drwhosc

Well I am almost there. Here is some background. been brining a 88s4 back from the dead. I am working on a high idle right now. The idle was erratic, and the symptoms looked like a sick MAF. that was replaced last weeked, and the idle is rock solid. I also got a hold of Theo's diagnotic tool, and it is tellimg me my WOT is active all the time. So I need advice on how to tackle this one. I know I will be taking my intake off agai, not a biggie, I have gotton good at it by now.

So here are my thoughts.

1. I installed a new TPS and ISV when I did the intake refresh. Could I have installed it imporperlly. I really did not see an adjustment, but reading prior posts, here, looks like there is an idle stop screw somewhere.

What am I missing on the install

2. bad switch. Quite possible the switch is bad.

Anyone got a method to test the switch.. Looks like I just need to see if there is a constant contact present or not.

3. Bad wiring. Everyting else seems to be working fine, but it is a 928

I saw the pin outs to the LH, and looks like the wot travels on two pins. what should I see there, and what abou thte ezk...

Thanks for your help. I am almost there with my tuning. So far very happy with the progress, adn even better I got my cruise control working last night. Another thing to cross of the list

John Speake

When the WOT switch is activated, it will ground the WOT switch line at the LH ECU connerctor.

When you're not at WOT the WOT line at the LH will be open circuit (everything above measured on the disconnected 35way LH plug.)

The same WOT switch line goes to the EZK, so if the EZK is not showing a fault on your tester that the WOT switch is always closed, the the problem is going to be a faulty LH ECU, as I suggested to your similar post a few days ago. You can send your LH to my agent Louie Ott for testing, when you've confirmed the above.

MarkRobinson

Agreed with Speake. Most TPS switches have to be "set" to the TB: ie, you set the switch where as soon as the throttle is moved, you'll hear the first tick. (this is the switch switching from idle map to cruise map). Then about 2/3 or 3/4 through the throttle's range of motion, the WOT map is engaged via a change in signal from the TPS: normally you cannot hear this tick, but in a silent garage, you should be able to hear the TPS tripping between the idle map & cruise map.

If you didn't specifically set this switch, it's surely incorrect. Not 100% about S4's, but the S3's and many other cars (Porsche's) I've owned are like this.

Mark

drwhosc

Ok from these posts, I need to look at the EZK first, and see if the WOT is lit there. If not, Louie get teh LH. that makes sense to me. As far as the adjustment goes, I can not imagine the switch is that far out of wack. I will have to be advanced by 2/3rds throttle at idle.

Looks like I also need to check for a ground on the 35pin LH harness. I will try to find the post that JS spoke about.

thanks for the help. It will be a huge milestone when I get all of this worked out....

SeanR

Did you replace the TPS connector? If so, you might have accidentally swapped pins so instead of reading the idle position it's reading WOT.

Just a though.

drwhosc

Not the connector, that was in good shape. Looks like I can see if the switch is working by looking at pin 3 of the LH. It should be open and the ground at throttle position. that is an easy test that will let me se if the switch is good. I have the multimeter with me, so I will test soon.

drwhosc

Well I looked at voltage on pin 2 and 3 of the LH, and I am not getting a thing. Looks like this is going to be a bigger diagnostic job than I thought....

Bill Ball

You don't look for voltage - you look at resistance of each of those pins (2 and 3) versus pin 5 on the LH plug, with the throttle closed versus open. Procedures for testing this switch at the LH and EZK plug are shown below. You can use contuinty test mode of your multimeter as you are looking for continuity (< 10 Ohms) versus no continuity (infinite Ohms). I've included the idle switch tests as well.

Also, for clarity, the "adjustment" of the switch position on the throttle is just for the idle portion of the switch. If you have the WOT switch active all the time that cannot be adjusted out period.

Do you still have Theo's Diagnostic program? It tests WOT to LH and WOT to EZK separately. Or you can do the procedure below.

Bill Ball

Per (small) chance the switch itself is at fault, you would pull the plug off the switch (easier said than done - remove the MAF for access) and put Ohm meter test leads on the switch connector pins as shown below. If the switch itself is faulty with WOT locked on, yours would show continuity all the time, not just with the throttle opened fully.

John Speake

Pin 3 of the LH connector is the WOT switch. (pin 2 is the throttle closed switch). The ground pin to use for the test is Pin 5. Meter on ohms or buzzer mode. But if your diag tester can show if WOT switch is working OK on EZK, then the problem is inside the LH.

I don't think there's anyway the WOT switch could be mounted so that it is showing closed all the time.

PS thanks Bill, you beat me to the reply :-)

drwhosc

thanks guys. this is good stuff. My instrument cluster went crazy on the way home, so another thing to work on. the flasher light and the Central warning Light alternate flash, and I have no Oil pressure, volts, gas or temp guages. central guages work ok. So have to track that one donw......

I will do the diag tomorrow....

Mrmerlin

the pod connectors sound like they are swapped a quick check of the connector wire colors and the pod connections will tell you what to do.
Bill ***** instructions should tell you the TPS condition.

NOTE the TPS is adjusted by loosening the 2 screws that hold it in position,
then it is simply twisted CCW till the click is heard then lock in place, this will position the TPS in the closed position

Then test by opening the throttle you should hear it click as the throttle plates just begin to open

drwhosc

Well Looks like a bad TPS. Dang it was replaced too. Hopefully I just did a crappy job installing it. Now I know what to look for.

Instrument cluster is a cluster ****. tracing the power back to find the fault. I know it is not in the cluster itslef, and I am back tothe central button pannel and workign on the timing realy control unit. Just have to find the dam thing, Ian I am willing to bet it is under my central console....

MarkRobinson

Try to adjust the TPS per post #12 above first: as soon as you move the throttle plate you should hear it click (needs to be quiet around you). If you don't hear the click or it doesnt' register on your Ohm meter, then good change it's just out of adjustment. I've never seen a bad TPS before, & i've seen them covered in oil before, inside & out yet still worked after cleaning & adjustment.

Bill Ball

Did you test WOT at the switch itself, as I showed in post #9? It could be a short in the harness and not the switch itself and that test will reveal that. WOT is not an actual switch that is easily stuck. It's a cam ramp that moves two spring steel contact arm together as the throttle turns, and it's hard to imagine them stuck together, especially in a new switch. They fail opened, not closed.

The adjustment of the TPS position will do nothing to help the WOT portion of the switch, although it is very important to have it correct for the car to idle properly.