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Help With scan readings

Uhrlto

Member
Joined
May 27, 2020
Messages
6
Location
Reno, NV
Corvette
1986 White base model
so every time I try to get some help with my C4 86 everybody always says what kind of scan codes do you have. Well up until just recently I was not able to answer that question as I did not have the scanner. That is been remedied through 1320 electronics, I have their USB scanner, And now I have a whole bunch of codes or I should say scan data that I don't fully understand. I'm hoping that there is some intelligent bright Vetter out there that knows how to decode these very strange numbers. First of all as I pointed out this is on a 1986 C4 L 98 engine I have and 253,000 miles on the vehicle with a rebuild that took place according to the previous owner at 120,000 miles. How true that is I don't know. I've replaced almost all the sensors in the car since I got it as well as all the vacuum lines and if someone could let me know whether these numbers are good or bad while then I'll be styling
. These were all taken at idle at approximately 195 on the temperature gauge. all in open loop, if I take it out of open loop I get really strange readings. readings taken with ALDLdroid. And sorry for the long post I just wanted to make sure I got all the information in their. as always any help will be greatly appreciated

Tony

Engine speed= 975 to 1000

TPS= 55

CT 144.5 172 on the dash reading
CT 63 ( I don't know why there's two of them perhaps someone can explain that)

MAT= 140 to 230 this number bounces all over the place and does not stabilize on any particular number
MAT= 50-110 also all over the place, and don't know why I have second one

MAF = 7.48 Fairly stable reading

Injectors BPW= 159
INT= 129-134

BLM= 3

o2 812 at idle open loop
o2 x over= 160

IAC 30-32
 

Uhrlto

Member
Joined
May 27, 2020
Messages
6
Location
Reno, NV
Corvette
1986 White base model
Does no one know what these numbers mean. I could use some help here. Thanks again.

Tony
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
I don't know what some of those mean as I've never used "ALDLdroid" which I suspect is an app on an Android phone. First of all, get a real scan tester.

What I can tell you is:

Engine speed means RPM and 975-1000RPM is too high if you got that reading at idle.
TPS is Throttle Position Sensor. If 55 is 55% that means the throttle is stuck halfway open which is likely not the case so that data might be inaccurate.
CT 144.5 172 and CT 63 are unknown to me.
MAT unknown
MAF is Mass Airflow Sensor and that's likely 7.48 grams-per-second air flow.
Injectors BPW= 159 I think that is injector pulse width.
INT= 129-134 That's Integrator and 128 is considered ideal when the engine is not in power enrichment so your pretty close there.
BLM= 3 That's Block Learn Multiplier and relates to fuel trim over a long period a 3 is ok.
IAC 30-32 That's Idle Air Control which bypasses air around the throttle place to control idle speed. IAC counts were 30-32.
 

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