Engine cylinder temperature question - Left vs right bank

May I suggest you add a bit more detail so the answers are more relevant to your problem and not just what other people had happen.

Is this only a problem on startup and warming up, ie goes away when at normal operating temperatures, or returns once cooled down at idle.

I think I recall that you had fuel fuel consumption issues that would worry a Saudi prince, is this the same with the new ecu?

Is the one ecu controlling both banks?

Is there one fuel pump or one for each bank? Are they operating at the correct pressure and flow, ie not just the dead head pressure, as a restriction would give the right pressure at dead head pressure with no flow, but at flow would give low pressure if the blockage is before the pressure measurement point...

Timing, has it been checked that the spark is firing at the right time for both banks. This can be an issue if cam timing is out between the banks and the timing is inferred for one bank. Ie timing set on number one cylinder but a resulting error on the other bank of six degrees could cause issues.

Injectors ok? Sounds like they are as you said only the banks have the temperature differential, one cylinder could cause a problem, unlikely but need to eliminate.

Are there any afr sensors before the catalytic converters or just the temperature sensors?

Coolant temperature sensors ok, I assume there is only one, thermostat checked and ok?

Knock sensor connected and ok?

EFI fuel map, need one of these, and presumable configured for the v12.

No air or vacuum leaks in the inlet side to the motor, or exhaust manifolds?

At the stoichiometric ratio of air and fuel the exhaust temperature is the hottest, either side will cool the gases. Typically run a bit on the rich side to keep temps down and help avoid detonation.

Timing has a similar effect, fire too soon and more heat is absorbed by the cylinder head, fire later and more heat escapes to the exhaust. Again want to get timing in the right area so that combustion does not happen in the exhaust manifold, but also where detonation is not going to occur.

EFI will start up in open circuit from a cold start, ie while the coolant temperature is below optimum levels. A fuel map with no correction is used, so basically the air flow meter reads the air flow and fuel is added in a ratio. For this case there is no correction to the fuel ratio based on the measured oxygen in the exhaust gases. A potential fuel supply issue or timing issue will cause the banks to run at different exhaust temperatures.

Once the coolant temperature gets to the normal operating zone the the EFI goes into closed circuit using the oxygen sensor. This tweaks the fuel addition based on oxygen levels in the exhaust gases. If the temperature differences are occurring in this mode, then it may be an oxygen sensor on one bank which is slightly contaminated causing a slower reading response time, or slightly incorrect reading.

The temperatures should be reasonably close together if both banks are doing the same thing, and there is no extra cooling of the exhaust on the cooler bank prior to the temp measurement.

I think something is not quite right and a process of elimination will sort it out. The fundamentals of air, fuel and spark need to be right, but it can be a pain in the arse to find the little problem that screws it all up.

Good luck with it.

 

+1 JL350 nice detailed post, not ur 1st rodeo.

I agree completely, lots of variables to sort. But in general no- all exhaust temps should be very close to each other 25-50 deg F (on my F cars it is less then 25 after warm up-8 cyl cars) when an EFI system is working properly.
Something is not right.
Good luck.

 

General rule on that design is if a problem of that nature exists on one bank and not the other there is a very high probability of a cam timing issue.

Most LM's have had upper chain and tensioner replacements and the incidence of being incorrectly timed is very high.

 

Good to see some progress, can be a long slow process of elimination. If it were me, I would replace all of the ignition leads and spark plugs if you are not 100% sure they are ok. Can be the really annoying source of an intermittent problem...

Was it running this bad before the rebuild? The afr reading being the same for both banks maybe a little misleading at idle with two cylinders reading low temps... Maybe more indicative of issue over a range of engine speed and load.

If you have an infra red temp gun it may pay to check the probes are reading ok, just so you can rely on the readings.

Anyway you guys seem to be working through it, best of luck.

 

I was going to say, that's not so surprising, as Rifledriver noted many times a difference between banks is timing related, but when the difference is that big (200 F) it's more likely a dead cylinder than anything else. Glad you are on the path to resolving it. If it were me, I would consider going to a COP setup to eliminate the spark plug wires which tend to be a wear item.

 

Good stuff. Now you can enjoy it.

 

I tend to leave the Italian cars mostly stock, at least visually, but I agree. When I do change something I hide it. If you are going to a custom set up there are many advantages to a COP and I would have probably gone that way.
On the Lambo there is that great screw in tube that would be easy to convert to hold a coil.

 

I build COP systems for the 550 Maranellos, but am not familiar with the Lambo engine layout or its plug wells. There's 2 important considerations for you when converting a 12 cylinder engine to COP using the PS2000:

1. You'll need 6 channels of ignition output to run a 12 cylinder engine in waste spark. This is possible with the PS2000, but it has to sacrifice 6 channels of injection to do it, so you'll no longer have sequential injection (one channel for each injector) but will have batch fire injection, where you fire 2 injectors at the same time. Perhaps Haltech offer a multiplexor expander module (as MoTeC do) where you can expand the number of ignition channels?

2. The Haltech uses external ignitors (high current switches for charging the coils), so you can use "smart" coils, which have the ignitors within the coils themselves, however they're a bit taller than "dumb" coils without the ignitors. How much space above the valve covers do you have for the "head" of a coil to stick out? This is a limitation on our 550's as too high a coil will foul the throttle linkage on both heads.

 

Well you can see one today and I'll show you what I mean about mounting the coils.

 

The pics below show what Brian was referring to. The Lambo engine has these sparkplug tubes that serve double duty as valve cover hold downs. Very cool way of doing it, which leaves more surface area on the valve covers for sealing to the head. Wonder if Lambos have better valve cover sealing than Ferraris?

Anyway, it looks like there'd be plenty of room to fit a smart type COP in there, but a little R&D would need to be done on coming up with a suitable weather proof boot for it.

I noticed that the plugs looked very close together, and learned that the bore spacing is only 95mm (vs 98mm for our 550's)

Brian was kind enough to loan me his Diablo WSM, so after some bedtime reading last night, I learned the Lambo's firing order is:

1-7-4-10-2-8-6-12-3-9-5-11

And the cylinder numbering begins at the left rear (when facing flywheel), and goes sequentially down the left bank toward the front, crosses over and continues down the right bank. So 1 & 12 are at the rear, and 6 & 7 are at the front. Also interesting that the Lambo has reverse rotation when compared to the Ferrari. It's CCW when looking at the front of the engine.

Last pic is (L-R) Ferraridriver, yours truly, & Rifledriver, having some BBQ over in Austin yesterday (pic is a little overexposed - likely because of all the flash bounce from the heads without hair )
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Interesting; your cylinder number seems to follow the Ferrari convention.

The engine I was looking at in Brian's show was a Diablo injected version, and it's called the L522. Perhaps it's only similar to yours, but it's odd that Lamborghini would number one of their V12's one way, and a different model a different way?

 

Just a correction/clarification on what I said earlier. I'm looking at a Diablo WSM, but can't confirm it's actually a Diablo engine in the LM002. After a bit of research on this, there's evidently a lot of opinions out there by people a lot smarter than me on whether the engine is based on the Diablo, Countach or is perhaps even a 3rd variety. The Diablo is a CCW rotation, as confirmed by its odd firing order which is a 132 phase sequence. Yours is CW, as confirmed by your 123 phase sequence.

This is not to say Lamborghini couldn't have thrown a special set of cams in a Diablo motor and ran it backwards (for them) in a normal front facing, rear mounted flywheel configuration for this truck.

At any rate, a COP setup could be done in that engine with your current ECU, if you're willing to sacrifice some of the injection capability that you have now.