Lost power on vnt15 1.6td?

[hamradio]

So,


I had an issue with surging and vibration.  I didn't have the mounting bolt on the end of the pump, by the dipstick, in place.  With the help of the dieselparts forum, it no longer vibrates and surges (the bolt was the cause).

However, the car seems to be a lot slower.  Before, the boost would hit hard at roughly 2000 rpm, and the car would pull very nicely.  That feeling is gone. 


I decided to open up the LDA last night.  Everything looked fine.  I adjusted the pin for more fuel, and it didn't help.  I have the fuel screw cranked in about as far as it will go while keeping an idle.  I'm only seeing egt's of about 500.  I'm running about 15 psi, and 1.05mm for timing.  I did notice that with the boost pin out, I had to move the throttle lever to nearly wide open for the little pin at the bottom of the hole to emerge.  Is that normal?  It doesn't seem right...that would mean the LDA is only effective at almost wide open throttle? 


I'm wondering if some linkage inside is sticky or something, and when it would vibrate like crazy with the bolt missing, it vibrated stuff loose?  I don't think the pump moved timing or anything...it was firmly bolted down in front, and still starts and idles exactly the same.



Thanks.

Devan

[saurkraut]

I did notice that with the boost pin out, I had to move the throttle lever to nearly wide open for the little pin at the bottom of the hole to emerge.  Is that normal?  It doesn't seem right...that would mean the LDA is only effective at almost wide open throttle?

Sounds like something is hosed with the LDA feeler pin.  I know I have to rotate my LDA pin to the lowest slope to get it past the feeler pin.  So normally, it should be protudeing even at Idle.  Something must have shaken loose. Hopefully it hasn't fallen down into the pump and set up a little machine shop.

Time to pop the top and see what's missing.  Jake's GTD page had a cross section of the LDA stuff.  I think there is a spring up in there that keeps the feller pin in contact with the cone on the LDA pin.  I had all that stuff appart last year when I was farting around with my 1.5TD pump, but my memory isn't what it used to be.


Here's the image stollen from Jake's page.


Mayby there is a better one somewhere else?

Here's Fatmobile's keen throttle lever reassembly technique: http://www.vwdieselparts.com/forum/viewtopic.php?p=52081#52081

[hamradio]

Hmm...


I took the pump top off tonight.  Everything seemed normal.  I did the gov mod while I was in there. 


The pin still isn't out at idle.  It emerges barely at about 1/2 throttle, maybe more.  I took it for a drive, and noticed no difference.


This is frustrating the hell out of me.  I wish I had a confirmed good 1.6td pump to compare to.

[Smokey Eddy]

Perhaps you want to advance the timing ever so slightly?

Sounds simple i know but perhaps the solution is equally simple?
9 times out of 10 i think a problem is bigger than it actually is. What is the timing set to? try playing with the timing free hand, ie; with the car running have the pump mounting bolts loose-ish and push the pump towards the head. Or very gently knock it towards the head with a wood/rubber mallet - depends how much you loosen the bolts obviously.

I have my timing very retarded to what it used to be at and the lack of zip is very noticable.

[rabbitman]

I'm pretty sure the LDA is only effective at full/almost full throttle, it's kinda like pushing the go pedal down farther and farther as the boost comes up. Hope you get it fixed

[hamradio]

It appears as if the LDA is fully functioning.  The pin emerges if the engine is running.


I also took the mounting bolt out.  No difference, besides vibrations again.


Here's my theory:

When the bolt was out before, it was ~40* outside.  Now I'm driving it in ~70* weather.  That car is definitely a lot quicker with the colder, dense air than it is at the warmer temps.  I'm thinking it's purely coincidental that I put the bolt in on a warmer day.  I had been babying it trying to get good mileage for a week or so before that, so I probably didn't notice the performance difference when it got warmer outside.  I can get my egt's up to 650-700 with the gov mod, now.

[rabbitman]

I can get my egt's up to 650-700 with the gov mod, now.

How much power do you think you got? A huge increase over stock?

With my NA I can get the EGT's up to 1100 fairly easy, one time I looked down and saw 'em at about 1250 . Scared me pretty bad. I don't know what was happening that trip but coasting barely got it down below 300, normally it'll go down to the peg if I coast.

[Rabbit on Roids]

700 degrees only? so you have ZERO smoke? and not much power either? im sure my EGT's are through the roof. if i step on the smoke pedal, you cant see the car behind me for a second, until the turbo picks up and cleans the smoke up.

[hamradio]

Barely any smoke.  If I'm hammering on it, I get a little haze.  The vanes on the VNT are fully closed all the time, until 12 psi or so comes...it creeps up to about 20 psi, though.    It's not a perfect system...I really wish I had a wastegate to work with the vanes. 


