MAF Question

[youngstr]

Can anyone tell me what number range does that maf transmit to the ecm? is it 0 to 175 or 0 to 255? and does the 87 maf have the same range of measure as the 85 maf?

 

[Jerryl]

Can anyone tell me what number range does that maf transmit to the ecm? is it 0 to 175 or 0 to 255? and does the 87 maf have the same range of measure as the 85 maf?

Typically, 4-255 gr/sec
84-87 MAFs have the same range.
FWIW; Range is dictated by the ECM, not the MAF.

 

[youngstr]

So I guess if I'm only showing 175 on the scan master in 3rd wot then I probably have a bad maf? hmmm I should have read that last line on your response... so could I talking about swappin for a known good ECM or does the TT chip have anything to do with the low count at wot? I'm guessing 175 is low for wot?

Heres some more info,

87 ecm , not sure if its stock maf or 87 maf, I think its 87, running wot 3rd gear, 11psi boost, numbers are

o2 - 785
kr - 1.5 on the shift into 3rd then falls to 0
af - 175 gr
L8 - 255


I know, 1 handing 3rd gear and pressing the little button to cycle thru the scanmaster #'s just call me jonnie dangerous

 

[Jerryl]

So I guess if I'm only showing 175 on the scan master in 3rd wot then I probably have a bad maf? hmmm I should have read that last line on your response... so could I talking about swappin for a known good ECM or does the TT chip have anything to do with the low count at wot? I'm guessing 175 is low for wot?

Heres some more info,

87 ecm , not sure if its stock maf or 87 maf, I think its 87, running wot 3rd gear, 11psi boost, numbers are

o2 - 785
kr - 1.5 on the shift into 3rd then falls to 0
af - 175 gr
L8 - 255

To clarify;
The Max reading has to do with the old ECM design. Try this; http://www.turbobuick.com/forums/ge...erences-what-translator-does.html#post2397792
Sounds like the ECM is fine, as is the MAF.

The 175 gr/sec @ 11 PSI reading on a stock type HA sounds about right.
What RPM was the 175/11 reading at?

 

[youngstr]

The 175 gr/sec @ 11 PSI reading on a stock type HA sounds about right.
What RPM was the 175/11 reading at?

I don't have the rpm I only had so much road to work with and thats at the bottom of the scan master list, only so much time to push that button, I was lucky to get the first 4 readings then I had to lift. It does have stock rear so if it helps I do recall that the o2 / kr reading was at 61 mph so thats 62 mph with the size tires I'm running.

its not exactly stock, and its a really long story that I won't get into, lets just say prev owner at sometime must have smoked the turbo, and the replacemet says garrett, but I can't find any info from any of the numbers on the (polished) housing. So basically I won't have any idea how much it flows and won't really know what that 11psi is worth until I take it off open it and start counting fins and measuring, if that makes any sense. And even better because its not what appears to be a stock or oem fit replacement turbo notice in the picture below how the throttle body is tilted back and almost shoves the tps sensor into the hood when closed. Yeah its come a long way since I bought it, but I still got a ways to go. ( And please no cracks about the roach clip holding the actuator rod down. )

Thank you for the info so far that you've given me, I'm have a local buick friendly shop take the top of the motor apart and do a cam and springs and lifters and timing chain for me at the end of next month the turbo will have to come off for that so I'll be able to get all the measurements and stuff I need then, and I do have a rebuilt stocker on hand so we'll see whatever is gonna flow more will probably be the way I go with it. Maybe my maf # is down at 175 cause of the size of that turbo sitting on there, maybe cause it spools lightning fast as in I slap the pedal down and look over and i'm at 10 psi right away maybe it doesn't flow as much air as a stock turbo. thats a lot of maybe's.

Guess I'll have to wait till then to find out, but again thanks for your help I think I do understand how that air measurement works better than I did before. I just wonder if that sensor isn't at 255 does that mean that the ecm is not commanding as much fuel as it possible could at wot?

