after replacing my map sensor with a 3 bar one to cure a missfire,i seem to have got a new problem!

on boost after a certain time,i get a slight thud noise from under the bonnet and the car will lose power and not run to great.

by the time i have nursed it to somewhere safe to stop,it will cut out,get out lift the bonnet to see if anything obvious is amiss,get back in the car ,it will then start and run normally !!

the spec of the car is,3 bar map sensor,greens,exhaust,filter ,actuator,and pectel management.

before the map sensor replacement the car would not do this,leads,cap plugs etc all check out fine.

any ideas guys?

cheers

 

check fuel pump voltage and fuel pressure under load

 

got it, the 90 degree bend in the map sensor pipe was partially blocked!

the car still doesnt feel very fast though!

 

grr just did it again,high boost,3rd gear uphill,felt like a rev/boost cut,need to switch off then on again,to make it run better,

please help!

 

inlet hose collapsing maybe?

 

amal valve perhaps? does it have correct chip etc for 3 bar map sensor?

 

possible,but its a silicon ggr,and seems pretty strong,only happened since i replaced the map sensor.

 

it doesnt have an amal valve,it has pectel,so i would have thought it would be fine with the 3 bar map sensor?

 

quick question...

the map sensor that came off the car... was it a 3bar one???

if not.....

 

I would check the chip you have, as it sounds what you are experiencing is overboost protection.

Martin

 

this is the ecu



and the other map sensor? i'm not sure tbh!

i still have it,but can't identify it.

this is a rather poor underbonnet shot





cheers guys ,any help is appreciated

had a guy look at it last week,used to work on them from new,plugs ,leads,coil and sensors all showing ok,when running with the old map sensor,the injectors went from 10ms unplugged to 30 ms with the map sensor all connected.

 

If the old map sensor was a 2 bar it was chipped for that - had the same issue on an rs500 last year.

 

You really would increase your enjoyment of the car if you had it set up professionally.

From some of your posts, you don't have a lot (any?) experience of cossies, which in itself isn't a problem - everyone has to start somewhere, but you could end up spending a few hundred quid buying parts to get the car to run better and fail, simply through lack of experience, and then you'd get pissed off with the car and curse the day you bought it.

Get someone who knows what they are doing to go through the spec, make sure everything is specced correctly and replace unsuitable parts, and then enjoy yourself. It'll be cheaper in the long run.

 

i totally agree,and your right no previous experience of cosworths,but i only get 1 day off a week,so time is limited to tinker or take it places to get it looked at,thought i would ask the question as i thought other cosworth owners might have had the same problems,

its definetley on the boost or fuelling side of things as the electrical side of things checked out fine.

is there any cosworth knowledge in the stirling/falkirk area?

 

what are the injectors ? 355s or 803s ?

what is the part number of the map sensor you removed ? APS 05/01 or 02/03 ?

is the chip for air injectors or amal valve ? (looks like the actuator is connected straight to the compressor housing, thus meaning that the boost is currently solely controlled by the actuator spring stiffness and shaft pre-load) what spec is the actuator ? is there more than half a hole of pre-load on it ?

have you changed the fuel filter ?

have you rewired the fuel pump and radiator fans ?

 

pic of the map sensor i took of the car




injectors,how can i tell the difference?

chip,not sure at all,doesnt have are injectors or an amal valve that i can see .

not changed fuel filter or rewired fans or pump,

and not sure of the actuator,again tell me what to look for and i will check.

thanks and all your help is appreciated!

 

That map sensor 200kpa is only 2 bar mate

 

That number on the MAP means either 2 or 3 BAR, can't remember which is which off hand, easiest way to tell injectors is to look at colour greens bosch 803's whilst light blue are 400's, I suspect your car will have the former or the Siemens 55LB equivilant.

Fuel pump and fan wiring should be checked for safety sake and ideally rewired, I don't think this is your problem though as you say when switched off and started again it's ok till next time, which indicates management problem hence me saying overboost but as said an incorrect map sensor will also cause this problem along will incorrect fuelling.

Martin

 

the injectors are green,does anybody want to swap a tried once 3 bar for a working 2 bar sensor?

i thought with that spec it should have needed a 3 bar?

cheers

does it help if i say it lacks power? and has a slight of idle miss?

 

There are chips for greens that only run 2 bar map sensors ,so i would defo try a working 2 bar sensor and see how it is then before you start changing things , the numbers 20/200 kpa are its operation window and relate to 2 bar

 

The colour of the injector does not tell you what they are. They should have numbers on them. You're looking for a part number with either 355 or 803 in (these 2 are typical cossie injectors, and both are green). As said, 355s usually run with a 2 bar map sensor, 803s a 3 bar sensor.

The map sensor you've removed is not a Weber-Marelli sensor. Its output voltage may not conform to what the ECU has been set up for, so may cause running issues. Don't waste any money buying bits trying to get the car to run nicely on a chip you don't know the spec of. Either buy another chip and the associated parts and when it's running get it checked over, or get the car to a tuner.

 

right defo 4 803's in there,when running on the old map sensor the injector duration was 10 ms when the pipe was disconnected then went to 30 ms wtih the pipe connected.

 

If they are 803s and you bought a 3bar map, then I would buy a new chip.
cos then you know what spec it is, and also fit a amal valve. Seems pretty strange to me, running the engine without one.

 

Thought they would be, I'm sure that should be a 3 BAR not a 2. You really need to test first with a 3 BAR if you can get hold of one, you will probably find that will solve your problem.

Martin

 

its been running like this with the 3 bar sensor,missfires and does not rev above 4500 with the 2 bar.

 

well said brilliant advice there matey

 

If they really are 803s then my advice is:

1) Get a chip in there that is DEFINATELY for your 803s and 3bar mate or this is going to end up in very expensive tears. The fact the tuner who fitted that chip didn't even want to put his name to it is worrying at best!

2) Get the amal fitted and wired in so ECU has some boost control and the wastegate pressure can be dropped. (have you checked it?)

3) Change the pipes on your control signal routes and bin that soft clear rubbish before it costs you an engine build.

4) Find out what the fuel pressure is as someone has messed with it. Ideally just fit new.

5) Change that fuel filter immediately.

4) Get a heatshield on that turbo before the whole car goes up in flames. And No, I am not exagerating...

These are only the things i would do based on the pictures you have shown and your suggestion you cant take it to a pro right now. I would strongly advise that ultimately you let a pro with AFR and datalogging equipment have a real look around and get this thing running right for you, then you just need to keep on top of it.

 

thanks now i know roughly what i need to do!

but no doubt i will have more questions soon!

 

much better now guys, its taken so long due to work.cheers!

 

did you get a new chip for it pal?

 

aye!

 

how far are you from AVA? would prob be a good idea to take it to them for a fueling check

 

i know,but 1 day off a week kinda mucks it up!
if i keep it i will get it someplace to fine tune it.