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newbie with an overfueling mk1

Just been reading the Omex 710 manual and wiring diagrams ... A very comprehensive ECU which looks fully stand-alone to me ... Maybe it is not actually possible to disconnect it then as it is probably not classed as a piggy-back ECU in the normal sense.

If the OMEX is controlling everything to do with fuelling and timing and you have eliminated any compression issues and fixed the timig, then yes checking all enginer sensors for operation, correct installation and calibration and wiring would be a good move. The manual can be downloaded and shows all the pin-outs for each sensor so GDI could check to make sure the ECU is receiving the signals it requires :-) The OMEX also has data logging so GDI should be able to do some of that and check to make sure all the sensors are working correctly and are calibrated.

Martin
 
thanks for all that. just about made sense of it all and im sure as scott from SG has been keeping an eye on this thread he may use this info if the car ends up with him.

ive not long been off the phone to GDI andy is away until monday so all was a little vague.

basically, the boroscope has detected det and rollover on the pistons. and poss a couple of bent valves. i suggested there must be bore damage but apparently the boroscope is not the tool for finding bore damage. ive been assured that whatever the weather a rebuild of the engine is whats needed. it may not be the solution to the prob but is needed. i suggested a leak down test to see if the compression rings had gone but as andy is away theyre not going to do it, i never saw any type of black smoke indicating knackered rings.

i think the car will either end up with scott or the fella who built it by the end of the month to get their opinions.

if a rebuild is needed can people give me an idea on costs of the following.

all bearings and seals
head gaskets
cambelt
valves
forged pistons.

if the above is too pricey i will be putting a standard engine back in it so price of one of those please.

am really hoping it doesnt need a rebuild but if needs must. preferably down the forged route. currently just finishing off my williams turbo, running forged low comp pistons! bit of a sucker for fast and unreliable renaults!!!!

dont think ive ever been this stressed out as i have so many options to figure out but no endless pit of cash. i would like to state that this car will be fixed properly with no cut corners, although as mine and my missus plans in the not so far future mean we cannot have a 2 seater car! the car will more than likely regrettably be up for sale when fixed with a fresh bill of health. :(
 
Sounds like you are well on your way and know your stuff too.

The timing being mis-aligned could have caused valve damage if the Vee is an interference engine, I assume it is, this could easily result in poor compression from 1 bank of cylinders. This may be the issue you never know - in which case some top-end work may resolve the issues. IMHO this would clearly be the best thing to determine first. Taking the heads off will tell you what you need to know I would say.

Ring damage wouldn't necessarily generate black smoke as you would get piston blow-by into the crankcase and a lumpy idle. You could try something, which you may not have done, which is to remove the oil filler cap and see if there is excessive positive pressure or oil smoke out the filler - this is a dead give-away of broken ring lands or compression rings. Bore damage is not always a given with cracked rings but scoring can occur though. Were any of the spark plugs melted at all when you took em out ?

The OMEX has an input for a knock-sensor so I assume it has one ? This is pretty essential though on forced induction cars to allow the ECU to adjust timing under detonation conditions. It is easy for people to say you should tune out detonation but it is often a fact of life with conversions and high inlet temperatures. Water injection is often used to mitigate this but as you say a low pressure conversion may have been done without the expectation of detonation.

A slightly heath robinson way of reducing compression ratios without changing pistons is to use a sandwich plate between the heads and block - food for thought maybe. It all basically boils down to reducing inlet temperature as you know by whatever means available - some are more paletable than others. Don't forget forged pistons only offer a higher resistance/tolerance to detonation but of course do not prevent it, so if this does turn out to be the cause of any damage, a forged rebuild will not resolve the root cause.

Good luck.

Martin
 
after further talks with GDI it could well be the mapping that wasnt great and det has occured damaging pistons etc, timing out worries me tho but im assured theres def engine damage. it had never had a decent motorway run since it was converted ive just found out and a 290 mile ride home could have seen it overboost for a long period of time (my thoughts not GDI)

i think its gonna have the heads removed 2mro to check extent of damage and if requires a rebuild i have a new engine lined up to put in it, a pace chargecooler (which is intended for the williams :evil: ) to sort them inlet temps out and a remap with a safe boost limit.

seems to be the answer at the mo.

lewis
 
one last question

is the omex 710 a cheap ecu and can it read boost properly????????????????????? ive been told i need to scrap it and get a kms.

as this is my latest info from a company who claim to have built a twin turbo v6 who are in dover, kent.
 
Yes heads off - reckon that will tell you ...

I concur that a long run and even a few squirts of boost could have done it if the mapping hasn't taken into account all operating conditions or the mixture is lean at high load and revs.

A charecooler will help, as perhaps would water injection and lowering the compression with a sandwich plate or perhaps some light head work to remove some metal ... And also knock sensor and ignition retard - which the OMEX does I think.

Good luck with the diagnosis ...

Martin
 
sam001":2fzqwl3s said:
one last question

is the omex 710 a cheap ecu and can it read boost properly????????????????????? ive been told i need to scrap it and get a kms.

as this is my latest info from a company who claim to have built a twin turbo v6 who are in dover, kent.

I have not done any engine mapping personally so only offer the following as what I have read or observed - I am sure others can comment more informatively than me.

OMEX isn't an ECU which I have seen banded about much. The OMEX specifications and manual do look pretty good but guess you would need to take a look on the net or maybe speak to OMEX themselves or some tuning companies that use them. If anything it seems to be pitched at DIY or more simplified tuning/mapping which, although tempting, can be dangerous I guess because engine mapping isn't as easy as sitting with a laptop and keying numbers into a spreadsheet which is what it can look like sometimes.

The ECU which people rate in most forums is the MOTEC, I know of friends that have used DTA and Autronic and also HKS but the MOTEC seems to be the boy ... At the end of the day though, everything I read and hear tells me it is the skill and quality of the mapping and the mappers experience which is the key and not necessarily the ECU - which after all is just a simple computer with a few sensors and actuators.

Martin
 
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