I was trying to accelerate past 100 mph but the car seemed to struggle and sputter, no significant power at top end. I already changed the fuel pump and the problem is still there. Any ideas? Thanks, Reno Also it's a 1984 928S Euro 310 Hp.

 

Maybe the engine can't breathe. Clogged air filter or cats? How about distributors or plug wires? Fuel + air + spark...

 

I changed the fuel filter, fuel pump, wires, plugs, fuel reg(2), Fuel dampner, MAF, temp II sensor. I know I need a clutch can that be the cause? Thanks, Reno

 

If you can drive your car from a dead stop in 3rd or 4th gear without stalling, the clutch is slipping. If it is slipping that could be the problem

 

If the clutch was slipping wouldn't the car still rev to red line but not transfer the power to the wheels??


What gear were you in when you went for the rip? RPM ??


BTW I have the same issue but haven't had time to trouble shoot with my T-belt alignment issue still lurking. My first plan is to test the CAT's for plugging.

 

How about vacuum advance on the distributors? spark coil? dreaded green wire? Timing?

If it were the clutch, the engine would continue to rev upward with little or no gain in speed.

It sure sounds like ignition to me

 

Hi Reno,
Is the car a Euro LH equipped (twin distributors, or the K-jet (single distributor, mechanical injection) ?

Has trhe car been modified in any way to pass US emissions ?

Did the "low power" develop quickly or slowly ?

 

LH Equipped, Reno

 

Has the car been modified in any way to pass US emissions ?

Did the "low power" develop quickly or slowly ?

 

Sorry for posting late, Scott c-Cannot adjust timing, my car has the dual distributors and I changed both coils. Steve C-I was able to start from a dead stop in fourth gear without stalling. When I did my run of 100mph I was in fifth gear. John Speake-My car is the twin distributors and LH equipped. My car was modified for US delivery. One other thing, sometimes not all the time, if i floor it in first or second gear the car feels like it has turbo lag or a late power surge. Thanks for all the replies, Reno.

 

Hi Reno,

What you describe sounds like weak mixture.

Has it been eqippped with cats and an O2 loop ?

 

John, Yes I Do Have cats. This weekend I had my car at my mechanic, where he performed a diagnostic of the exhaust gas. Originally I had failed for NOx, Standard reading is 1146 and my car's result was 1347. My mechanic told me it's fine. What causes a weak mixture? Thanks, Reno

 

Hi Reno,
There never was a factory version of the LH 16v with cats and a full O2 loop. Does your car have an O2 sensor, and loop back to the ECU ?

On an "open loop" Euro S2, the classic weak mixture problem is the MAF. You said you have changed it - was it a new exchange unit ?

If you car has some sort of closed loop O2 system, it must be a strange installation............as I said, there was never a factory O2 kit for the LH 16v.

There was of course for the early US 32v. but that system probably wouldn't work well with a 16v 4.7l

 

John, My X-mechanic charged me 870.00 for the MAF, it better be new. I failed inspection here are my readings CO%-Standard-0.86 My results-0.00 HC-Standard-152 My results 13 NOx-Standard-1146 My results-1347 With the above readings, can this be the source of my problems? I also have the computer serial # if it helps 928 618 123 00. Should I eliminate the cats? Thanks, Reno

 

Hi Reno,
Both your CO and HC very low readings suggest a very weak mixture, even taking into account the airpump. The NOx can be high if mixture too weak or too rich. Need to be near lambda =1 for lowest NOx.

Ask you garage to disconnect the air pump and asdjust the MAF for a CO reading of 1%. The set the idle speed to 700rpm.

Connect up the pump and try the emissions test again.

If the MAF won't adjust to 1% then it's faulty, or the car has another fault (air leak etc)

I assume your car has cats but no O2 loop, as the LH ECU number you quote is correct for a S2 Euro.

hope this helps.