I can't understand how the left front 3 cylinders B1, B2, B3 are not getting hot. I have the heat shield off so my thermal gun can read manifold temps. When I start from cold all the other ports quickly heat up to 300F .
But B1, B2, B3 rise only to 200F then after 90 seconds cool off to 130 or so, and stay there.
The injectors click using the screwdriver stethoscope test,: the car seems to have power but I can't imagine I get power from those cylinders if I get no heat. The harness is not cooked, and the electrical diagram shows those three cylinders have little in common that I can see. I have new fuel filter, plugs, wires, fuel hose, injector seals, all new cooling system, many upgrades. I thought the cat was bad, after pulling and inspecting, plus measuring manifold temps before cats, they were ruled out. You can put your hand on the manifold, and if you rev it, it gets cooler. Compression checks were excellent all the way around @ 59k miles. If I unplug one of those 3 injectors while running, the revs go up. Plugging back in will bring revs down. This seems counterintuitive, but there are other sensors at work which could account for this. Thanks, Brent

 

If the exhaust manifold is not hot the cylinders are not firing.

Pull each HT wire (hold with insulated pliers or similar) and while ticking over in a dark garage see if there is a fat blue spark.

Pull each spark plug and see what colour each is. Paleish brown indicates firing Ok, wet indiates fuel no spark, white indicates no fuel.

Then pull an injector plug and test for 12v in the loom. Also clean the power resistor plug (see sticky) which might be the trouble.

Interesting problem, do report back!

greg

 

Thank you Greg,
I will pull the plugs again ( did it last week looking for a misfire that seems related to this problem) and check color. They were all clean as a whistle last week, but I'll recheck. Have to pull A/C comp again. The car sat for a few years and it seems funny that the 3 cylinder are all on one manifold together.
I mention sitting because the injectors could be stuck closed or plugged. Just strange that they are all in a row. I suspect plugged injectors though.

 

I checked for spark. Very bright strong spark.
I pulled plugs B1, B2, B3, and found clean dry, white, no fuel.
I also pulled injector connectors while running and revs INCREASED with every disconnected injector on left bank. And DECREASED with every injector disconnected on right bank. Tells me left bank isn't doing much.
Where do I look for problem.? ECU, resistor block. I can imagine a much more powerful car if I get this sorted out.

 

Mmmmm.

Gregs resistor pack rejuvination is a MUST here.

I am suspect of the loom, for no other eason than old age, and particularly the section under the a/c compressor.

I am not sure of the revs fiasco you are getting. A shorting loom could possibly do that ??.

The injectors are linked:

1,3,5A
2,4,6A
1,3,5B
2,4,6B

Lets know.

 

thanks Grant, I think I will just go ahead and rebuild the entire injector harness. Also will investigate the resistor pack and plug. Will need new injector female connectors and a roll of Teflon coated appliance wire.
That will at least eliminate that as a source of trouble now and forever.
Going to read up on the resistor pack now.
Will update as I learn more what's going on.
Brent

 

You are definitely getting there! Blocked injectors a distinct possibility. As you are doing the loom (VERY good plan) looking at those three injectors (somewhat of a pain but the No I injector has a longer flexible and can come out more easily) and soaking them in injector cleaner may well do it. If you are very careful and have a mate to help, pulling one injector, removing the coil king lead so no danger of the engine starting, and then turning over the engine on the starter should let you see if it is spraying or not.

Greg

 

may not be related to your problem, also may have been done before(donno who).

a way to adjust the throttle plates evenly at idle and up to temperature with the engine running!

my noncontact temp gun has provision for plug in thermocouples(2), so i clamp them to each side exhaust pipe , and slowly turn the plate adjustment screws till each side temp is equal, made an improvement in throttle response, and smoother driveability!

middle of the night dreaming! HMM. gotta do something when retired.

 

Thank you for that Ronbros. I think I have failure to squirt fuel in 2 or more cylinders I will need to sort that out first then I'll definitely look into that. It seems that it would balance idle between the two banks accurately. I wonder what Roger Bywater would say about this method.
Brent

 

brent if you do find you have stuck injectors, you should pull all of them and have them flow benched/tested for equal flow!

dont want a partial flow in any of them, wont show up at idle, but a full throttle run could run lean on certain cylinders!

