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 A VVT question
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benny_toe




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224 posts [99%]
Seattle WA

 A VVT question Reply  Edit


Am building a Locost (Lotus 7 replica) with a Silver top with MS2 V3 PCB and EDIS.
When we first got the engine started and running it would not take throttle input of above about 30%. Would miss, pop,and bang. I had set the VVT to come on at 4,400 RPM but mistakenly thought I limited it at 8,000 but apparently it was not getting turned off once it was turned on.

Got that straightened out, got a wide band O2 sensor and had it running pretty darn good. Idle was good, throttle response was good, VVT was kicking in at the right time AND was turning off when it should. Life was good.

Then I moved from Omaha to Seattle, build progress got side lined for a couple of months. Picking up where I left off I fire it up and now it's acting just like it did when the VVT was screwed up. I disconnected the the sensor but it is still acting the same. Can the valve hang up somehow? Could something else cause this kind of behavior? AFR looks good when it isn't missing, super lean when it is.

Any help would of course be greatly appreciated.

Larry
mbnlwj3@gmail.com




rick q




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60 posts [100%]
Sunshine Coast Qld

 Re: A VVT question (benny_toe) » Reply  Edit


Larry,

If you take the plug off the VVT solenoid, you can put 12V straight onto it to turn it on and off and listen for any change in engine note. Do it at a fast idle - say up to 2000rpm. That'll tell you whether it's doing anything at all, just by the change in engine note.

The VVT solenoid is just an oil valve - you can also pull it out and switch 12V through it and watch whether the inner part moves if you can't hear in working in the step above.

7's with Silvertops in them are brilliant - enjoy it!!.

benny_toe




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224 posts [99%]
Seattle WA

 Re: A VVT question (rick q) » Reply  Edit


Thanks Rick,


I was thinking along those lines and having it verified is reassuring. But if it does cycle then he problem lies else where. Will find out.

Have gotten a little time in the car before it went bad. Was a blast.
Real close to getting it inspected and licensed here in WA.state and really looking forward to spending some time in it. Also have spent some time in the passenger seat of Graham Earley's Leitch. That's a nice car!



Larry
mbnlwj3@gmail.com
rick q




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60 posts [100%]
Sunshine Coast Qld

 Re: A VVT question (benny_toe) » Reply  Edit


Like the Leitch, mine is also from NZ - a Fraser [http://www.fraser.co.nz/].

Absolutely the most fun you can have with your clothes on!

yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: A VVT question (benny_toe) » Reply  Edit


The VVT should be activated around 2000 RPM and deactivated around 6K.
I forget the exact numbers stock and ideally you want to tune it on a dyno to get the ideal points.



http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
benny_toe




Offline

224 posts [99%]
Seattle WA

 Re: A VVT question (rick q) » Reply  Edit


Hi Rick,

The Fraser looks like an awesome ride! You guys in the Southern Hemisphere seem to have a lot more options then we stateside have and I"m jealous! Did you build yours from a ki t? And if so, did you do any photo documentation? Again if so, I would love to see it.

I hooked up power to the solenoid and it clicks. Not very loud but you can hear it. I tried to pull it off the engine but it won't come out of the hole. Took the bolts out and it turns but it is stuck in there pretty damn tight. Is there more to removing it than the 2 bolts? I would like to take a look at it. Want to see it work not just hear a faint click.

As for turning it on at 2K revs that is contrary to everything else I have read and been told. More like 4,400.



Larry
mbnlwj3@gmail.com
yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: A VVT question (benny_toe) » Reply  Edit


Quote, originally posted by benny_toe »
Hi Rick,

As for turning it on at 2K revs that is contrary to everything else I have read and been told. More like 4,400.


http://s-86.com/s-vvt.html
There is also a thread on here somewehre that has a lot of good info in it but I can't find it.
A lot of people get confused becasue they think VVT is like VTEC and should be activated high in the rev range. VVT activated is actually for mid to low RPM and is turned off at higher RPM.
There is a lot of misinformation out there about VVT and it can be easy to become confused on it's operation.

Quote »
Under normal conditions the VVT solenoid is not normally activated till approximetely 2000RPM. If activated at idle the revs will drop and the engine will run rougher.

