Lumpy running/ missing - very sluggish revs on 400

Off the subject , as a new owner , would you like to join the 400 club at the silverstone classic this year? Email me on [email protected]. Good luck with the lumpy running. I always use premium grade petrol. Also check petrol pump relays.

Good luck

Jerry

 

Now I have read your post again , this sounds like the petrol pump relay. If the same as the 412 , there is one pump for each bank and subsequently one relay per pump. If one relay or pump is defective you will only be firing well on one bank of six. After running , feel the rocker cover of each bank , the cooler one is the problem. If the same as the 412 the relays are found in the passenger footwell under the carpet and a metal plate.

Jerry

 

For more insight into your problem call me on 01908263227.

Jerry

 

bonjour as tu vu les vis platine dans les deux allumeurs !!!!!!!!
peut être qu'ils sont uses !!
christopher

 

The problem is most likely a failed warm up regulator (WUR), my reasoning is this:

Faulty fuel pump wiring will result in no fuel getting to one side of the motor = which means the spark plugs won't be sooty, they will be completely 'dry' as all the fuel will have been used up. Also won't cause backfiring ( no fuel to burn )

Faulty (no) ignition will result in no spark, so the plugs will end up "clean" as a result of being washed in fuel. No backfiring either, as there's no spark.

A failed warm up regulator will generally allow too much fuel in to one bank, resulting in the engine running rich ( sooty plugs ) and backfiring ( excess fuel in the exhaust )


Someone with good K-jetronic skills should be able to diagnose a faulty WUR, you need some pressure gauges to do it The WUR's can be rebuilt, there is some good info here
Ferrari 400 - Ferrari 400 parts Shop

This is where I go to have WUR's rebuilt, he is "the man" globally, and also posts on F- Chat
Contact Us - CIS Flowtech

M

 

David, where in the uk are you based ?

I'm in Ilford, Essex (near East London) and if not too far may have some local contacts which could be of help.

Feel free to PM me your details

 

Refer to part #7 in the Illustrated Parts Breakdown for the Warm Up Regulator (WUR)
http://eurospares.co.uk/partTable.asp?M=1&Mo=652&A=1&B=37673&S=

 

In this thread -- http://www.ferrarichat.com/forum/365-gt4-2-2-400-412/373121-checking-system-control-pressure-k-jetronic.html -- I posted up some photos of my effort at checking system pressure and control pressure on my '83 400i. The photos show my testing of the right-hand cylinder bank (i.e., the driver side in the UK). My extreme closeups make it difficult to know what you're looking at. But in the third photo you can see the shiny chrome engine oil filler cap, and it's near this cap that the WUR is located. If you scroll down to the last photo in the second post you can see the global view of the system that's being tested.

Although you're diving in at the deep end, a brief explanation of the K-Jetronic version of CIS (continuous injection system) will help. First take note that, when the ignition switch is in the "run" position and the engine is running, all 6 injectors on each side are spraying fuel continuously. The fuel-air mixture to each injector is controlled by a plunger located in the middle of the fuel distributor. The plunger moves up and down in a bore, in which there are six slits. As the plunger moves up in the bore, the slits are exposed to pressurized fuel. The fuel flows through the slits on its way to the injectors. Underneath that big J-shaped affair toward the rear of the cylinder bank -- it's made of soft black plastic and it connects to the throttle body -- is a large plate inside a conical opening. The plate pivots on an arm. Resting on that arm is a second pivoting arm. The plunger rides on this second arm. The system uses two pivoting arms, because they are separated by a set screw, and the rotation of this set screw is how you lean and richen the mixture. The flow of intake air causes the plate to rise. This causes the plunger to rise.

Where the WUR comes into play is that the freedom of movement of the plunger is dampened with hydraulic "control pressure," applied to the top of the plunger. The higher the control pressure, the lower the plunger will ride in the bore, and the leaner the mixture. The hydraulic fluid that this system uses is the fuel itself! From an outlet located on the fuel distributor, fuel at *system* pressure flows to the WUR. From the WUR, the *control* pressure flows back to the top of the fuel distributor, where its hydraulic pressure is applied to the plunger, to limit its upward movement. The WUR has a valve inside, which is operated by a bi-metal strip. As the WUR warms up -- at first with electricity, but ultimately from engine heat as well -- it blocks the flow of fuel back to the fuel distributor. Thus, the mixture is leaned out as the engine warms up.

This system probably seems very Rube Goldberg, but it actually works, furnishing a pretty good mixture "map" without using any electronics at all, not even an oxygen sensor.

 

David -- Can you please back up three steps, and give the year/model/condition of version/type of ignition?

Bill -- Your 1983 400i does not have the fuel line connecting the control pressure ports of the two WURs?

 

It did not come with one. But Larry Fletcher sent me the banjo fittings, bolts, and fuel line to make one. So it has one now.

Hi David. With my limited knowledge I hesitate to try to diagnose your problems from afar. But I know that you can adjust the mixture yourself quite easily, to see if this will smooth things out. You do this with a 3 mm Allen wrench, which you insert into a hole located between the fuel distributor and the black plastic J-shaped thing. I have attached a photo of the fuel distributor on the drive side of my car (passenger side in the UK). The hole where you insert the Allen wrench is at the 3:00 position on the fuel distributor. The hole is factory sealed, and in the unlikely event yours has never been messed with, you'll have to remove the seal.

