I have a boosted D16Z6 that has been built and tuned for over a year that has developed a problem and I don't know how to diagnose it because it's so intermittent.

The problem: It cuts throttle response completely. Regardless of being in or out of gear it will not rev up. It just stays at 1000rpm's until it "snaps out" of being stupid. It's not a boost cut issue because it will happen while cruising too. All of a sudden it will loose it's ability to respond to any throttle response. It last for 3-7 seconds and then starts to act normal again. In a couple of cases I've turned the key off and started it back up to it running fine. This has only happed a handful of times. Twice in less the ideal driving situations.

The car has ran flawlessly for over a year so that leads me to believe it's not modification related.

89 Civic
d16z6 turbo
h22 throttle body
tuned p28 crome 3bar e85 780cc
etc

 

CEL codes?

Have you tested the output voltages from the TPS at WOT and closed?

When was the last tune up?

 

No Codes and a recent tune up.

Haven't tested voltage because the manual I have doesn't get that specific. Whats a good manual that shows these specs?

Thanks Ron, you're a huge help as allways!

 

Turn the key to ON(II), and then back probe the Red/Blu wire (+) and Grn/Wht wire (-) in the TPS connector for voltage at closed and WOT throttle.

 

I unplugged the sensor and tested the wire side (not the sensor side) and came up with 0 for both closed and wot.

Is this what you mean by back probe?

 

The test is done with the connector plugged into the TPS. Backprobe means probing the wires in the rear of the connector.

 

After thinking about it that makes more sense Test out good! Is there any thing else that would cause this condition?

 

Is the ignition timing set to spec?

 

Yes. The coil, igniter checked out okay too. I'm really at a loss with this one.

 

Old fuel filter? Have you measure the fuel pressure? Are the fuel injectors possibly clogged?

 

Problem still exist after replacing the filter. Fuel pressure is 43psi like allways. There has been no change in cruising and boost afr, so I doubt an injector is clogged.

 

Maybe intermittent coil or igniter unit problem.

Cap, rotor, and plugs look good? Loose rotor?

Cylinder compressions?

 

How's your idle speed and stability?

I've had this sort of problem twice. The first was due to the ignition timing being way off (which you checked). The second was from having my idle screw in way too far.

 

Good compression and the tune up components still look new.

The idle has allays been a little bouncy because of the big injectors and cam. No change from when the car didn't have this issue.

It happened again today on an entrance ramp at wot. The car went from pulling like an animal to absolutely nothing. Instinctively I pushed in the clutch and put it in neutral. Tried revving it up and nothing happened it just stayed 1000rpm. Ended up coasting to about 25 mph in 1st gear and let the clutch out then it started acting normal again.

 

I'd start datalogging. You might have a loose electrical connection or something.

 

I spent all morning inspecting every wire and found nothing loose or questionable.

 

Bump

Drove the car for the first time since my last post and noticed a few things as I payed more attention.

Happened on the highway at constant speed and load. Engine turned off, no bogg or nothing, just turned off. I didn't push in the cluth and it restarted it's self after a few seconds. Everyting back to normal.

 

If the engine is actually dying.
Hmm, That might indicate a bad\intermittant main relay?