Throttle Valve Switch, Anyone Buy One Lately? Options

[jgara962]

My car's has a bad miss between 3,000 - 3,400 RPM and I'm gessing I need a new throttle valve switch or throttle position sensor or whatever it's referred to as. Anyway, Pelican's site says NLA and Performance Products has it in thier catalog but not on their site. Anyone know where to get one for a '74 2.0L? (IMG:style_emoticons/default/confused24.gif)

[JeffBowlsby]

The TPSs are NLA.

The component that wears out is the circuit board traces, everything else inside dos not geenrally go bad. Replace that circuit board and its pretty much good for another 50K miles. I *think* its pretty simple to make a circuit board, I think there are even some DIY processes available that with a little research, could restore a TPS to functionality. I will look into it someday when I need one if no one else does it first, but I am not there yet.

So who here knows how to make printed circuit boards and can build them inexpensively in small volumes?

[jgara962]

The TPSs are NLA.

So who here knows how to make printed circuit boards and can build them inexpensively in small volumes?

Who here can make at least one (IMG:style_emoticons/default/sad.gif)

[Mueller]

The TPSs are NLA.

So who here knows how to make printed circuit boards and can build them inexpensively in small volumes?

Who here can make at least one (IMG:style_emoticons/default/sad.gif)

3 boards for about $20 a pop..I have never used them...

http://www.expresspcb.com/

[william harris]

Hold on there Jeff - selected vendors still stock NOS units - I bought one about a month ago from Otto's of Venice (CA) and I am sure he still stocks these. Give Otto a call (IMG:style_emoticons/default/thumb3d.gif) www.ottosvenice.com or 888 901-6886.

[pbanders]

Even if a few vendors still have these, they'll eventually be NLA. If you have D-Jet and you want to keep it running, collecting a store of good parts for the system today is a good insurance policy.

[william harris]

Well, I didn't mention the dreaded AA, but George has them too, but for more $$$ than Otto. Yes, those of us who are still running D-Jet have to keep a few items in the parts dept. (IMG:style_emoticons/default/biggrin.gif)

[tradisrad]

My car was also missing in the 3k-3.4k rpm range. I checked the TPS and it was just fine, so I went on to check the trigger points and they were not ok, so I replaced them and all of my missing went away.

You can test your switch, I disconnected the harness from the "brain" and had a buddy open the throttle while I checked for the 10 pulses, I found that I had a clean break (no continuity) between pulses. You can also test this at the TPS, and you can take the cover off of the TPS and clean the contacts. What I've heard about the switch is that the traces get worn out and sometimes the copper bridges to the next trace.

I'd recommend checking the trigger points before you go and replace the TPS. Then clean up your TPS.

[pbanders]

Speaking of D-Jet items to stock up on, there's a vendor on eBay who has four NOS 914 fuel pumps for sale for $259 each, as compared to over $400 for most other vendors. He had five but I already snapped one up.

http://cgi.ebay.com/ebaymotors/PORSCHE-FUE...sspagenameZWDVW

[jgara962]

My car was also missing in the 3k-3.4k rpm range. I checked the TPS and it was just fine, so I went on to check the trigger points and they were not ok, so I replaced them and all of my missing went away.

You can test your switch, I disconnected the harness from the "brain" and had a buddy open the throttle while I checked for the 10 pulses, I found that I had a clean break (no continuity) between pulses. You can also test this at the TPS, and you can take the cover off of the TPS and clean the contacts. What I've heard about the switch is that the traces get worn out and sometimes the copper bridges to the next trace.

I'd recommend checking the trigger points before you go and replace the TPS. Then clean up your TPS.

Thanks, but I have a Pertronix - no points.

I'll definately give Otto's a call.

[Gint]

My car was also missing in the 3k-3.4k rpm range. I checked the TPS and it was just fine, so I went on to check the trigger points and they were not ok, so I replaced them and all of my missing went away.

You can test your switch, I disconnected the harness from the "brain" and had a buddy open the throttle while I checked for the 10 pulses, I found that I had a clean break (no continuity) between pulses. You can also test this at the TPS, and you can take the cover off of the TPS and clean the contacts. What I've heard about the switch is that the traces get worn out and sometimes the copper bridges to the next trace.

I'd recommend checking the trigger points before you go and replace the TPS. Then clean up your TPS.

Thanks, but I have a Pertronix - no points.

I'll definately give Otto's a call.

Tradisrad is referring to the FI trigger points in the bottom of the distributor, not the ignition points.

[tradisrad]

That is right, I am talking about the FI trigger points in the dist.
I also have pertronix points and they work great.
I will re-encourage you to check you FI trigger points, I had the the exact same problem as you and it was not the TPS it WAS the FI trigger points.

[jgara962]

That is right, I am talking about the FI trigger points in the dist.
I also have pertronix points and they work great.
I will re-encourage you to check you FI trigger points, I had the the exact same problem as you and it was not the TPS it WAS the FI trigger points.

Thanks for the clarification. I'll check the trigger points and clean the contacts on the TPS this weekend.

[tradisrad]

Any results?
-Rob

[jasons]

Thanks for the clarification. I'll check the trigger points and clean the contacts on the TPS this weekend.

Its not just the contacts that wear. There are 2 little black feet that ride the lobes on the distributor shaft. Those wear down and prevent the points from opening.

I bought a TPS from Otto about 2 months ago. I figured it was money in the bank. It can't hurt to replace both of those parts, while they are still available.

[jgara962]

Any results?
-Rob

Not really. I took the engine cover off and removed the air box. Stared at it for a while. Tried to remove the TPS but couldn't get the two screws loose so I removed the black plastic cover and there are black wear grooves on the contacts. Read through the Haynes manual so I could figure out where the trigger points on the distributor were and took of the distributor cap and rotor, and decided that I'm not confident in removing the distributor and taking it apart. (IMG:style_emoticons/default/sad.gif) I need to think about this for a couple of days.

[tradisrad]

Any results?
-Rob

Not really. I took the engine cover off and removed the air box. Stared at it for a while. Tried to remove the TPS but couldn't get the two screws loose so I removed the black plastic cover and there are black wear grooves on the contacts. Read through the Haynes manual so I could figure out where the trigger points on the distributor were and took of the distributor cap and rotor, and decided that I'm not confident in removing the distributor and taking it apart. (IMG:style_emoticons/default/sad.gif) I need to think about this for a couple of days.

the distributor needs to be removed so you can access the trigger points, the trigger points are located on the side of the dist. usually facing toward the cooling fan, with the 3-wire plug going into it. You will need to reset the timing after checking the trigger points. If you can set the timing and reinstall the trigger points so they are faily well centered you can do the job.
Some contact cleaner on the TPS may help clean that black away, I've got a big screw driver that has a fat and wide tip on it, it works really well for a lot of the screws in the car as well as the TPS mounting screws.
have you seen this: http://members.rennlist.com/pbanders/DJetP...tm#troubleshoot http://www.pelicanparts.com/techarticles/9...ttle_switch.htm

-Rob