Boost enrichment question

[jtanguay]

I just bought a 92 Jetta TD, and I've owned an older '86 Jetta TD.

On the older one when I revved the engine the rpm's exploded when they reached a certain point (I'm assuming thats the boost enrichment kicking in).

Now on my 92, I can bring the car up to 3k rpm without the boost enrichment coming on.  Is that normal?  The motor has some really good power, but I'm not noticing the boost enrichment coming on(that extra kick after the turbo spools up).  Any way of checking this? How easy is it to increase the boost enrichment?

Another question.  The motor has been replaced, and I do not know if it is the 1.9 or the 1.6.  The turbo comes on at around 1800 rpm and is fully spooled at around 1900-2000.   My 86 had to be around 2200 or more for it to come on.  It has the same intake as the 1.6 I had, but different looking pump.  Any quick and easy way of checking whether or not its a 1.9 other than crawling under it and reading the block?

thanks guys

[QuickTD]

It sounds like your old engine was on the verge of runaway. This occurs when the engine begins to fuel itself with its own blowby gasses/oil mist. The boost enrichment system is pretty linear. It begins to actuate with only a couple of psi boost, you won't usually notice any sudden, sharp increase in power as boost comes up.

Any quick and easy way of checking whether or not its a 1.9 other than crawling under it and reading the block?

A 1.9 will have 3 bolts down the center of the valve cover and none around the outside. The 1.6 has 8 bolts around the outside edge of the valve cover and none in the middle.

[fspGTD]

I know exactly what you're talking about... revving the engine in neutral, a few hundred RPM above idle, pressing your foot down on the throttle just a little bit more causes the RPMs to drastically increase.  Or in other words, the governor stops decreasing fuel quantity as RPM increases.  Since this characteristic exists under no load conditions, IE: revving the engine in neutral, it has nothing to do with your LDA.  The LDA can only make a difference under max fueling condition (IE: when engine is loaded and you are briskly accelerating...)

What I believe is happening is that when the idling spring of the governor reaches a fully collapsed state, if it is set up so that the intermediate spring doesn't yet start to collapse, then there will be an RPM/load area where the governor will not be responsive to a change in RPM.  Hence, engine RPMs will respond very wildly to very small changes to throttle position.

Given how many different versions (part numbers) of these pumps there are, you shouldn't expect any two to behave the same unless their part numbers match.  It doesn't necessarily mean one is broken or not working right if their governor characteristics are noticeably different.

[dieseltech]

the 92 is a eco diesel. it wont have that kick. there is ne extra fuel added with the boost.   change the pump over to a td pump, you will have much better results

[jtanguay]

thanks guys.  

I was wondering if the '92 was an eco diesel.  It does have the the line coming from the turbo to the top of the pump though, same as my '86.  Can it still be an eco with this line?  You also have to take into consideration that the engine was replaced.  

I checked, and the engine has the 8 bolts on the head cover, so it is the 1.6 litre engine.  I'm just so impressed with the amount of power the engine has compared to my old one.  I feel like my old engine had 1.3 litres  :lol:

[91 ECO]

If it's an eco engine, you will not have the LDA on top of the injection pump.  I wouldn't think that you would be impressed by the power of an eco.  They accelerate just like a non turbo.

[jtanguay]

It looks to have the LDA like my '86 Jetta  (with hose coming from compressor housing)

The main reason I am so impressed with the power is that my old jetta had some major turbo lag (seemed to take forever to spool up and power to kick in)  

The 92 jetta has nearly full boost just going into 2k rpm and is pretty peppy (good compression I suppose)