Efi Flat spot

[Russ]

Hi ,Ive got a fault with my 88 maestro efi which is that if you set off hard in first the engine revs free and sweet to 5000 then change up and it feels flat for a second or so it seems very hit and miss but its very anoying. Ive tried several used airflow meters but the fault remains. The car had done 50k but only done 2k in the last four years. I have another set of injectors I was thinking of trying. Anyone had a simmilar fault?

Cheers

Russ

[E_T_V]

Is the MAP sensor line free from oil and gunge and airtight?

Any traces of oil in the ECU MAP sensor?

[MAESTRO_MONTEGO]

Is the MAP sensor line free from oil and gunge and airtight?

Any traces of oil in the ECU MAP sensor?

dizzy cap may be cracked or may need changing

[Russ]

Is the MAP sensor line free from oil and gunge and airtight?

Any traces of oil in the ECU MAP sensor?

Was it just the turbos that had the seporator in the line? If I fit it with the M plate ECU snd that cures the flat spot will the power be down?

Will check ign system tommorow for some reason I was thinking fuel side.

Cheers

Russ

[E_T_V]

I think the later cars got the seperator as the oil doesn't do the MAP sensor any good at all.

M plate ECU will be mapped for 95 ron petrol and a catalytic converter
If you are using normal diet unleaded then I very much doubt you'd be able to tell the difference. Even if you were using superunleaded the difference would probably not be noticable on the open road.

[MAESTRO_MONTEGO]

Was it just the turbos that had the seporator in the line? If I fit it with the M plate ECU snd that cures the flat spot will the power be down?

Will check ign system tommorow for some reason I was thinking fuel side.

Cheers

Russ

it could be lots of things,you sould check the eazy things first and then to the fuel systems.it may be some thing simple!
ive gone to diesels now as i dont want any petrol motors,brain carnt take it any more :laugh: i am a veggy now :laugh:

[G Force]

The car had done 50k but only done 2k in the last four years. I have another set of injectors I was thinking of trying. Anyone had a simmilar fault?

Cheers

Russ

If the car has been stood for long periods 6 months+ for e.g. the fuel in the tank could have gone stale. A full tank of fuel and a good run may help the situation.

It could also be faulty HT leads or worn plugs causing the flat spot / misfiring. Cleaning the injectors can also help this problem.

Personaly I would leave the leaded ecu on the car unless you experience a lot of pinking, it should be fine depending on general engine condition.

[Russ]

I changed the ignition ecu,no better,old one back on. Changed dizzy cap and rotor arm both of which looked worse for wear.Still not that better so I put a secondhand set of injectors in its now not perfect but a lot better think ill try some injector cleaner before shelling out for new ones. Is there any cars that are common in scrap yard that have the same injectors?

Cheers

Russ

[E_T_V]

You can get injectors cleaned and rebuilt if necessary

[Russ]

Just bought 2 new bosch injectors off ebay for £5 each,shame he didnt have 4 but ill soak my old injectors in cleaner for a day or so and do a very basic flow test and fit the best 2 unless somemore cheap one come along.
However,things just got a bit strange, on my back from buying the cleaner I put some in the tank and on a stretch of dark open road I swerved about to mix it in the fuel. On doing this the flat spot was there right away. Im wondering if the inertia cut off switch is at fault ie reducing the pump voltage but not tripping? ill have ago at bridging it out tomorrow and see what that does or driving into a tree at 70 while watching the multimeter!!

Russ

[E_T_V]

Fuel pump on the blink?. Check the connections to it. It has also been known for the pickup pipe to rot sucking in air causing running problems too. I'd certainly change the fuel filter at teh very least.

[Russ]

Just had 2 new fuel pumps got a cheap one which lasted 100miles off ebay then go a new bosch one for £30 all connections ok and a new filter. If the pick up pipe was holed would the fault not clear itself when the tank is full?
I really hate faults like this, im very suspicious of the inertia switch as it the plunger feels quite slack perhaps its been used to many times as an immobiliser. Not sure how easy they are to come by or if the later non trippable ones will fit.

Cheers

Russ

[E_T_V]

Fuel pumps are usually more expensive than that if they are for the EFI rather than universal ones for carbed cars. Are you sure you have the right one?

Yes if the fuel pickup was holed the problem should stop when the tank is brimmed.

Inertia switch isn't usually a common fault.

Pump voltage should be 9v normally (think it rises to 12v under harsh acceleration though). You can connect 12v to it directly (temporarily) to rule the control system and the inertia switch out.

[Russ]

I got the pump from Fakenham Auto electrics they bought a job lot of pumps from a shop that had gone bust,the one I got was for a volvo 740 I think ,same spec but srcrew fitting on pump output. Looking at wiring diagram pump gets batt voltage on start but then 8v constant.
Its like driving an MG1600 with badly set floats. Theres something somewhere thats moving about,which I recon is doing it under acceleration too.
Well once I get this sorted back to the trip computer! Im trying to get my ARG maestro manuals back from a mate ,whos left them in his turbo thats being restored. I hope once I see the wiring for a digi efi things will make sence I just hope the trip comp isnt totally different.
Cheers
Russ

[Russ]

Bridged out inertia trip, no difference fuel pump getting 9.2v with engine running. Im now getting fed up of this!
I have a brandnew montego fuel pres reg but that wont fit. I was thinking if the pres reg has failed in the open possition,rare I know, would the car swereving about reduce the fuel for the injectors? Now off to remove pres reg.

Russ