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engine rpm surge. help needed.
12-29-2017, 04:35 AM
Post: #41
RE: engine rpm surge. help needed.
what can happen (now)
lets say the IAC port is blocked now, with duct tape.
I just thought about this, how to make it safer for engine,. well, clean the bore with carb cleaner, or brake cleaner, it's just metal taped, then run the tape so it extends out the bell, to the out side TB.
put back the Air horn piping locking the tape from sucking in to engine (bad), that big air pipe must be in-place or the MAF gets really upset, (angry limphome ,mode)
on a good IAC , hot, this does nothing at all. (or there is vacuum leaks; others) all we know now is it's not the contributor to illegal air supplies.

but if the engine races still , then that is a vacuum leak, where we don't know yet.

next close (CW turned) the bleed 100% gently, not forcing any cone valve damage. it's just aluminum and thin. (saying to all not just you this)
now the RPM will go to 800rpm or even down to 400 rpm, the ISC dictates this point, if the ECU works an that ISC modulates 200 times a second the ISC goes full open NOW.

The ISC may have trouble rising to 800, and is way lower. RPM. (800 is computer hard coded rule for ISC , AC off)
At this point it can be 400 rpm or stalled or 400 to 700rpm or even 800 now) I expect 400. (the rpm must be ISC only limited)
the bleed screw was closed above so , only the electric ISC is the only source of any air, and is very limited. (about 400 rpms worth of air. (over the bleed)(crude estimates)

(recap, bleed closed, IAC blocked)

If the engine still screams now, (say 1000) then pinch the ISC air hose closed (the cold hose is it) hot engine.
we are now at ZERO AIR:
the engine now has zero air, if not stalled now, there is a huge vacuum leak.(unknown , keep an open mind on where)

that is how i find leaks. there are better ways with the smoke machine.
Some leaks are very hard to find.
seen one TB with ice freeze damage inside it where no human can see or go, sucking air. yeah a beach ! or manifold cracks very very hard to view.
Brake booster leaks, remove hose, plug it with a wine cork (T shaped kind) or best you can. yes the diaphragm here can leak bad.
pinch all hoses.
the FPR vac hose, too. but know that doing so fuel pressure goes nuts)
pinch all vsv hose.
all vacuum hoses must closed to find them leaking air. pinched or using golf tees.
all that was the easy stuff, LOL

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Messages In This Thread
engine rpm surge. help needed. - Rapom - 12-05-2017, 02:08 PM
RE: engine rpm surge. help needed. - Rapom - 12-05-2017, 03:01 PM
RE: engine rpm surge. help needed. - Rapom - 12-06-2017, 03:11 AM
RE: engine rpm surge. help needed. - Rapom - 12-06-2017, 05:39 AM
RE: engine rpm surge. help needed. - Rapom - 12-06-2017, 11:43 AM
RE: engine rpm surge. help needed. - Rapom - 12-07-2017, 04:41 AM
RE: engine rpm surge. help needed. - Rapom - 12-07-2017, 02:05 PM
RE: engine rpm surge. help needed. - Rapom - 12-08-2017, 12:21 PM
RE: engine rpm surge. help needed. - Rapom - 12-09-2017, 12:57 PM
RE: engine rpm surge. help needed. - Rapom - 12-12-2017, 01:58 AM
RE: engine rpm surge. help needed. - Rapom - 12-14-2017, 12:46 PM
RE: engine rpm surge. help needed. - Rapom - 12-14-2017, 01:00 PM
RE: engine rpm surge. help needed. - Rapom - 12-15-2017, 04:35 AM
RE: engine rpm surge. help needed. - Rapom - 12-17-2017, 01:10 PM
RE: engine rpm surge. help needed. - Rapom - 12-22-2017, 02:54 PM
RE: engine rpm surge. help needed. - Rapom - 12-22-2017, 03:36 PM
RE: engine rpm surge. help needed. - fixkick - 12-29-2017 04:35 AM
RE: engine rpm surge. help needed. - Rapom - 12-30-2017, 12:39 PM
RE: engine rpm surge. help needed. - Rapom - 01-16-2018, 01:26 PM

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