Cruising, my egt's are about 285-325 or so.  I could maybe push a little more fuel...I have maybe 1/4" of the idle screw sticking out.  It still puzzles me how it's underfueled even with the fuel screw cranked in so far.



As for the gov mod, it didn't help anything but top end.  I did it on my NA pump, and had to undo it because it was pretty undrivable...the RPM's hung up in between shifts.  It works great on the TD.  I ran 2nd gear to 45 mph today.  It was awesome.

[Rabbit on Roids]

lol, i can run 2nd gear to 65 mph and grab 3rd with a good chirp. im fairly positive my engine spins up to about 7000 now with the gov mod. AAND I STILL HAVE NO VAIN CONTROL!! and your low exhaust temps seem pretty un real to me. i could make pretty good smoke from my N/a pump, and it was completely stock. stock 130 bar injectors, stock pump with a quarter million miles on it.

[hamradio]

I was seeing higher egt's than this with my old NA pump, but the car was slower with that pump.  I can spin the tires very well in 1st, but nothing beyond that. (might be due to having azenis?)  I'm puzzled as to why my egt's are so damn low, and I can't get a ton of fuel out of it.  Injectors are freshly rebuilt with chevy 6.5l nozzles and set at 160 bar.  Timing is 1.05mm.  Boost runs at about 15 psi, and creeps to 20 or so.


I think I don't know quite what the hell I'm doing with my injection pump as far as tuning goes, haha.  I have the fuel screw cranked, LDA cone adjusted to the most fuel part, starwheel turned clockwise a bit, and the screw on top of the LDA turned in a turn or two.


I'm stumped.  Do I have some form of really pathetic TD injection pump?  As far as I know, it's from an old jetta or something.  I can post up the part number, if anyone interested.



Edit:  Upon playing with settings and driving it more, I should be filling both lanes with smoke and burning up my pistons, with as far as the various screws are turned up.  On the last drive, the highest egt I saw was about 580, and 370, cruising.  It makes about 9 psi of boost, just cruising.

[Rabbit on Roids]

my car makes about 3 psi going down the highway. and yea, i can fill both lanes with a black cloud, and im sure microscopic chunks of piston. i make 22 psi on a good day, seen it all the way up to 28psi on a warm day tho, cause the intercooler wasnt working as efficiently. does your car pull like a mofo once it hits 10 psi? if i stand on the throttle, once it reaches 10 psi, if its wet out, it will just burn the tires.

[hamradio]

Well, I'm rarely ever below 10 psi while giving throttle input.   I make 1/2 psi, idling. 



A friend brought up an interesting point:

Maybe it's all my injectors can flow?  I have chevy 6.5 diesel nozzles in 1.6 bodies at 160 bar.  They should be flowing the same as OEM, however. 



This is making me absolutely frustrated.  I just can't figure it out.  My td pump is from a quantum with unknown miles; I got it for $50 off of vortex, so I'm not all that confident in it.  I'm almost to the point of getting a better camplate and 10mm head to put onto my spare pump, and try running that.  Really, for as much as I have this pump turned up, I should be filling the road with heavy smoke and burning holes in my pistons.  I have the fuel screw cranked up so much that, as mentioned, I barely have any of the idle adjustment screw left.  It just feels like there is something holding me back.

[Rabbit on Roids]

you got an old rabbit right? have you ever adjusted your throttle cable? if you make BOOST at IDLE.. then you should have way the F*** more power than i do.. ive NEVER had my turbo make boost at idle.. any possibility that you have an 8mm pump? look on the side of the pump.. should be a 9 or 10 digit number.. does the middle set of numbers say 494? number should be xxx 494 xxx. or 484 for an 8mm pump. or 404 for a 10mm pump. holy crap dude, if your car makes boost at idle, your gonna blow the head off when you finally get that thing running right. ive already blown one head off an engine..

[hamradio]

Yep.  I have an '82 rabbit that was originally an NA.  I have ARP studs and a coolant-leaking AAZ gasket torqued to 85 ft/lb.  It's an 11mm block, too.


Anyway, the turbo is spooling at idle for two reasons. 

1: high idle due to trying to crank the hell out of the pump. 
2: the vanes are fully shut on the turbo until the actuator opens at 12 psi or so.  I might open the vanes slightly, as it is just ridiculous cruising down the freeway pushing 10 psi (not to mention the woooshing noise gets old after a while). 


My pump has a 9mm head.  Number is: 0460 494 135.  It's from a quantum.


It seriously feels like something like the pump head or injectors are limiting it severely.