To determine the right points to turn the VVT solenoid on and off two dyno runs are needed; one with the solenoid locked on and vice-versa. Then with both power charts overlapped on top of each other the highest peaks are chosen of each of the two curves. As a guide the VVT will be turned on early in the rev range off at approximately 6000RPM. These figures are almost always different between engines due to their different combination of parts.





http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
rick q




Offline

60 posts [100%]
Sunshine Coast Qld

 Re: A VVT question (benny_toe) » Reply  Edit


Larry

If you've taken out the two bolts and it turns, you're almost there. GENTLY prise it away from the head as you twist it back and forth - it'll come out, followed by some oil. If you look into the end of it when it's out you'll see the centre part clicking in and out as you apply the 12V - watch for oil drops flying out into your eyes [ask me how I know]

I was going to build the Fraser but they got a bit too dear - and the one I bought pre-loved was meticulously constructed by an Aircraft engineer who certainly did a better job than I ever could!

I presume you're on LocostUSA and Locostbuilders? Our Australian site is http://www.ozclubbies.com.au/ [I'm a mod there] but you have to register to get in.

benny_toe




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224 posts [99%]
Seattle WA

 Re: A VVT question (rick q) » Reply  Edit


Rick,

I was reluctant to pry on it not knowing for sure whether or not there might be another fastener somewhere. But now I'm just not sure what might be the problem. The solenoid clicks but from what I have read it could be the cam gear itself. Someone suggested a vacuum leak. I did try to start it some time ago with rubber balls in the velocity stacks. Cranked a bit before I realized what I had done. Had to pry the balls out with a screwdriver!

Just one of the things that happened about the time it started doing the missing and banging.

I am a LocostUSA member, although not a regular contributor. Locostbuilders is one I'm not familiar with. Tonight I registered on the Ozclubbie sight. What do search to see your Fraser? I was pretty impressed by their web presentation. Car really looks good. You seem well pleased with yours ;<)

Mr. Scott,

Thanks for the link. Very interesting site. I did some looking around and Bill Sherwood, the first 4AGE authority I encountered, says the early 20V were using RPM to trigger the VVT. To quote 'The VVT comes in three types for the 20 valve. To the best of my knowledge, silvertop 20v's pre May 1993 have the VVT actuate at about 4400rpm.' Later versions use various meens. The black tops seem to have the most interesting triggers including MAP, temp, TPS, etc. RPM aren't even considered.

I do know that when my engine was running the way I thought it should I had the VVT kicking in at 4,400 and you could tell when it turned on. It was almost like a turbo spooling up. A real kick in the pants.



Larry
mbnlwj3@gmail.com
yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: A VVT question (benny_toe) » Reply  Edit


Quote, originally posted by benny_toe »
Rick,

Thanks for the link. Very interesting site. I did some looking around and Bill Sherwood, the first 4AGE authority I encountered, says the early 20V were using RPM to trigger the VVT. To quote 'The VVT comes in three types for the 20 valve. To the best of my knowledge, silvertop 20v's pre May 1993 have the VVT actuate at about 4400rpm.' Later versions use various meens. The black tops seem to have the most interesting triggers including MAP, temp, TPS, etc. RPM aren't even considered.

I do know that when my engine was running the way I thought it should I had the VVT kicking in at 4,400 and you could tell when it turned on. It was almost like a turbo spooling up. A real kick in the pants.

This is from Billzilla on the blacktop.

Quote »
Engine rpm. VVT will operate in any rpm between the range of 1500 and 7200 when the inlet manifold pressure is right. The min and max range can be a little out because I was reading from the car tacho. Trust me they are very close.

So you can see the BT does look at RPM and is disabled close to redline.
I do not know how he determined the operation of the silvertops and although there is a ton of good information on his site I always take it with a grain of salt. I have seen things that are outdated or just plain not 100% accurate. That said I have not personally studied the OEM systems to determine how they work. I have however studied the theory behind the systems and how they should work.
Toyota may have decided to control them how they did because it was cheaper and good enough or for some other reason we don't know. More important than how the OEM system functions is how an ideal system should function.

Now early VVT doesn't change lift or duration so we don't look at it like running different cam profiles. It's essentially just like having an active adjustable cam gear that can change while the enging is running.
Now overlap is good for high RPM but the valve closing later is more important. This is why if you are choosing a cam for high RPM you will choose a longer duration. If you are taking an existing cam and trying to move the powerband higher you will retard the cam.
Like I said to really optimize the system you would want to do a dyno pull with the vvt on and one with it off then use the points where the pulls overlap to set your activation and deactivation.

Short of that setting it to come on around 2k and shut off around 6500 will get you pretty close.
If you can feel it activate or deactivate you are loosing power in portions of the curve.
If you can feel it hit at 4400 it should be opening much sooner because you would be making more power below that with it activated. If it's at the right RPM there will be no power change as it switches. Same thing applies if you felt a hit of power when it deactivated in the higher RPM. This means you need to move the switch off point down a little bit.

