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Help with problem


Mike6

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Mike, to be brutally frank, it's difficult to get clear answers from you. I don't know for sure how the car is behaving, or what's been reliably checked, but I'll throw this in for consideration: is your turbo hose collapsing?

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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. Yes I am stubborn and dont like the idea of handing my car to someone else particularly as I dont know anyone trustworthy enough near me - I have seen jobs so called professionals have done!.

Mike if you are now selling it surely it wouldn't hurt to let someone look at it and maybe solve your problem and then the car would surely be worth a bit more than you are asking for it

hindsight: the science that is never wrong

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Tickover rock steady not missing a beat but as throttle moves up to 3500 rpm engine not happy at all and started backfiring and stumbling but as soon as throttle released back to nice smooth tickover.

Nothing to loose so imagine next step is to remove cam covers and see if there is any evidence of problems there.

 

Hang on, this is not the same as before. Are you now saying the problem happens when the car is stationary and the engine is simply revved? Before you said it was only showing up under load.

 

If it happens when stationary this should be easy to find. First thing: when the misfire happens does the timing light still fire properly and can you try triggering the timing light from each of the 4 plug leads in turn to check all of them.

 

If the timing light stops firing one possibility is the polarity of the pickup coil was originally correct and now might be incorrect so when the timing advances to full advance its firing when the rotor arm is out of contact with the distributor cap contacts.

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Hello Mike

 

Rather late to this one but...

 

My experience with this sort of problem is that it is very easy to look too hard. My dad always used to say "well it burns fuel with a spark. If either of those is missing then it ain't gonna work properly"

 

A very wise man my dad :-)

 

You have to exclude what you have looked at, played with, changed, rebuilt, analysed. In your case it's the carbs, the distributor, probably the coil, pick ups yadda yadda. What haven't you looked at?

 

I will give you an example. My lad has an Aprilia 125 two stroke bike. He left it standing for a fair time. Came to start it up, which it did. It happily revved stationary. Sounded fine. Yet when he came to try and pull away, the bloody thing died on him. Every time. He repeated the failure until the battery went flat. Under load it wasn't having any of it. Sound familiar?

 

I know a fair bit about cars and bikes but didn't offer to help as he doesn't have a manual. He had a play around, ignition all looked good, fuel system fine. He gave up and took it to our local specialist bike spanner man.

 

He changed the spark plug. Instant fix.

 

Just saying like...

I tempted fate...now my Esprit V8 IS in bits...(sob)

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Just to recap as I agree that this is getting pathetic. 

 

Car was running fine when I put her in the garage for a few weeks to change the front end rad hoses and then when I took her out on the road I fluffed a gear change at about 3000rpm and went into 2nd gear. Car let out an almighty backfire sound which seemed to come from engine rather than exhaust. I lost all power and car juddered back home basically on tickover refusing to accelerate. 

I fluffed around trying to find what was wrong including cleaning the carb jets and checking timing but just couldnt solve it. Car would start and tickover and gently revved ok but as soon as it hit the road it just died on accelaration, backfired and got me back with minimal revs. I called in an autoelectrian who spent hours remaking electrical joints and testing voltages etc. The only thing he could think of was the dissy itself under load

I had previously had a problem with the dissy pickup and had replaced it with new part from SJ Sportscars. I spoke with Pete at PNM and he said there were a lot of dodgy pickups about and that he could recon everything. So I sent him the dizzy for a full recon. I also purchased from him new rotor cap, arm, leads and plugs although there didnt appear anything wrong with the old ones - only about a year old. It was during reassemply I discovered autoelectrician must have reversed joints going to AB14. Since then I have been trying all the helpful suggestions including the one about disconnecting vacuum pipes from dissy and checking timing marks with strobe at about 3500rpm. It was only yesterday that I discovered that when revs approach this that engine starts hesitating and dropping revs and backfiring. 

Turbo hose is not that good but hasnt collapsed. Timing light still flashes at these revs on bore 1 but havent tried on other plugs (will give that a go).

