Engine jumping problem!

[rockpuck]

Hey guys, I don't know where to look anymore. I have a Corrado G60 1990.

I have those jumping problem, when I go ''hard (not really hard)'' on the car, it's start jumping, like no power for half a second, then it come back, and stop again, I have to down or press cluth to make it stop. Really anoying.

I have change:

- Spark plug
- Spark plug wire
- Coil
- Coil Wire
- Rotor (cap coil and everything down)
- o2 Sensor
- Fuel Filter

I really don't know what it could be, otherwise than the fuel pump, but a fuel pump, work or doesn't work right?

Thanks for your help!

[vdubCorrado]

blue water temp sensor possibly...

[crazynorweegian]

blue water temp sensor possibly...

Could be the pump. Still have a bunch of electrical to look at too. o2 sensor wiring and injector loom wiring can cause running problems.

[rockpuck]

What kind of number should I get on the blue temp sensor? And the o2?

[ThatsNotStock]

I have those jumping problem

What do you mean Jumping? What does the tach do? is it also "jumping" around? Will it also do it if you are sitting in neutral and rev the engine?
Mine has a spot right at 4000 to 4200 RPM where it only fires on 2 cyl. up to and beyond that it runs fine.

[rockpuck]

In neutral and reverse he runs perfectly.

When I go really soft (grandpa driving) he runs perfectly.

When I accelerate, it's ok till I it lile 2k then he ''jumps'' I mean like if all the power was drain (for like .5 sec) then it's coming back to normal for a 1 sec and it's droping again, and it's ok again! I might try to take a video.

I don't know what happen really, when I stop using it for the winter, the car was running great, but when I took it out it started doing this.

Like I said I changed some part that I tought it could be, the engine runs way better, and the car is starting really good, but I still have this freaking problem.

[vdubCorrado]

it can be a giant slew of things but O2 sensor and Blue water temp sensor are probably the most common things to do this... since the blue water temp sensor is like $9 from German Auto Parts (.com) i would replace it anyways...

then check your vacuum line from the throttle body to the ECU. make sure it's the OE size and 1 meter exactly in length.

if that's not it then you need to start inspecting your O2 sensor harness and fuel injector harness for severe cracking...

then possibly fuel pump...

or maybe your ISV is stuck open so when you try to drive it hard it's basically as if you have a 3/4" hole in your intake manifold which would severely mess with your A/F under load.

then also check your linkage to make sure it's functioning properly on your boost return pipe... it connects to your throttle body blade and it a very early style of a diverter valve.

then check your ignition... make sure there is good spark going through all 4 wires and hooking a timing light to it. if you don't get a good solid flash from the timing light on all 4 wires then possibly a bad distributor since you replaced the other parts...

then unfortunatly then it takes you to possibly a bad ECU since the Digifant computer controlled ignition timing under load...

***lastly and possibly the easiest... are you running the OEM Bosch plugs?!***