upgrading your TPI MAF and CPU links



upgrading your TPI MAF and CPU links

Postby grumpyvette » February 1st, 2010, 7:33 pm

theres a good deal of info in the links and sub links

http://tpiparts.net/85_89_maf_sensors/

http://www.eecis.udel.edu/~davis/z28/ecm_swap_730/

http://www.eecis.udel.edu/~davis/z28/ecm_swap/

viewtopic.php?f=36&t=10946

http://tpiparts.net/tech_articles

viewtopic.php?f=80&t=728&p=43477&hilit=camaro+sensors#p43477

viewtopic.php?f=32&t=169

viewtopic.php?f=80&t=2861&p=7410#p7410

viewtopic.php?f=36&t=10567&p=45108#p45108

http://tpiparts.net/305_tpi_to_350_tpi_conversion

http://tpiparts.net/installing_tpi_on_your_vehicle

http://hotrodlane.cc/PDFFILES/TPIStory.pdf

http://www.eecis.udel.edu/~davis/z28/ECMs/86to92.txt

http://tpiparts.net/85_89_maf_sensors/

http://tpiparts.net/90_92_speed_density_sensors/

http://tpiparts.net/retrieving_and_clearing_error_codes

http://tpiparts.net/1227730_pinout_diagram

Image

Image

Image

Image

Image

Image

Image

Image

Image
Image
Image
Image
Image

1985 - 1226870 ECM - Camaros, Firebirds, and Corvettes

Being the first year of production for the TPI system, there were some things that GM wanted to change almost right off the bat. This year was a MAF setup, and used the 1226870 ECM. This was an ECM in the C3 family (like a TBI ECM). This ECM was used only on 1985 models. It used a small box mounted right above the ECM called the Mass Air Burnoff Module. This ECM can be easily recognized by having the PROM access cover at the top of the unit, and has only two harness connectors.

This ECM was used both on 305 and 350 engines. Depending on the engine size however, it used a different PROM, and a different CAL-PAK. There is limited support for this ECM as far as PROM modifications. This does not mean that it is more difficult, or that PROM modifications can't be made. Its just that there hasn't been as large an effort to work on this ECM, enthusiasts often end up converting to a later model ECM. Also, it sends data to the ALDL port at 160 baud, which is very slow. This provides a "snapshot" of what all the sensors are reading once every few seconds. By comparison, the later TPI ECMs were 8192 baud. They sent data several times a second.

I have read on several occassions that late in the 1985 production run, GM had already changed to the ECM and harness that they later used in 1986. I have not confirmed this myself, so I can't say for sure that its true. If this is true though, it is possible though to come across a 1985 model which uses the 86-89 ECM.

1986-1989 - 1227165 ECM - Camaros, Firebirds, and Corvettes

This is the most common ECM which is used on MAF style setups. ECM number 16198259 is equivalent and can be used in its place without any problems. The same computer was used both for 305 and for 350 engines. The only difference between the two engine sizes was the PROM that was used. The Mass Air Burnoff Module that GM used in 1985 is no longer present. This model is part of the P4 ECM family. This ECM can be easily recognized by having the PROM access cover in the center of the unit, and has only two harness connectors.

Support for this ECM with regards to PROMs is much more common. Due to the nature of the MAF sensor, it is very easy to run a large or moderate cam without needing PROM changes. This system is not very sensitive to engine changes, and can adapt fairly well. However, many enthusiasts find that it is a little more difficult to fine tune than the later Speed Density system. Please realize that this is a matter of opinion and personal preference. Each of these systems have advantages and disadvantages over one another. ALDL data is sent at 8192 baud, much faster than the 1985 ECM. This allows for several sets of data per second.

1990-1992 - 1227730 ECM - Camaros and Firebirds

By far the most common ECM used on TPI conversions onto older vehicles. This is the later style Speed Density system. It does not use a Mass Air Flow sensor. Instead, a Manifold Absolute Pressure sensor is used in its place. This allows more flexibility in running air ducts to the throttle body, or an air filter can be installed directly on the throttle body. It is for this reason, that it provides a cleaner looking installation on many street rods, and hot rods. There are two equivalent ECM numbers which can be used in its place without any problems. These are numbers 16196344, and 16198262. This ECM is also in the P4 family. It mounts inside the passenger compartment, as it is not weatherproof. It can be recognized by having a very large PROM access cover that runs from one side of the ECM to the other, and has three harness connectors.

