355 Sticky Throttle

It may very well be a sticky pedal. Old hard grease makes the pedal feel sticky, the moving parts are dry.
Another guy had this type of problem a few months back, i suggested re greasing and that was indeed the problem.
I have a link to a step by step how to on another ferrari forum that i can pm you if needed.

 

Hi Scott, I also have a 95 GTS also and for years I have been trying to solve this throttle jerky reaction problem. Some days it can be a real pig in traffic and other days there are no problems. I find that it happens arround the 3500rpm area. It feels like there is a dead spot at these revs as you just come back on the throttle when cruising. Also the exhaust note gives a hollow sort of sound, then it jerks and the exhaust note goes back to its normal crisp sound. I have taken it to Ferrari to try and sort it out but they just shrugg their sholders and give no answer. I think it might be a sensor problem to do with the throttle position.
To see if it is the same problem try resetting the ECU. Do this by turning off the main power overnight to totally clear the memory then with a/c and other electrics off let the car idle for 10 minutes. This will reset all the parameters. I have found that the problems goes away temperarely and then slowly comes back as the ECU relearns. This is why I think it is a sensor of some type.
Let us know what happens with your car when you do the above and if you solve this riddle let us know what it is. email [email protected]
Cheers
James

 

This is one of those "they all do this' issues. I talked with my dealer service mgr who is very knowledgeable and he explained to me that the throttle bodies have adjustable stops for the throttle plates. It these aren't adjusted perfectly the plates will stick momentarily in high engine vacuum situations, like when down shifting or when your foot is off the gas while going around a corner. then when you apply a little gas in second gear it is a jerky 'on-off' squirt of gas that we get. It makes driving in this mode hard to do smoothly.
He said he could re-index these plates - cost about $800 for labor. I decided to just live with it and with practice I can apply the gas smother now over time. I've had my 95 spider for 2 years.

Also, If you are do the the major you could request this be done. Otherwise, most shops don't do it as it does add to the bill they are (or should be) sensitive to this.

 

I have the same issue could you PM me the link, I would sure appreciate it.

 

I agree with both points.

A) check, clean, and re-oil and re-grease the linkage

B) the throttle bodies WILL grab the throttle plates in the lower mid-range due to (lack of) manifold vacuum.

{I say "lack of manifold vacuum" not because there is not a vacuum, there is; but because there is no manifold with vacuum--the manifold is on the unthrottled side of the throttle plates.}

 

The SEARCH function is your friend...there are several threads on the subject, and you should find the ones either started by bigheadeddennis or contributed by him, as he has one (two?) 1995 355s and knows of what you speak and has worked through several possible fixes, including a couple factory ones. Also consider cleaning and lubricating the gas pedal itself, where it pivots...some have found some very cruddy hard grease in there that required disassembly to clean it up good and regrease. Also, adjusting the throttle bodies is another area of possibility as Mitch explains.

The 1995 year seems to be more prone to this issue. But by no means do "they all do it" as I have driven a couple and they had no symptoms.

 

i had a similar problem with my 95. turns out it was old hard grease in the pedal box. just did the fix a couple of weeks ago.

 

The other couple items are the cable can wear enough to "cut" into some of the housing it slides in. Replacing cable and portions of housing can help. There is an updated peice at the engine end of things...this part allows for smoother operation...that is one of the factory updates on the 1995 cars...again, it is laid out in the threads I mentioned above. You really need to find and read the previous threads to learn all the possible fixes.

 

The order of likelyhood from my experience.

Deposits on the plates
Bellcrank bearings between the intakes dry or rusty
Cable liner cut through
Pedal box issues

The sinc and balance of the intakes is time consuming to do properly but is quite doable for anyone with an accurate vacuum gauge (few have a 12 position mercury column, by far the quicker and more accurate method), patience, and the want to do it correctly. This is one case where the manual is actually well written and fairly easy to follow. Randomly turning screws will not have the desired effect, rest assured of that. The sinc and balance can only be done AFTER the plates and bores are cleaned, the bypass screws are removed and cleaned and the system is proven free of vacuum leaks. The reward of doing it correctly, priceless! The results of attempting a quick fix... pure frustration. Do it right once and you will be quite pleased with the results. Dont try to fool yourself, do a compression test prior to attempting the above to make sure you have near equal vacuum available on all ports.

JOW02... you have an altogether different problem. Dead spots in the power band that come and go and the throttle break away are seperate issues, both requiring attention.

 

I have had this issue on one of my customer cars and it turned out to be the throttle sticking in the engine. Where the throttle cable comes to the pivot point it gets dry and rusts. There is a small bearing that seizes, remove the linkage replace the bearing and clean the shaft. It was a little bearing causing a large issue. The bearing is about $10 if not less. Not a bad job to do

 

Absolutely +1 .. fixed my sticky throttle problem. I bought an 8-channel TB syncronizer and sync'd and balanced the butterfly's to idle at 900rpm without the IAC plugged in... it was a major improvement!

Its a delicate balance because the IAC was only "just" opening at ECU controlled idle when the base rpm was set at 900rpm. If the base RPM was set much higher, I found the IAC had trouble holding a steady 1050.

So.. it may compromise a 100% smooth idle, but you loose the pathetic off idle "stick" and gain driveability.

Also discovered that if you have a good sense of feel, it is pretty easy to check the pedal/ linkage smoothness with the engine off by operating the pedal and linkage by hand.

 

On the engine end of the accelerator cable, where the cable attached to the pivot Lever ( Accelerator control transmission Lever Part# 161826 or 175234 as a replacement part ). This pivot Lever have 2 Tie Rods connected to ( part# 166488 ), one Tie Rod lead to left Throttle body mechanism, the other lead to right Throttle body mechanism.

Does anyone have any idea of the correct angle of the Accelerator control transmission Lever?

As you shorten both of the Tie rods, result to the Lever turning clockwise, and as you lengthen both of the Tie rods will make the Lever turning anti clockwise.

I have tried adjusting Tie rods to have the Lever turned anti clockwise, this make the sticky throttle worse. But adjusted back the sticky throttle is better but not cured.

As I have tried changing everything possible to solved the sticky throttle and it is still not solved. ie changing all bearings, cable, and clean and grease the moving parts etc.

My only hope is adjusting the above mentioned Lever by mean of adjusting the length of these Tie Rods.

If you could help with guideline such as correct length of these Tie Rods or the angle of the Accelerator Control Transmission Lever would be very much appreciated.

 

Can u pm this to me please

 

I have the same issue to can I have the link please