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Post by thecurleyone on Oct 30, 2015 16:15:07 GMT 1
Hi all Been a while since I posted on here, but I frequently visit to see what is going on. Have a problem vehicle currently. BMW 318 1990 E30 twin cam manual transmission. Runs poorly when cold, idle a bit rough but when revs raised even with foot flat to the floor revs peak around 3000rpm with popping, banging and spitting back! When thoroughly warmed up it is not too bad although not perfect. Customer has recently had engine rebuilt (not by us) including high lift Piper performance camshaft! Scanner shows one fault code, camshaft sensor fault. With oscilloscope, wave form from cam sensor looks good. Thought I'd try scoping cam and crank sensors together and this is the image we get! Attachment DeletedI assume that cam signal should coincide with crank signal missing tooth spot, but according to picture cam sensor seems a bit early. Long story short, is the valve timing wrong or am I barking up the wrong tree!! Many thanks for reading |
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Post by rhyds on Oct 30, 2015 16:20:42 GMT 1
Do the performance cams have vernier/adjustable pulleys?
Personally, I'd point the lad either back to the original engine builder or to a proper performance tuning place with a rolling road to set it all up, as the standard ECU might not have the range or ability to make up for the performance cams.
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Post by thecurleyone on Oct 30, 2015 16:35:23 GMT 1
Do the performance cams have vernier/adjustable pulleys? Personally, I'd point the lad either back to the original engine builder or to a proper performance tuning place with a rolling road to set it all up, as the standard ECU might not have the range or ability to make up for the performance cams. Crikey, fast reply! I did ask about pulleys, apparently not vernier, standard bolt on (3 bolt in triangle formation he thinks) As far as I know the owner assembled the engine himself, just had machining work done as necessary. I too did think about the ECU being unable to cope with 'hot' cams, although Piper did not tell customer car would need remapping etc as they are fast road, not too hot! Again according to customer the cams are the only modification to the engine although I have spotted a performance exhaust system and air filter. Any opinion on the cam and crank sensor waveforms, showing valve timing issue maybe. Have thought myself it could well be a job for a remapper/rolling road guru. Thanks |
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Post by rhyds on Oct 30, 2015 16:58:15 GMT 1
In that case start with the basics. Check its all timed up properly and that the cams (or pulleys) haven't been installed wrongly
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Post by thecurleyone on Oct 30, 2015 20:01:06 GMT 1
Mmmm...
Have been doing a bit of looking online. I think the waveform I have looks as though it could be correct!
Will see if I can find any more information over the weekend.
If anyone has any information/opinion on my waveform I'd be delighted to hear from you.
Have given the vehicle a good check for air leaks with smoke machine and all is airtight.
One thing I have thought of to do which I have not as yet is to connect up the vacuum gauge to inlet manifold, as incorrect valve timing will show poor vacuum, another job for Monday.
Thanks.
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Post by Rhubarb on Oct 31, 2015 0:18:33 GMT 1
Check the wiring and plug to the air flow meter  |
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Post by thecurleyone on Oct 31, 2015 11:54:54 GMT 1
Check the wiring and plug to the air flow meter Thanks for reply, owner has already tried another airflow meter and I've tried it on both, including popping the top off one of them and adjusting the mixture screw and 'wiper board' on top. Older style mechanical/electrical air flow meter!!! Will have a second better look at wiring/plug, can't remember if I checked too thoroughly. |
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Post by Deleted on Oct 31, 2015 13:31:11 GMT 1
With this age what was the cam code description ? does it come back ? can you get any thing other than codes in your scanner ? if the timing wrong they are hard to start !!
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Post by thecurleyone on Oct 31, 2015 23:46:32 GMT 1
With this age what was the cam code description ? does it come back ? can you get any thing other than codes in your scanner ? if the timing wrong they are hard to start !! Hi. Code comes back after a while having been cleared. Can't remember exact code description without being back at work, it's very general one though, just says cam sensor I think. Will have to check. Starts OK ish, but not as good as I'd expect, bit rattly too! Scanner does live data, bit minimal though as older car, live data looks OK. Could still be a red herring, no air leaks with smoke machine and fuel pressure OK. Must put vacuum gauge on it when back at work and write down fault code... |
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Post by Deleted on Nov 1, 2015 18:52:12 GMT 1
With this age what was the cam code description ? does it come back ? can you get any thing other than codes in your scanner ? if the timing wrong they are hard to start !! Hi. Code comes back after a while having been cleared. Can't remember exact code description without being back at work, it's very general one though, just says cam sensor I think. Will have to check. Starts OK ish, but not as good as I'd expect, bit rattly too! Scanner does live data, bit minimal though as older car, live data looks OK. Could still be a red herring, no air leaks with smoke machine and fuel pressure OK. Must put vacuum gauge on it when back at work and write down fault code... Can you graph the injector on time when the car is under load with that fancy vantage scope !.? |
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Post by thecurleyone on Nov 1, 2015 20:14:44 GMT 1
Hi. Code comes back after a while having been cleared. Can't remember exact code description without being back at work, it's very general one though, just says cam sensor I think. Will have to check. Starts OK ish, but not as good as I'd expect, bit rattly too! Scanner does live data, bit minimal though as older car, live data looks OK. Could still be a red herring, no air leaks with smoke machine and fuel pressure OK. Must put vacuum gauge on it when back at work and write down fault code... Can you graph the injector on time when the car is under load with that fancy vantage scope !.? I'll see what I can do, there may be live data for injector duration, can't remember how much live data is available. |
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Post by Deleted on Nov 1, 2015 22:03:38 GMT 1
Can you graph the injector on time when the car is under load with that fancy vantage scope !.? I'll see what I can do, there may be live data for injector duration, can't remember how much live data is available. No dont use scan data far too slow, use the graphing meter in your scope ,it will have selection for all on time measure as well as duty. |
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Post by thecurleyone on Nov 1, 2015 23:20:41 GMT 1
I'll see what I can do, there may be live data for injector duration, can't remember how much live data is available. No dont use scan data far too slow, use the graphing meter in your scope ,it will have selection for all on time measure as well as duty. Ok, will try that. What is the thinking with checking duration, too short causing under fuelling and hence poor running, popping and banging etc. I did check emissions, admittedly only stationery at idle and fast idle, not rich certainly but not really weak. Thanks |
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Post by upkeep on Nov 2, 2015 18:15:59 GMT 1
Do you know if this was a pre-existing fault before the engine rebuild?
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Post by thecurleyone on Nov 3, 2015 9:05:43 GMT 1
Do you know if this was a pre-existing fault before the engine rebuild? Apparently it was fine before.... |
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