 

[Jerryl]

I don't have the rpm I only had so much road to work with and thats at the bottom of the scan master list, only so much time to push that button, I was lucky to get the first 4 readings then I had to lift. It does have stock rear so if it helps I do recall that the o2 / kr reading was at 61 mph so thats 62 mph with the size tires I'm running.

its not exactly stock, and its a really long story that I won't get into, lets just say prev owner at sometime must have smoked the turbo, and the replacemet says garrett, but I can't find any info from any of the numbers on the (polished) housing. So basically I won't have any idea how much it flows and won't really know what that 11psi is worth until I take it off open it and start counting fins and measuring, if that makes any sense. And even better because its not what appears to be a stock or oem fit replacement turbo notice in the picture below how the throttle body is tilted back and almost shoves the tps sensor into the hood when closed. Yeah its come a long way since I bought it, but I still got a ways to go. ( And please no cracks about the roach clip holding the actuator rod down. )

Thank you for the info so far that you've given me, I'm have a local buick friendly shop take the top of the motor apart and do a cam and springs and lifters and timing chain for me at the end of next month the turbo will have to come off for that so I'll be able to get all the measurements and stuff I need then, and I do have a rebuilt stocker on hand so we'll see whatever is gonna flow more will probably be the way I go with it. Maybe my maf # is down at 175 cause of the size of that turbo sitting on there, maybe cause it spools lightning fast as in I slap the pedal down and look over and i'm at 10 psi right away maybe it doesn't flow as much air as a stock turbo. thats a lot of maybe's.

Guess I'll have to wait till then to find out, but again thanks for your help I think I do understand how that air measurement works better than I did before. I just wonder if that sensor isn't at 255 does that mean that the ecm is not commanding as much fuel as it possible could at wot?

Ok, cool.
First off, looks like you have a 86-87 style turbo.
No way to say what it is untill you open it up as you said.

Futhermore . . .
The ECM commands fuel based on the MAF, TPS and RPM.
Those variables are very important for making sure the motor runs as it should.

Your O2's appear to be in range for pump gas, and you are not seeing KR (except on the shift), so you should be ok.
Your RPM was probably around the 2600-3000 range (Guessing with tires, converter slip, rear end etc).
I would not worry about the 175 reading it at this point.
It appears to be well in the range you should expect to see.

The best way to tell of the MAF is OK, is to replace it with a known good unit, and record a log with PL or DS. You can than analyze what is going on.
Hope this answers your MAF related question.

More importantly, clamp/tie wrap ALL the hoses, especially the one with the FPR.
(Is this a 233 regulator?)

 

[youngstr]

Ok, cool.
First off, looks like you have a 86-87 style turbo.
No way to say what it is untill you open it up as you said.

Ya know that makes sense, that explains the position, and the IC cars they ran what 12 psi stock? My TT chip that also came with the car has writing on the back of the chip, reads
"Hot Air"
12-13psi
160 ts
97 ot

Sounds like the previous owner used this to do a bit of racing, and I haven't tried mixing in 2 or 3 gallons of 108 to bring up the octane, and since I run 93 with this chip do ya think 4 octane pts is the difference between running 11psi and running 13psi ? I got an extra O2 sensor incase I kill the current one, maybe I should try a little experiment.

More importantly, clamp/tie wrap ALL the hoses, especially the one with the FPR.
(Is this a 233 regulator?)

Its a holley adjustable regulator, its set at 42lbs with line on, 46lbs with line off. you do have a good point, I think I'll go wire tie those lines down tomorrow, and maybe spray a little intake cleaner around the vac block and throttle body to check for any more leaks.

Thanks for your help with the maf question.

 

[cuzimoto]

Hears my 2cents. I'd been chasing intermittant surging problem for a long time. I'd changed a ton parts and finally dug deeper into the MAF. Cought the car surging with my scanner hooked up and when the readings dropped to 200 or less the car fell flat on it's face. Numbers went down to about 170. Felt like no fuel. Then it would kick back in and felt like 50hp boost and the #'s would go 215-240. Put a new MAF in and first one was defect. Went through a bunch of testing and eventually tried another MAF and thing runs like a rapped ape now.

