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Mini SPI Wont Take Revs, Popping!


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#1 Zeemax_Mini

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Posted 08 May 2007 - 07:16 PM

Having got my 1995 SPI sprite auto running (was a non runner), its running really rough and wont take up any revs. The plugs are all very black even though theyre brand new, put them in and have started it a few times and now theyre really dirty black. When I start the engine, it runs but every few seconds dies then regains its idle revs. If I very slowly give it some revs it will take them up (if I do it very slowly), then nearly dies, then regains revs, then nearly dies etc. If I try and give it revs too quickly it pops through the throttle body and dies. Ive changed dizzy cap/rotor arm/plugs, cleaned the ECU ground point, checked the vacuum pipes and blown them through. Im really stuck with this one, any ideas!? Thanks, Dom

#2 Sprocket

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Posted 08 May 2007 - 11:14 PM

This again sounds like a MAP problem. Check that the correct elbows are fitted and not blocking off any of the vac line when fitted to their corresponding ports.

when the plugs are black its rich. If the MAP is reading a high pressure, IE disconnected or completely blocked, the fueling is rich and the advance will be of that of what (wide Open Throttle) at the given advance, so at some point the advance is going to be wrong as is the fueling, resulting in backfiring.

Double check the vac lines are clear and in good leak free order


Extract from a rover workshop manual

PROBLEM:

FLAT SPOT - FUEL IN VAC PIPE
Flat spot, poor performance or stalling.

CAUSE:
Fuel contamination of manifold to E.C.U. vacuum pipe.

ACTION:

THIS TECHNICAL BULLETIN REPLACES BULLETIN ROVER 200/400 NO 33 -ITEM
56

Fit a fuel trap in the system using the following procedure:
1. Remove vacuum pipe from
manifold and E.C.U, note
which end was fitted to
E.C.U.
2. Check for evidence of fuel
contamination at that end.
3. Blow out any fuel from
vacuum pipe. If fuel was
found at the E.C.U. end of
vacuum pipe, remove E.C.U.
and drain off any fuel that may
have entered. A suggested
method of clearing E.C.U. is
to insert a piece of fine
synthetic thread at least 8 cm
long into stub pipe and invert E.C.U. on a hot surface, such as a radiator
(The thread will act as a wick to drain the fuel). If no fuel was evident at E.C.U.
end of vacuum pipe it is not necessary to remove the E.C.U.
4. Obtain new hose part number MLH10006 and shorten to 220 mm.
5. Modify the original vacuum pipe by removing the rubber hose from the hard
plastic pipe (E.C.U. end) and shorten plastic pipe by 110 mm.
6. Refit rubber hose.
7. Connect new shortened hose MLH10006 between inlet manifold and fuel
trap NPC10001 long stub pipe (black).
8. Fit the original vacuum pipe in a reversed orientation between the E.C.U.
and the fuel trap short stub pipe (green).
9. Secure fuel trap in an UPRIGHT position (stub pipes to bottom) to the fuel
filter bracket with cable strap GHF1267, a redundant square hole can be
found in the bracket for this purpose.
10. Position strap vertically between stub pipes and secure strap so that base
of fuel trap locates on to top of bracket.
11. Ensure an uphill run exists between inlet manifold and fuel trap, also that
fuel trap is positioned vertically.

#3 Zeemax_Mini

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Posted 09 May 2007 - 10:23 AM

Cheers for the reply, I did take the vacuum pipes/fuel trap and ECU out and blew them all through etc...there was a small amount of fuel at the ECU end, tried blowing into it and couldnt...im guessing its blocked in there and you're not supposed to be able to blow into the ECU connector bit? Ill take it out and use the cotton wool/radiator method to dry it out and let you know! Cheers, Dom

#4 seria

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Posted 12 November 2007 - 11:28 AM

Cheers for the reply, I did take the vacuum pipes/fuel trap and ECU out and blew them all through etc...there was a small amount of fuel at the ECU end, tried blowing into it and couldnt...im guessing its blocked in there and you're not supposed to be able to blow into the ECU connector bit? Ill take it out and use the cotton wool/radiator method to dry it out and let you know! Cheers, Dom


Hi there,
My car has a flat spot, therefore would like to know the result.
Thank you.




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