| Author | Message | ||
| HaK (Howard)
New member Username: Howard Post Number: 28 Registered: 4-2002 |
Dave do me a favour.......please explain in plain english what to do to get my 355 running like a normal car. If you set it out clearly I can print it off and take this sheet of paper togeither with my sticky 355 and solve this issue. By the way if successful I will pass this fix on to all known F mechanics in the UK and this problem will be a thing of the past. HaK | ||
| Dave Helms (Davehelms)
New member Username: Davehelms Post Number: 5 Registered: 5-2003 |
HaK Yes, as long as the static throttle plate is set with in reason, the computer will bring the idle speed into the correct range. It usually takes around 15 to 20 min. (for that period of time the idle is usually around 1800-1900 and slowly drops)for the computer to relearn and set the correct idle speed. When I was with the dealer this was quite simple as we had the Ferrari computer (SD1) that would reset all learned parameters in a moment. But there are ways around that also. I have been doing a lot of experimenting with a 360, and should have a procedue for a number of these types of things worked out soon. Dave | ||
| Mitch Alsup (Mitch_alsup)
Member Username: Mitch_alsup Post Number: 648 Registered: 4-2002 |
"Mitch, be careful about spraying/soaking the rod ends" Dave: thanks for the tip, But all I used WD40 for was isolation of the issue. Once I fund out it could be a lubrication issue, I had my mechanic do the lubrication per book. | ||
| HaK (Howard)
New member Username: Howard Post Number: 27 Registered: 4-2002 |
Dave are you saying that this adjustment fixes the sticky throttle on a 355 without altering the idle speed? | ||
| Dave Helms (Davehelms)
New member Username: Davehelms Post Number: 4 Registered: 5-2003 |
Thanks for the kind words, and turning me on to this site, Tim. This makes for some interesting reading to say the least. Stop by the shop Sat. (Tom will be there, Im still moving the house in the middle of a blizzard!), and bring your camera. Something big dropped out of the back of your car last night! Mitch, be careful about spraying/soaking the rod ends. The wd40 attracts dirt, and led to the seizure of the rod ends on the F50 engine I rebuilt a few years back. This happened with in a week, and you can imagine what happens when you put your foot down on this car, and when you lift to shift the throttle pedle dosnt follow your foot back. Spray them down with brake clean just to keep them clean and dry. | ||
| Tim Barnett (Tim_barnett)
New member Username: Tim_barnett Post Number: 14 Registered: 4-2003 |
Steve, Dave is located in Boulder, Colorado. 303-449-9112. But don't anyone call him next week - he's going to be hard at work on my 355.  | ||
| Dave Helms (Davehelms)
New member Username: Davehelms Post Number: 2 Registered: 5-2003 |
The fix was discovered when trying to correct an idle surge on a well used 348, quite a few years ago. I found the throttle plates to be everything but closed, with a small amount of carbon build up around the plates finishing the sealing of the plates in the bores. All of the idle air had to go through the idle by pass motors, which were operating at near full open, and are not fast enough to correct for throttle plates that slammed shut. When the throttle stop screws are opened up a slight amount more, less idle air had to go through the idle motors, which in turn required them to make far smaller movements and adjustments to correct the idle speed. The resulting side benifit was an incredibly smooth "break away" from closed throttle. The 355 is far more critical regarding the static set of the throttle plates, and should be done only with a 8 port manometer to keep all throttle plates in sinc, and the check engine lights off! | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1417 Registered: 11-2002 |
>>Just being picky about the selection of words; The order in science is: Postulate -> observation -> theory << Mitch, when one is repairing cars and balanceing the charges between time actually spent and time billed...there isn't the luxury of postulating...;-) | ||
| P. Thomas (Ferrari_fanatic)
Junior Member Username: Ferrari_fanatic Post Number: 204 Registered: 4-2003 |
Tim, you got mail. P. | ||
| HaK (Howard)
New member Username: Howard Post Number: 25 Registered: 4-2002 |
Tim, do not forget to post the results of this fix. I reckon your mechanic is onto something here. | ||
| Mitch Alsup (Mitch_alsup)
Member Username: Mitch_alsup Post Number: 634 Registered: 4-2002 |
"Agree, which is why I called the other "fix" a theory." Just being picky about the selection of words; The order in science is: Postulate -> observation -> theory In other words its not a theory until there is some confirmation based on evidence. | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1760 Registered: 1-2001 |
Is the 355 throttle plate pivot axis "centered" with respect to the thottle plate area (i.e., no moment on throttle plates from vacuum regardless of position), or is the 355 throttle plate pivot axis slightly offset? Tim B. -- what is the name/location of Dave Helms' shop? | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1414 Registered: 11-2002 |
