robingb

i bought an 87 911 recently from out of state that came with a bunch of undisclosed issues (i know i should have done a PPI). in any event, one such issue is proving difficult to resolve. when i take car to 5300 rpm, the engine sputters almost as if i was at the REV limiter. otherwise the car idles and runs great. we started with the simple stuff first like replacing the distributor cap, rotor and plug wire ends. we then all of the grounds. we then ruled out the speed sensor. now i am starting to buy parts. 1st will be the fuel pump, then the air mass and then the DME unit.

anybody out there that might have experienced a similar problem? thanks, gary

theiceman

who is "we"
a good mechanic should be able to diagnose without parts swapping

irobertson

Check the coil.
I once had one that worked fine down low, but wouldn't recover fast enough to provide good spark in the higher RPMs.
Not in my 911 mind you, but a coil is a coil.

ked

coil is a good guess. before buying a fp, replace the fuel filter. & before replacing the DME unit, replace the DME relay (which you need as a spare in any case). & did you replace the plugs & wires - you might as well do a thorough tune-up... I'd do those before going deeper... good luck.

SARGEPUG

My car sputtered on the low end from a bad tank of gas. Have you ruled that out?

kusee pee

I had similar, turned out to be a faulty alternator.

theiceman

well leys not convolute the issue ..sputtering is at high end right ?

so the car is faultering when under exreme stress... not enough fuel would be obvious . possibly spark recharge time as mentioned, what about a compresion leak ? are all the head studs intact ?

I think i would check the timing advance also . I dont know the carreras but do they have weights on the distributor ?

ron mcatee

Timing for the Carrera's is mapped out in the DME brain box. The only thing in the distro is the rotor. The rev limiter is also in the DME.

SPDADCT

Looking at your thread you said simple stuff but did not mention the actual spark plugs, have those been replaced?

robingb

UPDATE: Still having problem. We have now replaced distributor cap, rotor, coil, fuel pump, switched out chip in dme, switched out air mass and checked alternator. Compression is 175 on all 6 cylinders which I understand rules out compression leak and head stud issue. When plugs were out they looked good. Nevertheless, since we are running out of options, we will put new plugs into today. Only thing left is new plug wires and if new plugs don't do trick then we will do that. If that doesn't work , (heck , I don't know).

Ps--i do think the stuttering comes on sooner as car gets warmer. initially the stuttering comes on at around around 5800rpm. after about 5 minutes or saw it comes on at 5300 or so.

robingb

spark plugs replaced. next step plug wires. if that doesn't work, after 3300 spent, fire my mechanic and hire another one to start all over. wonderful!

dshepp806

Have you measured the resistance of the plug wires? I'd put my money on the wires..but not all of my money.

Tell us of your "mechanic".....Porsche guy?


Doyle

TroyN

Sounds like fuel. The fuel filter would be at the top of my list (as also mentioned above) and in my experience something people neglect to change.

Wideband O2 sensor would tell you if you're running lean, great diagnostic tool.

robingb

oops, i forgot to mention that we did change fuel filter. it was one of the 1st things we do.

robingb

Update: We are still have the problem after replacing plug wires, dme relay and checking O2 and head sensors. Only thing left is to swap out computer (if I can find one). After that, ???? Note, high RPM sputter only happens under load.