Larry
True Classic
Hi,
I have a 1979 X1/9 with a 1984 FI engine. The car has an odd miss and I'm trying to track it down.
It only happens when the engine temperature is between the midway point to 190 on the temperature gauge and 190 and it seems to be the absolute worst a tick below 190. Below the midway point and the car is perfect.
It only happens between 3000-4000 rpm and can happen in any gear. The most common RPMs are 3200 and 3800 - which are usually the rev ranges when I'm driving in 3rd or 4th gear. But it'll happen in 1st gear coming off the line - sometimes but not always. Above 4,000 RPM - the car is perfect.
The car feels like it's misfiring, but there's no backfire or noise I can easily discern when it happens. Instead the car feels like I've hit a large bump in the road and the rear wheels are bouncing over it, although the car doesn't actually bounce. When it first happened I was on a crappy road and thought at first I'd gone over a bump I didn't see.
After the problem first occurred, I replaced the distributor cap, rotor, wires and plugs. It's happened with both NGK and Champion plugs and the timing is set correctly.
I've since replaced the AFM and the water temperature sensor (that goes into the side of the thermostat), but the problem still happens.
Looking for suggestions on what it might be or what things to try...
Thanks,
Larry
'79 X1/9
I have a 1979 X1/9 with a 1984 FI engine. The car has an odd miss and I'm trying to track it down.
It only happens when the engine temperature is between the midway point to 190 on the temperature gauge and 190 and it seems to be the absolute worst a tick below 190. Below the midway point and the car is perfect.
It only happens between 3000-4000 rpm and can happen in any gear. The most common RPMs are 3200 and 3800 - which are usually the rev ranges when I'm driving in 3rd or 4th gear. But it'll happen in 1st gear coming off the line - sometimes but not always. Above 4,000 RPM - the car is perfect.
The car feels like it's misfiring, but there's no backfire or noise I can easily discern when it happens. Instead the car feels like I've hit a large bump in the road and the rear wheels are bouncing over it, although the car doesn't actually bounce. When it first happened I was on a crappy road and thought at first I'd gone over a bump I didn't see.
After the problem first occurred, I replaced the distributor cap, rotor, wires and plugs. It's happened with both NGK and Champion plugs and the timing is set correctly.
I've since replaced the AFM and the water temperature sensor (that goes into the side of the thermostat), but the problem still happens.
Looking for suggestions on what it might be or what things to try...
Thanks,
Larry
'79 X1/9