VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: big specht on December 20, 2005, 03:51:38 pm
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I have a extra set of injectors and a pop off tester to check pattern and popoff pressures. Just looking for some info on doing it and what are the best tips to get there are cheap and $$$ ones what works the best ?????
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As of now there are mainly 3 different nozzles people are using. Those being the OE replacement ones, 1.9TD, and GTD. GTD is the higher flowing of the bunch. Several people on the board sell them (I normally sell them but am out for another week or so). The biggest problem you will run into is that you will need a selection of shims to adjust the pop pressure which aren't typically available although many can be ordered from VW. The problem is that you need to know what sizes you need before you order them. I can get shim kits with a selection of all of the sizes but they aren't incredibly cheap. I'm just thankful that I can get them. Otherwise, making the injector halves seal back together can sometimes be difficult and you wouldn't really know it was going to leak until it was on the car if you're using a hand operated pop tester.
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a good way to see if the injectors will seal up is get a flat surface with some lapping paper and run the flat spot of the upper half of the injector on it until it shines, if the whole thing shines then it should seal up just fine, if its a little iffy then i would try another top injector half
later
Justin
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i dont have an injector tester but in my expierence used injectors awalys have something wrong with them. i at one time thought i could be frugal by buying a slew of used injectors for pennies each and having them tested, any using only the good ones.
after testing probably 50 used injectors, i managed to find 4 that had halfway decent breaking pressure and spray pattern.
a place fairly close to me rebuilds injectors, turbo or non turbo, for $35 each. its a bosch certified rebuild centre and i have known the owner for atleast a decade. they put new nozzles in, set the breaking pressure and double check everything to make sure its all good. they can actually take non turbo injectors and bump them up to turbo spec without charging any extra.
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Most of the time you'll find pop pressure is much lower than spec after 10+ years of service. I've seen many TD injectors pop around 1800-1900 psi when they should be at 2250 or so. I even had one injector which was sent in as a core where the spring was broken in 3 peices and I had to remove the nozzle from the holder with a hammer and drift. You just never know what you're getting with used injectors.
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What is the final torque setting?
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55 lb-ft is the final torque, or 75 nM
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I'll second the overtorqueing. The spec is like 51-52 but it takes more than that to make it seal.
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Thanks for all the info guys :D My car is a 86 golf na and is dd which nozzles would work the best and not hurt my mileage that bad, you know how it is power or mileage :x
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So can one of you guys fix my injectors from my 98 TDI? I had them checked and the shop said 3 popped at 400-500 below normal ( they said about 3100 was normal) and 1 popped at 1100. That cylinder had a melted piston top.
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Did someome try the GM 6.2D injector nozzles?
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With pop pressure that low I would be concerned that one of the springs may be damaged or something. Raising pop pressure 2000 psi would take an entire extra shim.
I haven't tried the 6.2 injectors myself though.
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I have seen a home made pop tester in some thread here in the forum, but i cant find it can anybody help me find it.
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Affecting the breaking pressures will affect your injection timing. As the injector wears and the breaking pressure lowers, the timing advances. The spray pattern also declines with age, somewhat offsetting the advancing of the timing (the poorer spray takes longer to burn).
With redone injectors often the max fuel can be increased for more power without additional smoke.
Andrew
That partially answered a question I have had. How much is the timing affected for each 100bar change in popping pressure? Also, how high can you raise it (breaking pressure) and what imposes the limit (eg; fuel lines, IP, head, etc) I know the higher the better (better atomization and cleaner/faster burn in my mind).
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Enjoy. Chicks dig trucker cologne. :D
Andrew
LOL, mine doesn't. Maybe I've been wearing it too long :oops:
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anyone willing to test/sell in the calgary area?
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Just read it ,it's in a mail of libbybapa,january 12 2006
Jan
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LOL! Libbybapa, you're right, 100 bar IS a lot! Sorry 'bout that, I meant to ask about 10 bar intervals (10 bar = 140 psi, right?)
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i think its 147 at sea level, or something like that.
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Guys,
On the topic of raising breaking pressure, the TDi's breaking pressure is 190 / 300 bar on the 90 bhp 1Z engine. They also use the same timing belt and tensioner etc... as the D and TD's. So for this reason, I wouldnt worry too much about the effect on the timing belt. They do however have an additional roller tensioner just above the fuel pump pully.
Whats the highest anyone has attempted to run with shimmed injectors ? Mine are set at 165 bar and the engine pulls strong.
What experiences has anyone else had with higher breaking pressure ?
I've always felt that each time I had them raised in pressure, the engine ran and pulled better with reduced smoke.
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if it is true that increased breaking pressure results in less smoke, better starts, better economy etc, then why didnt vw use turbo injector breaking pressure in every diesel? or why stop at 155 bar, why didnt vw just make every injector 200 bar across all platforms?
surely vw would not leave something as obvious as this out of the equasion when the little 1.5 and 1.6D guys are struggling to get over the next hill?
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Exactly! What IS the con to using increased breaking pressures? Is it the IDI's pre-chamber that's the restriction (both figuratively and literally) as in impeding (what I would suspect would be) the hotter and faster flame front? Where-as the TDI's ignition is already in the cylinder.
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You're comparing too different types of nozzles here. Increasing pop pressure will slightly retard timing and deliver slightly less fuel. There will be increased pintle chatter which is what atomizes the fuel. If the injectors just held themselves open you'd get nothing but a stream of fuel not unlike a fire hose.
Like everything there are compromises. If VW were to increase the breaking pressure they may have to reduce the timing belt interval and injection pumps may not last as long. Not to mention this will result in additional parasitic losses due to the increased energy drawn by the pump. So the question you have to ask is whether or not the slight increse in economy is worth sacrificing pump longevity and whether or not it outweighs the losses felt by working the pump harder.