i think my tps is going out (bucking at around 4k rpm)


i also have some fi leaks on the intake runners


my question, is how difficult is it to either fix the current tps, or replace it, and how long does it take



(i already have the intake runners pretty much dialed out for when i get to fixing it)




(btw, the car is a 73 1.7 with the fi, if that means anything)

There have been a few people on the site who have talked about making a replacement for the TPS, but it hasn't happened yet as far as I know.

I had the same issue. I purchased some contact cleaner at Radio Shack and used a q-tip to clean them. I think I did three or four applications and it helped a lot. It's pretty easy to do. You just have to get to the TPS and remove the black plastic cover.

What do you mean by " fi leaks on the intake runners"?

Unplug the TPS and drive the car without it. (Yes it works) If you still have bucking at 4k look elsewhere. I would check your trigger points. Specifically the plastic/rubber dogs that ride your dizzy shaft and open/close your trigger points. The contacts may be great, but when the dogs wear out, the contacts won't open and close accurately.

fi leaks=fire
i would work on that first

i redid all of my injectors with hardware store fuel lines some may say bad idea
but i have no leaks and it runs good. i know this wasnt your question but from the horror stories ive heard those leaks are important to fix.
and good luck with the tps

well, the bucking is intermittin, it doesnt happen al the time, just every once in awhile it will happen

so i guess i will clean it out, and check its progress




as for the leaks, its just the air (right at there the intake is seperated (those sleeves) and then down by the head too

that just results in crappy idle performance (which i have richened the fuel to compensate for the time being) but other than that, there is no other problems

but since i live at san luis obispo for school, and the car is in redlands, ca, it isn't driven, so my spring break i will attempt to fix both (i hear fixing the intake runners take a long time, yay lol)


thanks for the advice

cheers

since i am on the injection topic


does any one know what size of hoses i nead for the connection to the top of the intake on the intake runners


and also, the parts i need for where the runners connect down to the heads??


that way i can either hunt them down or order them off pelican, or just use any other hose

This is only my humble opinion, But I think you have several problems. None of which need to be expensive. Just a little time consuming.

Let's start with the basics.

If your 914's vacuum lines are more than 10 years old - they all need either replacement or trimming & re-seating (yes, it can work for a temp fix if they aren't split in the centers). 914's NEED to run in a closed environment. Any vacuum leak, and there can be many sources, will screw things up at all RPM ranges. Those intake runners are a prime source for leaks. Replace them - $40 at the most. All the other vac hoses need to be tested for leaks. If they leak, replace them - also fairly inexpensive.

Now - the TPS. Jasons in correct - you can unplug it, run the car & watch the effects. I would guess that your TPS is very old (maybe original), but there are things you can do to help it. Unfortuately, you must remove it to make the work easier - also, not a major deal! IF you decide to remove the assembly, which includes the throttle body, be VERY careful to NOT screw up the supple rubber gasket that fits below the throttle body on the plenum _ I am told that these are no longer available for 1.7's

Once you have the TB and TPS assy removed, pry off the black plastic cover on the TPS body(carefully). You'll see the tracking armature, much like an old record player turntable, and a probable groove cut into the surface. If the groove isn't too deeply cut, you can clean it up for re-use. Clean all the components with contact cleaner. I usually go the extra step to polished the surfaces with Simichrome, BYMMV. The throttle body will be full of gook too, so clean it up & Q-tip the side venturiis.

Once all parts are cleaned - replace & follow the easy adjustment tips -http://www.pelicanparts.com/techarticles/914_cooley/throttle_position_calibrate_17-18.jpg

If the TPS is too far gone, and they are almost unobtainum, look for a low mileage replacement (PM me if you need one).

Go after any vacuum leaks first & fix those. Then look at the TPS. None are a big deal, just remember - these cars are approaching antique status. Keep your head tucked up under the arms of the people on this site. They/we have all (well, almost) the parts to keep these things running smoothly. Just takes a little effort, dude.
Pat

thanks pat


i took the car down to precision motion (porsche shop) in riverside, and thye told me the leaks were def coming from the lower part of the intake runner

i probably do need to replace more, but so far it has been a when it happens ill fix it, due to my limited financial situation (college is way too muc money lol)


as far as the tps, i will check it (and you are right, the hose for the throttle body no longer is made for the 1.7 (as is many many other hoses )
if the tps is really bad, i will probably call up my buddy hershel, hes got i think 10 or so parts cars, so he should have one, and hes local


i have set to fix the car in a few weeks, so i can be home and when my buddy can help me too


thanks for the help, and ill give a heads up on the progress

Ben,
Good luck! If you need any other help, or a TPS (have 5 for a 1.7) LMK. Actually, I have ONE factory new TPS, but everyone will have to wait until I'm dead to bid on it.
Pat

yea, i know what you mean

it is amazing how rare good fi parts are, especially for the 1.7


i got a connector for a vacuum hose a year or so ago from precision motion

it was the only one they had, and it was from like 1990, and they don't make that part anymore lol

i will probably know about the tps sensor in like 2 or 3 weeks

there is a pca event coming up, with a good 914 turnout hopefully, so i will try to get this done beforehand (damn this distance, instead of studing id rather be fixin those issues, because i will be cutting it close to that event (friday night at about 10 ill probably be working on my car)

anyways, thats a side note



thanks for the tips pat

i wil also check that article


also, is there tips either job in the 700 tips, or the haynes manual too?

Slight Hijack....

I bought an NOS 2.0 TPS From Otto about a year ago. He sold it to me for retail too. He had an inventory of them but, I think they are all gone now.


I also concur with Pat. You really need to ring out all of your FI. My 2.0 was a non-runner when I brought it home. I dropped the motor and went through the whole FI system, fuel tank, hard and soft fuel lines, harnesses, all parts that could be replaced were replaced. The DJET FI works pretty damn good for what it is, when its dialed in.

well, except for the current intake runner leak, which happened recently, the car hasnt really had a problem with the fi in awhile


but yea, i do agree, i do need to get it all replaced (as far as hoses) to be able to keep it in better running condition, for longer

Yeah

I'm trying to get something lined up to allow me to reproduce replacement boards.

So far, it hasn't materialized--and now my laboratory was taken away, i ended a five year relationship and now have switched living venues.




My email for the time being britt man 914 at gmail dot com (no spaces)

If I may hop in here; I too have a '73 1.7 for which I may need a TPS. Cleaned it about a month ago with good results but a little of the bucking has recurred. I wonder if the grove I noted in the circuit board may have been too deep?

Pat, can you say what one of your TPS would cost?

Thanks,

M