Newbie Here on Forum needs help.

Hello to all members. Im new to the forum. I recently am going to start a project. Ive always wanted a TPI truck. I ran into the perfect canidate 1991 350/5 speed  SC/SB/SS   . New Jasper motor. And fresh tranny.

I have bought this TPI set up on a local sale, with a ecm that fits. Its injectors, uppper and lower manifold, runners, rail and some other small things.

The ecm is 12268780 went to the stealership and was told 85 vette and some other vehicules. Which was the MAF years i believe(dont quote me). Im missing the ecm harness. This has brought me to a stand still of contiuning on with my project. I want to park my other pick up(06 Cummins) to drive this. Help and advice is much appreciated. Thanks in advance.  

the harness for that set up can probably come from a bunch of different cars...

85 to 89 or possibly 92 firebird and camaros with the 305 or 350 TPI motors..

or 85 to 89 or possibly up to 92 corvettes...

i would bet that there are after market harnesses out there...


you might follow along as there is another thread here with a similar swap... and trying to get it right...

there are a lot of things you can do to your TBI to improve it... other than swapping on a TPI ...


do you self a favor first....  OHM the injectors.. all 8....    12 to 16 ohms ... i think is the spec... no use staring with shorted injectors....  

Cool Thanks waynep7122. Ill check the injector tomarrow. Im shutting it down for today. I got the step up from a older man that does restro, he was local. It thought it was cheap $150 for it. Could you track that thread for me that your speaking of. Cant you get more out of a TPI tha TBI. Besides that it looks cool under the hood when you open it. Still on the hunt for a harness. Thanks in Advance  

oh... you are also going to need a scan tool...... that will interface with the GM system..

a monitor 2000... a monitor 4000  or 4000E....   a otc genesys,..

some of the early autoxray units... snap on MT2500  some actron units..

you have to make sure they work and have the proper cables and cartridges to operate on the gm system.. as old stuff is almost impossible to get new from the manufacturers...   plug it into your truck.. make sure it displays live data streams... not just trouble codes...

as to verify everything is working properly.. you will need to view live data stream...  you can practice on your existing 91 system so you will know what you are doing when you actually swap systems..  start checking craigs list....   you are looking for something in the 50 to 300 buck range..  knowing what the sensors are doing is the easiest way to make sure the TPI   or even the TBI system is working right...   you  cannot depend upon codes... codes aim you at major problems.. live data will show you the small ones that drive you nuts...    knowing that you coolant temp is 215F and that its idling and displaying 6 grams of air it idle through the maf sensor...

oh.. one more thing.. you want to open the throttle body lever about half way.   wiggle it around make sure that the throttle body is not worn... it can mess with the idle stability...



you will probably want to read the info at this link....  

http://www.autozone.com:80/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c15280098fbf


here is a clipping...

The Multi-Port Fuel Injection (MPFI or MFI) systems were first introduced on the 1985 models. They may be called different names (Port Fuel Injection-PFI, Tuned Port Injection-TPI, Sequential Fuel Injection-SFI), however, all of the systems are similar in operation.

The systems are controlled by an Electronic Control Module (ECM) which monitors the engine operations and generates output signals to provide the correct air/fuel mixture, ignition timing and idle speed. Input information to the ECM is provided by the oxygen sensor, temperature sensors, detonation sensor, mass air flow sensor and throttle position sensor. A system may use all or some of these sensors, depending on the year and engine application. The ECM also receives information concerning engine rpm, road speed, transmission gear position, power steering and air conditioning status.

All of the systems use multiple injectors, aimed at the intake valve at each intake port, rather than the centrally located injector(s) found on the earlier Throttle Body Injection (TBI) and Crossfire Injection systems. The injectors are mounted on a fuel rail and are activated by a signal from the electronic control module. The injector is a solenoid-operated valve which remains open depending on the width of the electronic pulses (length of the signal) from the ECM; the longer the open time, the more fuel is injected. In this manner, the air/fuel mixture can be precisely controlled for maximum performance with minimum emissions.