 

[youngstr]

The ecm has been throwing codes lately but they don't seem to add up, yesterday threw a 21, I checked the tps out and it was fine didn't even have to adj it, it was right in range key off .42 key on .44 to the floor 4.38. today code 42, both times a soft bump to the kick panel that holds the ecm and car starts right up no codes in memory like I got a bad hot or ground right at the ecm plugs, just to be thorough I pulled the ecm today and pulled the chip and calpak, cleaned all the connections and made sure all my pins were straight. Looks like I read that chip wrong, the 97 on closer inspection is a 91 here's the correct version

tt chip 5.5 street91
hotair
13psi
180/190
28#

And theres no way I can run 13 psi on 91 octane and not knock, this is the chip that was bought for this car and set up, so something has to not be working right, I should be able to hit those #'s without knocking.


This kinda bites, I don't even know where this thread belongs now, its way off of the original subject about maf ranges.

I'm gonna go put the ecm back in and see if its still throwing random codes when I hit big bumps, either the board on the ecm is bad or I have a short in my wiring harness right at the ecm plugs.

Will keep everyone posted.

 

[youngstr]

Ok, this cars history is like a long mystery novel, the more I look around the more questions I end up with.

I said before the previous owner killed the turbo, racing no doubt, thats what I would of done....anyway, I put the ecm back in the car and it seems to be running with no errors, will keep an eye on that one, but like I was talking about, he blew the turbo, and put a replacement on only he didn't go stock 85 replacement its something else, what I'm not exactly sure of, but Jerryl had an interesting theory, that its an 86/87 stock turbo mounted on a hot air intake.

Either way thats not quite a big issue at the moment either, this morning while I was poking around the back of the motor I did notice something that I can't believe I didn't see before. It seems that on the small piece of tubing that runs between the turbo and the intake manifold, there is a nozzle mounted at a 45 degree angle, the kind that looks like prev owner was spraying something. This kinda threw me off at first cause I didn't see anything marked on the chip to indicate alcohol or anything else being sprayed, but after thinking about it, seeing what the car does now (11psi on 93 pump gas) it would seem to make sense that spraying alcohol or something else would let you run 13 psi on 91 pump gas with no knock or maybe he was running one of those 7th injector set ups that sprays extra fuel at wot. Not to mention when I got the car I had to turn the fuel up to get it to run without missing and a lot of knock under wot and if prev owner was spraying alcohol and took the kit off and didn't turn the fuel back up......yeah it was at like 36#s with line on when I got it, now I have it at 42#'s line on.

I'm a little pev'd at the prev owner, he should have told me all this stuff, I was buying the car regardless and knew it would be my project, but if he would have been a little more forthcoming it would have made getting this car back in shape a lot easier.

I got so many things going on all of a sudden I don't know where to start. Guess I should get you guys a set of Idle scanmaster #'s to start with?

 

[Jerryl]

This is what I would do :wink::

1 - Spring Cleaning.
2 - Contact TT and verify the chip. It is possible that the chip is in fact a non-alcohol chip. You can to a a large extend verify that with the timing at WOT.
3 - Verify the injectors. Use the numbers to do that, not the "looks".
4 - Go through the knock list and the hose hoop-up review in the sticky.
5 - Verify the turbo / injectors and chip match.
6 - Pull the plugs and make sure they are dry (No oil on the plugs)

There are MANY factors that may prevent you from running that level of boost. One of them being the gasoline we buy today, which changes pending the winter and summer months, as well as is area specific.
I am not going to get into all the detail as that is listed on the KR list. :smile:

If you are going to push the performance of the set-up, I suggest some kind of a recording scantool and a WB.

 

[youngstr]

This is what I would do :wink::

1 - Spring Cleaning.
2 - Contact TT and verify the chip. It is possible that the chip is in fact a non-alcohol chip. You can to a a large extend verify that with the timing at WOT.
3 - Verify the injectors. Use the numbers to do that, not the "looks".
4 - Go through the knock list and the hose hoop-up review in the sticky.
5 - Verify the turbo / injectors and chip match.
6 - Pull the plugs and make sure they are dry (No oil on the plugs)

Just put new plugs in month ago but I'll still pull and check'm

There are MANY factors that may prevent you from running that level of boost. One of them being the gasoline we buy today, which changes pending the winter and summer months, as well as is area specific.
I am not going to get into all the detail as that is listed on the KR list. :smile:

If you are going to push the performance of the set-up, I suggest some kind of a recording scantool and a WB.

