460SEi Posted March 26, 2008 Share Posted March 26, 2008 Hi all, I've just joined this excellent forum and I'm amazed at the amount of knowledge on here I'm hoping some of you on here might be able to shed some light on my little starting problem. I'm currently running a Defender 90 with a 4.6 V8 installed running a distributor and hotwire injection system. It's also got a chip in the ECU from a well known and respected tuner. I've just replaced the engine with a brand new 4.6 along with new heads, cam, rocker gear and generally overhauled everything. Magnecor leads and various other nice bits along with a full custom stainless exhaust and 4 branch headers. The problem I have at the moment is it seems to be running ridiculously rich from cold; sooty deposits on the wall and exhaust tips and it's got a little stutter for a few seconds when revved but it clears very quickly and then seems to run fine. It only happens from cold and is worse when left overnight. I've been through most of the fuel injection checklist including changing CTS just for fun and everything checks out ok as far as I can tell. The only thing left I think is to check for leaky injectors and/or dodgy fuel pump. Fuel filter is new and all fuel pipe is stainless braided stuff and appears to be free from chokes or blockages. It's been off the road for so long now as I've been attending to not only the new engine but also all the other little bits and pieces that I'd been putting off that I'm dredding taking it to pieces again to check the injectors so I thought I'd ask on here first in case any of you might have some other ideas or can confirm that the injectors are a likely candidate. I'm unsure of the age of the injectors but they've done at least 70k miles before the last 4.6 blew up; still suspect rubbish LPG install which I've since removed!! Any help or advice would be much appreciated. TIA Quote Link to comment Share on other sites More sharing options...
Coastcard Posted March 27, 2008 Share Posted March 27, 2008 I have exactly the same issue, except I am running a flapper system. Runs v. rich until warmed up a bit. Doesn't take that long on a normal day, but in deepest winter very rough for a few minutes. Anyway, I suspect the extra air valve (i.e. not opening fast enough/at all!). IIRC hotwires have a similar device (Air bypass valve?). Have you checked that this is OK? Also check the basics (NKG plugs and genuine cap and rotor) plus get your timing set up correctly. It doesn't have to be far out for clouds of black stuff! Let us know how you get on. There are others on here who are a great help. P.S. If you complete your profile, someone may be round the corner. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 27, 2008 Share Posted March 27, 2008 It is made by Lucas, unless it's bad I'd live with it. There's an air temp sensor in the airflow meter, coolant temp sensor on the engine (make sure you've checked the ECU sensor not the gauge sensor) both of which affect mixture at a given temperature. Fuel pressure regulator or injectors could be at fault but if it runs fine when warm it seems a little unlikely. Extra air valve shouldn't make a difference as it lets in more air after the airflow meter so it's the same as putting your foot on the throttle - the ECU sees the extra air go in and adds fuel (as it thinks) accordingly. If it's on the stock ignition module that could be poor (well, they're all poor, but you know...) but they usually develop heat-related faults not cold-related. Oh and welcome! Quote Link to comment Share on other sites More sharing options...
460SEi Posted March 27, 2008 Author Share Posted March 27, 2008 Thanks for the welcome. I've checked the correct CTS and all is well and I've also had the auxilliary air valve out and cleaned it although if it was faulty at start up I'd have expected it to run lean rather than rich unless I'm mistaken?? I'm also running an RPI ignition amp although I have tried a standard one which made no difference. Very happy with the RPI amp though; would highly recommend. I've also changed the ECU for a standard one and the air flow meter but to no avail. I'm determined to get to the bottom of it as there's definitley something not 100%. The only place left to go I think is the fuel supply system; although my favourite at the moment is slightly leaking injectors. Seems like they may be dripping a little bit of fuel into the chambers when sitting for a period of time causing the rich running at start up until the plugs have cleared. I'm just not sure how troublesome these injectors can be. Interestingly; when I started it from cold today it seemed much better although there was a slightly dark cloud from the exhaust when revved a little after initial start up which was obviously fuel and then as usual it all cleared to leave a lovely TVR-esque growl from the stainless pipes. Any thoughts?? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 27, 2008 Share Posted March 27, 2008 A standard hotwire ECU isn't going to fuel that properly anyway so I wouldn't count that as a great diagnostic for running-related issues. Is the "chipped" ECU specifically tuned to your vehicle or ? as that could well be the culprit. Does the system run lambda sensors or not? Injectors rarely go faulty unless they've been sat for ages, sometimes a sharp tap with a percussive maintenance tool can free them up, running Redex cleaner through the system is also worth a go. Quote Link to comment Share on other sites More sharing options...
460SEi Posted March 27, 2008 Author Share Posted March 27, 2008 The ECU is specifically chipped for this engine so I'm quietly confident it is sound. The car has been off the road for over a year now and has just fired into life for the first time over the last couple of weeks. I would suspect with the injectors lying idle for so long they may be at fault?? I might muster the motivation this weekend and start removing the plenum and check the injectors/fuel rail and see what transpires. It's a thought ripping it to bits again after just getting it running With hindsight I should have paid more attention to the injectors; everything else has been either replaced or meticulously refurbished and cleaned and painted and installed with all new stainless bolts, nuts, washers. Here's hoping it's a couple of leaky injectors. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 27, 2008 Share Posted March 27, 2008 You don't need to remove the plenum to get to the injectors, just unbolt the fuel rail (assuming it's the clamp-down-injectors flavour not the old hose-barb flapper flavour) lift it a bit and you can pull the injectors out. Cleaning & flow testing could be the best option as there's no guarantee a replacement set will all be within spec anyway. Quote Link to comment Share on other sites More sharing options...
460SEi Posted March 28, 2008 Author Share Posted March 28, 2008 It is the clamp down type. I was remembering I'd have to remove the plenum to get the fuel rail out so I could check the injectors in situ and pressured up so I'd be able to see any leaks. I've found a place locally that will clean and test the injectors so I think I'll just remove them all and get them checked later today. Fingers crossed. Quote Link to comment Share on other sites More sharing options...
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