i got ahold of a tech2 for a few minuites this morning and found (at idle)

spark advance jumping between 18 - 20 degrees

short term
bank1: 125
bank2: jumping between 122 - 124

long term
bank1: 121
bank2: 122

the o2 sensors were jumping a lot, just like normal

my problem is that it won't keep a smooth idle, it jumps about 50rpm's up and down, sometimes more. also, there is a slight miss below 2k rpm's. i've got new plugs, wires, opti, coil, fuel presure regulator... still have the problem.

i couldn't get any readings while the car was moving, they wouldnt' let me take the tech2 with me even driving in the parking lot.


i think my next step is to replace the fuel rail + injectors, if i can get them together, otherwise just the injectors.

any ideas why it'd jump around like that? the TPS seemed fine, no skips or jumps. there was no knock retard at all.

 

Just sold my stock 24lb injectors for $50.

 

The computer is percieveing a lean condition and richening the program.

 

iroczsource.com, wrong info dude...

Its the other way around...

If your Long term BLM's are lower then 128, its a rich condition, and it'll cut fuel to get your Short Term fuel counts as close to 128 as possible.

anasazi, you can look into your Throttle Body for the slightly rough idle... Do a search and you'll see what i'm talking about.

Jeff

 

do you mean the IAC? i've cleaned it already awhile ago, prolly 3 or 4 months ago. could it be bad? is there any way to test this...

 

damn i always get that backwards

 

The small changes in timing are normal. It would have been nice if you had gotten the IAC steps (or counts). That would have told you how much air it is letting in at idle (or commanding to be let in).

 

i *believe* it was 20....

or 40... it was a multiple of 20 though ... pretty sure it was 20.

 

20, 40...actually anything around there could be normal depending on your engine mods. More toward the lower number if stock. The lower the number, the less air is being added at idle. Way low or way high would have been a red flag.

 

Can tech2s be bought by mortals, or is it sold just to GM dealers?

 

You can buy one but they are about $2500. Does your engine stumble when the oil filler cap is removed? Could be an internal intake gasket leak, early LT1's are known for this. I didn't catch your year. Another symptom of this is excessive oil consumption. Good luck.

 

the intake gaskets are brand new, i fixed the intake oil leak about 7 - 8k miles ago, and its not leaking externally. i used fel-pro gaskets and high temp RTV. last time i changed my oil i left the cap off while i turned over the engine, didn't seem to stumble... tomarrow i'll take it off while the engine is warmed up.


the Tech2 is a neat little device, costs about 2500, and i think can only be baught by mechanics. i've even looked on egay and couldn't find them, or tech1's. the local community college has 9 of them, and they don't seem to know how to use them, hence it wasn't much help this morning

 

From my as yet unpublished writeup on the available scanners.....

OTC Tech-series:

Tech 2 Flash GM Dealership Scan Tool OTC ($3,000)
http://www.aeswave.com/framedcatalog...Tech2Flash.htm

 

mmmm thats lots of cash

are you going to put that writeup online somewhere? i'd like to read it