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The way race teams do it is get a cheap squirt oil can and put gas in it. Then you can safely squirt some gas down the throat under the air cleaner (where you are putting the hammer). Then put the air cleaner back on and start the car. If it starts right up and keeps running you know that the car's fuel system is not getting enough gas at the start of cranking. This is based on years of general wrenching and not Jaguar specific. If someone has more jaguar specific information please chime in.
If you ever try to start the car without the air cleaner in place make sure there is nothing flammable (like your eyebrows) in the area as it can backfire and shoot a flame out for an instant. You will only do that once, believe me.
Alright...have some specs, but they all seem to be in line, but no more answers.
Fuel Pressure at the rail: 36 PSI
Timing: 17
Sparks: All firing with appropriate charge
So, something with the injectors? But not with the injectors themselves, because the car runs great...must the signal that the injectors are supposed to get from the AFM when the Vehicle is cranked, or something like that. Does anyone have a wiring/ECU schematic or know where to start poking around?
Alright...have some specs, but they all seem to be in line, but no more answers.
Fuel Pressure at the rail: 36 PSI
Timing: 17
Sparks: All firing with appropriate charge
So, something with the injectors? But not with the injectors themselves, because the car runs great...must the signal that the injectors are supposed to get from the AFM when the Vehicle is cranked, or something like that. Does anyone have a wiring/ECU schematic or know where to start poking around?
When 'cranking', with the engine hot or cold, the mixture is enriched slightly for starting.
In one of the sticky-threads at the top of this section you'll find a download for the "S57" wiring diagrams. Everyone needs this !
Have you carefully examined the wiring and connector at the AFM? And, while you're at it, wiring and connector at the throttle switch underneath the throttle body?
Grasping at straws a bit while I mull the situation....which is a little weird. But, wiring/connector faults can give weird symptoms.....so maybe it won't be in vain.
Thanks! I've looked at those two connectors closely...only thing that looked weird was that the throttle connector is a 3-prong connector, but there were only two wires in the sleeve...not sure if that is normal or not. I will take a look at S57...there are some wires/vacuums that are unplugged or blocked off, that might be important. Will see what I can find. I took it into a local shop to confirm my readings and completely mystified all the mechanics, which was fun.
That big black arcing black strip on the printed board with green rectangles (overprinted with black ones, but you don't need to touch them).
You can't miss it :-)
Cheers,
Nigel
Hello, I have perform this exercise, the car starts when the AFM cable is disconnected but after and connect the AFM cable the engine suddenly goes off.
what is the actual problem with the car and what should I do to make fire stable when the airflowmeter cable is connected. Please help as usual.
That big black arcing black strip on the printed board with green rectangles (overprinted with black ones, but you don't need to touch them).
You can't miss it :-)
Cheers,
Nigel
Originally Posted by JagCad
Not skilled in AFM's on this engine. That is a certainty. It sure does look like a complex device!!
So, critical thinking time. What function does the device provide. Added air at start?
My thought as manual opening seems to aid the start. Adding air to an over fueled engine fires it?
Carl
Originally Posted by Jag-o-nomic
HI Mike,
That big black arcing black strip on the printed board with green rectangles (overprinted with black ones, but you don't need to touch them).
You can't miss it :-)
Cheers,
Nigel
Hello, I have perform the exercise as Carl recommended, the car starts when the AFM cable is disconnected but after and connect the AFM cable the engine suddenly goes off.
what is the actual problem with the car and what should I do to make fire stable when start with the airflowmeter cable connected?
Please help as usual.
there is a fix for the AFM, adding a resistor usually fixes them. I have the instructions and Doug has them too.
I also believe it is the cold start injector as Fraser described. And that is the one part you have not tested as far as I've read. Remove it and see if you get a squirt of fuel when you crank the engine.
Should the cs injector fire regardless of ambient temperature? It’s about 90 here, and it did not fire.
if so, how should I diagnose? As I understand it it is part of the starter relay, so that should be fine..I assume my multimeter should read a charge during cranking... so I can check that. Maybe replace the injector itself?
Plus the cold start injector works only on a cold engine. It won't operate at all if the coolant is above 70ºF or something like that and, even then, only for a few seconds before the internal heater in the switch disables the circuit. Going back to the beginning, the problem we're scratching our heads over happens with the engine hot OR cold.
I'm wondering if there's an ECU problem. Specifically, the ECU won't recognize the AFM signal until/unless the signal reached xxx-point....corresponding to the flap being open xxx-amount. I dunno. Weird problem.
Should the cs injector fire regardless of ambient temperature? It’s about 90 here, and it did not fire.
if so, how should I diagnose? As I understand it it is part of the starter relay, so that should be fine..I assume my multimeter should read a charge during cranking... so I can check that. Maybe replace the injector itself?
The CS injector has voltage whenever the starter is engaged. To actually operate it requires a ground.....which comes from the Thermotime switch. The TT switch will only provide a ground if the coolant is cold. Plus, to prevent flooding in the event of extended cranking, a bi-metal switch....sort of like an internal heater....opens up to break the ground circuit.
Unless you're in freezing weather about the worst that'll happen if the cold start injector doesn't work is the engine will take longer to start. Years ago I discovered...quite by accident....that mine wasn't working and I never even realized it; had no idea how long it was inoperative.
What this does is cure a problem with "double fueling" on a cold engine....typically evidenced by black smoke from the exhaust and poor running.....like a stuck choke on an old car.
Worth a try on a "what the heck, why not?" basis (easy and cheap, after all) and it's a good mod on general principles. Some have reported better running after the mod even if the specific double-fueling problem wasn't an issue. Just don't get your hopes up too high that it'll solve your existing problem
Ok, grasping a little bit here...looking at engine bay pictures, it looks like most XJ6s have a pipe that connects from the air filter to somewhere (see picture below that I pulled from the internet). Mine does not - the filter case just opens into the engine bay. Can someone confirm that theirs does have this pipe and, if so, could not having it somehow affect the airflow/vacuum when cranking thereby affecting the door on the AFM and thereby the injection process? What is the pipe called so that I can look for it?
that steel pipe connects to the Air Pump which most likely has been removed in your car. Many owners remove them because they remove the air pump system because the engine looks prettier without it. it has nothing to do with the AFM.
sorry misunderstood which pipe. The one you have circled is called a trumpet by us. it is part of the air intake system. It sucks cooler air from the front of the car through the grille. Yes it could affect the air induction system, but I don't know to what extent. If you don't have it, the air filter could be sucking hot air from the radiator.
Trumpet or snorkel, it's condition matters not in start. As plastic, many are busted and even gone ! As I recall mine did not exist when DOHC powered. Yet, it started easioy and ran just fine. that is until that fatal day....
Some even remove them. A trade off more air coming in, even if warmer is better.
OTH, mine now fires instantly. I don't even hear a crank, just instant snarl from the pipes. the it settles into an 800 rpm idle. for a bit before dropping to it's normal 500 idle.
Carl, as far as warm air intake, it is not better according to the experts. Cool or cooler air is denser so supposedly cool air is better for combustion.
check out the air intake videos by experts on youtube. Diesel and gas engine experts all say that cooler air is better.
also the "trumpet" (it looks like a Cornet), is metal, not plastic.
08-28-2018, 10:00 AM
