Hi , I've a freshly built g60 engine in my corrado that has a strange problom since installation in the car.basically the engine with not start when warm /hot . Bit of background on engine , Full rebuild with 1.9 bottom end ,head ported ,std size valves ,260 cam . Flowed charger with 68mm pulley. Compression ratio increased to circa 8.5 /1 . New 315cc Bosch injectors , max rpm chip to match all above mods ( supposedly !) So the engine will start instantly when cold albiet a bit rich , but leave it to run for a few mins and shut it off and attempt a restart, no go ! Cranks over but will not catch ,strong smell of fuel out the exhaust so it's getting fuel ,possibly too much maybe ? If I disconnect the fuel rail power socket and crank again the engine will fire up for a couple of seconds, presumably burning off excess fuel left in the combustion chamber , then reconnect the fuel rail power and crank it attempts to catch but ultimately fails to do so . I've checked to far , Check for spark on all 4 plugs ( plugs removed and rested on head ) all ok and firing . Plugs are a bit on the sooty side when removed but cleaned and working ok . Fit new distributor cap and rotor . Plugs are Bosch w6dpo ,I know I should have a cooler plug for this spec, ie w5dpo and are on order but would this cause a non start issue ? I didn't think it would ? Check fuel rail pressure using a guage connected to the port on the end of fuel rail , readings were 2.4 bar running , 3 bar with vac hose to pressure regulator removed , holds pressure also when switched off so I don't think the system is dropping pressure when switched off . Fuel regulator is standard 3bar reg. Now fuel pressure test was done on a cold engine, I'm wondering if heat in engine bay is causing fluctuations with the fuel pressure regulator causing over fuelling ? As mentioned the engine is running very rich at all times and i cannot get it down ? I have Tristan ,s afr meter fitted in the exhaust and afr with warmed up engine at idle is 10.5/11.0 ! Rechecked timing, perfect at 6deg btdc @ 2250rpm and cts unplugged . New genuine blue cts fitted at time of engine build ,I checked ohms across this with hot engine ,it's 260ohm,s it should be a little lower from what I've read so will replace but I don't think this should cause a non start?? Fitted another chip calibrated for green std injectors with 3.5 bar fpr fitted , not much difference overall ,still have the non start . My own thoughts are it's fuel related , 1 . Fuel pressure rising with engine temp causing over fuelling? Will retest this possibility with guage . 2.. injectors oversized , was recommended this size for my build spec by several sources . 3. Injectors not closing instantly or fully when switched off ? The supplier states that they are new with test certificate so should be fine . 4. New chip not calibrated to these injectors ? Full spec given to supplier at at time of order ,car is definitely over fuelling at all times ,warm or hot , disconnecting the cts leans it out a bit a d drives much better when disconnected . Any assistance appreciated.
Wow ,well over a year since i posted this problem, i got logged out of here and could not get back in cos of old mail address inactivated .Anyway sorted now. Just to close this off for future reference it turned out to be the lambda sensor that was causing this overfuelling issue , Fitted a replacement and it immediately run as it should .
