DJet help bucking, stuttering

[vwbill]

Does your engine still have the valve adjustment sticker on the tins?? I can't remember if the 70 had .006 or had a different setting for the exhaust... For some reason I think one engine had either the cyl. 3 different or the exhaust set a .008 for one eng.????? I need my brother to look at his for you... I was watching the video again and you can almost count the beats and the miss or cycle. Did you pull the ignition wires at the dist. to see if it is one cylinder or a over all change? What about pulling the injector electrical plugs one at a time? My brother's car had one bad injector.... How does the car rev up and does the missing happen at higher revs?? Did the T3 have a different TPS? Could the throttle not be closing all the way or need setting?? Did the T3 have a Aux air value? Wonder if that could be leakin??

[raygreenwood]

After re-watching your video.....this is a classic submarining idle common to D-jet.

A recap...any small changes that cause a change in ignitionj advance, or in injected fuel...cause the engine to change the wya it produces power. This in turn very quickly...a split second...causes a change in vacuum signature...causing a worse or better problem. That changes teh signature again...causing a cascade.

To fully get this idle problem worked out on numerous other cars....I found it was a stack of very small things.
First...change that CHT.
Try unplugging the intake air temo sensor. Many D-jet cars run better with it unplugged depending on ambient temps...for about half the year. What it signals if it does run better is a slight imbalance in programmed fuel from the MPS.
Next.... You need to get a jewelers screwdriver and remove each injector terminal from their plugs. Test fit them on the male pins in the injector. They should fight tight. If not either replace them or slightly tighten them by squeezing them lightly with a small pair of pliers.

Just the vibration of the engine can make these terminals have poor connection at interemittent intervals....like when idle drops. Do the same for the three prong trigger point plug and the ground bundles on the case centerline. Ray

[akokarski]

Hi Ray,

Today I got the cht out to write down part#s

On the side 022
On the top
VW: 022 906 041
Bosch: 0 280 130 012

Checked resistance and it is 2570 ohm



Then I swapped TVS and attempted to adjust it. I installed original one and was not sure if I got the directions right. This one does not have poles just whiskers.



Please check if my understanding of adjustment instructions is correct.
(looking at the switch from the right) Hold the throttle closed and turn TVS counter clockwise till rearward contacts close and continuity on the top 2 contacts. Lock the sensor.

Cycle throttle full range and let it return to closed position by spring. Wiper on the contact grid should be making contact or close to making contact with the first line on enrichment grid and forward contacts are making contact. My wiper is making contact but forward contacts are not. Seems like I don't have this correct?

In short when throttle is closed, rearward contacts should be closed and forward open?
With slight opening, forward contacts should make contact before moving off the first line in the grid?

Should I still use my older switch or later with poles?

When I was checking for intake leaks I was using wd40.

My next steps should be
1) Tighten up connectors on the injectors and trigger points.
2) Get TVS adjusted
3) Replace CHT (I think I can get one from BUS Depot)
4) Try un-plugging intake temp sensor
5) Try new injector seals.
6) should I still try a different advance canister?


Bill, it's all .006" on the valves, yes I've tried pulling ignition wires and same reaction from all cylinders.

Thanks again!
Anton

[vwbill]

Sorry about thinkin the valve adj. was dif! Have you checked the aux. air regulator/valve? I wonder if you are leakin there and changin the vacuum signature! Ray has a Mod for that too! It's good to hear all the cylinders changed when you pulled the plug wires! Have you checked those little rubber "L" boots on the hoses? You are close then! Ray will get you there!! Don't change The TPS if the original checks out OHm wise! Just adjust. Don't want to change too many things with the Djet setup! You are getting all the settings right and checking working ranges! I think timing and valve adj. was a big thing with my car and the vac. can leaking and fuel pressure!! You'll get it just a pain dealin with the vacuum issues with the Djet!

[zooty]

Then I swapped TVS and attempted to adjust it. I installed original one and was not sure if I got the directions right. This one does not have poles just whiskers.

I have never seen the Enrichment-Contacts on German 1600e TPS's so make sure the belong to the D-Jet-Parts and noting is mixed up because of Type-4 D-Jet-Part's

[akokarski]

Hello,

It's been a while since any updates from my side. Today got some time in two weeks to get some tlc on fastback.

Got cylinder temp sensor replaced. It's bosch made in germany, came from CIP1.

Then I went through points and injector connectors. Got them squeezed a bit to fit nice and tight. Successfully broke one connector on #4, luckily local shop had a few connectors, so I horded them. Got 2 spare injector plugs and trigger point connector.

Pulled a plug on air temp sensor, seems to be better unplugged.

Still getting a bit of hiccup once in a while on light throttle and missfire when going from dead stop in 1st. Thinking I have my tvs adjusted wrong. Idle seems to be better once warmed up.

Still need to get TVS and MPS connectors tightened up.

I also have new boots for intake manifold and brand new injector seals that I am going to try to replace.


Thanks,
Anton

[raygreenwood]

Also, let me take a look in my books at the diagrams of the TVS switches. What you have in that picture is a very early style 4 pin swithc. They are the absolute worst in all respects. In "most" cases....a later 4 pin switch can be subsituted with no problems.

Also....there are a great many type 4 parts that are identical internally to type 3 so there is little worry about that. The only difference are cosmetic and wire plug angle...which are 100% interchangeable.

Also, I just helped someone else this weekend solve a timing related D-jet issue. I deal with this so much...sometimes I forget to explain to people just how critical proper distributor drive position is with D-jet. I will be working on a full report and diagram this week. It can cause some of your problems.

Ray

[akokarski]

Thank you Ray!

I am looking forward to diagram. I do have 2 spare later TVS.

