78 280Z Troubles

[Znut]

To all,

Well, I've made it through some of the recommendations you good folks have provided, but in the course found something a little strange and figured I'd see what everyone thought?

Things I've checked:

AFM: removed and cleaned terminal and checked flap operation - seems fine

Fuel Pump: installed pressure gauge between fuel filter and fuel rail - constant 30 - 35 pressure. Pressure holds even when the ignition is turned off.

Electrical connectors: underhood connectors removed, cleaned and reinstalled - no apparent corrosion.

RESULTS: Starts better and no more gurgling in the fuel tank, but still falls on its face when trying to accelerate.

NEW FINDING: If the plug wires are removed while the engine is running I get no result when removing the wire from the sparg plug on cylinders 1 & 2, but I know there is spark because if I put the wire end to a ground I can see it - also got a little jolt while putting the wires back on.

Any new ideas???????

Znut

[webdawg1]

Fuel pressure is around 30-35 constant?? Should be more like 36.27 psi if I remember correctly. Check the vacuum hose that connects between the intake manifold and the bottom of the fuel pressure regulator. You may have a cracked vacuum hose. Also check PCV valve. It might be plugged up really good. Also check condition of AFM hoses for small cracks. Check resistance on spark plug wires 1 & 2 with them still hooked up to the distributor cap with an ohmmeter. If resistance is more than 30,000 ohms, remove cable from cap and check the cable resistance only. If it's still more than 30,000 ohms replace the cable.

webdawg1

[mlc240z]

two bad plugs.

[gator]

yep plugs is my bet ...

[LanceM]

Valves too tight on 1 & 2, bad injectors??? Pull and check plugs, if they look good switch with 3 & 4 and see if the problem follows the plugs or stays with the cylinders. If it stays with the cylinders I'd say injectors/wiring or valves on those two, follows the plugs bad plugs get new ones...

[Znut]

Thanks guys, another excellent round of advice which is very much appreciated.

Let me have another go at it with the proposed testing and see what that reveals. I'm going to give the wire swap a try and see if that narrows things down any.

How difficult is it to pull an injector and test its spray pattern and or is this a practical approach. I'm guessing its the injectors is why I ask, I took a look a the plugs which I recently replaced and while the ones in cylinder 1 & 2 were a little on the black side they were just bearly moist with fuel - I'd expected them to be very wet given the car had been running for about 10 - 15 minutes.

Znut

[ecp48]

Another thing for you to check. Do all of the spark plugs look the same or are 1 & 2 cleaner than the others. If a spark plug is not firing, it will be coated, due to the fuel injected into the cylinder without spark.

If the 1 & 2 plugs look particularly clean, possibly those injectors are clogged.

[Znut]

Well folks, I'm making a little progress, but I've run into a bit of a snag. I decided to pull the EGR valve to see what it looked like and wouldn't you know both the valvle and the intake manifold were alomost completely plugged up. The manifold was so corroded that I'm not sure what it is suppose to look like.

So, I'm hoping one of you good folks have a good picture or can send me to a location that has one?

Any ideas???

Znut

[webdawg1]

Have any pictures of what you are talking about? Like they say "a picture is worth a thousand words".

webdawg1

[sideshowbob]

Two bad injectors.

[sideshowbob]

The only good EGR valve is a missing egr valve.

[sideshowbob]

Do you have a bicycle pump or a small compressor (the tire type is fine)? Testing injectors for fun and profit is easy. Or you can do it on the car by disabling the ignition and cranking the whole set into six jars.