I have an 87 with the adjustable TPS. I checked the voltage and reset at .54v at 0 throttle. It ran great when cold, but when it warmed up again, I got the old familiar split second delay in throttle response which always bangs the drivetrain. I set it up to .62, which is the max the book recommends and it was marginally better when hot, but still there. Can you actually go higher to correct this problem or should I just get a new TPS. I have also seen some aftermarket "plug in" stuff that is supposed to improve throttle response. Anybody had any experience with any of those? thanks :flag PS. I am running about 8 degrees BTDC now, which for a stock engine seems to be about max based on other forum discussions.

 

good question.. i am waiting on some direction myself...

 

I run my TPS at about .65 Vdc; at around .67Vdc I get an occasional TPS code. I assume you set this at base idle of 450rpm??

Also, tweak the WOT setting to the max possible, while maintaining the low value.

You can bump base timing a point or three for crisper throttle response too.

 

Make sure the IAC pintel is fully extended before setting TPS (Jump ALDL pins A&B, turn ignition key on, wait 1 minute for ECM to extend pintal, disconnect electrical connector from IAC motor so pintal will remain extended).
Base idle stock voltage is 0.54 and performance setting is 0.65. I've got mine set at 0.65 and never thrown a code. WOT voltage should be 4.6 or above.

 

No code after 3 years so far....

 

Great info. I have been setting mine with the engine not running and the ignition on. I have not tried to set it hot yet, maybe that gives a different value? I'm not sure how you can set the upper limit, and not affect the lower value, once you are at the max lower value, its all your going to get at the top..or am I wrong about this? I've only been able to get about 4.5 at the top with a .62 setting at 0. PS I am at 8 degrees BTDC now, which seems about max according to other forum input for a stock engine.

 

A 4.5 setting is fine. A reading of 4.0 or greater is sufficient to signal the ECM of a WOT condition.

 

You need to first establish base idle at 450rpm, remove the connetor from the IAC module so the pintel stays extended when you shut off the engine.

Then, with the endinge off, you set TPS voltages.

The method description in on my site.

 

65Z01
Thanks a bunch. I went to your site and it's great.

B387

 

If you aren't able to get the L-98 as "crisp" off idle as you would like by fiddling with the TPS adjustment - try bumping the static timing up a couple of degrees. Try 8° BTDC as a starting point. Don't worry about getting too much in there - the ECM will retard it as necessary to limit detonation. The only negative effect would be when starting hot - the static timing is where it fires up at and it Does effect how the thing runs until it drops into closed loop ... I found that I could get the throttle responce better by doing this, and that the TPS setting really wasn't the way to get there!

 

Causing the IAC pintle to extend and cut off IAC air is necessary to set the base idle. If you are happy with your throttle position, there is no purpose to be served by extending the IAC pintle. When you release the throttle, it returns to it's closed position. Cold, fast idle, is a function of the ECM and the IAC, not a cold idle cam, like on a carbed engine. The closed throttle position never varies. Years ago, when I was asking questions, I wanted to know if there was any performance to be gained from "tweaking" the TPS sensor voltage. All I got was "deer in the headlight" expressions. So I decided to experiment. Of course, TPS voltage does NOT affect idle speed. The only discernible difference *I* could discover, was an overly sensitive throttle at highway speeds, with high TPA settings. It was difficult to maintain a steady, constant cruise speed. A higher TPS voltage may provide slightly better response going from one part throttle position to another, But it does NOT affect 1/4 mile times. I race every week. I've tested many different TPS voltages...Trust me on THAT one. Once you slap the pedal to the fiberglass, and the TPS puts out sufficient voltage to trigger the PE mode in the ECM, there is nothing more to be gained. If 4.0 volts triggers PE, 4.2, 4.5, or even 5.0 volts, won't trigger it more.

RACE ON!!!