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Fri Dec 13, 2024 7:22 am

Hi all, I own a 912E and had it upgraded with a 2270 kit. The motor is a killer! However, the EFI I now have is from CB Performance (not the most recent version, this was installed @ 3 years ago) and it is a nightmare - stumbling and hiccuping all over the rev range. I've spent numerous trips to the shop to fine tune and while initially all seems reasonably fine, within an hour or so of driving (especially at highway speeds) the hiccuping/stumbling returns and it just has us all scratching our heads. Time to throw this system into the fireplace and start over... also it would be ideal if the new system was something reasonably intuitive so that most any shop could work on the car, the CBP system has some shops very confused. Thanks all!

Sat Dec 14, 2024 1:17 pm

Could it be something like a faulty sensor or a vacuum leak that is causing the issues?

I had microsquirt on my past beetle project and it was okay, but I had some stuttering issues on occasion. But would go away.

I’m going to be going with the Holley Terminator X system in my ‘67 912 with a 2387cc VW powerplant. Pretty simple setup, has a solid self tuning capability, and a lot of tuners know how to use it as it’s one of the most popular LS/V8 systems.

It’s also the kit that CB is now selling. Also places like Red-E Motorsports uses it and they have a handful of really helpful YouTube videos outlining how the ECU can be used with a multitude of intake options. Works well with both naturally aspirated and boosted applications.

Hope that helps!

Mon Dec 16, 2024 7:32 am

Bret Young wrote: Could it be something like a faulty sensor or a vacuum leak that is causing the issues?

I had microsquirt on my past beetle project and it was okay, but I had some stuttering issues on occasion. But would go away.

I’m going to be going with the Holley Terminator X system in my ‘67 912 with a 2387cc VW powerplant. Pretty simple setup, has a solid self tuning capability, and a lot of tuners know how to use it as it’s one of the most popular LS/V8 systems.

It’s also the kit that CB is now selling. Also places like Red-E Motorsports uses it and they have a handful of really helpful YouTube videos outlining how the ECU can be used with a multitude of intake options. Works well with both naturally aspirated and boosted applications.

Hope that helps!

Thanks very much, yes quite helpful. I'll look into a possible vacuum leak or distributor problem (suggested to me elsewhere)

Wed Jan 01, 2025 12:41 pm

Most fuelling problems end up being ignition ones. I would start there from experience.
Perhaps something you have forgotten needs rechecking, but will seem so obvious once found.
Jenvey dynamics, Bridgnorth, Shropshire do fuel injection conversions.
I can't vouch for them as not used them yet.

Wed Jul 16, 2025 8:32 pm

At the original poster:

99.9% of the time it's not the ECU. Most times it's something about the engine (exhaust leaks, intake leaks, RF noise from high resistance plug wires, etc) or the install (poor electrical connections, bad grounding, fuel plumbing not correct, etc).

If the engine is perfect and the install is perfect, then it needs a good tuner to spend time on it or the owner needs to learn the tuning process (BEST PLAN) and tweak and improve it over many days and varying weather conditions.

With the said, if you are still dead set on changing ECU, consult the local dyno shops and tuner shops in your area. Once you have a guy/shop you're confident in, go with the ECU that he's most comfortable tuning. Some guys swear by Holley. Some guys prefer FuelTech. Some will only tune HalTech. Etc...

But know this: No matter that the ECU and who tunes it, if there is something not 100% right with the engine or the install, it will never run right more than a few miles.

Thu Jul 17, 2025 11:41 am

Along with what the others have stated....think about what you reported:

You said....It seems just fine until about an hour after leaving the shop driving at highway speeds.

So if it drives fine when you start out...its capable of driving fine. What happens or could happen during an hour of driving?

1. Number one thing is that something is getting hot/heating up. This does not always mean that its too hot. It could simply mean that whatever sensor is emasuring the heat may be in the wrong range or the worng place on the engine.

Think about cylinder head tmperature or many aftermarket systems use a water cooled vehcile coolant temp in the exhaust air stream under the head. If yours uses that it could simply be too close to an exhaust manifold.
Think about intake air temperature. Think about oil temperature.

What sensors does your system have?

2. It could be an ignition coil getting hot. What ignition do you have? What coil do you have?

3. It could be voltage dropping if the alternator is not keeping up and your system is pulling from the battery.

4. If your fuel tank is not squeeky clean it coul be silt plugging up the tube, the in tank sock filter (if you have one) or the fuel filter itself. This one is super common.

5. If your fuel pump runs hot it could be the pump overheating and dropping pressure. Very common.

Ray

Sat Jul 19, 2025 3:19 am

raygreenwood wrote: Along with what the others have stated....think about what you reported:

You said....It seems just fine until about an hour after leaving the shop driving at highway speeds.

So if it drives fine when you start out...its capable of driving fine. What happens or could happen during an hour of driving?

1. Number one thing is that something is getting hot/heating up. This does not always mean that its too hot. It could simply mean that whatever sensor is emasuring the heat may be in the wrong range or the worng place on the engine.

Think about cylinder head tmperature or many aftermarket systems use a water cooled vehcile coolant temp in the exhaust air stream under the head. If yours uses that it could simply be too close to an exhaust manifold.
Think about intake air temperature. Think about oil temperature.

What sensors does your system have?

2. It could be an ignition coil getting hot. What ignition do you have? What coil do you have?

3. It could be voltage dropping if the alternator is not keeping up and your system is pulling from the battery.

4. If your fuel tank is not squeeky clean it coul be silt plugging up the tube, the in tank sock filter (if you have one) or the fuel filter itself. This one is super common.

5. If your fuel pump runs hot it could be the pump overheating and dropping pressure. Very common.

Ray

Suggest to check the valve adjustment at first. Do a compression and leak test after valve adjustment. If installed, check hydraulic lifters and valve train.