Renault Clio 93 (Oasis) (Type 1 Petrol), with replacement E-type 1171cc engine of unknown provenance (previous owner).
I took it for an MOT. Emissions not tested because the CAT got extremely hot.
I did the other work. (replaced rear sub-frame/axle, one break pipe and steering gaiters), and bought and fitted a new CAT from PARTCO.
Took it back for a new MOT. All my work fine, except, the lambda and CO wouldn?t both go within limits at the same time. Then they noticed that the exhaust was over hot, and the cat was just glowing red!!!!
I was advised that the back box might be blocked?. So I removed, examined and put back the exhaust from the CAT to the tail pipe, no restrictions whatsoever!
Changed Oil and filter
The car seemed to be possibly missing a little, so I checked the plugs and found No.1 was thickly furred with carbon. After cleaning, this quickly returned.
Reading this (excellent) site and others realised that the problem is probably that cylinder 1 is not firing properly, and that excessive un-burnt fuel from there is being ?burnt? in the CAT (its job). Obviously this releases a lot of heat!!!!
Found distributor cover was very messed up so, replaced, plugs, leads, distributor cover, rotor arm, and air filter. AND oxygen sensor (in the exhaust manifold) the old one was rather carboned up. Spark good on all cylinders.
So after less than ten minutes running the CAT still gets red hot. Since it?s not taxed I can?t drive it far? even if I dared with the CAT like that. However the engine seemed to be at or above operating temperature when I tested it.
I tested the compression which came out at: 12.2, 12, 11.5, 11.5, on cyls 1, 2, 3, and 4.
This seems a little high, but I think rules out any major problem with the valves or head! (AM I RIGHT TO THINK THIS???)
I wonder whether a leak in the inlet or exhaust manifold gaskets or similar could cause the computer to inject too much fuel on/for cyl 1. ANY IDEAS????
I haven?t had any (computer) diagnostics done. Might this show up much? (it?s a 93 car). ANY ADVICE on BUYING DIAGNOSTICS (to run on pc) to show codes/ performance/ O2 concentrations etc?????
Spark still good on plug 1, even without cleaning off the carbon.
HELP I?m out of tax and expecting my fine in the post any day, fairly skint, and stuck.
What on earth could cause one cylinder to have a bad mixture and/or fail to fire properly.
I am NO EXPERT, and could have got this a bit wrong. ANY ADVICE / IDEAS welcome? DESPERATELY NEEDED!!!!
Edited by Pugugly on 04/10/2008 at 22:23
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Spark still good on plug 1 even without cleaning off the carbon.
Does it still get sooty, even with the new plugs/leads?
The compression tests show the engine is fine mechanically, so either you have an electrical problem (failing sensor???) or fluid leak (split/dislocated hose or leaking gasket).
Take a good look round at the hosing for splits... Not sure how to check gasket leaks - feel for blowing?
Diagnostics may be a lost cause if the engine management light comes on correctly at ignition and extinguishes when running - and doesn't come on again. If you've noticed no light on running then I doubt the ECU has noticed or recorded anything wrong. Check that the lambda sensor is cycling it's voltage correctly with a multimeter (should be once per second) to make sure it's working.
Do you notice any pinking (a tinny sound from the engine especially under acceleration)? - sounds like 'pink-pink-pink...'.
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Check the inlet path is clear on #1 cyl; also the inlet cam lobe for wear and the injector for correct type, resistance, wiring damage and failure. [Sticking open.]
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Thanks Screwloose for replying. I've read some of your other posts too.
Yes I'll look at the camshaft: lobes and clearences. I haven't had the rocker cover off at all yet. So you think a bad lobe could badly affect the mixture/firing?
The injector being common.... shouldn't any defect there equally affect all cylinders?
Inlet path to no.1. Well yes its obvious... but how could anything get in there to obstruct it? I havent disturbed the throttle housing yet. It looks as if I'll have to take it off and check the manifold from there I guess.
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I was considering the "replacement engine" mentioned - almost anything can happen to a second-hand engine; I've even seen a folded crisp packet blocking a port.
If that cylinder is firing; why is it rich? If this is single-point; [blowed if I can remember which of the E7s were that far back...] then it should get the same fuel mix as all of the others; so maybe it isn't firing?
The compression figures are fine; you've done cap, leads and plugs, so cam lobe is all I can think of.
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Thanks mfarrow for replying.
