Hi, I had an I/C, DSM blow off valve, modified pop up valve, and Greddy Profec B boost control and Blitz turbo timer put on my car the past week, and the one thing I've noticed is the car is reluctant to respond to throttle inputs when restarted after a 5-30 min rest after a warm up drive (say 5 mins). I suspect it is the blow off valve, since it has been making pretty poor sounds when the car is cold, like a New Year's Party horn, which isn't the way I think these things sound-but am not sure.

Does anyone know what else I or my mechanic should check? I don't think it's the pop off valve, but I don't want to just replace the blow off valve and find it's something else!!

Again, this happens after SHORT stops of a few mins after driving the car to slight warm up or better! The throttle has almost no effect, except to possibly starve the car more, while it sputters like chitty chitty bang bang! It eventually revs up to the throttle and then things are ok, but it is definitely a 45sec to 2 min experience of not being able to go anywhere, and the car sounding like it will die out, and sometimes does? Fuel starvation, or stuck blow off valve, or too much air? I have no idea...send your guesses and happy holidays!

John-83 280ZXT, 50K miles, tuned, new cap, rotor, wires, car was running well until I/C install...is also a bit rough idle! Help!

I haven't the foggiest about FI, however, this is suspiciously similar to fuel starvation caused by vaporisation.

Check your filter and fuel pump first, just to make sure they are OK and delivering fuel from a cold start, then re-check after you have warmed the engine up [similar to the time period when your problem starts].

Best I can suggest.

HIH

Hi erstewhile respondent,

can you be more specific as to how to check the air filter and fuel supply to be sure it's working at cold? I mean, the car is great at cold starts, almost instantaneous, but what would be a way to check these elements when warm? I have a cold air intake, basically a K and N on a pipe, so we can't get much more "open air" than that, except if there's a restriction I don't understand/know about!! How does one check the fuel supply once the car's warm? Would there be a way of changing the settings so the fuel pump delivers MORE fuel at warm starts..wouldn't that be helpful? Or should I think about putting on the Bosch high pressure pump I had purchased for future mods...can you tell me anything more about fuel vaporization, it sounds very mysterious and complicated to a novice like me!

Thanks/Happy ZXmas!

John

Thats the Fuel filter, it may be blocked/dirty, unlikely but worth ruling out.

The fix on carbureted zeds with this problem, [ my 260 suffers from it, while my 240 doesn't], is to isolate the fuel lines from any heat, usually by means of a heat shield.

As I mentioned at the start of my first reply, I don't now ANYTHING about FI & Turbo's, so I hope this doesn't lead you astray from the cause.

Once again good luck!

Sounds like the blow-off valve is leaking at idle.

On an air-mass metered engine, you MUST plumb any blow-off valves back into the intake pre-compressor. Else the engine will overfuel BADLY on gear changes & if the valve leaks at idle, the engine will run poorly at all times.

Sorry, I don't understand what you mean by "plumb" the bov! Is that a fancy way of saying replace the damn thing? Is there a way to check its operation? Is there a way to loosen it's workings, so it doesn't jam up intermittently (should I spray WD-40 in it? I am a novice, and in general, the only thing I am understanding is, if it is broke, I should pull it off and buy another-is that what you meant?

John

plump the bov back into the piping..

instead of the pressure being vented out into atmposhere it goes back into piping.

A ha! Now that I know what you meant, unfortunately, that's already been done with 1" hosing feeding it back into the turbo.

No, my car is in the shop this week with head gasket work and cleaning. I'll have to see how she runs after that, though I've been told that oil leaks don't necessarily cause drivability issues.

Thanks

John