jholley

iTrader: (13)

With the TP switch not closed the IACV won't operate. The rpm would slightly jump while idling at a stop or also while Idle Riding.
With a 0.012" gauge inserted I adjusted the TPS mounting to get the TP switch to close. This fixed the rough idling issue but it braught on another problem. If the engine is warmed up I need to apply a little gas to keep it running or it will quickly die after starting it. With a cold start this isn't an issue with the TB plate slightly pushed back. With a closed TB plate the TPS reads 510 ohms. I tried adjusting the TPS to a slightly higher resistance but the TP switch wouldn't close. Inserting a "0.010 gauge between the plate & stopper screw will start the warm engine. With the guage inserted the TPS read 538 ohms. This narrows it down to a lack of fuel caused by low TPS resistnce. So I either have to gently touch the pedal while starting a warm engine or live with a rough idle .

After getting the TP switch to close I read the resitance after tightening the TPS. It first read 562 ohms, then a few minutes later it read 510 ohms.

Does the TPS need replacement? It's not sending any codes.

njmaxseltd

iTrader: (19)

Try adjusting the default idle speed:

Do this on a completely warmed up engine no accessories or lights on
Disconnect the TPS and start the engine.
Set idle speed to ~550 RPM by adjusting the default throttle body set screw.
Turn off the engine and reconnect the TPS.
Check or readjust the TPS if necessary at this point with the feeler gauge.
Start the engine and make sure the idle speed is correct.
If not, adjust the IACV to set the correct idle speed.

You may want to clean the TB the day before you perform this process.

Hope it helps.

jholley

iTrader: (13)

I've tried everything you suggested. I've taken off and cleaned the TB, IACV, and the EGR guide tube. I've adjusted the set screw and the IACV screw the way you described it. I've also tried adjusting the TPS mounting screws. I've changed the fuel filter and threw injection & fuel system cleaners in the gas several times. I've gotten the idle running nice and smooth. It's just that to get the TP switch closed the TP sensor only outputs 510 ohms. With that low resistance it won't start on a warm engine without appyling a small amount of gas. With the engine warmed up I inserted a feeler gauge between the plate and stopper screw to find that it needs at least 538 ohms to start that warm engine. But if I adjust the stopper screw or TPS set screw to get that resistance then the TP switch won't close. I opened the IACV screw wider but that doesn't solve a lack-of-fuel problem.
Since the TP switch will only close with the TP sensor reading 510 ohms or lower is the TPS at fault? Should the TP switch close with a higher TPS resistance reading? Will replacing the ECTS solve the issue?

njmaxseltd

iTrader: (19)

The resistance reading isn't as important as setting it's position regarding the switch.
The TPS isn't your problem.

How does the car start with the TPS disconnected?
Have you measured and or checked the Coolant Temp Sensor?

jholley

iTrader: (13)

Until yesterday it started easily with the TPS disconnected. I had it running nice and smooth while idling or driving. It's just that it wouldn't start with a warm engine without appyling gas. I inserted the 0.010" feeler gauge between the set screw and plate and it started fine.
I adjusted the set screw yesterday to get a higher resistance so I wouldn't need to apply gas while starting the warm engine. After that it was stalling while idling and hesitating while driving because the TP switch wouldn't get closed.
I tested the coolant temp sensor 2 years ago and it was fine. It's not throwing any codes but such a low cost I'll try a new one tomorrow.

Do I only need to disconnect the TPS brown connector while setting the idle? Does the TP switch grey connector also need to be disconnected ?

njmaxseltd

iTrader: (19)

I believe both plugs must be disconnected. The key to that process is to put the ECU into limp mode for idle speed, causing the IACV not to work. That's how you get the default TB opening set.

I'm not so sure that's your issue. Have you checked fuel pressure at startup?

jholley

iTrader: (13)

I only disconnected the brown TPS connecotr while idiling it. I'll try disconnecting both connectors tomorrow.

I haven't tested the fuel pressure yet. I was considering that along with a pressurized fuel injector cleaning at a local shop for $130.

EDIT: I'll buy a fuel pressure guage and coolant temp sensor tomorrow at a local auto store.

njmaxseltd

iTrader: (19)

Disconnect the TPS while the engine is OFF, then restart it.
It should idle really low at that point. ~550.
Shut down before you reconnect.
Idle should normally be around ~650. You should see the 100 rpm diff. which is caused by the IACV not working when TPS is disconnected.

jholley

iTrader: (13)

You were right. The TPS wasn't at fault. It was the IACV.

The ECM was sending various voltages to the IACV and the impedances measured correctly at 30 ohms. With the AAC valve disconnected I turned the key on. It made a clicking noise but it didn't budge. I tried tightening the black plastic peice that mounts onto the magnetic valve but I couldn't get it firm. The fast idle solenoid for the AC was also malfunctioning. When I turned the AC on the RPM would drop. I measured 12V being sent to the solenoid so it wasn't the ECM.

I installed a new IACV that I ordered from courtesyparts for $138. This redesigned unit takes up less space. The car starts up with ease now, and it idles nice and smooth at 650rpm.

With a warm engine I checked the TP switch with the feeler gauge and it worked fine. The TP sensor resistance reading is now 545 ohms so I didn't need to touch the TPS after installing this new IACV.

The fuel pressure measured fine at 34 PSI while idling and 43 PSI with the key on. I purchased a 100 PSI fuel gauge with a t-fitting at harbor freight tools for only $20.

cashoit

nice!

TheRandish

grats, just hope my rough idle clears up a little cheaper than yours did!