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Discussion Starter #1 (Edited)
Hi, I've recently serviced my 146 1.6 boxer and performance seems to be down on what it used to be. Prior to the servicing the engine ran slightly rough at idle as one of the spark plugs was broken and the cylinder hadn't been firing very well (AFAIK).

I've briefly tried a K&N style air filter and performance seemed OK although I've noticed a slight decline since I started using it. Initially it was definitely more peppy, although now I'm not so sure.

My question is what could I have done wrong during the servicing and could the oil that these filters come with have messed up the MAF readings? Does the boxer engine even have a MAF sensor? I presume that's what the lead that connects to the intake pipe near the throttle body? If not what is this?

When the engine is started up in the morning for the first time the engine idles at around 1500RPM, I've been told this is normal for a petrol car but is this true?

One other thing - occasionally the car lurches forward while accelerating rather than having a smooth pattern, this is typically when I'm doing around 25mph in 2nd gear with 1/4 to 1/2 throttle input, is this normal?

Finally(!), my engine temps look a little low (around 70c), this is driving around in 3rd or 4th gear at 30mph, is this normal in this cold winter air? After driving on the motorway at 60-70mph the top of the engine where the injection takes place was bone-cold to the touch!

Thanks
 

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Aye, if you have injection and a catalyst you will have a MAF. It sounds like the beast could be oiled up from the K&N filter.

Spray some contact cleaner on it (Halfords sell it in a yellow can with a green lid.. or you can use carb/choke or contact points cleaner.. it's the same stuff).

That might sort the idle and the hesitation problem too... but until you get the beast running right those are probably not worth investigating separately, as they all started at the same time.

Tickover should be 11-1200rpm on startup, dropping almost immediately to 8-900rpm..

Ralf S.
 

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The 8v boxer engines don't have a MAF...they have a MAP (Manifold Absolute Pressure) sensor instead which is you won't find a MAF anywhere on your engine ;)
 

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Discussion Starter #4 (Edited)
Thanks guys, think I'll give that sensor a quick clean and refit the original air-box.

Do you think it's worth cleaning out the throttle body or is there potential to damage the gasket given that it's probably the age of the car
 

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Yes.. clean out everything you can see and get a rag into. Just the MAF doodah which looks like a tiny lolipop sticking out into the airflow on a waferpthin and brittle wire is easy to break off if you don't see it.. but apparently you don't have one.

Dunno which gasket you might break.. but if you don't unbolt anything then no gasket will be disturbed.

Anything that plugs into a rubber bung, trumpet or collar can be refitted - those are re-useable. If the weather is cold, heat anything rubber up wih a hairdryer.. it makes them softer and more supple.


Ralf S.
 

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Discussion Starter #6
Right, done that, the car seems to be alright now anyway, I think perhaps I was just getting used to the fury of one of these little engines after a big ol' diesel!

I did try the engine without that sensor connected and it seemed exactly the same as before, is this OK? I presume the ECU defaults the mixture to go slightly rich when the MAF/MAP/whatever it is stops measuring the air density?

One thing I have noticed though is that when I have the heater on the engine temps can drop from a solid 80 to 70, is this something that's to be expected?

I'm probably annoying you all now with my nitpicking! Sorry!
 

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Yes.. the ECU has a default setting which it uses if those intake sensors go AWOL. It'll tend to go rich on mixture, just to keep the engine running.. so re-connect it and job done.

If you turn the fan on, there's more cooling going through the cooling system (it's like giving the beast a temporarily bigger radiator) so the temp will drop when you crank the fan up.. but it should stabilise and go back to the regular working temperature (should be on 80C by the sound of it) if the thermostat is on the case.

From your original post, I'd say change the thermostat.. it sounds like it's not completely sticking open.. but I'm not sure it's working completely okay either.


Ralf S.
 

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Discussion Starter #8 (Edited)
Ahh, I was under the impression that the engine temps would vary depending on conditions, as I tend to drive very lightly the majority of the time, silly me!

Do you know where I can get hold of a thermostat? Is it possible to get a new one? I'm only able to find the 1.6 twinspark ones.

Thanks a lot!
 

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Discussion Starter #9 (Edited)
I think I've located this MAP thing, has GM written on it and is kind of like a square box. Looks pretty much exactly like this - http://www.iapdirect.com/images/T/steve gm map.JPG

edit* just noticed that the tubes connecting from it and to the throttle body don't have hose clips or any sort of securing clip in place - surely if these measure pressure they will need them?
 

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Ahh, I was under the impression that the engine temps would vary depending on conditions, as I tend to drive very lightly the majority of the time, silly me!

Do you know where I can get hold of a thermostat? Is it possible to get a new one? I'm only able to find the 1.6 twinspark ones.

Thanks a lot!
Any regular Motor Factors should be able to get one, even if they won't have one in stock.

The Boxer-engine OE part number is 60591817 - most Factors can cross-reference whatever aftermarket brand they have to the OE part number. Beware anyone selling a 'stat for a 1.6 - 1994-2001 ... ! Boxer was 1994-1996 only.

