Help - have been playing with my new BMTecnics diagnostic toy and wonder if anybody knows how they work out the `smoothness' figures. With a warm engine mine have come up as 64(No 1), 71(No 3), 193(No 4) and 260 (No2). No engine errors are reported but I have yet to do a service. Car is a '98 1.9 Z3 auto has got ~62k on clock and runs well. Does anybody know what are reasonable smoothness figures for an engine with this mileage. I notice in Robert T's knowledge base guide his figures were generally lower than mine but he had a known misfire.
Cheers
Colin
INPA `smoothness'
Re: INPA `smoothness'
Afraid I don't yet know the answer to this one, but there are two things I would like to find out. 1) What are the "normal" figures that we should be looking for, and 2) how is "smoothness" measured?
In my case, my car only misfires when cold, and not all the time. It sounds like it might be a sticking tappet/hydraulic lifter, which should improve after an oil change. Once the engine is warmed up it runs smoothly enough.
Cheers R.
In my case, my car only misfires when cold, and not all the time. It sounds like it might be a sticking tappet/hydraulic lifter, which should improve after an oil change. Once the engine is warmed up it runs smoothly enough.
Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Re: INPA `smoothness'
Thanks Robert - I'll ask the same question to a wider audience on Facebook Z3 owners page. There are a few guys (edited) on there who are quite clued up on these matters but you have to filter through the responses. Cheers
Last edited by Jonco on Mon 17 Dec, 2012 13:45, edited 1 time in total.
Re: INPA `smoothness'
I think you'll find that there are more on here.
Cheers R.
Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Re: INPA `smoothness'
I was being polite when I referred to filtering through responses
- Southernboy
- Joined: Thu 07 Oct, 2010 12:39
- Posts: 6437
- Location: Johannesburg
Re: INPA `smoothness'
Rob, I had a similar issue with a sticky lifter. My mechanic suggested this cure. Drive out somewhere where you can push the car to speed somewhat, then, in get it up to around 70mph or so, and put it into 3rd gear and let the clutch out so it revs hard. Apparently oil is delivered in volume to the upper cylinder / head areas under decelaration. I tried it, and it does work. He suggested it would dislodge any little bits of muck that may be causing the lifter to stick. I did it about 18 months ago, and so far it hasn't returned. I do oil changes twice a year -aprox every 4000 km - and this also helps preventing gunge building up. I add injector / valve cleaner to the fuel every 3 or 4 months, and also an "engine flush / cleaner" to the oil before each oil change. The "engine flush /cleaners" I add require either running the car for some 1 -200 kms or idling for 20 minutes before draining...I always drive the car, as this ensures the decelaration which pumps oil into the upper motor area in volume.
Do they work?? Well when I did the intake manifold upgrade from OEM to the M50..I had a look into the inlet ports, and all the valves were as bright as new steel. Not a speck of residue or any other deposits. So I must conclude it works.
Do they work?? Well when I did the intake manifold upgrade from OEM to the M50..I had a look into the inlet ports, and all the valves were as bright as new steel. Not a speck of residue or any other deposits. So I must conclude it works.
Re: INPA `smoothness'
I am no expert in this particular (smoothness aka roughness) test but my rudimentary understanding is that it is a general test on how efficiently each cylinder is working. I understood the scale to be 0 to 1000 with 0 being considered perfection. I’ve seen forum posts from people reporting readings well into the hundreds with no engine running problems or fault codes – I assume therefore that it is a very sensitive, almost academic measurement.
The engine oil is not only a lubricant but also cleans & cools the engine and acts as a hydraulic fluid. As Southernboy suggests it cannot be changed too often. Manufacturers seem to be stretching their suggested service intervals presumably for marketing purposes. In my experience (M44 engine) the car responds very well to frequent oil changes and I’ve cured a sticky valve issue myself with a series of quick succession oil changes.
The engine oil is not only a lubricant but also cleans & cools the engine and acts as a hydraulic fluid. As Southernboy suggests it cannot be changed too often. Manufacturers seem to be stretching their suggested service intervals presumably for marketing purposes. In my experience (M44 engine) the car responds very well to frequent oil changes and I’ve cured a sticky valve issue myself with a series of quick succession oil changes.
Re: INPA `smoothness'
Del,
The scale is 0 t 1000 and shows full green bar at zero. I posted the question on another forum and got a reply from a guy whose business is diagnostics and mapping that the value is not the important factor it is the difference between the readings ( i.e the closer together the better).
The scale is 0 t 1000 and shows full green bar at zero. I posted the question on another forum and got a reply from a guy whose business is diagnostics and mapping that the value is not the important factor it is the difference between the readings ( i.e the closer together the better).