I developed an oddball surging problem......it typically starts after I come off the freeway after a quick blask. I just spend about 2-3 hours running around monitoring different things. It appears that my TPS quits going to "0" and gets stuck somewhere higher?(I'm going to add a helper spring to make sure it isn't that)....but meanwhile; when it does this the IAC does not appear to respond to try and close down.

Will the IAC only respond if the TPS is reading "0" (zero)????

Anybody have any other ideas??? I'm open to all.
NOTE: It was all working fine till about 2 weeks ago when went for a drive....after about 20 miles it started acting up.

 

but I apparently can't figure that out....

I'm using S-aujp version 1024.

 

your tps should never go to zero. It should be set to read about .55-.65 at idle. Your IAC should be around 15-30 counts at idle. Set minimum air at the throttle idle screw so you iac controls the idle with the 15-30 counts.

 

I went and started the car and I'm monitoring. TPS at idle is at 0.0; everything is controlling fine.......engine warms up......still fine. IAC is responding as different Idle Air RPM is demanded and controlling fine.....

Then; all of a sudden everything else starts bouncing around; what I immediately noticed was that the the TPS jump up to 4.XX, and all the other parameters I was monitoring were bouncing, BLM Fine, RPM, RPM demanded, TPS, IAC at idle...

any ideas?

 

As stated above, TPS should be at .54 at idle, and around 4.5v at WOT I believe, and as you open the throttle, the voltage should increase smoothly. Start datalogging with the key on engine off and see if the TPS is behaving right.

0.0 v is not right, and if it jumps to max voltage, something isn't right there either, I would suspect either a loose connection at the TPS or the TPS itself is bad.

 

0% Not 0V.

If the TPS is not returning to 0% then idle parameters may not be enabled causing issues.

 

Ok then, I should be able to adjust my TPS voltage by tweaking the throttle position screw. correct?
And I need to make sure that I'm monitoring volts not percentage.

I'll give that shot sometime this week (well, perhaps the weekend).

Still odd that it's sitting there idling fine and then all of sudden it just starts going bonkers.

 

No you adjust the TPS ONLY!! should never adjust the throttle stop screw. All that it is a stop screw. Its set so the blade does not bind in the housing when closed.

Set the throttle stop screw until it just starts to open the throttle blade. Dont go any further, then with a volt meter, lossen the screws for the TPS and adjust till you hit the spec .54 Aprox.

 

Not necessarily. Depending on what's done to the motor, it may need to be adjusted a little bit to get a good idle. With the IAC completely closed and unplugged, and the engine warm, you should have an idle of around 5-600rpm with your foot on the brake in drive. (of course, my car will never idle that low, so mine is adjusted to where it idles the lowest without stalling out.)

There are plenty of walkthroughs on how to set the TPS and IAC. Do a search and several will come up.

 

I don't see any adjustment on the "TPS" itself - - I guess I'll go take another look.


Once I set that I'll just watch it idle. If it goes bonkers again and starts going-off all over the place does anybody have any most-likely culprits I should check first?

 

Does it need adjustment? What is the closed throttle voltage reading?

Actually unless it's way out of whack, you won't need to adjust it. The '7730 will using the reading at key on as the closed throttle voltage, as long as it's below .74V IIRC.

 

And see where that TPS voltage is at.

I will have to adjust the throttle blade position since I messed with that screw already.

I will have to determine the proper IAC position now too....

 

Its a balance between the Iac, throttle blade, tps is set after the idle is set. The Iac sets it self after you shut the car down and restart. Do a serch for the best sequence of setting idle. I was messing with mine just yesterday. You basically need to set the blades so you have a 20-30 Iac count, some do more, some less, but that range works well. If the Iac count goes way high, you need more blade, if low, you need less blade.

 

Is the TB worn? Is there slop in the TB shaft? How many miles on the TB? Ever rebuilt?

Hook up voltmeter to TPS with jumper and slowly open the blades witnessing the V's as they change . Should be smooth progression from .54V to 4.5V. No jumping around. I would check V both hot and cold.

 

So I doubt wear. I'll try to check all that stuff this weekend. First I'll set the TPS voltage, then I'll run and record the warmup.
After I get to ~177°F (about 80°C) ...then it started doing oddball self direction.
Anyway, I'll put my tunerprort on record and share what I find.