LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Scan readings- please help diagnose

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Old Jun 2, 2004 | 04:43 PM
  #1  
107's Avatar
107
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From: Olympia, WA
Scan readings- please help diagnose

My car is idling rough and has a slight stumble on light acceleration. I plugged it in and these are the readings I get in closed loop, idling. Do any look suspicious?

BLM is 128 on both sides
Spark is 19-20 degrees
Injector Pulse Left is 2.8-2.85 and right is about 2.8
BLM Left is 117 and Right is 120
O2 Del 130-133
Old Jun 3, 2004 | 12:57 AM
  #2  
JDBlaze85's Avatar
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From: dallas, tx.
looks good to me.

is the coolant temp sensor where it should be? 170-220F?
TPS - .30 -.90v?
MAP- 1.00-2.00v?

unplug your mass air flow sensor, see if the hesitation goes away or gets better.
Old Jun 3, 2004 | 11:58 AM
  #3  
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From: Hell was full so they sent me to NJ
A single "frame" from a scanner is next to useless, particularly without knowing all the data, and how long it was from engine startup.

A couple of observations:

"BLM is 128 on both sides"
"BLM Left is 117 and Right is 120"

***Which one is it?

"Spark is 19-20 degrees"

***Its normal, IF the engine was at idle.

"Injector Pulse Left is 2.8-2.85 and right is about 2.8"

***It's good that they are essentially both the same, but again, without knowing the RPM and mass air flow, its not possible to evaluate in any more detail.

"O2 Del 130-133"

***I've reviewed hundreds of scans for people over the last 7 years, and I've never seen "O2 del".... do you have any idea what this is?

As noted, above you need a lot more data to do an evaluation:
-rpm
-mph
-iat
-clt temp
-time from startup
-MAP
-barometric pressure
-AF gps
-knock retard
-tps
-throttle percent
-IAC counts
-Cell number
-O2 mV's, left and right
-integrators, left and right

You might want to review this to see the importance of each of these:

http://members.aol.com/InjuneerZZ/ScanMast.htm
Old Jun 3, 2004 | 08:08 PM
  #4  
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107
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Joined: Jun 1999
Posts: 222
From: Olympia, WA
Thanks for the replies. I reviewed injuneer's site before doing the scans and only reported the ones that looked suspicious (or values that were related to others that looked suspicious). The TPS was dead on, I forget what the MAP readings were but they were about 1/3 of the Baro as injuneer's guide specifies.

As I said in my post these are the readings were in closed loop, idling. I know you can get more information while running but the laptop I used had to be tethered(bad battery) so I was hoping to find some info here.

BLM was at 128 at first but then went to 117/120 after a while. My mistake for not specifying.

In any case I am working on an in-dash computer and will post some rolling logs once that is all set up, I was just hoping in vain that someone would see something odd right away.
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