Yes plug 1 soots up in under 10 mins with all the new leads etc. Others stay clean.
If people think it may do any good I could just replace the exhaust manifold gasket.... assuming the nuts are not seized etc. However I think the Inlet may be more difficult. I'll have to read Haynes. I don't really want to do either if its poinless!!! I agree its hard to figure out if they're leaking.
Fluids?
I don't see what fluids could affect this, apart from a head gasket leak, which I feel the comp test rules out.
Hosing? There isn't really any relevent hosing. The MAP sensor goes straight into the inlet manifold, without a hose. No other hoses seem to affect the inlet or exaust manifolds.
Would diagnostics with engine running show how long the (single) injection solonoid is energised for for each firing? Would it show high O2 in the exhaust manifold as c1 exhausts??? If so it would seem to confirm my guesses. Would that help? Are such details available on cheap software?
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I tend to agree with SL's hypothesis - sticking injector, or injector always switched on.
To check, turn the engine, so it's on the inlet stroke on No 1. This step will also allow you to check the cam.
Turn on the ignition, and by-pass the fuel pump relay to keep the fuel rail pressure up.
With the plug out, look into the cylinder using a small torch. You should see no fuel dripping past the open inlet valve. I suspect you'll see lots cascading in!
If you do see lots of fuel, then, you need to check to see if the injector is being incorrectly switched on, by dodgy wiring, or by a fault in the ECU, or, if the injector is simply mechanically stuck open.
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Hi Everyone,
This is a train of thought I had:
Before I bought all the new plugs points etc, (I hadn't checked the sparks then,) lets immagine there was not an effective spark on No.1.
Perhaps there built up a thick mass of soot/coke in no1.
Now with the new leads etc, there is a good spark, but there remains the mass of soot/coke from earlier, which interferes with the firing (flame path... etc etc) causing incomplete combustion.....
This mass of soot/coke by taking up some of the volume at TDC would logically increase the compression ratio.
IS THIS REASONABLE?????
CAN IT BE CURED (withiout removing the head)?????
I have heard of spraning a water mist into the throttle housing to dislodge carbon buildup. Is this effective? Does one have to be careful of anything?? HAve you ever done it???
Tahnks
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IS THIS REASONABLE?????
No.
You have a fault, and before spending lots of time and money, do some simple, quick, cheap tests, so you don't end up wasting time and money.
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Thanks Number _cruncher. I'll check the injector like you say. I was writing the bit about carbon build-up whils you were writing your comment... I hadn't read yours then.
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Your compressions are fine; for an E7F-708 the pressures are given as 11.5-13.5 bar.
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Well Its the weekend, and I'm back on the car, now an a friend's front drive, and registered SORN.
So bridged the fuel pump relay... no fuel leaking from the injector. Can hear pump running. Still poss that injector is sticky, but certainly not jammed on.
Next checked Valve clearences and Cam lobes. Lobes seem OK, if not perfect... a couple of slightly spotty patches on cyl 1 exhaust, but smooth to the finger.
Clearences mostly over by 4 thou. although No1 is the only one that's correct!!!! Adjusted incorrect ones.
Next... to look for "crisp packets" in inlet manifold. After two careful applications of WD40 lined up for a struggle undoing the nuts for the inlet manifold... and .... hey presto ... some are not even finger tight!!!!! SO THAT COULD MEAN LEAKS spoiling the mixture.
Continuing, undo the nuts and move inlet manifold aside, and find that an old gasket has been reused with lashings of silicon like gasket repair compound.... which has PARTIALLY OBSTRUCTED the inlet to No 1 Cyl. It protudes about 6mm around about 2/3 s of the perimeter.
The only mystery is assuming this is the problem, why did the heat problem and MOT failure only arrise this year??? I guess the terriable distributor cover I replaced earlier was the final critical nail in the coffin.
Well I plan to clean it all up and re assemble with new gasket, and see how she runs. I might replace the exhaust m. gasket while I'm at it too.
Thanks so far.... I'll update you one way or another.
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Sorry for not saying THANKYOU at the time for all the help. Well I replaced the inlet manifold gasket, and exhaust manifold gasket, after cleaning all serfaces etc, and I think I said before already done O2 sensor, plugs, etc etc. Well she ran better than she ever had; slower smoother idle, lower fuel consumption, more power, and went through the MOT OK. And has gone through again in 2009 as well!
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