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Discussion Starter #1
Hi all, and happy Thanksgiving!

A couple of weeks after a recent fuel pump replacement, my ‘91 164S started exhibiting an odd and highly irritating symptom.

When trying to pull away from a stop, at low RPM, as the clutch starts to grab, the power seems to fall off sharply. The car slows with a jerk, and almost as if caused by the slow down, it gets its power back, and jerks forward. I used to call this jackrabbiting, but searching the forum using that term showed that most of you use that term differently. Still, it feels as though you’re trapped in a steel bunny, as it’s trying to hop across an intersection.

If I leave the stop at 2,000 RPM, I can usually modulate the throttle so it’s much less noticeable.

Do any of you have any insight?
 

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Discussion Starter #2
Added datum points.
-I replaced the leaking radiator, around that time.
-This came on immediately after braking extremely hard, for a stop sign. (Yes, I had planned to out-accelerate the car next to me, and get into their lane. Guess how well that worked.)
-Since it started, I switched spark plug leads, distributor cap, rotor, and fuel filter, with no apparent change.
 

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But Mad North-Northwest
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My first guess would be an air leak somewhere
 

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I second Gubi's hunch. Keep in mind that as the clutch engages (or under hard accleration) the engine rotates CCW, then as the torque relaxes (or you deacclerate) the engine rotates CW. All the movement is taken up by the bellows of the air intake hose. This hose gets hard with age and this constant flexing of the engine (how much it moves is dependent on the condition of the engjne mounts and dog bone bushings), either splits the hose at the bellows, or it gets pulled loose on one end or the other. My favorite test is using an unlit propane torch (add a flexible hose to the end so the you can keep the canister upright) then as engine is idling direct the end of the hose all around the hose while at the same time tugging and pushing on the airfilter box to see if idle speed changes.
 

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Yup, that works well. Found an unconnected hose for the LS cruise control system that way, the little hose going to the vacuum ball in the left front fender ahead of the forward fender liner. Car had been throwing the check engine light now and then while still running well. Hooked that back up again and all became well.

You never know where there might be an air leak in these sensitive systems as compared to the old carb systems.
 

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Discussion Starter #7
GAWD! How I miss working on the triple dual-throat side drafts, on my TVR!
 

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Yeah, I used to watch Carlo set up the numerous downdraft webers on older V12 Ferrari engines. The master's touch.
 

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Discussion Starter #9
Winner, winner, chicken dinner!
You guys nailed it!!!
And I win, just for being on this forum with you!

As soon as my friend and I started squeezing the flexible pipe, the engine almost died.
 

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Great. You can do a temporary (or maybe not-so-temporary) fix of the bellows by cleaning the exterior well and wrapping it very tightly with black silicon tape. Di Fatta used to have a reproduction air intake hose for the S which was soft as baby skin, but they may have sold out.
 

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I thought I heard that the Difatta hose didn't fit right or something else wrong with it, but don't remember now just what the problem was. Wrong rubber? Dunno. A tape I've used on things to seal them up is the boating "self vulcanizing" tape, which adheres to itself after being wrapped around something. Have used it on our old sailboat.

I recommend continually slathering the new hose, if you find one, with ArmorAll to help keep it supple. I do that and I've still got the original hose installed on my 91S, now at 29 years and 195k miles. I think that at 200k miles I will put on the new, just because. The one installed on the 94 LS was also still the original, it also being treated with ArmorAll. The new owner of the LS will be getting the new spare I bought some time ago for that car.

Of course, as others have said, keep the dogbone mount as well as the others mounts in good condition in order to reduce engine movement.
 

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Hi Del! The Di Fatta hose just needs a little "cleaning up" where the small hoses enter on the side, easily done with an X-acto knife from the inside.
 

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Got it. Glad to hear it is ok otherwise. Maybe I was thinking of an aftermarket 24V version from Lithuania, Latvia, or Slovenia, or somewhere around there? Didn't fit correctly?
 

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Discussion Starter #14
I spent the morning looking for an NOS or repro (or any kind of) intake hose, and discovered that there are different types of hose for the different models.

I also came across this thread, which illustrates what the differences are. 164LS intake hose

Already tried calling DiFata Bros., this AM, but they’re not open weekends. I’m going to check in with them, on Monday, and see if they have the correct length and diameter version for my S. Also, there’s this one on eBay. ALFA ROMEO 164 3.0 V6 Silicone Air Intake Hose 60513173 60544488 60547303 | eBay and I’ve asked if it would fit my S.
 

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That ad is confusing because it combines contradictory part nos. But it also states in the description: "Not for QV" (a 'S' is the US equivalent of a 'QV'), so I think you are out of luck. Maybe Di Fatta will come through. Or silicon tape.
For reference:
60578720 = LS or Q (24v)
60544488 = B or L (12v)
60547303 = S or QV (12v)
60594238 = Q4 (24v)
 

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But Mad North-Northwest
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Yeah, in a pinch self-fusing silicone tape will work as a fix. Or you can use Shoe-Goo or Goop adhesive on the outside surface, that works too.
 

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Too bad di Fatta didn't make one for the S/Q, or did they?

Jason (Alfissimo) does list one I think.
 

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Discussion Starter #19
Repaired the existing part with black silicon RTV and over-wrapped that with silicon tape. I have every confidence, that it’ll last a very long time.

Went for a test drive. May or may not have done my first burn-out with it, across an entire intersection. It seems to run better than ever, now that I’ve changed many of the tune-up parts. Wonder if I should do the plugs, too. It is a little bit of an oil-burner, so there’s that.

Thanks again!
 

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I was told by my mechanic Carlo that the factory told him that some 91S were unfortunately delivered with defective oil rings and thus they used lots of oil as compared to the other V6 engines, which seem to use none ( I guess some were covered by warranty, some were not). When he installed new oil rings, the problem went away.

My 91S uses a fair amount of oil, and he said that my 164 was one of those with the affliction (alas, far out of warrant by time I bought it used). He didn't really think I would have the car as long as I have ended up, so at the time after I reported the oil consumption, he said, ah, just add oil now and then, as you can use a lot of oil before you reach the cost of a ring install. Hah, I far outlasted that. That's life I guess..
 
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