No and I also don't understand it either but I am convinced that it is the way to go. We first heard this when the cars were newer and the dealers were fixing them. Almost everytime the dealer would replace all injectors on that side of the engine. Regardless if the car had one or 4 miss firing cylinders. At least your car is throwing all 4 cylinders so no question to do all 4.

My car was even stranger as after the failure with massive white smoke I got caught with counterfeit injectors. I am currently running all my OEM injectors after cleaning despite the fact they massively failed on my car? How can this be? I don't know but I have over 2500 miles on the repair so far with zero problems.

One other factor is these are difficult to work on and the last thing you want is to go in and change one injector and then have another failure so you get to do it all over again!
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It’s been a while since my last post on here, mostly because I’m not clear on where things are myself. I had the four injectors replaced and the dealership suggested replacing all 8 spark plugs because the ones fitted were the original plugs. I thought the suggestion was reasonable.

The engine now runs fine but the issue with the car dropping into neutral under hard acceleration had not gone away - it is different though…

When I’m in Sport mode, using the paddles, and in higher gears I don’t have to accelerate hard for the car to drop into neutral. In 6th gear (worst) I don’t have to put my foot down much, sometimes just a little when going up a hill, and the car drops into neutral. 5th gear needs a bit more acceleration and 4th needs more still to cause the drop-out.

On occasion, rather than drop into neutral, the car selects another gear - I think maybe 3rd or possibly 4th and the engine revs high because of the lower gear. I’m not then able to change gear using the paddles and still have to pull over, stop and restart the engine.

On occasion, as I press on the accelerator, I can feel the power drop off just a little and if I immediately take my foot off the accelerator for a couple of seconds I can avert the issue of dropping into neutral. It almost feels like clutch slip at this point.

With the car in Drive mode I don’t seem to get quite the same effects but where the car would drop into neutral when in Sport mode, I get a sound that’s again like clutch-slip/judder for a second or so.

I have on one occasion, after dropping into neutral, stopped and restarted the engine while rolling and it made no difference, I had to physically stop and re-start the engine to restore control.

I also have the amber CEL illuminated and code P0236 which suggests a supercharger boost issue. I’ve read an incorrect reading from the MAP, possibly due to a vacuum leak, could cause the power to drop off under acceleration and in theory could blow the fuel injectors (through an overly rich mixture or backfire). I can’t see any connection between this though and the gearbox issues unless the power drop-off causes the transmission management system to disengage the drive - this still doesn’t explain the noise or my inability to change gear after. I have reset the code and the light has stayed off, I haven’t at this stage pushed the car to drop into neutral but intend to do so and see if the code returns at that point. If it does then maybe some of these inconsistencies can start to be linked and a story might develop.

 

The code may be the cause. Needs fixing.

 

Has the fluid level been checked?
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No, fluid level not checked but is on my radar as an option - together with failing solenoids in the valve block.

 

cracked separator seal can do this but usually you’ll get kicked out of reverse from time to time.

 

Hi Hazelwood,

Communication with the 8HP transmission is all via CAN, so there may be diagnostic trouble codes stored that are Network codes which begin with the letter U. Generic OBDII scan tools can only read the Powertrain codes (P-prefix). You need need a scan tool capable of also reading the U-prefix, B-prefix (Body) and C-prefix (Chassis) codes.

The TCM relies on the engine torque and speed signals from the ECM in order to orchestrate gear shifts, so it seems possible that the P0236 code could reflect a problem with engine torque or speed plausibility, which could theoretically cause the transmission to shift to Neutral. Here's a snip from page 17 of the document I have attached:



Cheers,

Don

 

Thanks. I do get U codes displayed and in fact have two error codes; P0236 related to the supercharger boost and U0104 related to a loss of communication with the cruise control system.

I’m focused on the supercharger issue for the moment 😉

I’ve just ordered some cleaner spray for the MAP sensors and tomorrow I plan to give that a try because it’s a quick and simple job….I hope!

 

I didn’t clean the MAP & MAF sensors in the end because while looking about I noticed a perished pipe that on closer inspection had gone hard and had completely broken through. The pipe was connected to the supercharger bypass valve actuator and was the one that connects to the supercharger inlet. I cut off the hardened end of the pipe and reconnected it to the supercharger.

I’m now in the strange position that the car no longer drops into neutral (or some other random gear), kickdown works perfectly, and there are no slipping issues. I can’t, and don’t yet, believe all these issues are down to one short length of rubber tube and are all now fixed but right now, that’s how it looks. Fingers crossed! I’ll report back.

 

Very common for the transmission to act up if the engine is not running right. It's all adaptable and the transmission is trying to adapt to an engine that has problems.
So count your good luck!

I think you did find the root cause of your problems so well done troubleshooting!
But from what you described I would plan to replace that entire vacuum line and maybe any others you find. They are all the same age.
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Here’s a thing…

Fixing that bit of pipe also cleared the U0104 (lost communication with the adaptive cruise control system) error!

Consulting Google, it seems the ACC talks to the supercharger and if there’s a boost issue it flags a U0104 code. Bizarre.

 

But again these are highly networked cars so yes it affects all systems. They are constantly trying to adjust to current conditions. That's why it's critical to keep the car repaired and NOT drive around with check engine lights on for years. Plus once a car starts sliding down the hill into junk with multiple problems it now becomes a very difficult game. Fix problems as they occur. Use the car to guide you as that's the entire point of the OBDII system.

I never understood guys replacing parts based on guess's and hunches or what some idiot on YouTube posted. Millions of dollars were spent to give us the tools to diagnose the cars problems. We need to use them.
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