@ Morning! I’m in need of some advice and I know that some of your guys are quite at home with the older cars. I’ve just finished building a Chevette hatch which has been built to fast road / track standard so it’s got a five link rear end, discs all round, it’s fully poly bushed and I popped a cage in for good measure. Now, it did have the standard 1256cc engine which I toyed with tuning up just to remain true to
PERFORMANCE VAUXHALL the original design but in my wisdom, I’ve fitted a C20XE and it’s turned out to be a bit of a mistake. The engine is in, it runs and she goes well but only about 3000rpm and on fairly aggressive throttle inputs. I’ve been through everything – air flow meter, coolant temp sensor, timing, I even swapped the ECU and the issue remains. Appreciate you don’t have the miracle answer but I’m hoping one of your guys may have had similar problems and could offer some advice. Thanks lads. Terry.
ASounds like an interesting, if a little frustrating project! We asked our resident 90’s kid to put down his Gameboy, tie his Air Max and take a look. We don’t have the miracle answer, but if you’ve covered the basics and based on the symptoms, a couple of common suggestions were made which were the engine speed sensors (e.g., cam / hall sensor and crank sensor) and also the throttle position sensor. The latter of which is always one worth checking as it can give all sorts of odd issues and would explain why the car is kicking into life with the throttle at a certain point and above. Check the sensor isn’t loose first of all and listen for it clicking when the throttle just starts to open. If in doubt, swap it.
One other suggestion was the fuelling. A weak fuel pump or restrictions in the supply could give similar issues so if you can get one, hook up a fuel pressure gauge and go for a drive. With the vacuum pipe connected to the regulator, you should be getting around 2.5bar at idle and 3bar under load but just double check what management it has as there are very slight differences, but assuming it’s not miles off then that’s a fairly reasonable measure. Also check your coolant temperature readings… the sensors on engines of this era should be viewed as a consumable and one that’s telling lies can create all manner of running issues. The only real pain is the car won’t have the ability to display live data so it’s back to the old school sadly – swap bits, get the multi-meter out and drink lots of tea whilst sucking your teeth and having a think. Hope you get it sorted.
Old school tuning has its pros and cons