[Vintre]

Hello All,

I was wondering if there is a difference between a Series 3 and Series 4 VVT?

The VVT on my Series 4 came loose and I lost it on a drive. I replaced it and I can see the new one engage but I was just wondering if there is a difference and would a Series 3 work in a Series 4?

Thanks,

Vin

 

[Tifosi]

AFAIK, there is no difference in the VVT systems between S3 and S4.

Cam profile mabe, but the advance range and such is very much likely the same, and certainly the soilinoid and bit of harness that connects to it is. Even the mounting block is the same part. (there might be a different trigger signal source though, like S3 is on the TPS while S4 may be on the ECU)

The most drastic difference you'd find would be from the early S3's where the VVT was inertia controlled. (range of advance would be the same, but method of getting it to advance is completely mechanical)

Short answer:

The solinoid and mount are the same and interchangable.

 

[andy303]

Vin:
Just curious: how the heck did it come off?? Its held on with three bolts. Not to mention the harness connector. I would think it would have made a hell of racket when it encountered the drive belts.

 

[Elio Comello]

Hi Darren,
Re VVT and ECU.
In late 84 early 85 the S3 Spider went to solenoid activated VVT.
The Bosch FI ECU changed from 0 280 000 206 (gold tag) to 0 280 000 221 (green tag)
The "new" ECU circuitry was modified to drive the VVT solenoid.
The literature says that the VVT is driven by the TPS. If you look at Papajams circuit diagram for the 86 Spider you will see that the FI ECU also plays a role. To me it looks like the ECU can activate the VVT and/or by the TPS.
Alfa was not very clear on explaining the functional logic of the ECU's both Ignition and FI.
The early FI ECU (206) will work in place of the later (221), but you lose the ability of the ECU logic to activate the VVT outside the TPS.

This info was in the Alfa Romeo Digest Archive posted by Michael at APE in April 2003.

I purchased a spare ECU for my 87 Quad and when the numbers were different (206, not 221) I began to ask why? I found that the ECU worked, but VVT activation took place only from TPS position. Logic will tell you that the VVT activation is often needed before a fixed TPS position is reached, like cruising...
I offer this just for information and discussion.

TTFN Elio

 

[Tifosi]

The solinoid is the same throughout though, correct? (that was the OP's oiriginal question)

Regarding the VVT going active via ECU activation while in a cruise state, my own logic says 'no, it shouldn't because it would mess with closed loop control/function' (running the cam in 'hot mode' while trying to maintain closed loop/econo/low emission mode doesn't make sense to me)

Cruising is just that: little loading, steady state throttle.

Now perhaps the ECU could/would need to activate it during that steady state cruise if the ICU detected more load on the engine (steep upgrade?) and told the ECU that it needed the engine to output more grunt/cam and a richer fuel mix to keep up with the different ignition timing relevant to that extra load without having to move the pedal much if at all. (dependant on how 'smart' the mapping actually is to know the difference of course)

That in turn would likely also drop the ECU out of closed loop.

 

[Elio Comello]

Good thoughts Darren.
The VVT solenoid is a two wire device. The "cap" or "plug" that goues on it is a three wire device. Its like a photo diode isolated "trigger" solenoid.

There is very little out there that discribes in detail the functional logic map and any "crosstalk" of info between the Injection and the Ignition ECU's.

Some logic must come to play to actuate the VVT from either the TPS and/or the FI ECU.

Yes you are right, I kinda was hijacking Vincenzo's thread.....To the best of my knowledge the VVT solenoid and VVT solenoid "trigger" are the same in the late S3 and S4.

BTW, if the VVT solenoid/trigger fell out because of a failed rubber isolation bushing. A fix was posted by P. Cordona in Alb. NM (can't remember his ABBhandle) who replaced it with a machined brass collar he designed.

TTFN Elio

 

[WopJob]

Not to hijack the thread even further, I think that Vin got the answer. I was wondering if there are any electronics engineers in this board that can come up with a simple circuit to light up an LED when the VVT solenoid triggers (otherwise how do you know that it's really working FROM INSIDE THE CAR WHILE DRIVING). I tried putting a resistor/LED combination in parallel with the solenoid but obviously that does not work.

 

[Joe Papa Sr]

do these aav's really make a difference, I mean, can one really notice the alfa with one vs without one?

Joe

 

[Vintre]

Vin:
Just curious: how the heck did it come off?? Its held on with three bolts. Not to mention the harness connector. I would think it would have made a hell of racket when it encountered the drive belts.

Andy,

Just the VVT itself came loose not the aluminum housing or your right, that would have been a noise.

The original VVT are held in with some kind of adhesive and over the years, it becomes gooey for lack of a technical term.

When I opened the hood that night, all was left was the aluminum housing and the 2 wires!

V

 

[WopJob]

Joe, my question exactly. When I did the test of the AAV as specified in the L-Jet troubleshooting guide it seemed to me that the AAV triggered to high in the gas pedal travel, more that I think I drive my car (seldom past 4K RPM) hence wanting to have a light to tell me exactly when the AAV was triggering.

 

[Elio Comello]

You are confusing AAV and VVT Wopjob.

