Cant floor it!

[dubber91]

Right i have a 1988 13b 6 port in my beetle that when i stamp my foot to the floor seems to limit itself........and wont rev. If i am gentle with the throttle application it will rev up to the redline no worries. The point at which it starts \'limiting\' is, i would estimate, at around the point at which the throttle spindle comes off the throttle position sensor. Any ideas as to what this might be?

Cheers in advance guys

Steve

[dubber91]

anybody? please help!

[MikeLMR]

could be somthing starving the engine for fuel ?

[dubber91]

Possibly, but its fine up to that point.....its the same relativ throttle position regarless of rpm...so even at 2000RPM and i nail it (go past this point on the accelerator pedal) it will seem to limit itself, likewise at 4000RPM...

STeve

[jon haines]

had the same problem a few days ago. have a 1990 n/a that i got a little while ago and gave it a first real run after doing some work and found if i floored it it would limit and pull very badly at mid revs but drive at very gentle throttle, turned out that it was running very rich and flooding itself at full throttle, put it on four gas and turned the fueling down and it know runs a treat.  could be lucky if youve never tuned it, jon

[dubber91]

how can you turn down the fueling?

[jon haines]

on the seven theres a resistor that adjusts the fuelling. its a round black tube slightly smaller than a penny in diamiter and about 15-20mm long you remove the top cap and inside theres a round spindall that youre supposed to use a mazda tool on but you can get it with a pair of long nosed pliers and twist it anti clockwise to turn down the fuelling and vise versa. on the seven it was located on the left of the engine bay just infront of the suspension strut, i am not great with a computer but could poss manage a picture to your email if it would help

[dubber91]

hmmm a pic would be really helpfull....cheers But is the phenomenon you speak off like the engine is still spinning but does not want to rev any higher? It actually sticks at whatever RPM you choose to floor it at?

Cheers for all your help
Steve

[jon haines]

no, it didnt stick. the car would yuck for want of a better word. the car would loose power for a second then pick again for a second and keep repeating until i let off ther pedal.

[dubber91]

i dont think this is the same problem then....it feels more electrical than fuel orientated as well. It really is like the engine hits a wall and wont rev any higher unless you let off, and the rev it

[jon haines]

fair doos, but dont write of fuelling, mine felt more like the coils or plugs breaking down or arching than fuelling. have you tried getting any fault codes, if its a sensor problem it might show. on more modern cars you would probably suspuct the air mass meter and unpug it and try running it to see if it improved.cavaliers had a simular problem on their air flow meters. jon

[dubber91]

ohhhh i might try the airflow meter...got another one of them to try

[dubber91]

right, AFM changed, no change.....Changed the fuel filter.....No change.....Really starting to get to me now!

[jon haines]

would still consider over fuelling/air intake restrictions or even air leaks causing fuelling problems.does it rev freely when stood or is it happening regardless of load conditions. under load might suggest the ignition is breaking down under pressure but i am crap at diagnoseing without having a play myself but i have some friends at bosch tech help line and will pick thier brains tomorrow just in case were missing anything obvious.

[dubber91]

ok....im impedence checking the injectors now


it revs freely when stood yes