Replacing TPS on 16V engine

krahm · 05-04-2005, 02:37 PM

This procedure isn't in my workshop manual, so a couple Q's:

1. Am I right that I'm going to have to pull the fuel rail and intake manifold off to do this job? Is there a write-up somewhere? Clark's just says to remove the tps and replace it.

2. What other parts will I need? Intake manifold gasket, I guess, but anything else?

3. What else should I do while I'm doing this? I've already had the injectors cleaned, and I'm replacing the vacuum lines at the same time. I'm trying to solve a stumble on acceleration.

As always, thanks for the help.

gtroth · 05-04-2005, 02:47 PM

Unfotunately, I believe you are right - you have to remove the IM to change the TPS on the 'S'. While you're there consider R&R-ing the ISV. And write up any issues you have for me since I'll be going after my ISV before next winter.

Have you tested your TPS? I don't see how that would cause your stumbling symptoms.

krahm · 05-04-2005, 02:59 PM

R&R-ing?

I haven't tested the TPS yet. It's so tight in there I thought I'd have to pull it to test it, and if I have to pull it, I figure I might as well replace it while it's out.

The Clark's website lists stumble on acceleration as a symptom of a bad TPS. I've been chasing this problem for a while, so I'm ready to try anything at this point. The car's had new rotor, cap, plugs, wires, new fuel filter, probably a few other things that I'm forgetting.

rb101 · 05-04-2005, 03:01 PM

you should be able to remove the 4 bolts on the throttle valve to get access to the TPS. But if you need to replace the vacuum lines, might as well pull the intake.

gtroth · 05-04-2005, 03:31 PM

R&R - remove and replace. You can test the TPS by first ensuring you hear the click when you pull the throttle cable a little. If it clicks, then you can check the switch electrically at the DME connector.

If Clark says so - I beleive it. I guess if the idle switch sticks closed, the DME will use the idle fuel map while not idling?

Rick - were you actually able to remove your throttle while on the IM? Seems quite impossible to me.

rb101 · 05-05-2005, 02:20 AM

I think I pulled the intake X 2, since I too needed to replace all the vacuum lines and then later idle stabilizer. I wish the intake for the S was made like the S2 which puts everyting up front and not tucked in the back.

mike944 · 05-05-2005, 04:48 AM

Does the 944S use a throttle-position SENSOR, or throttle-position SWITCH? It makes a big difference to the answer to your problem.

All the the 8V 944's use a switch. It's highly doubtfull that a throttle-position SWITCH will cause the problem you describe. The 968 uses a true throttle-position SENSOR, which will cause the problem you describe. I have no idea whether the 944S has a switch, or sensor, but i think it's a switch. If so, you should look elsewhere, like your air-flow sensor.

gtroth · 05-05-2005, 12:03 PM

It's a switch like the 8V's. Two switches, really, idle and WOT. Nice to learn that the 968 has a sensor - thanks Mike.

krahm · 05-07-2005, 08:54 AM

Well, I'll do the TPS anyway, since I'm going to have the manifold off to do the vacuum lines and replace the gaskets.

I'll check the air flow sensor, though, too. Thanks.

gtroth · 05-07-2005, 10:27 AM

Oh, if you've got the IM off, absolutely replace the TPS regardless of what any diagnostics tells you.