>>if the vacuum increases the load on the bearings supporting the shaft then this could induce sticking (especially as the bearing wears). If this is the real case, then the bearings are insufficient to carry the load. << Agree, which is why I called the other "fix" a theory. However, it's not totally unherd of that the edges of the plates will stick/rub against the bores if they are completey closed and even minutely worn or ever so imprecisly machined. Every problem (should) starts out with 'theories' as to the cause and effect, and all good solutions start out as 'theororizing' about the fix. Once actualities are discovered then procedures (cures) are developed. Interesting. | ||
| Mitch Alsup (Mitch_alsup)
Member Username: Mitch_alsup Post Number: 629 Registered: 4-2002 |
I'm going to question the physics of this explanation as follows: Consider a vacuum in the inlet tract below the throttle plate: does this vacuum not pull evenly on both sides of the throttle plate? and if so, then the plate can rotate as the shaft turns without hinderance as there is equal pull on both the tip-in side of the plate and the tip-out side of the plate, canceling out any forces that prevent rotating movement. However: if the vacuum increases the load on the bearings supporting the shaft then this could induce sticking (especially as the bearing wears). If this is the real case, then the bearings are insufficient to carry the load. Does anyone know if the bearings are plain bushings or ball bearings? If they are plain bearings, this indeed could be the problem point. | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1413 Registered: 11-2002 |
>>Apparently it's a question of adjusting the way the car idles. The standard set up uses a vacuum tube that bypasses the throttle bodies entirely. Vacuum pressure then causes the throttle bodies to "stick" when tipping into the throttle. The solution is to make an adjustment so that some air moves through the throttle bodies, even at idle, so no vacuum pressure has a chance to build up. << Sounds like a plausible theory. I'm try to remember the exact model, but anyway, there does exist a series of carbs that have about a 1/16" hole drilled (from the manufacturer) in the trottle plate itself towards the leading edge to prevent this excessive manifold vacum on the plate. It will be interesting to see if rerouting some of the vacum will alleviate the condition reference here. | ||
| Tim Barnett (Tim_barnett)
New member Username: Tim_barnett Post Number: 7 Registered: 4-2003 |
I have a 1997 355 and my car suffers from the same condition. To say it's irritating is an understatment. I've consulted with Dave Helms, head mechanic at Ferrari of Denver turned independent, and in his opinion this is definitely a vacuum issue. He says for years they tried to correct the problem by troubleshooting the linkage with little effect. But there is a fix he tells me! The following is my understanding of what's involved. (And keep in mind I'm no mechanic!) Apparently it's a question of adjusting the way the car idles. The standard set up uses a vacuum tube that bypasses the throttle bodies entirely. Vacuum pressure then causes the throttle bodies to "stick" when tipping into the throttle. The solution is to make an adjustment so that some air moves through the throttle bodies, even at idle, so no vacuum pressure has a chance to build up. My car is in his shop this week for its 30K service and he is going to specifically address this problem. I should have it back in a week or so - I should be able to report then on the success of his proposed fix. | ||
| Mfennell70 (Mfennell70)
Junior Member Username: Mfennell70 Post Number: 130 Registered: 7-2001 |
You're saying you definitely feel reisistance in the pedal on tip-in? It kind of sounds like a lean condition to me. | ||
| HaK (Howard)
New member Username: Howard Post Number: 24 Registered: 4-2002 |
I am also sure it's a vacuum issue and not lubrication. I have the updated quadrant, the rods adjusted to the correct length, a new throttle cable and everything oiled up in my 95 right hand drive 355 and I would say the car is 70% better than b4 these updates but still hard to drive smoothly. I also have a Tubi with no cats and can say that there is no difference in this annoying fault than with the original exhaust system. Doesn't half sound great though! If there is a definitive fix for the sticky throttle in a 355 then 11,500 drivers will be very happy. Someone who speaks Italian should contact Ferrari in Maranello to find out what the manufacturer's have to say on the subject. | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1411 Registered: 11-2002 |
>>As many of you know, early 355s had a problem with a "sticky" throttle -- not throughout the movement, but just initially, when the gas is first applied (i.e., after lifting, reapplying the throttle). << If you have the early 'plastic' runners and plates there was a Tech Bulliten to update to the later Metal Runners and Plates. Don't know if that's your issue of course, but it's something to think about . | ||
| Jeff B. (Azferrari)
New member Username: Azferrari Post Number: 3 Registered: 4-2003 |
