'30mph in 4th? You're asking too much of the engine '
With respect, I disagree, Richard.
Every other car I have driven does this on the flat, with ease, from 1.0 litre petrol, and upwards.
After all, 1200 or so RPM is plenty for any normal roadgoing petrol engine to tootle along at a constant speed with.
My Vectra GSi - 2.5 litre, V6*, and therefore less torquey 'low down' than a four cylinder engine of the same size - will happily pull cleanly and smothly out of mini roundabouts in 3rd gear, from 500-600 RPM, and even my tuned MG Metro many years ago (92 BHP from 1293 CC A-series, with an idle as lumpy as h*ll) would happily do the same trick from about 800 RPM.
Speaking to a friend who until recently owned a 1.6 litre 306 (basically a smaller version of the same engine that my wife's car has), he says that he never had the problem we do. He could drive at 30 MPH in 4th or 5th gear, very happily.
I therefore remain convinced that a minor mechanical or electrical fault exists, especially given what the stutter 'feels' like.
I may try some injector cleaner out of interest, as you suggest, but other than the fault, the car is so sprightly, and with no exhaust smoke at all, or any colour (I followed my wife the 50 miles home), that I don't think they, or the air metering, are at fault.
Most of the car's life has been spent doing 30 mile main road round trips from village to nearest town, so it shouldn't be suffering from short journey disease, though I admit it has probably never really been made to work hard (rev).
I will check tonight (ie in the dark) for signs of plug lead breakdown, but am hoping this might be a well known 306 1.8 characteristic, for which a known solution therefore exists.
If I find something worth sharing, I'll do so here.
Cheers for now,
Steve
* Before I am corrected by a pedant such as myself, I have no idea if it is a 'true' Vee engine, whereby the opposite conrods are attached to the same crankpin!
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No there's definately something wrong, really don't know what. I mistakenly had mine in 4th at 15, yes 15 the other day and it still accelerated reasonably well. At 30 it'll pull fine. Mine's the 1.4i 309 so shouldn't be much different to SJ's 306. Having said which it ran better after a few weeks of ownership, presumably because I thrashed it when I first got it. Its running better still now after a full service with fuel filter change, a couple of tanks of Optimax and some fuel system cleaner - I think its called hotshot or something and it claims to boost power by 10%, not sure about that but it works.
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Just whipped the plug leads off, and found moisture both on the inside of the deeply recessed plug caps, and at the foot of the plug 'well' in the cylinder head, despite the warm sunny weather.
I guess this from lack of use over a long period of time, so will dry everything out, and hold my fingers crossed that it be so simple!
Stay tuned...
/Steve
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Hi Steve,
I think you might have found the problem...
I while ago I test drove two separate Mazda MX3's. The first one started and idled fine, but when putting the engine under any sort of load it stuttered / misfired / went stupid.
The cause? The garage had decided to jetwash/steam clean the engine, leaving BIG pools of water in each spark plug well. The second MX3 I looked wouldn't even idle in the showroom - caused by the same problem.
I suggest you dry out the leccy and spray it with WD40...
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Steve,
I had completely forgotten that I'd had a similar experience, even though I posted it in the forum only a few months ago.
I had pressure washed a Citroen ZX 1.4 engine and let it dry off. Several days later I went on a journey and the engine kept cutting out. The cause was water in the spark plug wells which did no harm until it got hot and evaporated, then condensed on the inside of the spark plug caps. Drying out the spark plug wells cured the problem.
Sorry I didn't think of this sooner. What a wally!
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OK, I stand corrected - I was forgetting you were talking about petrols that are much shorter geared. However, if you're really sad (like me) and know about the specific consumption curve for engines, I expect you'll find that the minimum occurs somewhere around 2000 - 2500 rpm (kg fuel / kW or some such units) and therefore third is a more efficient gear than 4th at 30mph. It also has the advantage of giving you better control over the car.
Richard
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Ooops, then should I not be driving my 1.4 Xsara at 30 in 5th? It seems quite happy, I can actually drive from 25 in 5th if I don't use the throttle too much.
I still get 40mpg even when driven round town. I have just changed my oil at 6000 mile interval using the same synthetic 5W40 stuff as ever, now my car seems to pull better than before at low revs.
8 valve engines do pull better than 16v at lower revs in my opinion.
Ben
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Well, having found the moisture in the spark plug wells and inside the plug caps, as described above, and them out, things are much better, but the engine still stutters to a degree.
Actually, to be more precise now I have driven the car longer (it was very new in our hands when I first wrote), the stutter happens if the car is held at exactly 2000 RPM on a steady throttle, in 3rd, 4th, or 5th gear, but not when under no load in neutral, or in 1st or 2nd gears. It manifest just as a momentary cut, for a split second, every few seconds, but at any other revs, and any other load condition, the engine works perfectly, just as described in the original post. Even being really cruel, and asking the engine to pull on full throttle, up a gentle hill, from tickover in 5th gear, doesn't result in any protest or misbehaving. It just pulls. Cleanly.
Given that investigation could be a needle in a haystack job, and the car is otherwise running well, I think I'll just live with it whilst the car gets some 'real' miles under it's belt, and see what happens.
BFN, and thanks for the suggestions,
Steve
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hello steve
just bought a 1996 306 1.8 litre, and i´m having exactly the same problem.
Did you find the solution?
please write at martin--gomez@hotmail.com
thaks in advance
martin
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