"hanging" throttle on my 1991 testarossa

If you decide to try the TPS, get the part number and get it from a local parts supply. You will save a lot of money. I changed mine a few years back and paid $26 for it, from Ferrari it would have been much more, I am sure.

It's a Bosch unit.

 

Rather unlikely IMO. It's really just an idle and WOT detecting switch (not a TPS) and only slightly affects the amount of fuel going to the engine. In order for the engine to (wrongly) run at ~3000 idle, a huge amount of unwanted air must be entering the engine. The more likely suspects IMO would be:

1. Something in the throttle linkage holding the throttle plates open (good action here when the engine isn't running is a good sign, but not 100% conclusive),

2. Bad Vacuum Limiting Valve (if you have a F113B engine TR)

3. Bad Auxillary Air Valve

I'd work on ruling these in or out first -- JMO...

What is your engine family? F113B, F113A040, F113A046, something else?

 

You can get the PNs from the SPC figure at the Ricambi America website, but don't buy parts until you really determine if a part is not working correctly (and much more economical to buy them from a Bosch supplier using the Bosch 10-digit PN rather than from a F part supplier). This jpeg shows the locations of the VLV and AAV on a F113B engine and both should be fully closed at warm idle -- so, by simulating a fully closed condition, you should be able to determine if one is not sealing well sometimes when warm as it should. (This jpeg was made for another prior thread so ignore the instruction about turning the air bypass screws.)
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This is exactly how a problem in #1, 2, or 3, described earlier, would/could appear.

The cold start injectors only function is to squirt a little extra fuel at cold start-up to initiate engine firing -- it really has nothing to do with the cold idle RPM. More likely your AAV have become "tired", and aren't opening up as much when cold (although this time of year in your hemisphere it isn't very cold anyway). I'm not sure if your F113B uses the same AAV as a US TR, but, on my US TR, the AAV have an adjustment screw that can be reset to increase the opening when cold. I'd suggest that you have a look thru your AAV air path to see how much they are opening when cold (i.e., at room temperature); however, your cold idle RPM being the same as the warm idle RPM really isn't a serious flaw, unless the cold-running is rough/unsteady. You might want to wait for the winter time to see if the cold idle comes up a little more when the temperatures go down.

 

The database at www.allferrariparts.com shows 115741 = Bosch 0280160111, but it should be stamped somewhere on the outer body of the VLV itself so please post confirmation or denial if you find it (and please post the Bosch 10-digit PN on your AAV too).

 

Looks to me a mechanical problem more than a sensor / electronic problem.

Were you able to have a person looking whilst running the car on your poarkingplace....

Maybe he can see / feel what or where is someting obstructing ?

I had a cable problem once .... and we found it that way ... good luck !

 

I agree that the TR SPC is very confusing in this regard. I can confirm that the US version TR (that also has cats) use the 0280140104 AAV (125880). In the past, I (wrongly) purchased the 146557 part and received 0280140176. The difference is that the ...176 part has a triangular shaped cutout in the sealing disc, while the ...104 part has a half-moon shaped cutout in the sealing disc. They both have the external stud & nut that allow the selaing disc position when cold to be adjusted, but the maximum size opening can be adjusted to be larger on the ...104 AAV.

I'd recommend that you match whatever Bosch PN is on your car now (if it/they need to be replaced) -- but please post the Bosch PN on your stock AAVs regardless.

 

Any final solution on this? My TR is having the same throttle response delay at low revs.

 

I had exactly the same problem last year. It turned out to be an air leak from the large rubber seal between the plenum and fuel injection system LHS.


P

 

so very easy to fix it then

wenn es nicht mehr ist ! ! !

 

.... this happens to many others .... I am SURE !

 

Happened to me as well. Car had been sitting, the mats took a set. Also they can shift.

Luckily the first thing I did was to look on F-Chat for advice, problem solved easily.

 

Im having the same issue with my 87 328. and its not the floor mats!!

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Check the throttle stop microswitch on the side of the throttle body or fuel distributor.

 

I appreciate the tip. how exactly do i test it?

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I'm posting a follow up to this exact same symptom on my 86 Testarossa.

My car just came back from some excellent belt service but before I called my service man I went over the car myself, starting with the pedal. I found the two mini-hose clamps on the hoses that come off the rear of the plenums and go to the evaporative canisters were both loose. Tightened them up and the problem was solved.

I have tracked down vacuum leaks on other cars, and every time it really is amazing how just a little leak of air raises the idle.

I have also experienced the floor mat problem; a Coco Mat (remember those) in a 1976 Lancia Beta Coupe produced a little wide open throttle excitement.

 

LOL!! Throwing stones at you just because it's funny and you deserve the punishment. You can throw them back at me. I've done stupid stuff too!

 

Yup yup!!! Have had this excitement on a 300ZX as well. Tough to troubleshoot. In my case it was a borrowed car, and the owner (my best friend who knew about the problem but didn't think of mentioning it to me as I rode off for a short drive) still gives me flack for it...I took an hour to get back as I stopped every time it happened...didn't want the overrevving motor to blow and I was looking for the cause in the engine bay.

Floormats should be banned. I'd much rather have pebbles bouncing around a al Lotus Exige!