unca

Need to set TPS to a new throttle body, is this hard to do ?

THE 383 admiral

Congrats on the quality BBK tb. The answer is not hard. Dialing in the TPS voltage.
The L98 slotted & LT1 non adjustable. Slotting is possible to perfect a specific voltage. each, have 2 different TPS designs. A scan tool or data logging makes dialing in the voltage effortless. The next method piercing the harness or making extended pins to allow connecting a volt meter.

aklim

You sure? Apparently the earlier L98 has a slotted one but the 90-91 and maybe a year or two earlier, IDK, isn't slotted. At least that is what the parts guy said when I asked why it was different for my 91.

THE 383 admiral

OE 90 - 91 L98 TPS. the holes are big enough allowing +OR - a few voltage points. Also note the slots were never machined. Easy mod! The LT1 TPS has a lil room for a slot mod. Allowing ajustibility.

bill mcdonald

It is not slotted on the 90 and 91 because the ecu compensates for the voltage, unlike the older versions that need to be set correctly.

When I replaced mine, I found that it was slotted and the same BS with the parts guy. So I slotted the new one and set voltage both high and low, which tool a few tries, like with most things.

aklim

My under, which is standing, is that the ECM sees starting voltage as base so what would be gained by slotting it?

bill mcdonald

Much time, have you must
Retired is you.
the nitpick is strong with this one.

If I remember right I put it on and drove, and of course naturally it did not seem right psychologically. So I checked voltage and it was .36... mind you I am remembering back about 15 years. I checked high voltage and it was 4.5 or so. This will not do.

So I slotted it till it was .54, and whatever is ok on top, but that did not work out now. So a few more tries and I was in spec of L98 of old.

Also remembering back now 17 years, I thought I read that you could adjust to try and make up for throttle response. Which if you built an engine, you get really into this kind of nit picking. TPS, Initial timing, Idle resets, etc...

Plus the one I removed was slotted.

After all that, I learned it did not need to be adjusted.

but if I did not question it, how would I know anything?

aklim

OK. I don't think I am yet. I'll check with my accountant but last I knew, I paid taxes. I just have a short work day but a lot of dead time in between.

The reason I asked is that if there is no difference and the ECM just figures out "We started with 0.7V and that is base" it is different from it expecting 0.54V and after say 0.1V it considers it "off idle" which is why people try to trick the ECM into thinking that so it might go off idle faster. But if that doesn't matter, whatever you set it to might not matter and all it does is maybe lose some adjustment range.

Like you, I question everything and maybe pick something up here and there.

unca

Mines a 1986 Indy Pace Car and I started it today, it she went up to 2200 rpm, just wee bit off.. So tomorrow I'll get it dialed in.

aklim

You sure it isn't an air leak?

bill mcdonald

I guess if the throttle is open too far, which means IAC reset and TPS dialed in again once you close the blades. Otherwise you have a big vacuum leak.