I would welcome anyone having a look for me and will lay on food etc if there are any takers.

i

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  • Gold FFM

But does the hose collapse when you rev the engine?

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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Have you checked the fuel, will take 5 mins?

88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

Evora NA

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Not checked fuel yet a bit busy at the mo . Exhaust looks ok, its not old, is stainless steel doesnt have the cat etc so am not sure how to check how it is internally other than stripping down which isnt an easy task. I can see where you are coming from though so can do this when I get back from hols if you think it the next step.

Really appreciate all the help I am getting

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Not yet had time to check fuel. I know where you are coming from with restricted exhaust, its not that old, is stainless steel with no cat etc and outwardly looks fine. Not sure how to check the internals easily but can strip down and ask kwikfit to check when I get back from hols if you think that the best next step

 

Thanks for all the help.

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Dave

 

You are 100% on the button. I hate to be beaten but this is just getting me down. I have asked Bibs to pull my ad as I will cry like a baby if I sell it.


I have checked cam timing over and over - its spot on. Havent yet pulled the cam covers to see if anying is amiss but along the blocked exhaust will give these a try although exhaust check will not be a 10 minute job.

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I fluffed a gear change at about 3000rpm and went into 2nd gear. Car let out an almighty backfire sound which seemed to come from engine rather than exhaust. I lost all power and car juddered back home basically on tickover refusing to accelerate. I

 

 Hit the rev limiter, which has screwed something up?

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Mark from Stock Coachworks called before I could pull ad. He agreed that I should next look at exhaust blockage or bent/damaged valves and then pull the carbs and send to PNM for refurb. If I do decide in the end to sell he asked me to give him a call. Sounds a really nice friendly chap.


Rev limiter has been disconnected for a while now but good thought.

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My guess is fuel starvation

Often gives appearance of timing/ignition problems. I had a motorbike with a rusty tank-which blocked the filter. So it ran fine on the drive, but coughed an spluttered under load.

very frustrating though...

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Yep I think fuel too. Backfire through the carbs could also have caused inlet manifold gasket failure or the MISAB (Sandwich between Carbs and inlet manifold) plate seals to be unseated and leaking air in under load. 

 

Does the engine sound smooth and rev cleanly while standing, not lumpy?

 

Good Luck

 

Regards Mike 

Edited by G_Reaper2
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Its quite easy to tell fuel starvation from a misfire.

 

If there is a lot of loud popping and banging from the exhaust its a misfire. If uneven sounding and revs varying its fuel starvation.

 

Has a compression test been done? If this is OK there is nothing really to be gained by removing the cam covers.

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My guess is fuel starvation

Often gives appearance of timing/ignition problems. I had a motorbike with a rusty tank-which blocked the filter. So it ran fine on the drive, but coughed an spluttered under load.

very frustrating though...

Also, if it idles *perfectly*, bear in mind carbs supply the idling petrol through one hole, and the needles move in another to provide petrol when moving.

(and apologies if this is basic, or already covered!)

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Was all perfectly fine  until the fluffed gear change and then not fine immediately after?  I cant give you an answer but it might allow us to rule out certain things things that don't have any connection.   Are we talking going up 3-4 but going 3-2 from highish revs by mistake.  Is there a difference in the sound at tickover or any mechanical nasty noises?

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If your fluffed gearchange over revved it...then I reckon the cambelt has slipped a tooth or two. Get the flywheel to TDC with the valves closed on no.1 cylinder and check the timing marks point to each other on the cam pulleys. Then do it AGAIN...I'd bet the cam timing is wrong; I had exactly the same thing on mine...no power to speak of at medium to high rpm. Like an idiot, I carried on driving it until it slipped another tooth and bent all the inlet valves!! Be VERY CAREFUL...it's easy to think it's OK when it isn't. Check the timing marks on the crankshaft pulley against those on the flywheel, too..... This fits in with the situation you describe.  

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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As sure as I can be that it has not jumped a tooth and have checked and rechecked cam timing and static ignition timing and with strobe and nothing wrong. But will check again along with cam cover removed  plus the earlier suggestions.

 

Have now pulled ad but wow did it generate interest!!

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