There are two different types of fuel management systems used on the multi-port fuel injection engines. The mass air flow system and the speed density system.

The mass air flow systems measure the mass of air that is drawn into the engine cylinders, rather than just the volume. The sensor contains a hot-wire sensing unit, which is made up of an electronic balanced bridge network. Whenever current is supplied to the sensor, the bridge is energized and the sensing hot-wire is heated. As the air enters the mass air flow sensor, it passes over and cools the hot wire. When the hot wire is cooled, it's resistance changes and additional current is needed to keep the bridge network balanced. This increase in current is sent to the computer as a voltage signal and is used to calculate the mass of the incoming air. The ECM uses this information to determine the duration of fuel injection pulse, ignition timing and EGR operation.

The speed density systems calculate the volume of air moving through the intake. The ECM establishes the speed factor through a signal from the ignition module. The Manifold or Intake Air Temperature (MAT/IAT) and the Engine Coolant Temperature (ECT) sensors work together to assure that proper temperature information gets to the ECM while the Manifold Absolute Pressure (MAP) sensor monitors the changes in manifold pressure which results from changes in engine loading. These three sensors contribute to the density factor. Together, these inputs (engine speed, coolant temperature sensor, etc ...) are the major determinants of the air/fuel mixture delivered by the fuel injection system.

The following engines and fuel management systems are covered in this section:



1985-1989 2.8L MPFI - Mass Air Flow

1990-1992 3.1L MPFI - Speed Density

1985-1989 5.0L and 5.7L TPI - Mass Air Flow

1990-1992 5.0L and 5.7L TPI - Speed Density  

Okay, Had to gett a new acc setup because it wasn't letting me login in ? I went to a salvage yard a pickup a new ecm 1227165 they just took the one i had for even swap. Found a new harness for this (1227165), Quiet proud of them they are. Just for some copper and plastic  . I tried to test the injector. Not sure how but i put the voltmeter to them they all read .5 . Do this injectors have to be conected to ecm explain to me the process  ? So i tried today to get some fuel lines made that connect to the silverado fitting on back of the engine bay. And get it routed to the front to the TPI. No luck there, I would like to use AN Pushlock fittings. I got looked at funny because they didnt know. Thought I was wrong. Where can they be found and what size of fuel fitting,  Where it connects to the TPI to the factory silverado fuel line. Thanks  

they may have gotten the better deal... i have not found the cross reference on that ecm...

to OHM the injectors... find the OHM setting.. looks like an UPsidedown U...  set the meter to 200OHM scale...

touch the probes together...  the meter should read 00.3 or 00.4  sometimes 00.0  ..  

with the leads not touching...    it will read 1    or OL        look at the decimal point..

if its on the proper range.. you will get two zeros and then the decimal point. and one more number...


00.4 is four tenths of an OHM...     and that is usually what the test leads read...   unplug one lead.. touch the other into the hole .. you should get half the reading..  00.2..

now.. touch the fuel injector connectors...   12.0 to 16.0 is what you should get...

if all of them read 5.0... then they are all shorted or somebody has swapped them to a different injector.. see if you can read a part number off the side of the top of them...


do you have a wiring diagram.. for the TPI.???? so you can verify every wire is intact...  from the ECM connection to the ends of the harness.....  

Hey thanks waynep7122. You been the only help I've gotten. This website isn't helping either. Had to make another acc. It keeps telling me information incorrect. I went to walmart to purchase this voltagemetter.  

I put it up the injectors and they all read 16.6 . Im asumming there'll all good haha I got the better deal.....

The 1227165ecm I personally pulled it from the vette off inside of the firewall in the salvage yard. The vette has wiring in it still just not. If I need to go back and get some more parts. But missing motor and tranny.

I don't have the harness yet, I found a new one on eBay. I'll purchase soon now that I know the injectors are good. I also have a question is this VATS on all year model cars. I read it started in 1986 but I also have a 85 ECM? I could go back to the yard to see if the vette still has it just don't know what I'm looking for.  

Heres the injector numbers

And the meter on one of the injectors