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tii fuel injection questions


schuetz1619

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I have an early euro 71 tii (27000056). My mechanic says I need a pump rebuild, and I wanted to be sure that my pump and associated components are correct before proceeding, so I did a little checking, which raised questions.

 

I have the throttle body pictured in the enclosure. The pump is a PL04 124.02.

 

An article by Mike McCartney in the it register (http://www.2002tii.org/kb/133) says that this pump was only for the 1974 US tii and that it contains a V6 cone (cam), whereas all other tii pumps (PL04 124.01) contain the V7 cone, which has a different supply curve, richer on the bottom end.

 

post-33115-0-63683100-1417643644_thumb.j

 

My questions:

 

(1) Is the throttle body in the picture O.K. to use with this pump?

 

(2) Is the other emissions equipment that came on a US 74 tii necessary with this setup, or can it be omitted?

 

(3) Any other thoughts on the problem that I am told necessitates rebuilding, which is:

 

When adjusted according to normal procedures, the mixture is ok or slightly rich throughout the entire RPM range, except between 2500 and 3000, where it goes "full lean." Richening the mixture in this range via the throttle body adjustment (to the point where I don't risk cooking the engine) creates an ultra-rich mixture elsewhere and lousy performance and mileage. 

 

Ideas gratefully accepted! Thank you.

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Your throttle body looks like the one on my 73. I had a similar problem after having my pump rebuilt (leaning out at mid-to-part throttle). I had to adjust the coupling under the throttle body housing which changes the pump and throttle plate opening position. My adjustments started at the factory settings then were modified. I highly recommend installing a wideband oxygen sensor and gauge to assist with tuning a tii. Your distributor may also require checking for the proper advance curve (most likely worn out springs or seized weights). Make sure you are not using platinum type spark plugs and have set the valve clearance to BMW specs.

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Is it completely stock? Stock air filters and housing, stock exhaust manifold and down pipe, stock camshaft?  If you change any of these things it changes the amount of air that flows through the engine at different RPM and throttle settings,  The injection pump does not know you changed the amount of air so it can't compensate with a change in fuel delivery.  I'm not a big fan of hot rodding Tii's unless you can find the Alpina injection systems and then you can only use the Cam, Pistons, Filters, Headers etc that they used or it won't be right!

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There's a seized tii injection pump currently listed on eBay. I mention it only because it appears to be dated April '71, suggesting it may have been manufactured for a very early Euro tii, as yours is. The casting date on the pumps is on the engine (i.e., right) side of the pump.

As Jim mentioned, you appear to have aluminum intake runners, suggesting those were replaced after the car's original manufacture. Others here will likely have a sharper cut-off date or VIN, but I tend to expect tii's manufactured after May-ish '72 to have the aluminum runners; and any cars earlier to have plastic runners. Many of the aluminum runners have cast-in casting dates, as do the aluminum accumulators/plenums.

As to the throttle body, it does appear that yours is of the "second style," which both replaced the first style in production and became the sole factory replacement throttle body. I've not yet seen a trustworthy changeover date but it seems it might have been during the '72 calendar year (not necessarily the '72 or '73 model year). 2762757 (October 19, 1972) has this second style but I can't verify it is original to the car. I don't believe the changeover to the second-style body is coincident or related to the '73 - '74 model year change.

If you wish to assemble a matched early-Euro tii injection system, it's certainly possible -- to the extent your tii might be missing applicable original components. But many experts say that matching components are not essential IF you're having the entire system rebuilt. My gut, however -- and speaking as someone who enjoys originality -- says that such an early tii should be preserved in its original form, or close thereto, not because it is necessary to make the car run well but because an early tii is an important piece of automotive history!

Best regards,

Steve

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As to the throttle body, it does appear that yours is of the "second style," which both replaced the first style in production and became the sole factory replacement throttle body.

 

 

Is this the "first style?"

 

(I purchased some parts from the owner of an early (plastic runner) Euro tii and this was in the box). 

 

004.jpg

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Is this the "first style?"

(I purchased some parts from the owner of an early (plastic runner) Euro tii and this was in the box).

004.jpg

I believe that is a "first style" throttle body whereas schuetz1619's throttle body is of the second style.

There is a long thread on this topic:

http://www.bmw2002faq.com/topic/139559-which-tii-throttle-body-is-early-and-which-is-late/?hl=+late%20+throttle%20+body

But you must read it carefully as it starts off with a reversed characterization of the first and second styles. Post #2 brings the discussion back to what I believe is the correct characterization. Then there's lots more data -- some ambiguous, but most pointing toward the style in your photograph being the first style and the style in schuetz1619's original post being the second style.

I'm hoping some ambitious forum member takes on the task of collecting VIN numbers and throttle body styles for a relatively large population of cars so we can better understand when the new "second-style" body was first implemented!

Regards,

Steve

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I believe the throttle body you show is the later style.

 

If you spend an evening and pore over the Kugelfisher pump-related posts here on this wonderful forum, you'll find that the opinion of the cognoscenti seems to be that, after over 40 years, the difference between the early and late pumps with the different cones is not terribly significant.

 

Conventional wisdom is that, if you're having tii driveability issues, or lean/rich problems in certain RPM ranges, to suspect the pump last. A pump rebuild will cost between $1000 and $2000, depending on who does it and what it needs. I had mine done, and it ameliorated certain issues, but was not a magic bullet.

 

You say "When adjusted according to normal procedures, the mixture is ok or slightly rich throughout the entire RPM range, except between 2500 and 3000, where it goes "full lean." Richening the mixture in this range via the throttle body adjustment (to the point where I don't risk cooking the engine) creates an ultra-rich mixture elsewhere and lousy performance and mileage. " What is the metric you're using to judge this? Seat of the pants / smell (not that you smell the seat of your pants), or do you have an ultra wideband oxygen sensor and an air-fuel gauge? I installed an 02 sensor and a gauge, and played with a number of variables, and made it better, but finally moved on to tinkering with other things to salvage what small amount was left of my mental health.

 

--Rob

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Three thoughts on this

  1. +1 on using a wide band AFM to really see what it is doing.  I use this one (http://www.aemelectronics.com/?q=products/wideband-uego-air-fuel-controllers/x-wifi-wideband-uego-afr-controller) which does not require adding a gauge, as you read it through your phone
  2. When you say it goes "full lean", is that at WOT, part throttle, or both?
  3. If you do have your pump rebuilt, please ping me, as I now have some well informed opinions of various rebuilders

J

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