A little diagnostic help, por favor?

[TheGoodDR]

So here's my problem. My car starts fine, idles fine, and revs fine when you goose it. But it has a sputter/misfire at around 3500-4000 rpm. Right around when it starts to make boost. I've checked everything I can think of and am sort of stuck. I have a couple main suspects.

Timing. I set my timing with a light to factory specs but It's possible my harmonic balancer has moved on the crank or the timing notch is in the wrong place. Unlikely I know but still a suspect

Gummed up injectors. The car sat for almost two and a half years being rarely started and never driven. With fuel in it. I removed the injectors and cleaned them inside and out with brakleen but had no way to effectively test volume and spray pattern. I did add a can of seafoam in with the fresh fuel I put in it and it seemed to run smoother but still sputters.

Intake manifold gasket. I had to replace the gasket when I first got the car and I used some heavy duty Karopack gasket material. I made double sure to exactly match the ports and bolt holes for a good fit. Again, unlikely, but still a suspect.

Any help would be great as this has been going on pretty much since I bought the car. Thanks in advance.

Ferris.

[themadscientist]

sat with the same plugs in it? Sounds like ignition to me. My DR does the same thing of an on. When I am cruising along and suddenly hit it there is a noticeable stumble as it enters into boost which sorts itself out. Could be the 23 year old wiring

[bcar240]

I had a very similar if not that exact problem. Mine ended up being the injectors, two of them actually. One was intermittently sticking closed and another was leaning out its cylinder. My engine wasn't turboed, but I imagine the demands there would aggravate most injector problems.

You might get more responses if this is in one of the engine specific or mechanic sections.

[TheGoodDR]

My bad for the wrong section (though there is no FJ section.) And TMS I changed the plugs right when I got it and installed and MSD box and blaster coil as well. That said I have had the same plugs in there for over a year. They could very well be fouled. I'll check those out.

Edit: and it's not a stumble going past 3500rpm, that's as high as it will rev.

Edit no2. Oh and TMS, what are you top speeds in each gear like? I've heard some crazy figures for DR's?

[themadscientist]

I can do 160K in 5th and hover just over 4000 rpm. My car is a converted automatic so I think that has to do with the rear end.

[Murdered_T]

what kind of car is it, and if you already said, im sorry, its early.

[DevilMB3017]

what kind of car is it, and if you already said, im sorry, its early.

They're referring to a DR. Most likely a DR30 Skyline with FJ20ET. It's an awesome car, go Google it

[IanS]

I would check your plug wires for cracks, also check your spark plug gap. What spark plugs are you running, and how much boost are you making. Have you checked your fuel pressure lately?

A good way to check plug wires, let the engine idle, and spritz the wires with an old windex bottle filled with water, if there are any carbon tracks at all you will notice arcing between the wires themselves, or the wires and head.

[bcar240]

A good way to check plug wires, let the engine idle, and spritz the wires with an old windex bottle filled with water, if there are any carbon tracks at all you will notice arcing between the wires themselves, or the wires and head.

Just make sure and not to use anything flammable, like this "mechanic" around here who used wd-40 to do this and started a fire in the engine bay.