I haven't found the thread on here yet but here's my thread on the MR2OC as I was trying to figure it out myself and wade through all the misinformation out there.
http://www.mr2oc.com/showthrea...pp=20




http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
benny_toe




Offline

224 posts [99%]
Seattle WA

 Re: A VVT question (yoshimitsuspeed) » Reply  Edit


[quote=yoshimitsuspeed]


Short of that setting it to come on around 2k and shut off around 6500 will get you pretty close.
If you can feel it activate or deactivate you are loosing power in portions of the curve.
If you can feel it hit at 4400 it should be opening much sooner because you would be making more power below that with it activated. If it's at the right RPM there will be no power change as it switches. Same thing applies if you felt a hit of power when it deactivated in the higher RPM. This means you need to move the switch off point down a little bit.


That is quite logical. I have a dyno session coming up and we will definitely set the VVT on/off where it does the most good.

Tried your link to the MR2 board. Had to register and now wait until I get permission to view your write up. Anxious to read it.



Larry
mbnlwj3@gmail.com
rick q




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60 posts [100%]
Sunshine Coast Qld

 Re: A VVT question (benny_toe) » Reply  Edit


But now I'm just not sure what might be the problem

If it clicks, that's a good sign. If the engine note changes when you put 12V across it [with the engine at 1500 - 200 'ish], then everything there is also fine and dandy as the change in cam timing changes the engine note.

So if that all ticks off ok - any problem you have is likely to be somewhere else.

a minimum of 2 dyno runs [VVT off and VVT on] will show you where to switch it [where the two curves cross]. FWIW, mine comes on at 2500 'ish and stays on to the redline.

yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: A VVT question (rick q) » Reply  Edit


Really?
Do you have your dyno runs that show this? I would be very interested to see them.



http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
rick q




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60 posts [100%]
Sunshine Coast Qld

 Re: A VVT question (yoshimitsuspeed) » Reply  Edit


Can't help you with mine unfortunately - it was all done on the laptop screen while it was on the dyno.
benny_toe




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224 posts [99%]
Seattle WA

 Re: A VVT question (rick q) » Reply  Edit


Didn't try to pry the solenoid out of it's hole but did set it at 2,000 RPM and connected the wires to the spades in the connector and the engine dropped 200 RPMs. So the VVT is working. That's good/bad news. Good because finding a replacement solenoid would have been tough and the cam gear is expensive if you can find one. Bad because now I have to try to trace down why my engine is running so crappy and I"m not sure where to start. It has been suggested that I might have picked up a vacuum leak. I did try to start it one night with racquet balls in the T3 velocity stacks. Not just a quick spin before I realized what a monstrous cock up I was doing, but I cranked it for at least 30 seconds. So perhaps I did break the seal on the intake manifold.

What do you think?



Larry
mbnlwj3@gmail.com
yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: A VVT question (benny_toe) » Reply  Edit


I think if it's showing lean when it does this you should look at fuel.
Just to cover bases I'd do a compression check. Next when it's running bad I would pull one plug wire at a time and see how much the idle drops then plug it in and move to the next one. If the idle drops less or not at all on one cyl that's where your problem is be it fuel, compression or spark. If it's the same across the board then your problem is effecting all cylinders.



http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
benny_toe




Offline

224 posts [99%]
Seattle WA

 Re: A VVT question (yoshimitsuspeed) » Reply  Edit


According to the AFR gauge it goes so lean you would think there was no fuel at all in there. Sensor is just aft of the 4 into 1 collector. When it smooths out (and it does occasionally for a brief moment) gauge reads between 13 to 15.

'when it's running bad' would be all the time. Only thing it does reasonably well is idle. I don't have a compression gauge but can probably come up with one. Pulling the plug wires one at a time is a very good suggestion. Embarrassed I didn't think of it.

Thanks for your input. Need all I can get.



Larry
mbnlwj3@gmail.com
benny_toe




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224 posts [99%]
Seattle WA

 Re: A VVT question (benny_toe) » Reply  Edit


Checked cam timing. They line up as they should. Got a compression tester. All cylinders are within 4 lbs. of 130. Sprayed ether all around the manifold when it was idling and no increase in idle speed. Did the plug wire test and it passed, idle speed dropped the same on each cylinder. The VVT control valve clicks on and off.

I thought I heard a 'rattle' in the intake cam gear but not sure. Lot of noise when it's running.

Could the injectors be damaged by the high volume of vacuum I subjected them to when I tried to start with the TBs sealed?



Larry
mbnlwj3@gmail.com
yoshimitsuspeed
Member

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286 posts [100%]
Carbondale Co

 Re: A VVT question (benny_toe) » Reply  Edit


So much has happened in this thread I think it would help me for a simple rehash of what exactly it's doing.

