would and tpi system off of a 91 work on a 87? is there a cold start injector on the 91? thanks for the help in advance.

 

the only real difference that i know of, besides maybe some computer work, between the 87-89 and 90-92 tpi system is that before 1990 they used a Mass Airflow Sensor (it's mounted in the middle of the air neck in the front of the engine, between the filter and the intake manifold) and from 90-92 they used a manifold density sensor, which does the same thing i think, it's just more accurate because it's mounted right at the intake system.
so to answer your question, if you are going to take the manifold, harness and computer out of a 91 and put it on an 87 model's engine then sure, it'll work.

 

Eh....not exactly.

Maf systems and Speed-Density systems work in different ways. Maf has a sensor that measures the actual mass of the air going into the engine, while SD uses vaccum and temperature sensors and some math to figure it out. They use different ECMs and have different sensors. It's possible to convert from Maf to SD, but I'm not sure exactly what has to be done. I know the ECM has to be changed, and the wiring harness needs to be changed/modified as well as some sensors.

Also the '91 has no 9th injector.

 

the 91 WONT have a cold start injector and the 87 does have 1,thats 1 difference. since the 91 has speed density,wont it use a MAP sensor too? im not sure about this 1,but im sure some1 w/ more knowledge than I will come in and help out on that 1.

 

since were on the topic of speed density and changing a pre-1990 car over...

i got an Accel DFI gen 6 stand alone system from a friend that will be going into my heavily modded 89 iroc along with its new motor, fuel system, ignition setup, etc. i just got it and havent had much time to look into it...but will this system be a speed density system? i imagine it would be and if it is, will it come with everything needed to swap over my existing MAF setup to SD??

can anyone using Accel DFI give me some insight?

thanks for the help

Damien

 

What he said. I know for a fact my 91 has only 8 injectors. Just get a JY one and stick in a different EPROM.

 

thanks for the info guys i know one is speed and the other is maf but all i was really needing to know was about the 9th injector. the reason i wanted to know was because i was tring to sell just the upper and lower intake and runners to some. he has a 87 and we were wondering if just those parts would interchange. he was still going to use his computer because mine is still in use but i switched to the holly stealth ram intake. thanks for all the help.

 

Check at EbayMotors - TPI for the following parts to convert a non-TPI over to a '91 - '92 TPI:
- ECM # 1227730
- throttle body
- wiring harness
- sensors - map, intake temp, coolant temp, O2, throttle position
- intake duct, snorkel and filter assy
- throttle cable, throttle valve sensor and cable
- small-cap distributor and coil
- fuel pump and relay
- egr valve and relay

It may be easier to just buy a complete TPI assy, rather than trying to gather all the individual pieces.

 

It will interchange, but he will lose the Cold Start Switch for the 9th injector.
Here is all the info on the TPI setups from 85-92,
http://www.hotrodlane.cc/Streetstories/choosetpi1.htm

 

Just to be VERY CLEAR...you CANNOT switch parts on the tpi itself!!....

if you want to use a 85-89 maf TPI on a 91 motor you have to use the entire tpi...you cant use a 87 base with 91 runners...

 

You can if you don't plan on using the cold start injector.

 

you cant use a 87 base with 91 runners...

Ahhh, well actually you can, but you need to install a cold-start block-off plate and gasket (available from Accel) to prevent a possible vacuum leak and a PROM that doesn't try to use the cold start injector.