By far the most support for PROM work exists for this ECM. Most enthusiasts feel this is the easiest system to tune. However, it is also very sensitive to engine changes. Any change that affects the engines volumetric efficiency significantly (ability to fill the combustion chamber) will not show its true potential until the system has been tuned. Volumetric efficiency is affected mostly by cam and head changes. This does not mean that you cannot run a moderate or large camshaft with this setup. It only means that tuning is required to see the true potential of engine modifications. This ECM provides ALDL data at 8192 baud as well. This is relatively fast, as it provides several sets of data every second.

This ECM is internally the same as the 1227727. The only difference is that the 1227727 is weatherproof and can be mounted in the engine compartment whereas the 1227730 cannot. The PROMs will interchange between these two computers. Harnesses will not interchange, as the ECM connectors are very different.

1990-1991 - 1227727 ECM - Corvettes

This ECM is internally the same as the 1227730 mentioned above. The difference is that this one is weatherproof and can be mounted in the engine compartment. This is the later style Speed Density system. It does not use a Mass Air Flow sensor. Instead, a Manifold Absolute Pressure sensor is used in its place. This allows more flexibility in running air ducts to the throttle body, or an air filter can be installed directly on the throttle body. It is for this reason, that it provides a cleaner looking installation on many street rods, and hot rods. There are two equivalent ECM numbers which can be used in its place without any problems. These are numbers 16197128, and 16198260. This ECM is also in the P4 family. It can be recognized by the four large ECM connectors.

This ECM as well as the 1227730 can use each others PROMs. Due to this reason, there is plenty of support for PROM work available. Because this is a Speed Density system, most enthusiasts feel this is the easiest system to tune. However, it is also very sensitive to engine changes. Any change that affects the engines volumetric efficiency significantly (ability to fill the combustion chamber) will not show its true potential until the system has been tuned. Volumetric efficiency is affected mostly by cam and head changes. This does not mean that you cannot run a moderate or large camshaft with this setup. It only means that tuning is required to see the true potential of engine modifications. This ECM provides ALDL data at 8192 baud as well. This is relatively fast, as it provides several sets of data every second.

This ECM is internally the same as the 1227730. The only difference is that the 1227730 is not weatherproof and must be mounted inside the passenger compartment. Harnesses will not interchange, as the ECM connectors are very different.
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: upgrading your TPI MAF

Postby grumpyvette » February 5th, 2010, 9:28 am

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: upgrading your TPI MAF and CPU links

Postby grumpyvette » July 18th, 2010, 3:07 pm

Here's some info I found on another site, maybe this helps;

How to Modify L98 Mass Air Flow (MAF) Sensor



WARNING
1. The sensor wire is FRAGILE, so handle the MAF with care..
2. NEVER run the engine without an air filter in place once the MAF screens are removed.


Backgroud
The MAF end screens and internal heat sink fins limit maximum air flow.
529 CFM - max. flow rate stock
711 CFM - max. flow rate with screens removed
750 CFM - max. flow rate with screens and cooling fins removed
Reference - TPIS "Insider Hints", pp 10.


Preparation
1. Disconnect the tubing connected to either end of the MAF.
2. Lift the MAF slightly and disconnect the signal/power from it.
3. Carefully but firmly clamp the base in a vise.


Remove End Screens
There is a cap glued to either end of the MAF that holds the screen assemblies in place.
1. Locate the groove separating the end cap from the MAF body.
2. Frimly run a sharp knife blade around this groove till you hear a crack.
3. It may be necessary to use a thin screwdriver blade and the knife to crack the
remainder of the glue that holds the end cap to the MAF.
4. Remove the end cap and use the knife point to pry out the screen ring.
5. Repeat for the other end cap.


Remove Cooling Fins
Within the MAF body there are 7 Al cooling fins projecting from the heat sink base and
a central tube which contians the delicate sensor wires.
1. Carefully cover each end of the center tube with duct tape to prevent accidental
damage to the sensor..
2. Insert a round silicon-carbide hack saw blade through the MAF body.
3. Cut each heat sink fin off as close to the base as possible. Use care not to scuff the
inner surface of the MAF body.
4. Remove the hacksaw blade and use a Dremmel to smooth the fin remnants..
5. Clean all debris and dust from within the MAF body.
6. Remove the duct tape that covered the center tube.


Reinstall MAF
1. Remove the modified MAF from the vise.
2. Carefully reattach the electrical cable to the MAF connector..
3. Reattach the front and rear air ducting and tighten the two clamps.