What are AFRs at idle?
Is it still doing it over 30% throttle or what exactly is it doing. How does it run at WOT?What do the AFRs look like at WOT through the RPM range?

I havent read this thread in a while so I may rehash some things here.
\If this is only happening at mid throttle I would most suspect the 02 sensor.
Have you done all the 02 sensor tests? Does your wideband have the ability to emulate a NB? If so you might hook it's NB output up to the 02 input on the ECU and see what it does.
My car had closed loop AFR issues for a long time. It would be fine most the time then suddenly drop really rich or really lean. I replaced the 02 with 2 brand new ones. Neither fixed the problem. I got an LC1 and emulated the NB and never had a problem since. Due to the fact the problem persisted over a couple sensors I suspect it was some sort of noise or short or something that was causing the problem. After too may hours trying to diagnose it I decided I'd rather emulate it anyway.

If it's not 02 then my next thought would be AFM or TPS. It may be that the potentiometer may be glitched somewhere and causing bad readings in an area of it's travel.
Do all the BGB tests for TPS and for AFM. There are two different sections for on car tests and off car tests. The on car tests check for voltage going into the ECU. These are the best tests. The off car tests measure the resistance between terminals these can also be helpful.
Also when checking voltage or resistance across the potentiomiters do a slow smooth sweep from closed to all the way open. It should read nice and linear on the meter. If you see any big jumps or weird readings it's likely you found your problem.






http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
yoshimitsuspeed
Member

Offline

286 posts [100%]
Carbondale Co

 Re: A VVT question (yoshimitsuspeed) » Reply  Edit


Damn I forgot you were on MS.
Sometimes I hate this thread layout where you can only see one post while you are posting.
Anyway if you are running TPS and AFM the same tests would apply to both.
You could also watch them in tunerstudio or whatever you use as you move them through their range of motion. This should make visible any bad spots in the potentiometer easier than a gauge.
Also are you using a NB or WB for the MS to adjust fuel?

Have you posted this in the MS forums to see if it's an issue with the MS?
Sorry for not reading through the thread better tonight but I'm too pooped to make it through the whole thing.




http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
yoshimitsuspeed
Member

Offline

286 posts [100%]
Carbondale Co

 Re: A VVT question (yoshimitsuspeed) » Reply  Edit


The one thing that is really suspicios is your compression test. It's a really good sign they came in so close together but unless you are running supercharged pistons that is crazy low.
I don't know what the ST should be but the BT should be near 200 PSI. I am at 8000 feet and my BT still hits 160 PSI. Now maybe your gauge is bad. Or maybe you live at 12000 feet but something seems fishy to me.



http://matrixgarage.com/
AW11
E51
Blacktop, all stock internals
4AGZE ECU, 3SGTE AFM, 4runner coil, DSM T25, 1JZ 380CC injectors, W2A IC
benny_toe




Offline

224 posts [99%]
Seattle WA

 Re: A VVT question (yoshimitsuspeed) » Reply  Edit


I'm running MAP and not an AFM. The TPS could be suspect. And after reading some of the BGB (big green book? Really? I didn't know anything about it. I do now and that's a good thing!)

I didn't do the compression test the way they say to do it. Mine was on a cold engine with the throttle closed. May make a difference to do it right. Oh and the tester gauge is Harbor Freight that a friend gave me after using it on his MG TF.
Oh and I live at about 50' above sea level. Slightly down hill for about 2 miles to Richmond Beach on the Puget Sound coast. The sound and the Pacific are the same level. When we set up the MS I was in Omaha, about 1,200' elevation.

Didn't get a chance to get out in the garage today but will tomorrow. Tuner Studio has a TPS gauge so I can test that. I do have a multimeter but I don't like it much. Radio Shack crap. Difficult to use.

I have never had much luck finding anything I searched for on the MS forums. Again, probably was doing it wrong.

Many thanks for your time and great comments. Will get this thing going again.




Larry
mbnlwj3@gmail.com
benny_toe




Offline

224 posts [99%]
Seattle WA

 Re: A VVT question (benny_toe) » Reply  Edit


TaDa!

I had totally forgotten that I was 'playing' with some settings with Tuners Studio. Thought it wouldn't have any effect on ow it ran.

I set the 'ACCEL/ENRICH' to 50% MAP nad 50% TPS. Apparently there are things about the MAP that I really don't understand.

Set it back to all TPS and the problem went away Running a little rich but runs, revs, idles, and has good power.

Rick, I was looking more at the Fraser. Down loaded their brochure. That's a VERY nice car.

Larry



Larry
mbnlwj3@gmail.com
 



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