driveability

Hesitation (Sorry I'm a gear head not an writer )
Happens very intermittently approx 1 present of the time. To my memory only in Drive and from a stop moving forward. The car will take off fine and in second / third gear. It stops accelerating no vibration / misfire feeling. Last only a second or two. Seems to happen in pairs / then is fine for the rest of the drive. No codes stored etc. I have replaced the crank sensor and had a spare throttle pedal and installed that as well and still have the issue.
2005 CL65 180k otherwise runs perfect. Coils replaced at 100k. Fuel filter is 2 years old or so . I was told the spark/injector computer/controller was replaced at 80k. (the unit that sit in the center of the engine on top sorry don't have the correct name ) I drive the car a lot and don't beat it.
Any advise besides the dealer LOL Been doing this for about a month. I did tune-up and driveability work for 25 years, so engine controls, modern efi is not new to me. It almost feels like the throttle is being taken away from me wile driving more abruptly than just backing off from the driver seat. What ever happens it does it very smoothly void of vibration.
I remember when the coils failed and its not at all similar. I did a session of crude data logging and didn't see any odd readings and I have done this many times through the years.

Dr Matt

Is this occurring in open or closed loop? Have you watched the O2 sensor readings when data logging to see if they are normal? Sounds a lot like a lazy O2 sensor to me.

driveability

I have and its in closed loop, the hesitation is IMO outside the scope of an O2 sensors job of trimming A/F ratio. I dont see a lean situation. Driving it today it happened twice and I'm wondering how the car would react if the boost was dumped inappropriately. I don't run the car hard and I see the issue with around 10 psi of boost maybe more. Cheep boost gauge so how accurate is up in the air. With this gauge I have never seen over 15 psi of boost even at wot.
The car stops accelerating abruptly but doesn't stall or run rough and no CEL I'm not looking for someone to know what's wrong as much as a general discussion about the systems operation. HST if someone has the answer be my guest and chime in

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biker349

maybe try disconnecting battery for an hour. maybe it will reset the computer. make sure to reset all settings afterward.

driveability

Certainly worth a try !

driveability

I drove it a bit today (haven't done the battery disconnect yet) and I noticed my boost gauge may have given me some clews. When the hesitation happened the gauge boost dropped quickly and as the engine hesitation came in and out the gauge fluttered and spiked up higher. Not so high to be dangerous but it moved upward past where it was before the event . Maybe this is just what would happen when engine power/vacuum pulsates.
I am thinking at least should look at the vacuum hoses controlling the boost.

NRL

Would checking the TCU module where the ECU is have any merit?

See if there is any excessive Transmission oil that has wicked into the TCU module..via the tcu harness.. filling the tcu module.

It's quite famous oil ring issue - where the transmission oil slowly gets passed an old harness connector o-rings and wicks all the way up to the TCU module.. slowly filling the tcu module. If you pulling some G's taking off, it might be splashing around more if it's more then 1/2 or more full..

My TCU module was 1/4 full when my TCU tune was done.. and had then connector replaced with a new one to stop the really really slow filling leak.

driveability

NRL,
good idea, forgot all about that issue.
Happened again a few times, this time i held the throttle steady and looked at my boost gauge. It went to zero and stayed there until the problem cleared approx 3 seconds then it jumped up to where it should be.

driveability

I did take a look at my transmission TCU, and it had trans. oil in it. I need to deal with that now.

I am going to get a new TCU and recommendations on where to buy ?

Crissus

You can just clean it and re-use it. Otherwise the tuners like Eurocharged or BIP will sell you a TCU tune including used TCU. Thats well worth it.

NRL

Yes, just dump it out.. the Oil doesn't hurt it.. but not sure if it messes with it when it's really full..with no error codes..

Mine was 1/4 full when EC was tuning the TCU..

I need to check the level on mine again(TCU unit) and see if it's slowing down, since I changed out the harness plug connector near the transmission..to check on the wicking, boy was that fun; Not.