TPI L98 engine from an '89 IROC...

I'm about to pull the intake mainfold off and I was wondering--for future reference--is it really neccessary that I get each injector plugged into the exact same connector? Of course, they come out of the harness in groups of two, so it's really a 50/50 chance of getting it in right. I just heard somewhere that, on these engines, each side of injectors fires at the same time (i.e. all of the odd numbered injectors fire at the same time), which would leave me to believe that, as long as I don't put a plug from the passenger's side on the driver's side (which would be really hard to do), it doesn't make any difference at all.

Just wondering for future reference--so I know if it's okay for me to be lazy and not label or not.

Thanks

 

Not 100% sure but TPI is batch fire, and according to the manual the ECM just fires left 4, right 4. I.E. 1,3,5,7 fire, then 2,4,6,8 fire. So it shouldnt matter as long as all of the left bank injectors go to the left side, and all the right ones to the right.

 

Ward is right, they are batch fire, so you don't need to worry about labeling them.

 

Sancho,

It doesn't matter if you throw them all into a bag, shake it up, and pull them out one at a time blindfolded (excecpt that you may rough-up the injectors a bit). All the injectors are supposed to be the same, with the exception of the cold start, and I believe your '89 doesn't even use one. They flow the same, mount the same, have the same electrical connectors, use the same seals, and have the same impedance/resistance. They are batch fired in banks, as you describe. You can take two from the left and two from the right, install them anywhere, and it just doesn't matter.

The same holds true for the spark plugs, unless they have been indexed. If you've indexed the plugs/heads, then you'd be checking the electrode positions with your index gage when installing them anyway, so it STILL doesn't matter.

 

Oh, I forgot about the cold start injector. 89 Should have one, 90-92 TPI is speed density, which does not have a cold start injector. You can label the cold start injector plug if you want, but if you look at it closely it is different than the rest. It has a little rubber boot looking thing coming off the back of it which the wires go through, and I believe the wires for it are a little longer coming out of the harness. Just put a piece of tape or something on it to be sure when you put it back.

 

Now here is some attention to detail. Since each cylinder will flow a little different, try to match the injector to that flow.

Example say #1 spark plug looks a little lean and #6 looks a little fat. Swap injector #1 and #6 and watch the spark plug coloring.

May be an act in futility!

 

That's about what I thought. You know, that really seems like a waste of fuel--that's 4x more fuel than needs to be injected at a given point in time. Or does that extra fuel stay in the cylinder and just wait to be ignited?

BTW -- '89 cars and up do not have the cold-start injector; '88 was the last year for that.

 

Not to argue here,but... 89 T.P.I in fact did come with the 9th injector. My donor car for my Monte SS was a 89, and had the cold start injector. Maybe just a fluke in my car, but... Just so you know.

 

...or just send them all off to Cruzin' Performance and get a cleaned and nearly perfectly flow-matched set back for $10 each.

 

Cold start was gone by 89. Sounds like someone was messin with your donor car.

 

Not what I ment Vader. With an assembled engine, say cylinder #1 flows 72 CFM and cylinder #6 flows 68 CFM of air. Even with matched injectors, cylinder #1 plug will show lean and cylinder #6 will show rich. So you'd want a fatter injector in #1 and a leaner injector in #6.

This is all "bench seat" talk here tho...