Vvv8 Posted May 19, 2022 Share Posted May 19, 2022 Hi guy glad to be here but I need help I have a rover v8 classic in my landy and I'm have trouble with it It will drop revs and picks up again then if you stop at a junction it will stall, but sometimes when its restarted it will be fine or it will switch while ticking over and run nice when it messes around it runs rough, I have gone through all the normal thing can you wise folk help Paul Quote Link to comment Share on other sites More sharing options...
Escape Posted May 19, 2022 Share Posted May 19, 2022 We'll need a bit more info to be able to give accurate help. What year is your Classic? That will determine if it's on carbs, flapper or hotwire EFI. Did the problem occur all of a sudden or become worse over time? Anything recently changed or done? First thing to look at when a petrol engine is running poorly is ignition. The Rover V8 will tolerate a lot and continue running, but not as well as it should. You say you've gone through all the normal things, please elaborate. Did you check fuel, ignition, timing, compression, ... ? Filip Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted May 20, 2022 Author Share Posted May 20, 2022 Sorry I got this engine of a guy who had it on carbs but changed over to efi flapper I'm told its late 80s the alternator is on the right look from the front I have changed fuel tank for new new pump injectors regulator alternator water pump plugs leads I have order new distributor coil and cap etc but the cap is new on it I also check compression and changed head gaskets The problem has been there since I got it running sometimes it just switches over and runs fine when switches over again thank you for all your help I have checked timing with gun a have checked for fuel leaks and vacuum leaks as well I have change sensors and got a injector checker all good Quote Link to comment Share on other sites More sharing options...
Escape Posted May 21, 2022 Share Posted May 21, 2022 You seem to have checked or changed all the likely culprits... My first call for rough running is always ignition, but you seem to have that covered. Only thing left I can think of is the MAF. If you can get hold of a known good one, try swapping it. If that cures it, hold on to it 'cause there hard to find these days! Good luck and keep us posted, Filip Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted May 21, 2022 Author Share Posted May 21, 2022 Fingers crossed and thank you Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted May 21, 2022 Author Share Posted May 21, 2022 I have looked into this more and more and found I'm an extra air valve missing the plug is there for it I have now plumb this in and seem to have sorted it out but this engine always come back to bite me also anyone know the tap and dye size for the for the extra air valve hose were it connects to the plenum as I only had a small bore nipple to screw in once again thank you so much for the help Quote Link to comment Share on other sites More sharing options...
Escape Posted May 21, 2022 Share Posted May 21, 2022 The extra air valve is used mostly for cold starts and cold idle. If it's not there you might have to keep the revs up yourself to prevent stalling. Once a bit up to temperature it shouldn't matter. But it is possible the idle air bypass screw is set too low, not allowing enough air in to keep the engine running at idle. A bit strange that you say sometimes it does run fine. Quote Link to comment Share on other sites More sharing options...
smallfry Posted May 22, 2022 Share Posted May 22, 2022 I would also have a look at the power resistor for the injectors. There may be a dry joint or semi break inside, which could cause your problem. Hard to diagnose by just putting a meter on it as its intermittent. From memory I think each circuit is 60 ohms ? Only real way is to try a substitute. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 23, 2022 Share Posted May 23, 2022 On 5/22/2022 at 9:26 AM, smallfry said: From memory I think each circuit is 60 ohms ? The low impedance injectors are about 2.something ohms each so each bank plus the power resistor is not many ohms - certainly under 10 I think. Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted May 31, 2022 Author Share Posted May 31, 2022 Hi guys I now have a power resistor to try on thursday I will keep you up dated as this problem is driving me nuts and also if I (we) can solve it it could help others once again thank you for all your help Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted June 2, 2022 Author Share Posted June 2, 2022 Afternoon people well here with an up date I have tried the other power resistor and it is still doing it 😭😭now I'm stuck I think the next port of call is get the ecu tested other than that give up Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 2, 2022 Share Posted June 2, 2022 There's a full step-by-step EFI troubleshooting guide in the technical archive, work through it step by step without skipping any that you "know" are OK. I don't know where you'd get the ECU tested but I'll put money on that being a waste of time & money. Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted June 2, 2022 Share Posted June 2, 2022 5 hours ago, FridgeFreezer said: I don't know where you'd get the ECU tested but I'll put money on that being a waste of time & money Those ECU's do have a relatively common problem, however, it is probably beyond the scope of Joe average to fix. The power transistors (IIRC one for each bank) suffer from dry joints on the board. They are TO3 style and IIRC the emitter pin is the culprit. I had intermittent 4 pot / rough running before I went to MS on a 3.5, and it took me a while to track down the issue. Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted June 3, 2022 Author Share Posted June 3, 2022 I've manned to find a ecu and flapper that someone is selling on a running engine so I have brought that and see what happens keep you all informed Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 3, 2022 Share Posted June 3, 2022 If it is the ECU I'd be happy to take a gander & re-solder any bad joints by return of post as @Bull Bar Cowboy suggests. Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted June 9, 2022 Author Share Posted June 9, 2022 Your a star thank you so much I have just put on another ecu and flapper from black box and guess what ?????????? Its fxxxking still reving up and down 😫😫😫 Silly question or not does efi and carbs run the same cam the guy put this on carbs ran badly due to un match carbs I never changed the cam as it was in new condition Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted June 9, 2022 Share Posted June 9, 2022 Revving up and down when it is supposed to be idling is normally a vacuum leak, I.e inlet manifold, plenum etc. 1 Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted June 9, 2022 Author Share Posted June 9, 2022 Yes that was my first thought but have check for leaks it seem to come and go it will sit there doing it and then it's also like something kicks in and it goes then comes back then goes again Quote Link to comment Share on other sites More sharing options...
smallfry Posted June 9, 2022 Share Posted June 9, 2022 6 hours ago, Vvv8 said: Silly question or not does efi and carbs run the same cam the guy put this on carbs ran badly due to un match carbs I never changed the cam as it was in new condition No. the camshafts are not the same, however, I have run both types on carbs and EFI and vice versa. Difference not really noticable, and it would not cause this problem in any case. Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted June 9, 2022 Author Share Posted June 9, 2022 Thank you I'm starting to grab at straws now 🤣🤣 Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted June 10, 2022 Author Share Posted June 10, 2022 I made a smoke machine and found a vacuum leak I cant believe it I sprayed easy start in these areas and showed 0 leaks its around the plenum which is a pain as it has a new gasket 🤬 But happy at the same time so you can all sit back and say told you so 🤣🤣😂 but seriously guys thank you so much for all the help I will keep you posted but on a lighter note I do have a spare ecu flapper power resistor etc etc etc 3 1 Quote Link to comment Share on other sites More sharing options...
smallfry Posted June 10, 2022 Share Posted June 10, 2022 Glad you have found the problem (hopefully) but i have to say that spraying easy start over a running spark ignition engine really is not a good idea. Might have ended up looking like a scene from Saving Private Ryan ! Quote Link to comment Share on other sites More sharing options...
Vvv8 Posted June 10, 2022 Author Share Posted June 10, 2022 🤣🤣🤣at that point I was at breaking point so ever way I was on a winner 🤣🤣I did have marshmallows at the ready Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 15, 2022 Share Posted June 15, 2022 Glad you found it - honestly flapper is dirt simple as a system there's not much to go wrong or get confused - it doesn't "learn" anything, it doesn't have limp-home modes, etc. it's basically a ZX Spectrum running a very basic carburettor simulation Although I'd still megasquirt it if it was me Quote Link to comment Share on other sites More sharing options...
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