Dennis, As I think you know, I had this problem on my '95 F355B. I ordered and installed the new "half-circle thingy" on top of the engine that receives the throttle cable. The only difference that I can see from the old "thingy" to the new "thingy" is that the throttle cable does not wrap around the new thingy quite as much. After replacing the thingy, I thought that the problem was better, but it was still there. I am convinced that IT IS NOT A LUBRICANT issue. It is a VACUUM issue. I think that in order to overcome the initial vacuum when opening the thottle, I takes undo pressure on the accelerater. I don't know if anything can be done. If you find out something, please let me know. Jeff AZFerrari | ||
| Mitch Alsup (Mitch_alsup)
Member Username: Mitch_alsup Post Number: 615 Registered: 4-2002 |
Dennis: As one whe has an F355 that used to have same problem; You an isolate which end of the system causes the problem with WD40. Start by spraying WD40 onto the throttle bearing, go out for a quick drive. If it is better, the lube the throttle (WD40 will evaporate in a couple of hours.) If problem remains, shoot the rod ends (all 4 of them) on the bell crank assemble in the middle of the engine, and go for a drive. On my car this required raising the water catch tank. If problem remains, shoot the throttle housings themselves. Once you isolate which item is causing the friction, then disassemble down to the point you can get at that part, clean and lube all similar parts. Hope this helps | ||
| Dennis (Bighead)
Junior Member Username: Bighead Post Number: 96 Registered: 2-2003 |
This topic has been discussed before, but I'm hoping for some new enlightenment. As many of you know, early 355s had a problem with a "sticky" throttle -- not throughout the movement, but just initially, when the gas is first applied (i.e., after lifting, reapplying the throttle). The "stickiness" would be apparent only in the first movement of the pedal. This is especially noticeable in first or second gears, as the stickiness makes smooth acceleration difficult. Bob Ziino suggested, "the problem is the grease that was used by the factory in the throttle bearing at the bell crank. The factory grease gets hard with heat and the trottle will stick. Remove the bearing and repack with grease and 95% of the sticking throttle will be gone. I did this to mine because the car was next to impossible to drive smoothly at low throttle and now it drives at low speeds without a problem." Peter Pless weighed in with "replace the 'thingy' in the middle of the engine where the throttle cable joins...i spose it's like a 1/2 wheel and it's where you adjust the throttle cable play with the nut at the end...hell I hope you know what i mean...... WELL....this gizmo was redesigned in the later (97 i think) cars...just the shape of it. Changed the leverage a little or something. Fixed the problem in mine totally." I resolved my problem previously with the fitment of that revised part; it's like a cam for the throttle linkage. Ferrari DID change the design of this piece, sometime in the 1997 production run. They call the redesigned piece the "quadrant", which is no more descriptive than what Peter called it, the "thingy". It looks a little like the brass "thingy" that you install on a door hinge that keeps the door from slamming into the wall when someone opens it forcefully. This replacement solves almost all of the problems. I'm told that residual problems can be solved by adjusting it to compensate for the vaccum, per Ric Rainbolt's advice. When the new quadrant is installed, it requires shortening a throttle rod, and massaging two heim joints, and slaughtering a virgin lamb, but it worked! * * * BUT, the problem has reappeared. My 355 had a MAJOR service done over the winter, including a valve job. My mechanic found that I wasn't getting full throttle and that the throttles weren't properly aligned between the two banks (I think; I'm paraphrasing here). Also, we put a Tubi on the car. After I get the car back, it runs incredibly well, and FLIES at the track. And it sounds great too. So I'm delighted, EXCEPT... the dreaded throttle stickiness problem is back. ARGGH. It's driving me crazy. It's mostly apparent at low RPM, mostly between 2k and 3k. Makes slow driving in traffic very difficult, and tight turns on the street where I lift and reapply the throttle really, really bad. The car JERKS when I apply throttle at low RPM. Very unsmooth, and unimpressive (both to me and the passenger). It's most noticeable - and problematic - when trying to accelerate in a corner with low RPM. This happened in many ramps and such, if RPM would dip to below 3k, and the car is in 2nd, 3rd or 4th. It's incredibly tough to get smooth acceleration when transitioning from off-throttle to on-throttle. The feeling in the right foot is a sensation of vaccum; it feels like, as the throttle is applied, at the top of the travel, it's "pulling the lid off a can of tennis balls". Once the initial bit of travel is done, and the lurching is felt, the throttle runs perfectly fine and progressively. Since I don't want to be a moron buzzing through town at 5k RPM all the time, I really want this problem cured. Any suggestions? My mechanic has played with the linkage, and thinks now that the addition of the Tubi has reduced restriction at lower RPM, hence the increased "vaccum" feel (again, I'm paraphrasing). He wants to adjust this by playing with the chips (fuel injection mapping), and maybe getting more fuel at lower RPM. I'm already running Autothority chips (came with the car when I bought it). Anything else we should try?!? Any and all suggestions and help would be most appreciated!!! thanks, --Dennis |