Here is the 3 mm key I have, which I bought off eBay for the same $10 price as the one in the link: 3mm Hex Tool Adjust Air Fuel Mixture on Bosch CIS Fuel Inj Item ZDM10152EC | eBay .

A clockwise turn enrichens and a counterclockwise turn leans the mixture. (Righty-richy, lefty-leany.) Always make a note of each adjustment, to avoid confusion. (I know you are prone to confusion or you would never have bought this car.) If your car is close to the mark, a 1/8th turn (22.5 degrees) is a lot. But it doesn't hurt to start with more drastic adjustments with a car that's way off. This is why you want to keep notes, or you'll get completely lost.

I'm suggesting this experimentation with the mixture control first, because what your car sounds like to me is a car that's way off. However, there are many other sources of problems. The K-Jetronic just does not like to sit for extended periods. One result can be a plunger that does not move freely, or gets stuck. Other similar things can happen, from sitting too long.

Keep in mind that the system on each side is independent of the other. (There is no connection between the exhaust system on each side.) So if find the sweet spot on one side, you will need to find it on the other side as well.

So here's my advice: (1) get a copy of a book called "Bosch Fuel Injection," by Charles Probst ( Amazon.com: Bosch Fuel Injection and Engine Management: How to Understand, Service and Modify (9780837603001): Charles O. Probst: Books ), (2) get a 3 mm Allen key and fiddle with the mixture screws, (3) contact Larry Fletcher CIS Flow Tech LLC (you can personal message him as fletch62 her on FChat), and (4) get a K-Jetronic fuel pressure gauge rig like the one I was using in the thread I linked to before. Actually, the "pm" to Larry Fletcher is probably the first thing to do. But the pressure test is also a base line for all K-Jetronic problems.

And about your suggestion to dismantle the fuel distributor to clean it up, yes it can be done, but I would definitely try to eliminate everything else before I attempted that project.
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That's probably best. It's not strictly needed, but it makes sense to have the control pressure the same on each bank at the "average" value. I thought all of the later 400i like yours would have it, but maybe its presence is more "variable" -- i.e., if the OP's 400i has it, a control pressure problem couldn't affect just one bank, but, without it, it could.

 

first things first: have you checked the sparkplug leads and distribution cap? Are they okay and are all of these in the correct order of firing? Sounds like you could have mixed up some wires there. Secondly: do a compression test. Maybe it just needs some new valve shims. Both these problems can cause the symptoms you discribed.

 

I'm pretty sure you've worked it out by now but if not, touch my name at the top of this message and a drop down box appears.

Select the option to "Send a private message to rustytractor" and bobs your uncle (or in my case he's my dad !!).

You're getting good advice here although there's quite a lot to think about, especially for a person who's had no time to acquaint themselves with their car. Maybe it would be helpful for those "in the know" to list the areas they feel may require attention in an order of priority, that way David can easily see if there's an obvious 1st, 2nd, 3rd choice etc as to where to look.

I can't help because I have no experience of the Bosch Injection system as my car has good old carbs (admittedly it has so many of them that I've lost count) but there's a wealth of information on this forum and we're a friendly and helpful bunch so someone will have the answer.

Hopefully the car won't end up dismantled and in boxes before you find it !!
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Good Check

As wrxmike pointed out, Larry is the 'go to guy globally' & he also rebuilds the fuel distributors. If I'm not mistaken, the WUR's are on the control pressure side of things & if that's the case, that balance line is very necessary for 'smooth & even running operation' these injected cars are touted for. Control pressure is huge

Larry Fletcher's site that Mike posted earlier.
Contact Us - CIS Flowtech

 

There's something that's been bothering me about my previous posts to this thread. I hesitated to correct or explain for fear of confusing the issue further. (The K-Jet system is pretty confusing for a beginner.) But here's my clarification: the function of the WUR is to bleed off system pressure from the top of the mixture control plunger. That is, the flow of fuel is away from the top of the plunger, to the WUR, and then back to the fuel tank. I frequently get this fact 180 degrees out in my own thinking. But the way it works is that there is a passage in the fuel distributor body, which exposes the top of the plunger to system pressure. The greater the pressure, the less the plunger can rise in the fuel distributor for any given level of air flow, and the leaner the mixture at the cylinder. At cold start, you want the richest mixture. Therefore the valve at the WUR is wide open, allowing the system pressure to escape to the fuel tank. The low control pressure which this allows -- the pressure at the top of the plunger is at its lowest -- allows the plunger to rise higher, which enrichens the mixture. As the WUR warms up, its valve closes. This holds in more of the pressure, and the control pressure increases, eventually reaching its maximum. This causes maximum leanness at the cylinder.

Clear?

 

Speak to Ian Arthur at Hagery insurance 01327 810600

They insured my 400 for far, far more than that and didn't bat an eyelid.

They are the best and easiest insurance company I've ever dealt with bar none. I insure all of my classics with them and have nothing but praise for them.

PM me if you need any more info.

Russ