Yeah this looks like a good list to start, the spring cleaning is gonna wait till after I get my cam put in, but the rest do need done. I'll call TT tomorrow and try verifying the chip. After I put the ecm back in I re-adjusted all the main stuff, starting with the IAC, I had it up a little to high and was posting 00 in park at idle, so I backed it off till I got it at about 14, tps got some extra top end its now at .42 - 4.42 key off. I dropped another pound of boost and took it out, O2 - .757 kn - 0.0 3rd gear wot, @ 71 mph 10psi and the maf posted a 182 gr using a pound less boost, weird. (175gr on run yesterday with 11psi) I think I'm gonna try what you said earlier and swap the maf with a known good one and compare the #'s see if there's any difference. Thanks for the list though, I had gotten flustered and lost my direction and focus.

 

[O SO LO]

Ok, cool.
First off, looks like you have a 86-87 style turbo.
No way to say what it is untill you open it up as you said.


I agree with Jerryl... it looks like a 86-87 style turbo...
sent you some pics

 

[youngstr]

Limit engineering wouldn't happen to be from Arizona would they? Thats where I bought this car.

 

[Jerryl]

Limit engineering wouldn't happen to be from Arizona would they? . . . .

Yes.

 

[Boost231]

Ok, this cars history is like a long mystery novel, the more I look around the more questions I end up with.

I said before the previous owner killed the turbo, racing no doubt, thats what I would of done....anyway, I put the ecm back in the car and it seems to be running with no errors, will keep an eye on that one, but like I was talking about, he blew the turbo, and put a replacement on only he didn't go stock 85 replacement its something else, what I'm not exactly sure of, but Jerryl had an interesting theory, that its an 86/87 stock turbo mounted on a hot air intake.

Either way thats not quite a big issue at the moment either, this morning while I was poking around the back of the motor I did notice something that I can't believe I didn't see before. It seems that on the small piece of tubing that runs between the turbo and the intake manifold, there is a nozzle mounted at a 45 degree angle, the kind that looks like prev owner was spraying something. This kinda threw me off at first cause I didn't see anything marked on the chip to indicate alcohol or anything else being sprayed, but after thinking about it, seeing what the car does now (11psi on 93 pump gas) it would seem to make sense that spraying alcohol or something else would let you run 13 psi on 91 pump gas with no knock or maybe he was running one of those 7th injector set ups that sprays extra fuel at wot. Not to mention when I got the car I had to turn the fuel up to get it to run without missing and a lot of knock under wot and if prev owner was spraying alcohol and took the kit off and didn't turn the fuel back up......yeah it was at like 36#s with line on when I got it, now I have it at 42#'s line on.

I'm a little pev'd at the prev owner, he should have told me all this stuff, I was buying the car regardless and knew it would be my project, but if he would have been a little more forthcoming it would have made getting this car back in shape a lot easier.

I got so many things going on all of a sudden I don't know where to start. Guess I should get you guys a set of Idle scanmaster #'s to start with?

i agree with alot of the above posts. one thing i see is your fuel pressure

i would get a good adjustable regulator. i dont care for the one you have. i like the one GBodyParts.com Online has. for now you need to put the fuel pressure to 43 line off and leave it set there. also as the above posts said verify the chip and its setting and maybe get a new one burned.

as for the fitting in the turbo adapter can you post a picture? is it a alky type nozzle or a nitrous type nozzle?

also a set of idle scanmaster readings would be great.

i agree with everything jeeryl put down.

one thing to check which could be a reason for the low boost before knock is the turbo. make sure it has a carbon backing plate and seal. if you take a picture of the motor from the other side i could tell you if its good to go. if it doesn't have this you can be pushing oil into the motor. Ask me how i know anyways good luck and let me know if you need more help

 

[Eric Stage I]

Like Jerryl said, all your numbers look good. The boost level written on the chip is just an estimate of what some people can run, but on 91 octane, 11psi for a hotair car sounds completely normal. That's an older chip. These days I would have put 17* timing. The MAF numbers are pretty typical for 11psi on a hotair.

 

[Boost231]

Well you heard it. I would get a new chip.

Eric, those air temp numbers I gave you probley changed your way of thinking forever right. I'm sure the small turbo helps with that. I'm running 19 deg at wot on my pump tune. Seems fine so far