11 replies to this topic

[Ipod]

Ok my Mpi (1999) is holding back in power, feels like missfire @ between 2000-2500 RPM...hmmm
Heres what iv done to try n solve this....

New plugs and leads
ECU cleared of all fault codes
Full rolling road/dyno run
Injectors sonic cleaned, and baskets changed
Borrowed minibonkerz coil pack (cheers cocker)
New CAT

But it is still doing it, and as i said only happend between said RPM's

I am now thinking of throttle sensor, but to be honest I am just grabbing at straws

So has anyone got any ideas what the problem could be...or even had the same problems with thier MPI's

Ok cheers.... Ipod

[Ipod]

Shameless BUMP

Is the Throttle posistion sensor also know as the MAP sensor ??

[Ipod]

VERY last bump...then im going to buy stuff i dont need for her

[shadydaverave]

Hi, just a thought, i have n mpi, had snags starting and came across a little problem... i have an aftermarket metal oil dipstick, and found at night one of the outlets for cylynder 4 on the coilpack was arcing out onto the oil dipstick, was damp condition too, and this happened between 2000-2500, one to check if u have a metal dipstick! fixed it temp with insulating tape around the coil and ht lead + taped round the dipstick!

[Ipod]

Thanks shady, i do have a metal dipstick...worth a look,
Again thanks for the heads up

[Phil-R]

Check that the conectors on the pastic vacuum pipe haven't perished. Check the fuel trap and pipe for blockages (and that the fuel trap is pumbed in the right way - green connection on ECU side).

The pipe connectors are a common problem - I've repaced several of mine over the years. When one does leak bady, it may idle 'ok', stutter its way up to 3000 revs, then behave much better above 3k.

[Ipod]

Check that the conectors on the pastic vacuum pipe haven't perished. Check the fuel trap and pipe for blockages (and that the fuel trap is pumbed in the right way - green connection on ECU side).

The pipe connectors are a common problem - I've repaced several of mine over the years. When one does leak bady, it may idle 'ok', stutter its way up to 3000 revs, then behave much better above 3k.

Chrome, that is the exact problem im having...glad (sort of it wernt me going mad)..

Im a numpty but can you tell me where abouts is the connector and vacuum pipe are situated please

And the fuel trap ?

thanks for notifiying me too

Edited by Ipod, 24 November 2010 - 03:41 PM.

[coyttl]

Is the Throttle posistion sensor also know as the MAP sensor ??

As an aside - no it is not. The throttle position sensor should be up by the throttle somewhere. (Not familiar with MPi Injector setup.) The MAP is what measures the vacuum in the intake, should be connected to the intake by a vacuum hose. (On an SPi, the TPS is the black item on the opposite side form the throttle linkage. The MAP sensor is in the ECU.)

[Phil-R]

Check that the conectors on the pastic vacuum pipe haven't perished. Check the fuel trap and pipe for blockages (and that the fuel trap is pumbed in the right way - green connection on ECU side).

The pipe connectors are a common problem - I've repaced several of mine over the years. When one does leak bady, it may idle 'ok', stutter its way up to 3000 revs, then behave much better above 3k.

Chrome, that is the exact problem im having...glad (sort of it wernt me going mad)..

Im a numpty but can you tell me where abouts is the connector and vacuum pipe are situated please

And the fuel trap ?

thanks for notifiying me too

Not sure on the MPI, but on the SPI the fuel trap is close to the inlet manifold. Remove the 3 bolts holding the air fiter case and lift it out the way. There's 2 vac hoses from attached to the back of the manifold; One goes to the air filter casing and another to the fuel trap (black plastic, matchbox sized). From the fuel trap, another hose makes its way down to the bottom of the ECU on the inner wing.

Remove all connectors, check they're not cracked or split and repace any bad ones. If you can't find a replacement, you could reuse some of the connector ends between the air filter casing and manifold. Just need to make sure that there's no air leak into the manifold by blocking off any redundant hose with a self tapping screw. Finally, make sure you can blow through the pipe from the ECU end.

[nicksuth]

I had the same problems with my 98MPi when I first bout it and spent a fortune on all new sensors, plugs, coil pack, leads, ECU check and it turned out to be a fueling problem (low pressure) so I bought and fitted a PBV took it to a rolling road and got it set up = now runs like a dream.

When I removed the old pressure regulator from the fuel rail I found the O Rings perished and damaged but after a bit of a search I found that it is not a replaceable item, you have to fit a new fuel rail (bit expensive?). Personally, I think it can be changed using a bit of care?

If you go for the PBV option make sure you have a pressure gauge fitted to it.

[elliemicky]

Ok my Mpi (1999) is holding back in power, feels like missfire @ between 2000-2500 RPM...hmmm
Heres what iv done to try n solve this....

New plugs and leads
ECU cleared of all fault codes
Full rolling road/dyno run
Injectors sonic cleaned, and baskets changed
Borrowed minibonkerz coil pack (cheers cocker)
New CAT

But it is still doing it, and as i said only happend between said RPM's

I am now thinking of throttle sensor, but to be honest I am just grabbing at straws

So has anyone got any ideas what the problem could be...or even had the same problems with thier MPI's

Ok cheers.... Ipod


Hi I have a 98 MPI and it does the same thing, found oily spark plug no.4 cylinder, mechanic said may well be worn piston rings getting oil on plug and causing misfire which meant engine out and new rings, not convinced though, I am wondering if it is electrical as sometimes it runs ok! Looking at perhaps damp issues as it seems worse when raining heavily. Compression on mine seems ok, so bit confused! If you have sorted, please let me know what yours was! Have you checked plugs/cleaning any oily ones to see if fault goes temporarily? I am going to change to thicker oil 15w 40 instead of 10w 40 as wellto try and help if it is rings that should make a difference, my coil pack seemed ok and spark seemed ok when checked. Could also need valve clearance doing.
Regards, Ellie.

[Scott MPI]

ive been trying to solve my hesitation/misfire for a while now

does your car run ok when cold, the geting worce as its warming

to me it feels like the timing is out,popping exhaust on idle and misfires slightly when trying to hold a constant speed.

working on my d.i.y cylinder head ,geting near finishing but not a lot of spare time with work at mo

but no work = no money = no mini