Had a new one today with SD2

T

TurboTdr3.8

Well-Known Member
Joined
Jan 15, 2013
I have been tuning on my SD2 in my 87 bone stock and got it running real good so I went for a 3+ hour cruise to the mtns and back home right before getting home after my car run so sweet all day long the SES light came on with a code 33 , it said too high signal in mass air flow , does that mean my cheapy 3 bar sensor is not doing right or was it a flute ? The stock mass air is unplugged .
 
Code 33 and 34, which were MAF codes, are now MAP codes on the SD2 chip. So code 33 means the MAP reading is on the high side for the current conditions. The code itself won't cause it to run any different. It's just telling you that something "could" be wrong. I would try to recreate those conditions while logging so you can see what's happening.
One example that could set code 33, the map vacuum hose comes off which causes a reading of 0", but the car is idling and should be seeing vacuum.
 
It's just telling you that something "could" be wrong
Click to expand...
Trying to log after driving 400 miles in the last 3 days is not going to happen as all my numbers on the SM all looked good when the SES came on as I have been watching the SM all day . I am going to try another 3 bar and see what happens cause all the lines were on when I got home and like I said it ran like it did all day after that happened just the SES light on
 
most likely the trouble code is a little too sensitive.

just keep an eye on it. and perhaps email Eric a log of a cruise under similar conditions (even if it doesn't set the code)

Bob
 
most likely the trouble code is a little too sensitive.
Click to expand...
The driving I did today up the mts and down the mts coasting and cruising at 45 to 55 at times and 75 on the interstate ,gentle rolling hills in town stop and go and all the above , Went from 700 ft to 5000 ft and back to 700ft and 3 hrs driving and then the SES came on on level ground at 48 mph locked up and smooth going to hit interstate . I tried to put in all kinds of different driving before this happened plus I turned the AC on and off a bunch also putting more load on the engine at times . I will keep you updated as to what happens as I am going to try another 3 bar sensor in the mean time .
 
update , I put another 3 bar sensor and it will not run hardly at all ,put original back in and runs fine , I noticed the volts on the original is around 1.70+ volts key on engine off and the one I put on reads around 1.50+ volts key on engine off , what is the voltage supposed to be at this point , as I can tell the replacement is a no go for sure .

this is the one I just tried and did not work ,http://www.ebay.com/itm/160361291853?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
 
Last edited:
"Racing Innovation" brand sounds like China junk to me.(n) I think I'ld stick with a GM part.
 
according to the GM specs for that sensor, the output voltage = Vs * (.00318 P + .003531) (P is in KPA, and Vs is your 5V supply).

so assuming 98KPA (near sea level), and 5V from the ECM, the sensor should read 1.57v the allowable error (from the GM spec is +/- 4.7Kpa in that range)

so, valid voltages (assuming 98kpa actual pressure) are from 1.50 to 1.65

so, bottom line, the China sensor is probably "within spec", but just barely. The GM sensors, while not a precision sensor, have all been pretty close to the spec.

I think your first sensor is probably fine, and the diagnostic routine in the SD2 is a little too sensitive. The replacement sensor can be kept as a "backup"

Bob
 
Would I be better off and going with one like this with a name brand ,http://www.amazon.com/ACDelco-213-1562-Original-Equipment-Manifold/dp/B000C9HX1S , what you are saying the china model I just used is off calibration from my original one that's reading around 1.70.numbers ,.the china one was so lean it added 30% fuel to keep up from what I had , junk for sure . I want a spare but not the china version I just bought and I want to go with the ac delco brand and at least we will know for sure .
 
I've never seen a 3-bar read in the 1.70's at atmospheric. That would have made it rich and you probably tuned around it. You will most likely need to retune when you have a good sensor in there.
I am at 600 feet, and every 3-bar I check reads 1.54 to 1.56v at atmospheric.

Like Bob mentioned, I can also tweak the malfunction code map limits in the chip.

Eric
 
Eric Stage I said:
I've never seen a 3-bar read in the 1.70's at atmospheric. That would have made it rich and you probably tuned around it. You will most likely need to retune when you have a good sensor in there.
I am at 600 feet, and every 3-bar I check reads 1.54 to 1.56v at atmospheric.

Like Bob mentioned, I can also tweak the malfunction code map limits in the chip.

Eric
Click to expand...


Now I am wondering if the 2 , 3 bar sensors that I just got was reading in the 150 `s was doing what it was supposed to be and the one that was reading 1.70`s is the bad one that I am using at the moment , I figured I would have to retune it as it was way off as I tuned for it like you said My elevation here is 817 ft , so how much would it be off from 600 feet to 817 ft . What do you think now
 
there has always been variability with the 3 bar GM sensors, they changed vendors a few years back and it made a lot of MAFt Pro cars run funky.....

the differences in the calibration can be tuned around easy enough. I just worry about the knock-off sensors' reliability.

I would find 2 sensors that read close to each other, run one and keep the other as a spare.

Bob
 
. So code 33 means the MAP reading is on the high side for the current conditions
Click to expand...
The 3 bar sensor that I am running with the readings in the 1.70`s range might be why the ses light came on after all . Also today when I installed the 3 bar sensor with the readings of 1.50`s I could not zero the boost level on the pl to zero at all , it kept reading -3.0 on boost . With the sensor that I was running it would zero boost out with no problem .

Thanks all for all the help I am getting as sooner or later we will get it figured out
 
Here's my questions.....

Where do you live? IOW, what altitude are you above sea level, and....
What is your manifold pressure reading KEY ON, ENGINE OFF? (in Kpa)
(with each sensor)
 
TurboDave said:
Here's my questions.....

Where do you live? IOW, what altitude are you above sea level, and....
What is your manifold pressure reading KEY ON, ENGINE OFF? (in Kpa)
(with each sensor)
Click to expand...

I am 817 ft above sea level , I will get them precise numbers tomorrow and let you know for sure with each sensor ,
 
TurboDave said:
Here's my questions.....

Where do you live? IOW, what altitude are you above sea level, and....
What is your manifold pressure reading KEY ON, ENGINE OFF? (in Kpa)
(with each sensor)
Click to expand...

The sensor that I am using , KPA 111.81 volts 1.724
the other 2 sensors that I just got KPA 98.95 volts 1.526 , KPA 99.57 volts 1.536
This is key on and engine off .
817 feet above sea level
 
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