Strange Engine Problem Maybe ECU ???

hello peeps, just about to start to complete my disco 1 project, bodys done now however im at the point to try to sort out a strange problem with the engine but i have absolutley no idea whats wrong

ok its slow, real slow, powerless infact, its a 3.9 v8i with a lpg conversion
it drives exactly the same on petrol and gas
the odd thing is that i can disconect any sensor, lambda , airflow etc and it makes no difference, the car starts and runs exactly the same
i dont understand it at all, now my brother has exactly the same vehicle and his would run circles around mine
also when he had a problem with nhis we narrowed his problem down using my parts which sorted his, i fitted his knackered parts to mine and guess what, it started and ran exactly the same, i dont undersand it

so any help would be appreciated
thanks

Tried with the exhuast unions open ? I have had petrol engines strangled by blocked cats before now . And no , not blocked WITH cats , before someone asks .

loli see what you mean lol, the cats are new exhaust is clear too i cant find a mechanical problem and engines im quite good with lol, this is definatley a management problem, im wondering if it sounds familiar to someone, the basics of it are being able to run the car perfectly with things like the airflow the coolant the lambda sensors idle valve everything disconected, i can get in start it and it will run exactly the same as if they were plugged in, ive never heard of this i would assume that if the idle valve was disconected it wouldnt idle, i dont get an engine management light or any running problems it has a great idle, no misfire no funny noises but its mindnumbingly slow and give it a hill and it really struggles, im wondering if the ecu is fckd and im just lucky that it starts but its lcearly not looking for or using any of the sensors
dunno im stumped

Plug in a tester... the engine management on petrol is OBD compliant so any code reader will do it

Yeah Theres no codes But i didnt expect any either as its very basic system

The diagnostic covers the sensors so if the sensors are unplugged and it doesnt store fault codes IMO you might be spot on suspecting the ECM

actaully yes that makes sense i just have a gut feeling that the ecu is i dunno just stuck frozen whatever you wanna call it and im just lucky in the fact that it does start and run, but i cannot think of anything else to cause that problem
and im assuming its not a comon fault as no one has commented but your goodself lol

Well, I've unplugged various sensors on mine and tested it out, it runs different but still doesn't put the engine light on, so I don't entirely trust the fault code system on mine at least!

Regards your problem, simple stuff like blocked exhaust as above, blocked air filter, collapsed inlet pipe (very common) or bad fuel pressure regulator.

Will it redline on tickover with WOT? That kind of eliminates an air issue but doesn't rule out a fuel problem.

However you say its same on petrol and LPG so that's bizarre too.

Is it over fuelling perhaps? An LPG leak making it super rich?

More info required

...and what i said is based on pure logic cos i dont know much about petrol engine management

ok fuel pressure regualtor replaced no difference, new cats ( yes i paid 600 quid for them lol) and exhaust no difference heads removed de coacked reground valves no difference, changed dizzy replaced cap plugs leads coil no difference , also airflow meter coolant temp sensor both lambda sensors even down to the viscous coupling for the fan has been replaced still no difference, it is a manual too so i would have thought it would have been pretty quick, the constant has been the ability to run the car with everything disconected engine management wise thats the problem, i cure that and im laughing, just dunno what to do, im hoping somone else may have come across this, Difficult to find out because we dont get an engine mamagement light at start up aparently by design so im stumped

oh and the lpg runs exactly the same as the petrol no difference i get about 250 miles to 70 litres of gas or 40 quid in money lol

Is the cam timing out then? Skipped a tooth or similar?

well that was checked when the engine was done but that wouldnt cause the electronics problem, im certain that mechanically it is fine, its something to do with the management system

Have you rechecked the distributor timing by that I mean the gear alignment?

Have you tried borrowing your brother's ECU and plugging it in to see what happens?

Have you checked your ignition timing?

The_Doctor said:

well that was checked when the engine was done but that wouldnt cause the electronics problem, im certain that mechanically it is fine, its something to do with the management system

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I didn't know you had an electronics problem!

yes lol, its the removal of things like the airflow coolant lambda making no difference at all, ive dont abit of reading over the last couple of days and im trying to understand open and closed loop operation, im also going to buy one of these dedicated fault code readers about a hundred quid thats specific for the 14cux ecu and see what that does,

hello guys and gals, just to let you know that my problem did actually turn out to be the ecu, was 1000% better and my god does it shift now, thanks for your replys people

The_Doctor said:

hello guys and gals, just to let you know that my problem did actually turn out to be the ecu, was 1000% better and my god does it shift now, thanks for your replys people

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Always depressing when you hear that I spose cos they are supposedly reliable, but I guess the positive outcome means that dodgy problems in future should not overlook the ECU!