TR Fuel Distributor Rotted Inside?

At least he's using the right tool........"hit it with a hammer, it gets worse"........

 

There is a gentleman that I have dealt with regarding the CIS woes. His name is Larry Fletcher and he lives in alabama, his business is rebuilding WUR's and fuel distributors. He will tell you never do one bank only, do both because it will only fail a short time after. You can send both to him and have them rebuilt. He is a member here and on "the other" ferrari site.

P.

 

I talked with him a few years ago... he seems to really know his stuff.

 

I rarely comment directly on another shop/mechanic but your descriptions of his work and comments introduce a little doubt in my mind of his expertise in this area, just my 0.02.

Brian

 

could be the wires are worn out

 

This is an interesting thread. As a do-it-yourselfer, I have performed 3 engine out services on TRs, and also tuned the fuel systems. First we need to truly define what "misfire" means as per your mechanic's description. I usually think of misfire as either pre-ignition or failure of ignition. This can be caused by lack of spark, or too much/too little fuel. But here's the issue I have with this: TRs use constant fuel injection...no pulsing or anything like that. The fuel flow is based on the amount of air flow across the air diffuser plate inside the fuel distributor base. Twice as much air results in twice as much fuel. Actually the fuel distributor is sorta like a needle and seat in a carburetor...but a bit more advanced with some electrical controls. I do believe there are some steel parts in there that can corrode and create problems that are nearly impossible to diagnose....if water is present in the fuel and the car has been stored for long periods of time without starting, almost guaranteed problems. This is just another reason why "garage queens" can be a nightmare. Did your mechanic verify the tail pipe emissions with a gas analyzer? You can get a cylinder bank that "appears" to misfire if the fuel mixture is incorrect. The effect of tapping with a hammer, that changes the running conditions, does seem to support the notion that the fuel distributor may be the problem. But from what I understand about this system, once things are set they are extremely reliable. Did your car set for a long time? And I do agree with others that if one side is a problem then closely watch the other side too. You may be okay doing just one side.....but just don't be shocked if the other side experiences the same problem.

One thing I recommend is that if anyone is having a mechanic get a fuel dist. rebuilt, be sure it really gets done. Use a punch and make a "secret" mark or dimple in the distributor so you can see that its been changed out or use some other method if they are having the original unit rebuilt. There are lots of great mechanics out there, but I've caught a few by marking parts that they said were replaced...and when I looked at the parts....there was my "secret" mark still on them!

Overall it sounds like your mechanic is doing a thorough job. But do verify the mixture settings. Did he analyze the mixture? If so and when he tried to adjust thingsm and the results were erratic behavior or lack of response, I think he is being up front and honest.

Closing Advice to All: WHEN YOU FIND A GREAT MECHANIC YOU CAN TRUST, TREAT THEM LIKE GOLD....CUZ THAT'S WHAT THEY ARE! WORTH EVERY PENNY THEY CHARGE.

 

ditto.

more than a little.

Paul

 

You've spent an awful lot of money and your car seems just as bad as when you brought it in. Maybe you should try a new mechanic. Your guy does a lot of guessing at your expense.

Ken

 

If you have a US TR, one easy thing to try is just unplugging the O2 sensors when you're in the "bad/warm" condition so that the injection system stays in the open-loop mode and see if the runability changes significantly (you just need to unplug the single wire from each O2 sensor -- you can leave the 2-wire heaters hooked up, but label the wires so that you don't get the connections swapped).

If the FD+injectors aren't all delivering the near-exact same amount of fuel to each cylinder, it is possible to set the (cold) open-loop mode (which relies only on the mechanical tweak) slightly rich so that the leanest cylinder is OK and the other cylinders are running slightly rich, but when the system tries to run closed-loop (based on the O2 sensor outputs) it will lean things out (via the EM valve) such that the leanest cylinder in the bank starts to misfire.

The other thing I would check (if "unplugged" warm-running is a lot better) is that the O2 sensors are not already swapped -- if you have a multimeter and would like to confirm/deny let me know and I'll post the info.

 

Don't know how far you are from Boston, but if you're within reasonable distance, give The Boston Sports Car Company a try. I do believe they specialize in Ferrari and have a good rep.

Cheers,
Aaron
'82 GTSi

 

Kevin -- No problem with unplugging the O2 sensors at any time warm or cold or with engine running or not. Your mechanic makes the tweak warm at idle with the O2 sensors unplugged so it's not a great sign that the warm idle seemed to dis-improve in that mode. Also (if the engine has cooled below ~35 deg C), the system runs open-loop and extra fuel is added (until the water temp reaches ~63 deg C) which can help mask uneven fuel delivery (and might explain your "golden" early 10 minutes).

The trouble with warm-running and having the O2 sensors plugged-in (i.e., the stock situation) is that the individual fuel delivery from each injector must be very near-equal, and this relies on the individual tweaks inside (under) the FD being set equal and all of the injectors in that bank being identical. I've never seen the "official" F tool in person for measuring the volume of fuel actually coming out of each CIS injector (I'll post a jpeg this PM -- it's a frightening thing ), and IME when the Fo_ dealer rebuilt my 1-6 FD even they didn't have one (i.e., the mechanic had a special set-up to make the FD adjustments, but didn't have the equipment to measure the overall system behavior so instead of actually measuring/understanding the problem, the fix is "replace injectors -- if not OK -- rebuild FD -- better be OK" ).

The water temp sensor is a critical component so making sure that the contacts are OK is a logical step, and if your mechanic is working from a TR WSM, it has the resistance vs temp values that he would check by measuring the resistance at the (unplugged) injection ECU connector. Mine had "aged" enough to be a little out of spec so I replaced it, but I really didn't notice any difference runability-wise. If they go completely "open", it will kill the corresponding bank.

 

I did not rebuild any TR fuel distributors last month, so if he did not send them to europe, it leaves only two other major rebuilders both in CA.

It sounds to me like you may have more than one problem. I would start with setting up and checking all functions of your FI system and then look for systems that would cause intermitent problems. If you contact me I can talk you through the tests you need to do.

Larry

 

Has anyone seen, or have, this Bosch KDJE 7451 fuel delivery testers?
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Steve I do not have one but have used one many times. I think Dave Helms has one. Is there something you wanted to know about them?

P.S. If anybody has one kicking around that wants to be rid of it let me know.

 

Necron, cut your losses and take it to Boston Sports car. They will fix it right.

 

Strange but I have 2 of them. One in the restoration process I have promised to another shop and one NOS unit. I built jigs to flow and adjust the dist's after I rebuild them. I only started doing this after I have had numerous rebuilders attempt ohauls all to check them on return and find huge variances in flow from port to port. That said, I also at the request of a good friend (former FNA rep) flowed 3 new units he sent from FNA. The "consumer acceptable" variances that come directly from Bosch are far too wide for my taste. The variances on new injectors is equaly shocking with it requiring me to order 15 injectors to find 12 that are acceptably close to one another in flow and opening pressures. On the average the steel Ferrari injectors are far closer to one another but the price is getting prohibitive.
Can one feel the difference seat of the pants when everything is matched? You bet! No different than setting the cam timing correctly.

Dave

 

Ebay is your friend. None out there now, but a couple have sold recently. Last couple of weeks one went for about $30.00 plus shipping.

Dave <

 

I get Ferrari tools there all the time but for some reason I never check Bosch.

Thanks, I'll keep an eye out.