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: upgrading your TPI MAF and CPU links

Postby grumpyvette » October 8th, 2011, 7:50 pm

http://www.mamotorworks.com/corvette-c4 ... 6-893.html
Image
Image

http://www.corvettemods.com/Corvette-C4 ... _6306.html


RELATED INFO
viewtopic.php?f=32&t=661

http://www.corvettefever.com/tipstricks ... index.html

http://corvette-parts.zip-corvette.com/ ... f%20Sensor

http://www.wellsve.com/sft503/Counterpoint3_2.pdf



Suggested Installation Instructions for:
601-096, Mass Air Flow Sensor Test Tool
INTRODUCTION:
The Mass Air Flow Sensor (MAF) is a form of “hot-wire anemometer” that measures air volume
and density. It produces a frequency output. A constant voltage source is applied to the hot wire.
The wire has a positive temperature co-efficient meaning, that as it gets hotter its resistance
increases. The incoming air tends to cool the wire, lowering its resistance thereby increasing the
current. Hot dry air, being less dense (and having less mass), cools it less than cool moist air that
is more dense (and has more mass). The greater the air masses passing the hot wire the greater the
current flow. A circuit mounted on the top of the MAF sensor converts the current flow into a
square wave whose frequency changes depending on the mass of the air flow.


Image
MAF (Mass Air Flow) Sensor. Front of engine ahead of throttle body. .4 Volts @ idle, 5 Volts @ Full Throttle.



INSTALLATION AND TEST PROCEDURES:
1. With ignition switch “OFF”, disconnect the ECM connector from the Mass Air Flow Sensor.
Refer to the GM Shop Manual for sensor location.
2. Plug in the MAS-1 Test Tool connector into the Mass Air Flow Sensor. Plug the MAS-1 Test Tool
pins into the ECM connector. Take care to insure each pin location on the MAS-1 coordinates
with the same pin location on the ECM connector, i.e., A to A, B to B, C to C, etc. Stamped on
the connector body are letters A through E. CAUTION: DO NOT reverse the pin configuration.
DO NOT force test jumper into connection. Damage to pins or sensor may result. DO NOT allow
pins to touch. Carefully move test jumper from side to side to align pins into place.
3. Take voltage measurements by using a digital voltmeter (10 megaohm impedance required) by
touching the MAS-1pins. The ignition switch may be on or off depending on the type of test.
4. Voltage may vary depending on make and model. Refer to the GM Shop Manual for proper
voltage readings.
5. Remove the MAS-1 Test Tool and re-connect the ECM connector to the Mass Air Flow Sensor.
Image
Image

I found these bits of info
tequilaboy wrote:Here's a plot to illustrate the pw limitation for constant flow of 255 gm/sec assuming a stoich AFR of 14.73:1. This will give you an idea of the excess air that can be supported via PE tuning alone with a pegged MAF at mid-high rpm. Pegging at low-mid rpm is unlikely, but could be a concern for a very large displacement or turbo car.

Image

For this condition (pegged MAF for all rpms), AFR targets below (richer than) the dark blue line (or richer than the yellow line below 3800 rpm intersection point) will not result in any additional enrichment, since the pw will be internally limited.

The medium blue line represents the richest AFR target that you can achieve by tuning the PE vs coolant temp and PE vs rpm tables. This is approx. 5.89:1.

Note: This plot alone doesn't tell the whole story, the pw limitation can also come into play below approx. 4,000 rpm if the MAF flow should exceed the dark blue line of death. This plot is based on a fixed 12.8 target AFR. Richer or leaner targets will skew the resulting curve.

Image

Note: This post is intended to give 86-89 MAF users an idea of what can be achieved via traditional PE tuning methods only. These limitations can be overcome with MAF upgrades and/or special tuning. This does not reflect an overall limitation of a MAF based system.


Lemme wrote:Found this equation on how pulse width (pw) is calculated for an efi controlled engine. May be able to relate it to the c4 ecms calcs

http://en.wikipedia.org/wiki/Fuel_injection#Sample_pulsewidth_calculations

pw ms = (air lb/min)/(rpm*strokes per rev*afr*fuel lb/min)*1000*60

Example at idle for 350 ci

air lb/min = 1.03 (approx 8 g/s)
rpm = 700
strokes per rev = 2
afr = 14.73
fuel lb/min = 0.37(22 lb /hr injectors)

Substituting in values gives pw ms = 8.4 ms [COLOR="Red"]Actual bpw from datalog = 2.23ms[/COLOR]


Example at 5000 rpm for 350 ci

air lb/min = 28.42 (approx 215 g/s)
rpm = 5000
strokes per rev = 2
afr = 14.64
fuel lb/min = 0.37(22 lb /hr injectors)

Substituting in values gives pw ms = 32 ms [COLOR="Red"]Actual bpw from datalog = 10.23ms[/COLOR]

Interesting that this formula seems to be giving pulse widths 3 times that of my 87! Does the batch fire system fire more than once per cycle?
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida


Return to Engine: Repairs and Modifications & generally corvette related

Who is online

Users browsing this forum: No registered users and 1 guest

cron