OS2 447 Rt-OS2 434
Left BLM 128 Rt-BLM 128
A/F Learned No FT Cell 0
TBS(v) .60 Throttle 0%
Left BPW(ms) 0 Rt BPW(ms) 0
Air Flow 0 IAC Position 159
Coolant 43 MAT 42
Fan1 No Fan 2 No
MAP 27.9 MAP (v) 4.56
BARO 27.9 BARO(v) 4.56
Knock No Knock Retard 0
Spark Adv 0 Ignition(v) 11.6
CCP Duty Cycl 0 EGR Duty 0
Time 0:0 Desired Idle 3188
A/C Request No A/C CLutch Off
A/C Press 4 A/C Press(v) .24
TCC Command P1 TCC Switch Closed
Veh Speed 0

Started Vehicle

Idles Very smooth
Acceleration (in Park) Very Smooth
Transmission in (D)-Brakes on- Spins Tires


Coolant temperature 164
Idles Very smooth
Acceleration (in Park) Very Smooth
Transmission in (D)-Brakes on- Spins Tires

Coolant temperature 183
Idles OK but feels like very slight miss

Coolant temperature 207
Idles somewhat rough
Acceleration (in Park) Initial Miss
Transmission in (D)-Brakes on- Pushing on Accelerator - Engine misses Badly- Almost stalls





RPM 743
Left-INT 123 Rt-INT 128
Open/Closed Clsd Coolant 207
Left-OS2 80-680 Rt-OS2 75-700
Left BLM 108 Rt-BLM 111
A/F Learned Yes FT Cell 16
TBS(v) .62 Throttle 0%
Left BPW(ms) 2.3 Rt BPW(ms) 2.4
Air Flow 6 IAC Position 23
Coolant 207 MAT 65
Fan1 No Fan 2 No
MAP 8.4 MAP (v) 1.02
BARO 27.9 BARO(v) 4.56
Knock No Knock Retard 0
Spark Adv 19 Ignition(v) 13.8
CCP Duty Cycl 0 EGR Duty 0
Time 28:41 Desired Idle 663
A/C Request No A/C CLutch Off
A/C Press 4 A/C Press(v) .24
TCC Command P1 TCC Switch Closed
Veh Speed 0
Tuesday, May 20th, 2008 AT 6:00 PM

4 Replies

Tiny
RHALL77
  • MECHANIC
  • 3,361 POSTS
What is your fuel trims and temp sensor reading when this happends? Are you sure you are getting injector pulse to all cyclinders when this happends?
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Wednesday, May 21st, 2008 AT 9:21 AM
Tiny
BAHERMIT
  • MEMBER
  • 2 POSTS
I modified my original question and added the scanner readings- Thanks again- sorry it took so long to reply - I couldn't figure out how to reply
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Tuesday, June 3rd, 2008 AT 8:26 PM
Tiny
RHALL77
  • MECHANIC
  • 3,361 POSTS
Did you check your injector pulse
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Wednesday, June 4th, 2008 AT 7:10 AM
Tiny
IMPALASS
  • MECHANIC
  • 3,112 POSTS
I put a less expensive (not GM) on my 95 Impala SS and the spark was still coming through and arcing off of the heat shield around the plug then to the manifold. You can also take a spray bottle of water and mist in on the plug wires when running to get a spark jump. I ordered a set of plug wires (GM OEM type) and removed the metal heat shield and have never had a problem since.
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Sunday, September 28th, 2008 AT 12:10 AM

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