rough idle issue with scanmaster readings...help....!

B

bluehair

Member
Joined
Apr 22, 2005
86 buick gn. recently put a scanmaster on it...trying to fix a miss in engine...small miss but its noticeable..it will stumble a little at idle sometimes too...but not die. i have put new plugs, wires, on it the last week or so with no change. i have pecked on the MAF to see if something was loose or...no change.

Scanmaster reading.
Millivolts 328
AF 04
L8 29
bat 13.6
int 128
bl 156
mph 00
clt 164
ats 82
rpm 775-800
tps .42
iac 21-22
cc 00
pl 00
mal 00

anything alarming here? stock chip, ta49 turbo, 50# injectors, hot wire kit, everything else stock
seems to be running poorly also. like its lacking power....15lbs. of boost....

thanks for any help guys.
 
sorry yes has a 94 red armstrong chip i beleive...for the injectors and turbo. sorry about that. i have replaced a few vacuum hoses but not all. i have done the spraying carb cleaner around hoses and couldn't find any leaks...but ive never had luck doing that either way. when it starts missing worse the iac gets down to 15-20....does that mean anything? how do you know if your iac is good or bad or in check etc... i have never messed with that on any of my turbo regals.
 
My blm was also high. I checked the lines that go to the vacuum block on top of the throttle body and found them to be loose. I put zip ties around them and put them snug on the rubber part. That seems to have fixed my blm problem.
 
on the way to work this morning re read my numbers... about the same except for the cc was anywhere from 33 to 150ish...didnt stay still for a minute. is this normal? anything else cause your blm's to be high? they were 156 this morning again. is that "just" a vaccum leak issue? would a bad or going bad 02 sensor cause a little rough driving and idling?
 
The faster the cross counts rise the better. A sign of a good working o2.

More than likely that chip has closed loop idle. That will make most cars idle rough. Take note of the blinking dot on the scanmaster. When the system goes into closed loop the dot will stop blinking and light up solid.

Allot of things can cause high blm. Bad maf, vacuum leak, exhaust leak, bad pcv, etc. etc..

Get a Bob Bailey chip. Best money you can spend IMO. ;)

Rick
 
As mentioned vac leak...could be a IC hose tweaked or leaky.

MAF is typically around 7 at idle with a stocker so that could be a issue as well.

Do you have at least one screen in the MAF (stock sensor)

CC should rise rapidly...good working O2 jumps 10 or so per counts...0...13...27...38....etc etc.

When was the last time the o2 was replaced?

What is your fuel PSI with line off regulator?

Also, if your chip is open loop idle you can raise your fuel psi while idling and watch the o2 richen and the BLM's drop. Thats based on good 02 sensor tho and closed loop idle.
Even open loop and rasing fuel psi the 02's will richen assuming 02 is good.
 
if the screen is suppose to be inbetween the maf and the air hose then no there isnt one. If its between the filter and the maf then i havent checked that...
i do not know what the fuel pressure is at this time...dont have a gauge.
what is a good idea of fuel pressure at idle with line off?
thanks for the help guys....learning today...you think i would get the hang of this after owning a few... :)
 
Updated reading from Lunch today. Seems like the "open loop/closed loop" scenario of the computer does make a difference...idled better before it closed. some weird numbers going on though.... its possessed maybe. New numbers in ( ) as of lunch today. nothing done to it yet just normal driving. Oh and yes sometimes when i look and watch the cc its on 00 ...so im not crazy... but then it will jump up after a few seconds...all this while in park and car running.


Scanmaster reading.
Millivolts 328 (574)
AF 04 (04) was 06 when cold and not up to temp....then back to (04)
L8 29 (31)
bat 13.6 (13.5)
int 128 (126)
bl 156 (108) this ones weird...
mph 00 (00)
clt 164 (168)
ats 82 (105)
rpm 775-800 (775)
tps .42 (.42)
iac 21-22 (25)
cc 00 (00) but then fluctuates some after a few seconds....very weird. it does go up when driving normal...and acts normal.
pl 00
mal 00 (00)

what gives....still think vacuum leak? fuel? what should my fuel pressure be at idle with hose off?
 
bluehair said:
if the screen is suppose to be inbetween the maf and the air hose then no there isnt one. If its between the filter and the maf then i havent checked that...
i do not know what the fuel pressure is at this time...dont have a gauge.
what is a good idea of fuel pressure at idle with line off?
thanks for the help guys....learning today...you think i would get the hang of this after owning a few... :)
Click to expand...

The screen will be inside the ends of the MAF.
Get a gauge, and check to see if the psi is 42-45#, vac line off and plugged. [The original regulator may show pressure at less than 40.]
 
update...and its not getting any better. checked fuel pressure, it was actually a little low and i put it at 45lbs. it seemed to respond well to that. it is still idleing rough and has a slight miss in it. i replaced the rest of my vacuum lines and bypassed my egr valve but have not taken it off yet and put a blocking plate on. My main concern now is in high gear under boost i am getting over 7 deg. of knock... and when i check my scanmaster its .087mv and7.7 deg retard.. me no likey that. its only at 15lbs of boost and 93 octane. should it be doing that? im used to stock turbos... is it the chip? i hear bad things about older red armstrong chips...?? green top injectors by the way..so 45?
 
update...i installed a turbotweak chip and wallah...all my troubles dissapear... took out the old red armstrong chip from early 90's and wow what a difference....right out of the box
 
Cool glad you got it fixed man!!
My car has made me paranoid so I read every problem thread now I think that's making it worse lol.
 
update... I checked my AF reading at WOT and it was 255, is that good or bad? what should it be? 15-16 lbs of boost no knock... was just curious.
 
bluehair said:
update... I checked my AF reading at WOT and it was 255, is that good or bad? what should it be? 15-16 lbs of boost no knock... was just curious.
Click to expand...

Don't think that's the a/f reading, but the MAF reading. 255 is pegged at full, [WOT], on a stock MAF.
Post the rest of the SM readings...
Sounds like you have a handle on it!:cool:
 
Chuck Leeper said:
Don't think that's the a/f reading, but the MAF reading. 255 is pegged at full, [WOT], on a stock MAF.
Post the rest of the SM readings...
Sounds like you have a handle on it!:cool:
Click to expand...

AF not AFR. That's how the scanmaster shows it. And 255 is what it should show at wot with a tt chip. An extender chip and translator will read af at a increased capacity but even a stock turbo will max out an maf at 12psi and display 255. That means everything is working as it should.

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