Mexican Beetle won't accelerate smoothly

[paullanzarotti]

I am appealing to other FI Mexican Beetle owners

I have a 1998 Mexican beetle that has a weird issue at low revs. I have replaced the relay, ICU, Engine Temp sensor, Rotor arm, cap etc etc and cleaned out all the breathers but the problem persists. I have even changed the ECU as I have a spare and that has made no difference.

It is hard to describe, but basically, my car idles fine, and accelerates decently...but when idling, giving it the minimum amount of throttle input will cause the car to go straight from idle to 1300 RPM. I have tested it quite extensively...its nearly impossible for me to get the engine in between idle and 1300. Its either idle (800 rpm) or 1300+

It's really annoying while I am driving, because if I am just cruising i can feel the car jump when i let off the throttle, and then when I give it a bit of throttle again, i can feel the car jerk forward because the engine trying to get more gas then I'mm telling it to. Accelerating from a stop can also be a bit jerky, but that can be smoothed out with the clutch.

I have checked the angle of the Throttle Sensor with VAGCOM and it increases in 1% increments and looks normal. The Lambda sensor also seems to be registering a normal voltage.

I was wondering if this is normal for the Digitfant system?

P

[zumsel]

Hello,

is this only with cold engine, or also when the engine is warm?
Cruising with 1300 rpm is a little bit low, I think. It's not the most modern engine, although it has FI.
I don't have a RPM-meter in my car, but I guess, 1300 rpm is less than 30 km/h in 3-rd gear, or < 40 km/h in 4-th gear.

Greetings Zumsel

[paullanzarotti]

I have checked a few things since my last post and this is what I discovered.

The problem I am having is that when I open throttle by 1% the TPS (sensor) is delayed in reading 1% angle. So, the throttle opens and the extra air makes the car run lean and the revs drop until the TPS sensor eventually reads 1% and then the revs jump from 820 RPM to 1100 RPM.

I have replaced the TPS, Idle Control, Head Temp Sensor and still the problem remains. It seems as if the TPS registers movement to late and it makes driving the car i traffic very, very difficult.

If I put my foot on the gas just a little the car jumps and jerks. I don't know how to fix this. I have tried a different ECU (I am using Manfred's 1603 chip but also have a regular ECU) and it is the same with both.

Any ideas?