The car is a 91 n/a.
The main issue just started, cold start and stumbles in higher rpms. The hot start has been a minor issue for a while now.

Recently I changed the spark plugs and wires, drove it a couple hundred miles, and now it barely starts. It barely fires up, and you have to get on the gas to keep it from dieing, until it's completely warm. While doing this, it backfires terribly.
After operating temp has been reached, it will idle fine. But when you take it up into higher RPMs it seems to stumble and I feel a major power loss.

It's also had a problem hot starting for a while. While at operating temp, I'd have to hold down the gas right after starting or it would rev up to about 700 rpms then just fall down and die. This also happens occasionally at stop lights if the RPMs drop too quickly.

I first suspected a bad water thermo sensor when it was having trouble cold starting, but checked it at the ECU and is reading normal voltage. Now I think it may be a bad coil pack? But I wanted some other opinions as to what it may be.

Thanks for any help.

 

Any opinions?

 

Check your injectors. You may need them cleaned. Also check the pins on the injector clips. I dunno about the S5s but on S4s they can have a tendency to back out.

That's where I would start. Down to the nitty gritty.

 

I think i have the same or similar problem...
Here is my case...


A few days ago my 91 turbo FC convertible started to act really weird.

My mods are:
New engine core (5000km on it)
Front mount intercooler
3" downpipe and complete motoria exhaust
HKS "mushroom" air intake
Blitz BOV
SARD fuel pump 230lt/h
air pump removed
The car is running rich below 3800 rpm.

The car turns the ignition, starts and dies immediately if i dont start with a gear on (that has something to do with the warm up system,right?) but starts fine with a gear on.

Also the car stumbles and bulks if the engine is cold and i try to boost it lightly but runs fine when the engine is at normal temperature.

A few days ago now the car started to bulk and stumble at random times when the engine is at normal temperature. When it does that i press the throttle pedal less or i change to a higher gear and it seems to get back to normal. After a while the car might be ok or it might stumble again.If i try to floor the pedal, the car seems to hesitate and stumble for a while and the engine might turn off.

So...any ideas?
Cant it be the spark plugs?
A sensor maybe? (crank angle or AFM?)
Something else?

Thank you in advance