Aftermarket 'stat is about £16 ... gennoine Alfa one will be around £22. Depends who your local dealer is.. but they should be able to supply one too.


Once your coolant is heated up to 80, driving along normally should keep the temperature around there. If you have the chance to watch the needle, you'll see that the temp' actually dips a bit when the 'stat opens... as colder coolant enters the block/passes the sensor when the 'stat opens (hot coolant goes to the rad').

But it should heat back to 80 again almost immediately.. in normal driving you won't even see the "dip".. it recovers that quickly.

If the temp' plummets to 70 or less on the open road, and stays there, then the stat is definitely knacked. His job is to keep the temperature as close to 80 as possible, at all times. Sure, the temp will dip if you turn the heater on full blast, or drive through a ford/flood etc.. but recovery should be pretty quick.. 20-30 seconds, something like that.

Ralf S.
 

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Discussion Starter #12 (Edited)
Did the cambelt yesterday and the car seems to run very smoothly now, still got the problem with temps not picking up though so I'll definitely be getting a thermostat at some point. Thanks a lot guys.

Edit*

Giallo, just read your post in another thread about doing a cam-belt change, and you say it's necessary to use blocks otherwise the timing won't be correct. My friend and I simply marked the pulleys with a bit of paint and it's definitely lined up as it was previously, and the car seems to run fine. Is there another degree to getting this right or would I know if the timing was out?
 

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You don't use cam locking blocks on a Boxer engine. They are only used on a Twin Spark engine. On the Boxer engine there are special markings on the flywheel and cam cover casings that you use and there is a specific set procedure to follow to get the timing spot on using those markings.
 

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Discussion Starter #14
You don't use cam locking blocks on a Boxer engine. They are only used on a Twin Spark engine. On the Boxer engine there are special markings on the flywheel and cam cover casings that you use and there is a specific set procedure to follow to get the timing spot on using those markings.
But the general idea is to get the markings lined up as they were before, right? I don't wanna have to go back and re-do it! The car seems to run the same, if not better than it did before, so is it safe to presume that the timing is right? Cheers
 

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You're probably OK as you are to be honest. If you think it's running right then maybe you should just leave it. It's much more critical with the Twin Sparks to get the timing spot on (thus the need for the cam locking blocks) otherwise you do actually notice it.

If you do want to double check it though then take a look at this document (second column of page 60 titled "Replacement of the Transmission Control Belts" and ending on the second column of page 62).
 

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The cam-locking tools hold the cam-shaft in the position where the marks line up.

As at least one of the cam lobes is at maximum lift, it's very easy for it just to slip away from the very top (the steepest part) of the cam lobe. The valve springs on the open valves are trying to rotate the cam to a more "closed" position.

Just using the marks is all you need to do.. locks "just" make sure that the timing doesn't move at all while you're doing it. If your beast is running well, then chances are you did it right.

Thermostat: Anything priced around £40 is likely to be a T/Spark one.. so easy to get the correct one.

When you change the stat. flush out all the coolant from the radiatore and put new gloop in there, mixed 50:50. Buy the stuff you mix with water so when you top it up, you can top it up neat (it keeps the strength up, as antifreeze becomes weaker with age, as the alcohol evaporates out).


Ralf S.
 

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Discussion Starter #17
Acceleration is still quite lumpy, it's like the car doesn't know how quickly to accelerate at times. Sometimes it accelerates normally though, so it's quite intermittent. It couldn't be the lambda sensor could it? The car's only done 45,000 miles.
 

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Aye! Lambda could do it, though MAF (if you had one) also might. I dunno about the different sensors on that fella, unfortunately.. :D

Ralf S.
 

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Discussion Starter #19
Would performance be REALLY bad if one of the sensors wasn't working or was off? It's not terrible, but it can splutter a bit under acceleration. Let me put it this way.. it's not slower than a 1.7 diesel Vauxhall Astra :D
 

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Lambda usually causes the idle to be lumpy and for the engine to "hunt".. the rpm won't settle.. just fluctuate between 800 and 1500.. maybe almost stalling then catching again. It might affect the car when it's pulling away but once you're past 1500rpm or thereabouts the engine runs fairly normally... just you get a lot more fuel consumption (if you have a shiny chrome exhaust pipe you'll see a lot more soot on it).

If the car has a "spliced in" replacement lambda (new probe part but with short wires which you have to connect to your existing wiring and connector block) then it may be worth checking the connections.. even if you have to cut them out and re-do them. You'll need reeeeeally fine connectors... the wires are wafer thin.. so it's easy for the connection to go awry. Personally I prefer the lambdas with all the wiring and the block connector attached.. they're a bit dearer but I never had any trouble with them.

I'd have a look elsewhere too.. It may be worth cleaning and WD40'ing the TDC sensor connections, anything to do with the coils, HT leads and plug connections as it sounds like it's just an odd misfire for some reason rather than a fundamental problem.

The sensors usually adjust the ignition to the optimum, rather than completely controlling it. if a sensor is missing (apart from the throttle position sensor) the car runs at it's default settings for that parameter. The fuel consumption and performance might be a bit off but generally the car will still run.

Ralf S.
 
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