Wierd transmission problem?

[Etienne]

About 6 months ago, the day I was moving to philadelphia, my car wouldn't reve past about 2k rpm. If the car was in neutral it would rev through, but driving, it would start to buck. However, the next day the problem was gone -- until yesterday.

Yesterday I start off to work, and the same thing happens. So I park the car and take the lady's car. This morning I start the ti and she seems to be fine... only now it happens at about 3500 rpm.

I am assuming this is transmission related in some way because the car will rev to red-line in neutral.

Any thoughts?

[andyman7931]

is it an auto? I'm assuming it is... also, how many miles are on it?

Do you have a check engine light? if the bucking is coming from the engine, it should trigger something. The problem could be engine related since there's no real load on it when in neutral, which is why it can rev up to redline.

also, you should check the transmission fluid level.

don't know if this is applicable or not, but I'll throw it in anyway... When I put an auto transmission with a broken throttle position cable into an e30, it would only rev up to 2 grand and would accelerate very very slowly. I've never checked how the feedback to the transmission works in these cars, but it could be related to that somehow too.

[Etienne]

No its manual... and as I thought about throughout the day I started thinking it is probably not transmission.

I was thinking maybe a timing issue or something?

The car runs perfectly fine as long as it doesn't get to the "bad" RPM... which seems to vary.

[DustenT]

No its manual... and as I thought about throughout the day I started thinking it is probably not transmission.

I was thinking maybe a timing issue or something?

The car runs perfectly fine as long as it doesn't get to the "bad" RPM... which seems to vary.

Do some maintenance. Change (in this order): fuel filter, spark plugs and air filter. Next in line would be the fuel pump.

[Etienne]

The problem has gone away again... until another day at least.

plugs and air filters have been changed already... fuel filter is an option, and I've thought about doing it anyway, but if it was related to fuel pump/filter why would it be so intermittent? Why would it be at a random specific RPM every couple of months?

[andyman7931]

you could try scanning codes and see if there's something there...

could you have had bad gas? one of my ti's intermittantly stumbles on acceleration when I run some 87 octane gas, my solution is to run 91 or higher.

[Etienne]

I never put anything less than 91 octane... though I had considered that as a possible reason. Usually I run 93 or so since 91 is actually somewhat hard to find unless I can get to a Sunoco (which is my preferred stop).

No codes or anything come up (the CEL isn't on). At this point its a minor annoyance since it is very rare and generally goes away within a couple hours to a day, but I'm concerned about it perhaps being a red flag to some other issue...?

[dave45056]

I have bought bad gas twice in my life... both times at Sunoco. FWIW
Have you thougt about your plug wires or Camshaft postion sensor?

[Etienne]

plug wires on the next item on my list of things to be replaced... so I'll see if that makes any difference. the Camshaft position sensor... wouldn't that be a more static problem?