Bad stuttering when downshifting into 2nd @ WOT.

Post by **guadofreak** » Wed Feb 16, 2005 4:23 pm

I have noticed this only really happens when I Am doing about 50-80 and the car downshifts when I floor it to pull ahead in traffic.

1994 Q45t 153K miles

Usually only happens after the car has been running for over 15-20 minutes or so. It is very anooying. Also happens when I am in the higher rpms in 1st.

Any ideas? possibly transmission related? when the car is has only been running for about 5-10 minutes it runs perfect and like a champ!!

Post by **911/Q45** » Wed Feb 16, 2005 5:17 pm

Low fuel pressure? Failing pump or FPCU, clogged fuel filter.

Post by **DAEDALUS** » Thu Feb 17, 2005 12:50 am

Could be. Everytime you floor it you increase injector pressure 30% or so, in addition to duty cycle and pump voltage (3-speed pump). If the pump or FPCU is marginal it might be having trouble keeping up with demand. Problems with the FPCU have been known to show up only after running for a while, after the solder joints have had time to heat up.

Post by **guadofreak** » Thu Feb 17, 2005 4:18 am

interesting indeed. The fuel pump was replaced a while ago I have to check on the FPCU...

Post by **Aussie Q45** » Thu Feb 17, 2005 2:05 pm

Hope you don't mind me asking a Q on your subject. My '89/90 Q45 is doing the same thing (97K's) and I am in the process of replacing the spark plugs. I noticed that you have 153K's up. Have your plugs been changed? Or am I hoping for a cheap fix and should I be looking elsewere for my problem. I have replaced the fuel filter. Where would I find the fuel pump and FPCU?

WOT=????????

Post by **911/Q45** » Thu Feb 17, 2005 4:48 pm

You are right on the money for your plug change, 60K miles in US=97K klicks in AUS. The fuel pump is inside the tank and the FPCU is suspended above it. Your pump and FPCU should be good at your mileage(kilometerage?). WOT=wide open throttle.

Post by **squeefoo** » Thu Feb 17, 2005 5:19 pm

guadofreak wrote:I have noticed this only really happens when I Am doing about 50-80 and the car downshifts when I floor it to pull ahead in traffic.

Also happens when I am in the higher rpms in 1st.

Any ideas?

Rev Limiter.

Post by **guadofreak** » Thu Feb 17, 2005 6:59 pm

squeefoo wrote:Rev Limiter.

Definitely not the rev limiter. Also happens from 4.5K rpms up.

my plugs were changed 30K ago so i know those are ok. I think I am going to try a newer FPCU and see what happens.

Bad stuttering when downshifting into 2nd @ WOT.

Bad stuttering when downshifting into 2nd @ WOT.

Re: Bad stuttering when downshifting into 2nd @ WOT. (guadofreak)

Re: Bad stuttering when downshifting into 2nd @ WOT. (guadofreak)

Re: Bad stuttering when downshifting into 2nd @ WOT. (squeefoo)

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