Vincenzo. I have a drawing and an actual machined sample of the brass bushing to replace the "goey"
There has been several threads on the rubber bushing turning to goo.

let me know if either the dimensioned engineering drawing or the sample is useful to you. Will send for the price of postage or will scan dwg and post free.

Ciao Vince.....Elio

 

[Tifosi]

do these VVT'S really make a difference, I mean, can one really notice the alfa with one vs without one?

Definitely, particularly in the mid to upper RPM band, though there is a increase in torque down low too, so it's kind of an 'all round' enhancement.

it seemed to me that the VVT triggered to high in the gas pedal travel, more that I think I drive my car (seldom past 4K RPM) hence wanting to have a light to tell me exactly when the AAV was triggering.

If the is TPS set properly, 56+ degrees deflection of the TPS, regardless of the RPM at the current time. (RPM has little to nothing to do with it in other words. EG: pulling away from a dead stop with more than 1/2 a pedal is enough to kick it. So will rapping the throttle while sitting there in neutral, or even with the key on and the engine off)

I did a LED with resistor on mine for a period of time by connecting to the + side of the solinoid harness and taking the other side to ground.

With the resisitor in-circut, the 'short' is so small that it doesn't effect the operation of the solinoid proper.

BTW, papajam discovered that the harness puts around 8 volts to the solinoid, not 12 like one would expect. This would have great bearing on the type of resistor used in an LED setup.

As to 'needing' a light to see when it's on, kinda useless actually as you can indeed feel he difference when it's not on vs if it is, and if it tests as functional per the given means of doing said tests, then it's working the way it should and having an indicator light ends up being more so much fluff rather than anything useful.

A periodic check of function, like during oil changes or something, is more than adiquate to let you know things are going right.

If the idea behind adding a light is to try and get better economy by keeping the engine out of the VVT, then adding an econobox to to the private car collection would be much more sensible than adding a light to the VVT so one could avoid using it.

There is very little out there that discribes in detail the functional logic map and any "crosstalk" of info between the Injection and the Ignition ECU's.

I fully agree with that. Knowing exactly what the magic (or logic ) behind it is would be great.

Perhaps a VW or Volvo mechanic from back in that era would have an idea. (presuming they got more information in general than Alfa mechs)

 

[WopJob]

You are confusing AAV and VVT Wopjob.

Vincenzo. I have a drawing and an actual machined sample of the brass bushing to replace the "goey"
There has been several threads on the rubber bushing turning to goo.

let me know if either the dimensioned engineering drawing or the sample is useful to you. Will send for the price of postage or will scan dwg and post free.

Ciao Vince.....Elio

Holy Cow. I did confuse the AVV with the VVT. boy is my face Ferrari Red.!!!
SOrry I willnot interject with any B posts on a Friday anymore. THank Elio you are the voice of reason. I hope I didn't screw up the whole thread. My apologies.

 

[Joe Papa Sr]

Im getting the creeps, you guys.....In post #8, I mistakenly said aav, instead of VVT, but when tifosi posted a quote from me, in post #12, the quote said "VVT". Whats going on here guys???

Im geting the spooks too early for Halloween!!!!!!!!!

I swear, I mean, LOOK AT IT!! Someone above understood my error, and when Tif quoted it, The up above guy fixed it , like an angel or something........

 

[Tifosi]

I changed it from aav to VVT in yours and WopJobs quoted text before posting my response

 

[Vintre]

You are confusing AAV and VVT Wopjob.

Vincenzo. I have a drawing and an actual machined sample of the brass bushing to replace the "goey"
There has been several threads on the rubber bushing turning to goo.

let me know if either the dimensioned engineering drawing or the sample is useful to you. Will send for the price of postage or will scan dwg and post free.

Ciao Vince.....Elio

Ciao Compare Comello,

As soon as I saw that brass bushing I bought one!

Ciao,

Vincenzo

 

[Vintre]

harness?

One more thing is that on my '87 Quad there was a plastic housing that connected the wires to the VVT but my '91 doesnt have the housing.

Can someone confirm for me that the series 4 DO NOT use a housing?

What I have is 2 separate wires connected directly to the VVT.

Thanks,

Vin

 

[Elio Comello]

Darren, I always thought you were spooky! LOL

Ciao, Elio

ps: Darren, there are some clues in Bosch Fuel Injection & Engine Management by Charles O Probst, but not many.

 

[Tifosi]

One more thing is that on my '87 Quad there was a plastic housing that connected the wires to the VVT but my '91 doesnt have the housing.

Can someone confirm for me that the series 4 DO NOT use a housing?

I think Murray (msiert) has the housing on the intake cam of his S4, but I could be mistaken, and am actually too lazy to look it up right now LOL

(mayhaps a browse through the picture subsection in the 'post a pic of your engine' thread might yield some results also)


@ Elio:

I'll have to take a peeksee into that as you've gotten me curious.

I've got a couple books that touch on the L-jet, but nothing to any really deep direct degree.

 

[Joe Papa Sr]

I changed it from aav to VVT in yours and WopJobs quoted text before posting my response

OK, that explains it.....no ghouls/ghosts here. Thanks, Darren.