 

That's good advice Ronbros. Hadn't thought of that, but it's certainly cheap insurance. After sitting for a few years the fuel was pretty dark and foul. No doubt other injectors were subjected to varnish. I saw a home built rig that used compressed air to force cleaner through the fuel rail while running. Have you seen this idea. And what do you think about it's ability to really clean. How do the pro shops do it.
Brent

 

[QUOTE=brentleew;1199330]That's good advice Ronbros. Hadn't thought of that, but it's certainly cheap insurance. After sitting for a few years the fuel was pretty dark and foul. No doubt other injectors were subjected to varnish. I saw a home built rig that used compressed air to force cleaner through the fuel rail while running. Have you seen this idea. And what do you think about it's ability to really clean. How do the pro shops do it.


Brent[/QUOTE.

Brent pro shops have a dedicated injector flow bench machine, you install a set of injectors and it uses a cleaning fluid,under an adjustable pressure, that has electrical pulses,also can adjust pulse width and simulated RPM.

i had a machine when i was operating my race engine business, it would show exactly how much each injector flowed,(in CCs), and at what pressures.

a very handy machine for diagnostic work, and i also had a Ultra Sonic cleaning unit for stubborn injectors, probably saved 90& of dirty injectors!

if water got into an injector, those can be diffecult to save, also if you buy a new set,they should be tested for flow charicteristics.

simple enough ,you want all injctors within a 3% equal balance range.

but we talking 10-15 yrs ago, newer machines have more resolution!

 

I pulled the fuel rail and set up a jar to test the injectors. I made up a switch and small medical 12volt battery and using fuel pressure from the car tested each injector. They all seems to work well. I also pulled the injector harness out and found 6B harness lead was worn or melted through to both conductors, exposing them to ground shorts. I have ordered new crosslinked cable, new connectors and loom to replace the whole damn thing. I may take my injectors to a guy here in Concord who can check flow rates better than me. Of course I hope this was my problem, but one step at a time.
Brent

 

Keep plugging away. you'll get there.

 

ive built a couple of 5.3 injector wiring harnesses and one thing i remember is that the injectors are paired in 4 groups of 3. those 3 injectors either share a 12v source, an earth, or both.

i know you said you hear clicking but it could be just vibrations reverberating through the fuel rail from the other injectors on the rail. switch your injectors to B4, 5, and 6 and see if the rear manifold isnt the one getting cold.
if not then its the wiring harness itself thats the problem. check for 12v with a multimeter if you can, although the test might throw some false negatives given how fast injector pulses are fired.

if fiddling with the injectors doesnt work i would definitely do a compression test. cylinder sleeves are grouped together in 3's as well. could be a head gasket issue

 

Thanks M90power. I decided to build a whole new harness. The wire, EV1 plugs (14), heat shrink all arrived last night. I got the pigtails assembled by this morning. The original harness had a burn, cut, or wear through at B6 that was clearly shorting to ground. Laying it out and cutting the the high twmp wire to length, I broke the original harness in many places, and the car has only 59k on the clock. I managed to keep the loom near the connector with the original silicone label, but heat shrinked new boots. Tonight I will lay out the harness as a whole. This will be harder: getting the lengths right. I'll shorten it to secure to the intake bolts- out of the V. The mystery is that B1,2,3 were cool, but B6 was shorting to something, presumably ground. I may have the injectors flow tested but I'm on the fence about the value. I tested them all myself and I know it was not very conclusive other than they seemed to work. So opinions are requested on that. If I knew how to test the resistor block I would do that, but guidance is needed. I checked the injector resistance by the way and they were all in spec.
I cracked one of the pintle caps and to find a source for a new one or set. Thanks for the great support everyone. Brent

 

Sounds like you are onto one of the problems, at least ! When you make the new harness, it is best, in my view, to secure it to the actual fuel rail, rather than to the floor of the V where it was originally. It will run quite a lot cooler in this position and be less likely to cook - even though you are using cook-proof wires.

Greg

 

Thanks Greg, I was looking at that this morning. I of course wouldn't think I'm smarter than the original engineers, but in this case having the wires up where cooler is smarter anyway you look at it. I believe I can make it look pretty good too. I have the rail on my desk in my office where I can see how it's going to fit. As Kirbert said it only needs 5 separate wires. 1 power and 4 branch grounds. 1 larger power lead will supply all 12 injectors just fine. And being up on the fuel rail would shorten the whole harness. And reduce V clutter.

 

i built one not so long back, the thread below shows lots of detailed pictures

https://www.jaguarforums.com/forum/x...ctures-127573/


IMG_1933 by MyPix on Talk Photography

BB

 

Thanks Brake Buster . Looks good.