Anton

[raygreenwood]

Also.....I am working on a timing primer. I just realized last night that I took care of my timing issues so long ago...that I forget that this is very necessary...and that a huge portion of those with D-jet drivability problems are actually suffering from injection timing issues.

For example...if the installation of your distributor drive pinion is not spot on...meaning you cannot be 1 tooth off in either direction and correct for it at the distributor. It must be spot on from the start for D-jet
There are 12 teeth on a type 4 pinion. I "think" there are 12 on type 1 and 3 as well. Each one works out to 30* for each tooth. I think the crank drive reduction being 1/2 means about 15* for each tooth....which is why the book shows a +/- of 12* because the tooth and helix itself spans 3* of arc.

Bear in mind that once the cam and crank are meshed together...short of catastrope....they are alwasy meshed in time. This means that valve opening point is meshed to crank permanently. With me so far?

So the factory tells you to install that drive pinion within a 12* arc from teh case centerline...in the book...right?. That means they want it in a specifc place....within 12* is one tooth. 1 Tooth off is within a 24* span...incorrect.

Why?...because the valve timing is locked between crank and cam. And.....the drive pinion must be locked to the cam accurately to keep the distributor timing locked in proper arc sequence to the cam...which controls the valves....timed to piston position. With me so far?

But....the wild card here is that your injection timing start point....the trigger points...is locked in a fixed position to the distributor body.

So....if your distributor drive pinion is out of time by even one tooth...you will have to adjust the distributor body position to get your ignition timing set right....but...since the injection timing is critical to intake valve opening point....moving the distributor body to compensate for improper drive pinion mesh....moves the injection trigger point location away from proper mesh point with intake valve timing.

This is why D-jet factory literature is specific about ignition timing and drive pinion position.
Your drive pinion must be installed spot on at known exact TDC. Also...your ignition timing must be set at the exact factory point and correct rpm and vacuum condition...or the resulting variation you use to correct your ignition timing...will change your injection timing.

It can stand a small amount of variation...no problem...with adjustment of ignition timing...maybe 5-8*.....but only if your drive pinion is installed spot on. If the drive pinion is off...say one tooth....just setting ignition timing to exact factory spec will mean that your injection timing is now a bare minimum of 12*. Variations in timing rpm and distributor wear...can increase that by another 5-10* or more....causing very strange running, poor combustion efficiency and really poor tunability because it screws with vaccum signature....and that screws with fuel pressure stability.

Also bear this in mind: If you have a type 4 and are running a web # 73 or Raby 9550....those both sue the earlier valve timing code from the V series. That changes your ignition timing slightly. That measn that when you compensate for this....your injection timing will be slightly off...if you are using a late distributor (71 and on) for 411 and 914.
If you use a pertronix module...that also changes your ignition timing....and further messes with your injection timing when you compensate.

A fix for this is to slot the breaker plate on the trigger points so you can mark it for stock position...and then retard or advance injection timng for best running and fuel pressure stability as your ignition timing is modified. Ray

[akokarski]

Looks like I should have some time on my hands soon (knock on wood). Going to pull distributor to check on the pinion position. I've tried readjusting tvs. Seemed like it was better wasn't bucking as much, but after 3 days went back to square one.

I understand points on timing and everything else that's been mentioned before. What makes it frustrating is it will run fairly well and then start acting up.

Anton

[raygreenwood]

Bear in mind.....the TVS will have no effect on anything the engine does...unless the throttle is moving. So...if you are idling...foot off throttle...and it starts acting up...its not TVS. If you are running at hwy speed.....and are in mid-acdleration...say..meaning throttle is floored or in known forward motion.....and it misfires...its probably not the MPS unless you have one bad track that is running over.
Its when you are crusing at hwy speed with very narrow throttle angle....just feathering it...and it appears to misfire that it can definately be the TVS. Ray

[Piledriver]

OT, Ray, you have a PM.

[akokarski]

Hi Ray,

So what you are saying that it's probably not TVS?

It acts up on light throttle, when it does that if I push harder, I can get out of misfire. Sometimes it takes more throttle and sometimes not so much. It does misfire at cruse, but all of this is not consistent.

Thanks,
Anton

[raygreenwood]

Hi Ray,

So what you are saying that it's probably not TVS?

It acts up on light throttle, when it does that if I push harder, I can get out of misfire. Sometimes it takes more throttle and sometimes not so much. It does misfire at cruse, but all of this is not consistent.

Thanks,
Anton

Ok....very good diagnostic information! That right there very well can be the TVS. Thatcan happen in either earlier models like yours...but is more prevalent in late model TVS.
What can cause that is this:

You have the rearward switch which is essentially telling your ECU the throttle is clsoed and TVS is parked. You have the foward switch that is allowing the ECU to be connected to the enrichment wiper/contact strip.
In a perfect world....in less than 2* of movement (preferably about 1*).....the rearward switch should break contact....the forward switch should make contact....and simultaneously upon making contact ....your wiper switch arm should be on a metal finger in the wiper strip so you get immediate enrichment.

If the arms get bent or for some reason the switch contacts get worn......or you have a bit to much slack in the floating plastic collet that mounts to the shaft...you can have a degree or so of slop at at light throttle....where the switch carrier floats back and forth between cut off and cut on.

The normal short term fix for this in the books...is to give it one mor egraduation on the marking plate (2*)...that preloads the unit a bit forward. What this assumes is that the problem is simply the location geometry of the wiper strip to the wiper arm and that moving an extra garduation will put the wiper contact in the right position.

However...if its the switchs or contacts worn or bent....or a sloppy shaft collet....no amount of movement will fix it. Ray

[akokarski]

Hi Ray,

Does this mean I should be looking for another tvs, or should I continue to play with mine and see if I can get it to function better?

Thanks,
Anton