Hunting! Help!!

[allan-m]

Hi Gents
hoping someone can throw some light on this problem.
I have a 450 which has done a grand total of 12,000 miles on a T Plate.
the problem is on steady throttle at any revs i can feel the car hesitating under my foot, making it very difficult to drive smoothly with a steady throttle.
if i hoof it, it seems ok with no hesitation or jerkyness although there is a flat spot whilst accelerating between 70 and 80mph.
Have had it looked at, the guys have tried plug leads, throttle pot, ECU,Airflow etc etc. They have suggested the injectors are sonically cleaned and have also said the Cam may be knackered (can this be the case @ 12k miles??) suggestions of an "air leak" have also come up.
your help would be great!!

[grngriff]

Hi
My griff 430 wasn't dissimlar to your symtons,mine was a loose earth near the fuel tank which kept somehow giving the lambadas a wrong signal so kept overfueling the garage said, the other one was just under the thottle pot was a wire that kept shorting on the throttle pot body a bit off rerouting by the garage all sorted
Maybe of somehelp?
Pete

[blitzracing]

You really need some proper diagnostics on this, not guess work. The Steve heath ECU mate is a good weapon for any ECU / fueling / sensor errors at around 110. The ignition side is harder as you either need one of the good old fashioned Crypton tunes to look at ignition traces, or a hand held HT tester. Ive not yet experimented with the cheap neon plug cap testers- but a set of 8 of these may well show up misfires. Mind you a complete ignition replacement (amp, coil, distributor cap, rotor arm, leads, plug caps and plugs) is not the end of the world cost wise, as long as you dont buy Magnecores and silly ignition amps! Its unlikely to be an air leak.

[Dr Mike Oxgreen]

allan-m said:

the Cam may be knackered (can this be the case @ 12k miles??)

The cam may or may not be the cause of your particular problem, but the answer to your question is yes: an under-used cam shaft could have a very short life.

An engine that only gets used every few weeks or months will suffer, because the protective film of oil will drain off. The cam lobes end up with tiny specks of corrosion, which act like sand paper next time you start it up. Once the hard outer layer wears through, the cams will wear very fast indeed. Lack of use is the very worst thing for any engine's cams.

Contrast that with an engine that's used every day. The oil film never disappears from the cam lobes, so corrosion doesn't happen. Coupled with sympathetic treatment whilst the oil's warming up, and the right oil, and that cam shaft could go on and on and on...