loss of high revs

Post by **5lab** » 17 May 2004 01:08 pm

i b*ggered somethign on my engine whilst doing something (not sure what).. and now it wont rev very far.. ie i cant get above 15mph in first.. used to be able to get 25ish.. cant get above 80 at all.. any ideas what i need to change??

Post by **Janitor** » 17 May 2004 05:07 pm

could be anything !

is it running on 4 cylinders ?
check obvious first,fuel/air filters etc ok,electrical leads etc all on,take plugs out replace/clean. wedge throttle down and check you get full throttle(ie the cable hasnt slipped). you havent ran out of petrol recently have you? muck can be sucked into pipes/carb etc.......

Post by **5lab** » 18 May 2004 10:05 am

thing is its not running out of power at low revs - just at high. for instance, even in second gear with my foot lightly down it wont get above 30..

Post by **Lonewolf** » 18 May 2004 11:39 am

I suggest you do a compression test, replace the timing belt and check the spark plugs.

You say the power is there at low rpm but it dies in the rear at high rpm, is it sudden loss of power or gradual? If it is gradual, i think whatever it is is simply worn and not coping with higher rpm, if it is sudden i would assume multiple things are worn or something is failing to work properly when reaching whatever rpm you suddenly lose power.

- Valve seats may be allowing air/fuel to leak past them if worn
- My thoughts are the spark plugs are too hot and fail in the high revs causing some light pinging or misfiring that is sapping power.
- The timing belt may have stretched or otherwise not be doing its job properly causing bad high rev power.
- The valve springs are crap and it valve bounces easy.. maybe check/replace them.
- Carbon build up may be stopping high air flow with higher rpm, but if it was sudden it is unlikely, but still possible nonetheless.
- The piston rings may be worn and failing at higher rpm's allowing too much air/fuel to pass by

Hope it helps, thats all i can think of for now

Post by **5lab** » 18 May 2004 01:23 pm

its sudden, rather than gradual. i'll get full performance up to say, 30 in 2nd, then nothing, no accelleration, the car seems to start firing about once a second.. its only started happeneing since i serviced the car thou, i altered the valve clearance (to its correct amount) but i would doubt this would cause the problem.. changed the sparkplugs and hte mixture too, im guessing its the mixture?

Post by **Lonewolf** » 19 May 2004 02:15 pm

If its sudden then something is basically "giving up" at that point

- Check there isnt valve bounce, the springs may effectively be "dead" stuffing up the output when they start bouncing
- The fuel system is possible, if the pump is dodgy and cant supply enough fuel there would be a major loss in power, though normally when this happens i would expect similar results to running a highly tuned car on a stock fuel system, usually massive detonation and a dead engine. Nonetheless checking the fuel/air mix at higher rpm will remove or identify that possibility.

firing roughly once a second? if the above doesnt fix it maybe the electrical system is sh#!ed somewhere, hell it could be a dodgy alternator, turn the lights on during the night and get it to do its thing, if the lights dim right down or play up i'd almost put money on the alternator or electric system has reached the end of its life

Post by **5lab** » 20 May 2004 03:03 pm

apologies for him

dunno how he found this place. its a lad called either ian or andy

Post by **Lonewolf** » 20 May 2004 03:26 pm

I salute th poor fellow, i mean wow what a destiny, what a grand purpose in life he must have if all he amounts to is a petty flamer... I wonder what it would be like to be a lost soul without a purpose in life...

Post by **Duvel78** » 21 May 2004 08:19 pm

The message is deleted and the user banned...

A moderator will be necessary shortly...

Post by **5lab** » 22 May 2004 11:07 am

lol dont worry about it, he's just a mate of mine who was drunk

Post by **5lab** » 12 Jun 2004 12:33 pm

shees aliiiiive

replaced the carb yesterday, with the one that james sent (thanks mate). only took 45 mins!! works beutifully, full revs, mUUUCH smoother. love it.

Post by **foggyjames** » 13 Jun 2004 02:36 pm

My bet was it was something to do with the carb - worn / wrong jets, mixture, etc....but then I saw the last post! What a result!

Rest will be in the post Monday - been too busy packing my uni stuff away!

cheers

James