I have an 03 with 45000 miles on it. Manual transmission. A while back, when it was being lugged, it would stutter realy bad. By lugged, I mean starting in first with not enough clutch or caught out a gear low with the accelerator mashed. Giving the car more gas made it stutter and lose power worse. It never stalled though.
I gave it a tank full of injector cleaner (chevron) and it cleared up a little, so I took it to the dealer, and they did a full injection cleaning ($150). They said it was from the ethanol in the gas around here. The stuttering completly cleared up...for about a week.
So I asked myself, what is different? I've been using 10% ethanol for a while and this is the first time this has happened. The only thing different is that I was trying to shift at 2500 rpm, to see if I really COULD save 10% on gas mileage like the magazines say. Well you can. I've also read that on Porsches, the quickest way to ruin a motor is to baby it. So I thought, maybe this 10% gas thing isn't worth it, and started running the motor to hard at least once a day, and I hold my shift points a little longer 3500 or so.
Haven't had a problem since. The car is more fun to drive and I hardly miss the extra 30 miles a week I went on a tank. Still, it seems weird that shifting early would lead to deposit buildup in the engine that is cleared away by hard driving. I feel silly even writing this, but its what I observed. Maybe I'm missing another obvious explanation....
stuttering baja
Moderator: bajabob
Lugging ANY motor is bad for it, as bad as over-revving or worse.
The stresses on the crankshaft, pistons and bearings are as bad or worse, as the shuddering produces a hammering which occurs repeatedly.
It's most certainly not worth the gas mileage in my book.
Anyway, what you are feeling likely has NOTHING to do with deposits forming in the engine and especially not from them forming due to shift points.
Ehtanol is an interesting possible culprit IF you indeed needed an injector cleaning and ONLY IF you ran on non-ethanol fuels for say 30-40k miles and then suddenly changed to fuels with ethanol.
This CAN be a (usually one time) problem BECAUSE ethanol can act like a solvent. For instance, IF you had a particularly dirty fuel system (from deposits left in the tank which were caused by evaporating fuel over the first 30-40k miles) the regular non-ethanol fuels you used during that time would not affect the deposits. HOWEVER, once you switched to fuels that contained ethanol the alcohol could soften/loosen and free those deposits sending them off to clog fuel filters and possibly injectors.
It's mostly been seen in the marine industry BECAUSE those tanks tend to be older and to sit and allow evaporation of fuel leaving deposits behind and after 10 years had enough deposits to wreak havoc with fuel systems once freed.
But I'm not convinced that is your case.
Kev
The stresses on the crankshaft, pistons and bearings are as bad or worse, as the shuddering produces a hammering which occurs repeatedly.
It's most certainly not worth the gas mileage in my book.
Anyway, what you are feeling likely has NOTHING to do with deposits forming in the engine and especially not from them forming due to shift points.
Ehtanol is an interesting possible culprit IF you indeed needed an injector cleaning and ONLY IF you ran on non-ethanol fuels for say 30-40k miles and then suddenly changed to fuels with ethanol.
This CAN be a (usually one time) problem BECAUSE ethanol can act like a solvent. For instance, IF you had a particularly dirty fuel system (from deposits left in the tank which were caused by evaporating fuel over the first 30-40k miles) the regular non-ethanol fuels you used during that time would not affect the deposits. HOWEVER, once you switched to fuels that contained ethanol the alcohol could soften/loosen and free those deposits sending them off to clog fuel filters and possibly injectors.
It's mostly been seen in the marine industry BECAUSE those tanks tend to be older and to sit and allow evaporation of fuel leaving deposits behind and after 10 years had enough deposits to wreak havoc with fuel systems once freed.
But I'm not convinced that is your case.
Kev
Drive it properly.
i shift at 2500 occasionally but when i do i dont mash the gas pedal. Im only about 20% throttle, therefor very low engine load and no shutter.
you can get away with short shifting if you give very small throttle inputs and keep the engine loads low. Of course everyone behind you will be all upset but it really does save gas.
Mashing the throttle at low RPM however can be harmful to your engine as stated. There is no reason to do it. It does no good and does quite a bit of bad.
i shift at 2500 occasionally but when i do i dont mash the gas pedal. Im only about 20% throttle, therefor very low engine load and no shutter.
you can get away with short shifting if you give very small throttle inputs and keep the engine loads low. Of course everyone behind you will be all upset but it really does save gas.
Mashing the throttle at low RPM however can be harmful to your engine as stated. There is no reason to do it. It does no good and does quite a bit of bad.
I tried paying attention to shift points tonight.
In 1st and 2nd I rarely shifted below 4k.
In 3rd maybe a little lower.
YES in 4th I could shift earlier.
and rolling along in 4th or 5th revs could get as low as 2k...
But if acceleration was needed with even the slightest amount of speed after that it required a downshift.
Though I didn't feel ANY shuddering. Even when pulling SLOWLY away from 2k.
Kev
In 1st and 2nd I rarely shifted below 4k.
In 3rd maybe a little lower.
YES in 4th I could shift earlier.
and rolling along in 4th or 5th revs could get as low as 2k...
But if acceleration was needed with even the slightest amount of speed after that it required a downshift.
Though I didn't feel ANY shuddering. Even when pulling SLOWLY away from 2k.
Kev
yes, its gone away since I started driving properly 
I wasn't typically lugging the motor except when I was in the wrong gear accidently, or had to accellerate unexpectedly.
Its interesting what you say about ethanol, because I avoided it for years. No ethanol went into my tank for 35000 miles. But then, as a pollution measure, all of the pumps in houston switched to 10% ethanol, so I was forced to use it. Of course I didn't try this fuel mileage experiment until then either so who knows.
I think the lesson is no sort shifting under power in the baja...
I wasn't typically lugging the motor except when I was in the wrong gear accidently, or had to accellerate unexpectedly.
Its interesting what you say about ethanol, because I avoided it for years. No ethanol went into my tank for 35000 miles. But then, as a pollution measure, all of the pumps in houston switched to 10% ethanol, so I was forced to use it. Of course I didn't try this fuel mileage experiment until then either so who knows.
I think the lesson is no sort shifting under power in the baja...